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c44ed5b7 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: remove a use of write_cache_pages() from do_writepages() Use the new writeback_iter() directly instead of indirecting through a callback. [hch@lst.de: ported to the while based iter style] Link: https://lkml.kernel.org/r/20240215063649.2164017-15-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
cdc150b5 |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: add a writeback iterator Refactor the code left in write_cache_pages into an iterator that the file system can call to get the next folio for a writeback operation: struct folio *folio = NULL; while ((folio = writeback_iter(mapping, wbc, folio, &error))) { error = <do per-folio writeback>; } The twist here is that the error value is passed by reference, so that the iterator can restore it when breaking out of the loop. Handling of the magic AOP_WRITEPAGE_ACTIVATE value stays outside the iterator and needs is just kept in the write_cache_pages legacy wrapper. in preparation for eventually killing it off. Heavily based on a for_each* based iterator from Matthew Wilcox. Link: https://lkml.kernel.org/r/20240215063649.2164017-14-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a2cbc136 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: move the folio_prepare_writeback loop out of write_cache_pages() Move the loop for should-we-write-this-folio to writeback_get_folio. [hch@lst.de: fold loop into existing helper instead of a separate one per Jan] Link: https://lkml.kernel.org/r/20240215063649.2164017-13-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e6d0ab87 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: use the folio_batch queue iterator Instead of keeping our own local iterator variable, use the one just added to folio_batch. Link: https://lkml.kernel.org/r/20240215063649.2164017-12-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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807d1fe3 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: simplify the loops in write_cache_pages() Collapse the two nested loops into one. This is needed as a step towards turning this into an iterator. Note that this drops the "index <= end" check in the previous outer loop and just relies on filemap_get_folios_tag() to return 0 entries when index > end. This actually has a subtle implication when end == -1 because then the returned index will be -1 as well and thus if there is page present on index -1, we could be looping indefinitely. But as the comment in filemap_get_folios_tag documents this as already broken anyway we should not worry about it here either. The fix for that would probably a change to the filemap_get_folios_tag() calling convention. [hch@lst.de: update the commit log per Jan] Link: https://lkml.kernel.org/r/20240215063649.2164017-10-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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751e0d55 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: factor writeback_get_batch() out of write_cache_pages() This simple helper will be the basis of the writeback iterator. To make this work, we need to remember the current index and end positions in writeback_control. [hch@lst.de: heavily rebased, add helpers to get the tag and end index, don't keep the end index in struct writeback_control] Link: https://lkml.kernel.org/r/20240215063649.2164017-9-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b1793929 |
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14-Feb-2024 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: factor folio_prepare_writeback() out of write_cache_pages() Reduce write_cache_pages() by about 30 lines; much of it is commentary, but it all bundles nicely into an obvious function. [hch@lst.de: rename should_writeback_folio to folio_prepare_writeback per Jan] Link: https://lkml.kernel.org/r/20240215063649.2164017-8-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f946e0d2 |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: rework the loop termination condition in write_cache_pages Rework the way we deal with the cleanup after the writepage call. First handle the magic AOP_WRITEPAGE_ACTIVATE separately from real error returns to get it out of the way of the actual error handling path. The split the handling on intgrity vs non-integrity branches first, and return early using a goto for the non-ingegrity early loop condition to remove the need for the done and done_index local variables, and for assigning the error to ret when we can just return error directly. Link: https://lkml.kernel.org/r/20240215063649.2164017-7-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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5d899d43 |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: only update ->writeback_index for range_cyclic writeback mapping->writeback_index is only [1] used as the starting point for range_cyclic writeback, so there is no point in updating it for other types of writeback. [1] except for btrfs_defrag_file which does really odd things with mapping->writeback_index. But btrfs doesn't use write_cache_pages at all, so this isn't relevant here. Link: https://lkml.kernel.org/r/20240215063649.2164017-6-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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98103258 |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: also update wbc->nr_to_write on writeback failure When exiting write_cache_pages early due to a non-integrity write failure, wbc->nr_to_write currently doesn't account for the folio we just failed to write. This doesn't matter because the callers always ingore the value on a failure, but moving the update to common code will allow to simplify the code, so do it. Link: https://lkml.kernel.org/r/20240215063649.2164017-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a02829f0 |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: fix done_index when hitting the wbc->nr_to_write When write_cache_pages finishes writing out a folio, it fails to update done_index to account for the number of pages in the folio just written. That means when range_cyclic writeback is restarted, it will be restarted at this folio instead of after it as it should. Fix that by updating done_index before breaking out of the loop. Link: https://lkml.kernel.org/r/20240215063649.2164017-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6768907e |
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14-Feb-2024 |
Christoph Hellwig <hch@lst.de> |
writeback: don't call mapping_set_error on AOP_WRITEPAGE_ACTIVATE Patch series "convert write_cache_pages() to an iterator", v8. This is an evolution of the series Matthew Wilcox originally sent in June 2023, which has changed quite a bit since and now has a while based iterator. This patch (of 14): mapping_set_error should only be called on 0 returns (which it ignores) or a negative error code. writepage_cb ends up being able to call writepage_cb on the magic AOP_WRITEPAGE_ACTIVATE return value from ->writepage which means success but the caller needs to unlock the page. Ignore that and just call mapping_set_error on negative errors. (no fixes tag as this goes back more than 20 years over various renames and refactors so I've given up chasing down the original introduction) Link: https://lkml.kernel.org/r/20240215063649.2164017-1-hch@lst.de Link: https://lkml.kernel.org/r/20240215063649.2164017-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Brian Foster <bfoster@redhat.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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f814bdda |
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23-Jan-2024 |
Jan Kara <jack@suse.cz> |
blk-wbt: Fix detection of dirty-throttled tasks The detection of dirty-throttled tasks in blk-wbt has been subtly broken since its beginning in 2016. Namely if we are doing cgroup writeback and the throttled task is not in the root cgroup, balance_dirty_pages() will set dirty_sleep for the non-root bdi_writeback structure. However blk-wbt checks dirty_sleep only in the root cgroup bdi_writeback structure. Thus detection of recently throttled tasks is not working in this case (we noticed this when we switched to cgroup v2 and suddently writeback was slow). Since blk-wbt has no easy way to get to proper bdi_writeback and furthermore its intention has always been to work on the whole device rather than on individual cgroups, just move the dirty_sleep timestamp from bdi_writeback to backing_dev_info. That fixes the checking for recently throttled task and saves memory for everybody as a bonus. CC: stable@vger.kernel.org Fixes: b57d74aff9ab ("writeback: track if we're sleeping on progress in balance_dirty_pages()") Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240123175826.21452-1-jack@suse.cz [axboe: fixup indentation errors] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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9319b647 |
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18-Jan-2024 |
Zach O'Keefe <zokeefe@google.com> |
mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again (struct dirty_throttle_control *)->thresh is an unsigned long, but is passed as the u32 divisor argument to div_u64(). On architectures where unsigned long is 64 bytes, the argument will be implicitly truncated. Use div64_u64() instead of div_u64() so that the value used in the "is this a safe division" check is the same as the divisor. Also, remove redundant cast of the numerator to u64, as that should happen implicitly. This would be difficult to exploit in memcg domain, given the ratio-based arithmetic domain_drity_limits() uses, but is much easier in global writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g. vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32) Link: https://lkml.kernel.org/r/20240118181954.1415197-1-zokeefe@google.com Fixes: f6789593d5ce ("mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()") Signed-off-by: Zach O'Keefe <zokeefe@google.com> Cc: Maxim Patlasov <MPatlasov@parallels.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b5612c36 |
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08-Nov-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: return void from folio_start_writeback() and related functions Nobody now checks the return value from any of these functions, so add an assertion at the beginning of the function and return void. Link: https://lkml.kernel.org/r/20231108204605.745109-5-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Cc: David Howells <dhowells@redhat.com> Cc: Steve French <sfrench@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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fa151a39 |
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19-Dec-2023 |
Jingbo Xu <jefflexu@linux.alibaba.com> |
mm: fix arithmetic for max_prop_frac when setting max_ratio Since now bdi->max_ratio is part per million, fix the wrong arithmetic for max_prop_frac when setting max_ratio. Otherwise the miscalculated max_prop_frac will affect the incrementing of writeout completion count when max_ratio is not 100%. Link: https://lkml.kernel.org/r/20231219142508.86265-3-jefflexu@linux.alibaba.com Fixes: efc3e6ad53ea ("mm: split off __bdi_set_max_ratio() function") Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e0646b75 |
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19-Dec-2023 |
Jingbo Xu <jefflexu@linux.alibaba.com> |
mm: fix arithmetic for bdi min_ratio Since now bdi->min_ratio is part per million, fix the wrong arithmetic. Otherwise it will fail with -EINVAL when setting a reasonable min_ratio, as it tries to set min_ratio to (min_ratio * BDI_RATIO_SCALE) in percentage unit, which exceeds 100% anyway. # cat /sys/class/bdi/253\:0/min_ratio 0 # cat /sys/class/bdi/253\:0/max_ratio 100 # echo 1 > /sys/class/bdi/253\:0/min_ratio -bash: echo: write error: Invalid argument Link: https://lkml.kernel.org/r/20231219142508.86265-2-jefflexu@linux.alibaba.com Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com> Reported-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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762321da |
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25-Oct-2023 |
Christoph Hellwig <hch@lst.de> |
filemap: add a per-mapping stable writes flag folio_wait_stable waits for writeback to finish before modifying the contents of a folio again, e.g. to support check summing of the data in the block integrity code. Currently this behavior is controlled by the SB_I_STABLE_WRITES flag on the super_block, which means it is uniform for the entire file system. This is wrong for the block device pseudofs which is shared by all block devices, or file systems that can use multiple devices like XFS witht the RT subvolume or btrfs (although btrfs currently reimplements folio_wait_stable anyway). Add a per-address_space AS_STABLE_WRITES flag to control the behavior in a more fine grained way. The existing SB_I_STABLE_WRITES is kept to initialize AS_STABLE_WRITES to the existing default which covers most cases. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20231025141020.192413-2-hch@lst.de Tested-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
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2580d554 |
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04-Oct-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: use folio_xor_flags_has_waiters() in folio_end_writeback() Match how folio_unlock() works by combining the test for PG_waiters with the clearing of PG_writeback. This should have a small performance win, and removes the last user of folio_wake(). Link: https://lkml.kernel.org/r/20231004165317.1061855-18-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7d0795d0 |
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04-Oct-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: make __end_folio_writeback() return void Rather than check the result of test-and-clear, just check that we have the writeback bit set at the start. This wouldn't catch every case, but it's good enough (and enables the next patch). Link: https://lkml.kernel.org/r/20231004165317.1061855-17-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ab428b4c |
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17-Sep-2023 |
Jianguo Bao <roidinev@gmail.com> |
mm/writeback: update filemap_dirty_folio() comment Change to use new address space operation dirty_folio(). Link: https://lkml.kernel.org/r/20230917-trycontrib1-v1-1-db22630b8839@gmail.com Fixes: 6f31a5a261db ("fs: Add aops->dirty_folio") Signed-off-by: Jianguo Bau <roidinev@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ed2da924 |
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28-Jun-2023 |
Christoph Hellwig <hch@lst.de> |
mm: remove folio_account_redirty Fold folio_account_redirty into folio_redirty_for_writepage now that all other users except for the also unused account_page_redirty wrapper are gone. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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8344a3d4 |
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28-Jun-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
writeback: account the number of pages written back nr_to_write is a count of pages, so we need to decrease it by the number of pages in the folio we just wrote, not by 1. Most callers specify either LONG_MAX or 1, so are unaffected, but writeback_sb_inodes() might end up writing 512x as many pages as it asked for. Dave added: : XFS is the only filesystem this would affect, right? AFAIA, nothing : else enables large folios and uses writeback through : write_cache_pages() at this point... : : In which case, I'd be surprised if much difference, if any, gets : noticed by anyone. Link: https://lkml.kernel.org/r/20230628185548.981888-1-willy@infradead.org Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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6c77b607 |
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14-Jun-2023 |
Kefeng Wang <wangkefeng.wang@huawei.com> |
mm: kill lock|unlock_page_memcg() Since commit c7c3dec1c9db ("mm: rmap: remove lock_page_memcg()"), no more user, kill lock_page_memcg() and unlock_page_memcg(). Link: https://lkml.kernel.org/r/20230614143612.62575-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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452a8f40 |
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07-Mar-2023 |
Christoph Hellwig <hch@lst.de> |
mm,jfs: move write_one_page/folio_write_one to jfs The last remaining user of folio_write_one through the write_one_page wrapper is jfs, so move the functionality there and hard code the call to metapage_writepage. Note that the use of the pagecache by the JFS 'metapage' buffer cache is a bit odd, and we could probably do without VM-level dirty tracking at all, but that's a change for another time. Link: https://lkml.kernel.org/r/20230307143125.27778-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com> Cc: Changwei Ge <gechangwei@live.cn> Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: Gang He <ghe@suse.com> Cc: Jan Kara <jack@suse.cz> Cc: Jan Kara via Ocfs2-devel <ocfs2-devel@oss.oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joseph Qi <jiangqi903@gmail.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Jun Piao <piaojun@huawei.com> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
2d683175 |
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07-Mar-2023 |
Christoph Hellwig <hch@lst.de> |
mm,jfs: move write_one_page/folio_write_one to jfs The last remaining user of folio_write_one through the write_one_page wrapper is jfs, so move the functionality there and hard code the call to metapage_writepage. Note that the use of the pagecache by the JFS 'metapage' buffer cache is a bit odd, and we could probably do without VM-level dirty tracking at all, but that's a change for another time. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
d585bdbe |
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26-Jan-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: convert writepage_t callback to pass a folio Patch series "Convert writepage_t to use a folio". More folioisation. I split out the mpage work from everything else because it completely dominated the patch, but some implementations I just converted outright. This patch (of 2): We always write back an entire folio, but that's currently passed as the head page. Convert all filesystems that use write_cache_pages() to expect a folio instead of a page. Link: https://lkml.kernel.org/r/20230126201255.1681189-1-willy@infradead.org Link: https://lkml.kernel.org/r/20230126201255.1681189-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
9cfb816b |
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16-Jan-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/fs: convert inode_attach_wb() to take a folio Patch series "Writeback folio conversions". Remove more calls to compound_head() by passing folios around instead of pages. This patch (of 2): The only caller of inode_attach_wb() which doesn't pass NULL already has a folio, so convert the whole call-chain to take folios. Link: https://lkml.kernel.org/r/20230116192507.2146150-1-willy@infradead.org Link: https://lkml.kernel.org/r/20230116192507.2146150-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
0fff435f |
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04-Jan-2023 |
Vishal Moola (Oracle) <vishal.moola@gmail.com> |
page-writeback: convert write_cache_pages() to use filemap_get_folios_tag() Convert function to use folios throughout. This is in preparation for the removal of find_get_pages_range_tag(). This change removes 8 calls to compound_head(), and the function now supports large folios. Link: https://lkml.kernel.org/r/20230104211448.4804-5-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: Matthew Wilcow (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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e9adcfec |
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03-Jan-2023 |
Mike Kravetz <mike.kravetz@oracle.com> |
mm: remove zap_page_range and create zap_vma_pages zap_page_range was originally designed to unmap pages within an address range that could span multiple vmas. While working on [1], it was discovered that all callers of zap_page_range pass a range entirely within a single vma. In addition, the mmu notification call within zap_page range does not correctly handle ranges that span multiple vmas. When crossing a vma boundary, a new mmu_notifier_range_init/end call pair with the new vma should be made. Instead of fixing zap_page_range, do the following: - Create a new routine zap_vma_pages() that will remove all pages within the passed vma. Most users of zap_page_range pass the entire vma and can use this new routine. - For callers of zap_page_range not passing the entire vma, instead call zap_page_range_single(). - Remove zap_page_range. [1] https://lore.kernel.org/linux-mm/20221114235507.294320-2-mike.kravetz@oracle.com/ Link: https://lkml.kernel.org/r/20230104002732.232573-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Suggested-by: Peter Xu <peterx@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Peter Xu <peterx@redhat.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> [s390] Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
c2ca7a59 |
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29-Dec-2022 |
Christoph Hellwig <hch@lst.de> |
mm: remove generic_writepages Now that all external callers are gone, just fold it into do_writepages. Link: https://lkml.kernel.org/r/20221229161031.391878-7-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
5a9e3474 |
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21-Dec-2022 |
Vishal Moola (Oracle) <vishal.moola@gmail.com> |
mm/swap: convert deactivate_page() to folio_deactivate() Deactivate_page() has already been converted to use folios, this change converts it to take in a folio argument instead of calling page_folio(). It also renames the function folio_deactivate() to be more consistent with other folio functions. [akpm@linux-foundation.org: fix left-over comments, per Yu Zhao] Link: https://lkml.kernel.org/r/20221221180848.20774-5-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
2c44af4f |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_set_min_ratio_no_scale() function This introduces bdi_set_min_ratio_no_scale(). It uses the max granularity for the ratio. This function by the new sysfs knob min_ratio_fine. Link: https://lkml.kernel.org/r/20221119005215.3052436-19-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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4e230b40 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_set_max_ratio_no_scale() function This introduces bdi_set_max_ratio_no_scale(). It uses the max granularity for the ratio. This function by the new sysfs knob max_ratio_fine. Link: https://lkml.kernel.org/r/20221119005215.3052436-16-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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803c9805 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_set_min_bytes() function This introduces the bdi_set_min_bytes() function. The min_bytes function does not store the min_bytes value. Instead it converts the min_bytes value into the corresponding ratio value. Link: https://lkml.kernel.org/r/20221119005215.3052436-13-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8021fb32 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: split off __bdi_set_min_ratio() function This splits off the __bdi_set_min_ratio() function from the bdi_set_min_ratio() function. The __bdi_set_min_ratio() function will also be called from the bdi_set_min_bytes() function, which will be introduced in the next patch. Link: https://lkml.kernel.org/r/20221119005215.3052436-12-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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712c00d6 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_get_min_bytes() function This adds a function to return the specified value for min_bytes. It converts the stored min_ratio of the bdi to the corresponding bytes value. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The returned value can be different than the value when the min_bytes value was set. Link: https://lkml.kernel.org/r/20221119005215.3052436-11-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1bf27e98 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_set_max_bytes() function This introduces the bdi_set_max_bytes() function. The max_bytes function does not store the max_bytes value. Instead it converts the max_bytes value into the corresponding ratio value. Link: https://lkml.kernel.org/r/20221119005215.3052436-8-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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efc3e6ad |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: split off __bdi_set_max_ratio() function This splits off __bdi_set_max_ratio() from bdi_set_max_ratio(). __bdi_set_max_ratio() will also be called from bdi_set_max_bytes(), which will be introduced in the next patch. Link: https://lkml.kernel.org/r/20221119005215.3052436-7-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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00df7d51 |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_get_max_bytes() function This adds a function to return the specified value for max_bytes. It converts the stored max_ratio of the bdi to the corresponding bytes value. It introduces the bdi_get_bytes helper function to do the conversion. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The helper function will also be used by the min_bytes bdi knob. Link: https://lkml.kernel.org/r/20221119005215.3052436-6-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ae82291e |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: use part per 1000000 for bdi ratios To get finer granularity for ratio calculations use part per million instead of percentiles. This is especially important if we want to automatically convert byte values to ratios. Otherwise the values that are actually used can be quite different. This is also important for machines with more main memory (1% of 256GB is already 2.5GB). Link: https://lkml.kernel.org/r/20221119005215.3052436-5-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8e9d5ead |
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18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add bdi_set_strict_limit() function Patch series "mm/block: add bdi sysfs knobs", v4. At meta network block devices (nbd) are used to implement remote block storage. In testing and during production it has been observed that these network block devices can consume a huge portion of the dirty writeback cache and writeback can take a considerable time. To be able to give stricter limits, I'm proposing the following changes: 1) introduce strictlimit knob Currently the max_ratio knob exists to limit the dirty_memory. However this knob only applies once (dirty_ratio + dirty_background_ratio) / 2 has been reached. With the BDI_CAP_STRICTLIMIT flag, the max_ratio can be applied without reaching that limit. This change exposes that knob. This knob can also be useful for NFS, fuse filesystems and USB devices. 2) Use part of 1000000 internal calculation The max_ratio is based on percentage. With the current machine sizes percentage values can be very high (1% of a 256GB main memory is already 2.5GB). This change uses part of 1000000 instead of percentages for the internal calculations. 3) Introduce two new sysfs knobs: min_bytes and max_bytes. Currently all calculations are based on ratio, but for a user it often more convenient to specify a limit in bytes. The new knobs will not store bytes values, instead they will translate the byte value to a corresponding ratio. As the internal values are now part of 1000, the ratio is closer to the specified value. However the value should be more seen as an approximation as it can fluctuate over time. 3) Introduce two new sysfs knobs: min_ratio_fine and max_ratio_fine. The granularity for the existing sysfs bdi knobs min_ratio and max_ratio is based on percentage values. The new sysfs bdi knobs min_ratio_fine and max_ratio_fine allow to specify the ratio as part of 1 million. This patch (of 20): This adds the bdi_set_strict_limit function to be able to set/unset the BDI_CAP_STRICTLIMIT flag. Link: https://lkml.kernel.org/r/20221119005215.3052436-1-shr@devkernel.io Link: https://lkml.kernel.org/r/20221119005215.3052436-2-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Jens Axboe <axboe@kernel.dk> Cc: Chris Mason <clm@meta.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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611df5d6 |
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12-Sep-2022 |
Stefan Roesch <shr@fb.com> |
mm: export balance_dirty_pages_ratelimited_flags() Export the function balance_dirty_pages_ratelimited_flags(). It is now also called from btrfs. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Stefan Roesch <shr@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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f87904c0 |
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01-Aug-2022 |
Khazhismel Kumykov <khazhy@chromium.org> |
writeback: avoid use-after-free after removing device When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback. Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work. Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock. Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload") Signed-off-by: Khazhismel Kumykov <khazhy@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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fe6c9c6e |
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23-Jun-2022 |
Jan Kara <jack@suse.cz> |
mm: Add balance_dirty_pages_ratelimited_flags() function This adds the helper function balance_dirty_pages_ratelimited_flags(). It adds the parameter flags to balance_dirty_pages_ratelimited(). The flags parameter is passed to balance_dirty_pages(). For async buffered writes the flag value will be BDP_ASYNC. If balance_dirty_pages() gets called for async buffered write, we don't want to wait. Instead we need to indicate to the caller that throttling is needed so that it can stop writing and offload the rest of the write to a context that can block. The new helper function is also used by balance_dirty_pages_ratelimited(). Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Stefan Roesch <shr@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220623175157.1715274-4-shr@fb.com [axboe: fix kerneltest bot 'ret' issue] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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e92eebbb |
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23-Jun-2022 |
Jan Kara <jack@suse.cz> |
mm: Move updates of dirty_exceeded into one place Transition of wb->dirty_exceeded from 0 to 1 happens before we go to sleep in balance_dirty_pages() while transition from 1 to 0 happens when exiting from balance_dirty_pages(), possibly based on old values. This does not make a lot of sense since wb->dirty_exceeded should simply reflect whether wb is over dirty limit and so we should ratelimit entering to balance_dirty_pages() less. Move the two updates together. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Stefan Roesch <shr@fb.com> Link: https://lore.kernel.org/r/20220623175157.1715274-3-shr@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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ea6813be |
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23-Jun-2022 |
Jan Kara <jack@suse.cz> |
mm: Move starting of background writeback into the main balancing loop We start background writeback if we are over background threshold after exiting the main loop in balance_dirty_pages(). This may result in basing the decision on already stale values (we may have slept for significant amount of time) and it is also inconvenient for refactoring needed for async dirty throttling. Move the check into the main waiting loop. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Stefan Roesch <shr@fb.com> Link: https://lore.kernel.org/r/20220623175157.1715274-2-shr@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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21f0dd88 |
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29-Apr-2022 |
Chen Wandun <chenwandun@huawei.com> |
mm: rework calculation of bdi_min_ratio in bdi_set_min_ratio In function bdi_set_min_ratio, min_ratio is unsigned int, it will result underflow when setting min_ratio below bdi->min_ratio, it is confusing. Rework it, no functional change. Link: https://lkml.kernel.org/r/20220422095159.2858305-1-chenwandun@huawei.com Signed-off-by: Chen Wandun <chenwandun@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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3c6a4cba |
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15-Apr-2022 |
Luis Chamberlain <mcgrof@kernel.org> |
mm: fix unused variable kernel warning when SYSCTL=n When CONFIG_SYSCTL=n the variable dirty_bytes_min which is just used as a minimum to a proc handler is not used. So just move this under the ifdef for CONFIG_SYSCTL. Fixes: aa779e510219 ("mm: move page-writeback sysctls to their own file") Reported-by: kernel test robot <lkp@intel.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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aa779e51 |
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17-Feb-2022 |
zhanglianjie <zhanglianjie@uniontech.com> |
mm: move page-writeback sysctls to their own file kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the page-writeback sysctls to its own file. [akpm@linux-foundation.org: coding-style cleanups] akpm@linux-foundation.org: fix CONFIG_SYSCTL=n warnings] Link: https://lkml.kernel.org/r/20220129012955.26594-1-zhanglianjie@uniontech.com Signed-off-by: zhanglianjie <zhanglianjie@uniontech.com> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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2ca456c2 |
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28-Apr-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
filemap: Update the folio_mark_dirty documentation The previous comment was not terribly helpful. Be a bit more explicit about the necessary locking environment. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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566d3362 |
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24-Mar-2022 |
Hugh Dickins <hughd@google.com> |
mm: warn on deleting redirtied only if accounted filemap_unaccount_folio() has a WARN_ON_ONCE(folio_test_dirty(folio)). It is good to warn of late dirtying on a persistent filesystem, but late dirtying on tmpfs can only lose data which is expected to be thrown away; and it's a pity if that warning comes ONCE on tmpfs, then hides others which really matter. Make it conditional on mapping_cap_writeback(). Cleanup: then folio_account_cleaned() no longer needs to check that for itself, and so no longer needs to know the mapping. Link: https://lkml.kernel.org/r/b5a1106c-7226-a5c6-ad41-ad4832cae1f@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Jan Kara <jack@suse.de> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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854d8e36 |
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22-Mar-2022 |
Miaohe Lin <linmiaohe@huawei.com> |
mm/writeback: minor clean up for highmem_dirtyable_memory Since commit a804552b9a15 ("mm/page-writeback.c: fix dirty_balance_reserve subtraction from dirtyable memory"), local variable x can not be negative. And it can not overflow when it is the total number of dirtyable highmem pages. Thus remove the unneeded comment and overflow check. Link: https://lkml.kernel.org/r/20220224115416.46089-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3a3bae50 |
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09-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Remove aops ->set_page_dirty With all implementations converted to ->dirty_folio, we can stop calling this fallback method and remove it entirely. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs Tested-by: David Howells <dhowells@redhat.com> # afs
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46de8b97 |
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09-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Convert __set_page_dirty_no_writeback to noop_dirty_folio This is a mechanical change. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs Tested-by: David Howells <dhowells@redhat.com> # afs
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#
e621900a |
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09-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Convert __set_page_dirty_buffers to block_dirty_folio Convert all callers; mostly this is just changing the aops to point at it, but a few implementations need a little more work. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs Tested-by: David Howells <dhowells@redhat.com> # afs
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6f31a5a2 |
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09-Feb-2022 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: Add aops->dirty_folio This replaces ->set_page_dirty(). It returns a bool instead of an int and takes the address_space as a parameter instead of expecting the implementations to retrieve the address_space from the page. This is particularly important for filesystems which use FS_OPS for swap. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs Tested-by: David Howells <dhowells@redhat.com> # afs
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#
a229a4f0 |
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20-Dec-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Improve __folio_mark_dirty() comment Add some notes about how this function needs to be called. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
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#
452c472e |
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12-Aug-2021 |
David Howells <dhowells@redhat.com> |
folio: Add a function to get the host inode for a folio Add a convenience function, folio_inode() that will get the host inode from a folio's mapping. Changes: ver #3: - Fix mistake in function description[2]. ver #2: - Fix contradiction between doc and implementation by disallowing use with swap caches[1]. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Jeff Layton <jlayton@kernel.org> Tested-by: Dominique Martinet <asmadeus@codewreck.org> Tested-by: kafs-testing@auristor.com Link: https://lore.kernel.org/r/YST8OcVNy02Rivbm@casper.infradead.org/ [1] Link: https://lore.kernel.org/r/YYKLkBwQdtn4ja+i@casper.infradead.org/ [2] Link: https://lore.kernel.org/r/162880453171.3369675.3704943108660112470.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/162981151155.1901565.7010079316994382707.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/163005744370.2472992.18324470937328925723.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163584184628.4023316.9386282630968981869.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/163649325519.309189.15072332908703129455.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/163657850401.834781.1031963517399283294.stgit@warthog.procyon.org.uk/ # v5
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#
c3f4a9a2 |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: centralise timeout values for reclaim_throttle Neil Brown raised concerns about callers of reclaim_throttle specifying a timeout value. The original timeout values to congestion_wait() were probably pulled out of thin air or copy&pasted from somewhere else. This patch centralises the timeout values and selects a timeout based on the reason for reclaim throttling. These figures are also pulled out of the same thin air but better values may be derived Running a workload that is throttling for inappropriate periods and tracing mm_vmscan_throttled can be used to pick a more appropriate value. Excessive throttling would pick a lower timeout where as excessive CPU usage in reclaim context would select a larger timeout. Ideally a large value would always be used and the wakeups would occur before a timeout but that requires careful testing. Link: https://lkml.kernel.org/r/20211022144651.19914-7-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8d58802f |
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05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/writeback: throttle based on page writeback instead of congestion do_writepages throttles on congestion if the writepages() fails due to a lack of memory but congestion_wait() is partially broken as the congestion state is not updated for all BDIs. This patch stalls waiting for a number of pages to complete writeback that located on the local node. The main weakness is that there is no correlation between the location of the inode's pages and locality but that is still better than congestion_wait. Link: https://lkml.kernel.org/r/20211022144651.19914-5-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: NeilBrown <neilb@suse.de> Cc: Rik van Riel <riel@surriel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
121703c1 |
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09-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_write_one Transform write_one_page() into folio_write_one() and add a compatibility wrapper. Also move the declaration to pagemap.h as this is page cache functionality that doesn't need to be used by the rest of the kernel. Saves 58 bytes of kernel text. While folio_write_one() is 101 bytes smaller than write_one_page(), the inlined call to page_folio() expands each caller. There are fewer than ten callers so it doesn't seem worth putting a wrapper in the core. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Howells <dhowells@redhat.com>
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#
cd78ab11 |
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02-May-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_redirty_for_writepage() Reimplement redirty_page_for_writepage() as a wrapper around folio_redirty_for_writepage(). Account the number of pages in the folio, add kernel-doc and move the prototype to writeback.h. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
25ff8b15 |
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03-May-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_account_redirty() Account the number of pages in the folio that we're redirtying. Turn account_page_dirty() into a wrapper around it. Also turn the comment on folio_account_redirty() into kernel-doc and edit it slightly so it makes sense to its potential callers. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
9350f20a |
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28-Feb-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_clear_dirty_for_io() Transform clear_page_dirty_for_io() into folio_clear_dirty_for_io() and add a compatibility wrapper. Also move the declaration to pagemap.h as this is page cache functionality that doesn't need to be used by the rest of the kernel. Increases the size of the kernel by 79 bytes. While we remove a few calls to compound_head(), we add a call to folio_nr_pages() to get the stats correct for the eventual support of multi-page folios. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
fdaf532a |
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08-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_cancel_dirty() Turn __cancel_dirty_page() into __folio_cancel_dirty() and add wrappers. Move the prototypes into pagemap.h since this is page cache functionality. Saves 44 bytes of kernel text in total; 33 bytes from __folio_cancel_dirty and 11 from two callers of cancel_dirty_page(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
fc9b6a53 |
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04-May-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_account_cleaned() Get the statistics right; compound pages were being accounted as a single page. This didn't matter before now as no filesystem which supported compound pages did writeback. Also move the declaration to pagemap.h since this is part of the page cache. Add a wrapper for account_page_cleaned(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
85d4d2eb |
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03-May-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add filemap_dirty_folio() Reimplement __set_page_dirty_nobuffers() as a wrapper around filemap_dirty_folio(). Eventually folio_mark_dirty() will pass the folio's mapping to the address space's ->dirty_folio() operation, so add the parameter to filemap_dirty_folio() now. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
b9b0ff61 |
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13-Jul-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Convert tracing writeback_page_template to folios Rename writeback_dirty_page() to writeback_dirty_folio() and wait_on_page_writeback() to folio_wait_writeback(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
203a3151 |
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04-May-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add __folio_mark_dirty() Turn __set_page_dirty() into a wrapper around __folio_mark_dirty(). Convert account_page_dirtied() into folio_account_dirtied() and account the number of pages in the folio to support multi-page folios. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
b5e84594 |
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26-Apr-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_mark_dirty() Reimplement set_page_dirty() as a wrapper around folio_mark_dirty(). There is no change to filesystems as they were already being called with the compound_head of the page being marked dirty. We avoid several calls to compound_head(), both statically (through using folio_test_dirty() instead of PageDirty() and dynamically by calling folio_mapping() instead of page_mapping(). Also return bool instead of int to show the range of values actually returned, and add kernel-doc. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
f143f1ea |
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23-Apr-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_start_writeback() Rename set_page_writeback() to folio_start_writeback() to match folio_end_writeback(). Do not bother with wrappers that return void; callers are perfectly capable of ignoring return values. Add wrappers for set_page_writeback(), set_page_writeback_keepwrite() and test_set_page_writeback() for compatibililty with existing filesystems. The main advantage of this patch is getting the statistics right, although it does eliminate a couple of calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
269ccca3 |
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15-Jan-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add __folio_end_writeback() test_clear_page_writeback() is actually an mm-internal function, although it's named as if it's a pagecache function. Move it to mm/internal.h, rename it to __folio_end_writeback() and change the return type to bool. The conversion from page to folio is mostly about accounting the number of pages being written back, although it does eliminate a couple of calls to compound_head(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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#
cc24df4c |
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20-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Change __wb_writeout_inc() to __wb_writeout_add() Allow for accounting N pages at once instead of one page at a time. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
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be5f1797 |
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20-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
flex_proportions: Allow N events instead of 1 When batching events (such as writing back N pages in a single I/O), it is better to do one flex_proportion operation instead of N. There is only one caller of __fprop_inc_percpu_max(), and it's the one we're going to change in the next patch, so rename it instead of adding a compatibility wrapper. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz>
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#
101c0bf6 |
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03-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/filemap: Add folio_wait_bit() Rename wait_on_page_bit() to folio_wait_bit(). We must always wait on the folio, otherwise we won't be woken up due to the tail page hashing to a different bucket from the head page. This commit shrinks the kernel by 770 bytes, mostly due to moving the page waitqueue lookup into folio_wait_bit_common(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Jeff Layton <jlayton@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com>
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a49d0c50 |
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04-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_wait_stable() Move wait_for_stable_page() into the folio compatibility file. folio_wait_stable() avoids a call to compound_head() and is 14 bytes smaller than wait_for_stable_page() was. The net text size grows by 16 bytes as a result of this patch. We can also remove thp_head() as this was the last user. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Jeff Layton <jlayton@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: David Howells <dhowells@redhat.com>
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490e016f |
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04-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add folio_wait_writeback() wait_on_page_writeback_killable() only has one caller, so convert it to call folio_wait_writeback_killable(). For the wait_on_page_writeback() callers, add a compatibility wrapper around folio_wait_writeback(). Turning PageWriteback() into folio_test_writeback() eliminates a call to compound_head() which saves 8 bytes and 15 bytes in the two functions. Unfortunately, that is more than offset by adding the wait_on_page_writeback compatibility wrapper for a net increase in text of 7 bytes. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Jeff Layton <jlayton@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: David Howells <dhowells@redhat.com>
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#
20792ebf |
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02-Sep-2021 |
Jan Kara <jack@suse.cz> |
writeback: use READ_ONCE for unlocked reads of writeback stats We do some unlocked reads of writeback statistics like avg_write_bandwidth, dirty_ratelimit, or bw_time_stamp. Generally we are fine with getting somewhat out-of-date values but actually getting different values in various parts of the functions because the compiler decided to reload value from original memory location could confuse calculations. Use READ_ONCE for these unlocked accesses and WRITE_ONCE for the updates to be on the safe side. Link: https://lkml.kernel.org/r/20210713104716.22868-5-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Cc: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
42dd235c |
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02-Sep-2021 |
Jan Kara <jack@suse.cz> |
writeback: rename domain_update_bandwidth() Rename domain_update_bandwidth() to domain_update_dirty_limit(). The original name is a misnomer. The function has nothing to do with a bandwidth, it updates dirty limits. Link: https://lkml.kernel.org/r/20210713104716.22868-4-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Cc: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
45a2966f |
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02-Sep-2021 |
Jan Kara <jack@suse.cz> |
writeback: fix bandwidth estimate for spiky workload Michael Stapelberg has reported that for workload with short big spikes of writes (GCC linker seem to trigger this frequently) the write throughput is heavily underestimated and tends to steadily sink until it reaches zero. This has rather bad impact on writeback throttling (causing stalls). The problem is that writeback throughput estimate gets updated at most once per 200 ms. One update happens early after we submit pages for writeback (at that point writeout of only small fraction of pages is completed and thus observed throughput is tiny). Next update happens only during the next write spike (updates happen only from inode writeback and dirty throttling code) and if that is more than 1s after previous spike, we decide system was idle and just ignore whatever was written until this moment. Fix the problem by making sure writeback throughput estimate is also updated shortly after writeback completes to get reasonable estimate of throughput for spiky workloads. [jack@suse.cz: avoid division by 0 in wb_update_dirty_ratelimit()] Link: https://lore.kernel.org/lkml/20210617095309.3542373-1-stapelberg+linux@google.com Link: https://lkml.kernel.org/r/20210713104716.22868-3-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Michael Stapelberg <stapelberg+linux@google.com> Tested-by: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
fee468fd |
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02-Sep-2021 |
Jan Kara <jack@suse.cz> |
writeback: reliably update bandwidth estimation Currently we trigger writeback bandwidth estimation from balance_dirty_pages() and from wb_writeback(). However neither of these need to trigger when the system is relatively idle and writeback is triggered e.g. from fsync(2). Make sure writeback estimates happen reliably by triggering them from do_writepages(). Link: https://lkml.kernel.org/r/20210713104716.22868-2-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Cc: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
633a2abb |
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02-Sep-2021 |
Jan Kara <jack@suse.cz> |
writeback: track number of inodes under writeback Patch series "writeback: Fix bandwidth estimates", v4. Fix estimate of writeback throughput when device is not fully busy doing writeback. Michael Stapelberg has reported that such workload (e.g. generated by linking) tends to push estimated throughput down to 0 and as a result writeback on the device is practically stalled. The first three patches fix the reported issue, the remaining two patches are unrelated cleanups of problems I've noticed when reading the code. This patch (of 4): Track number of inodes under writeback for each bdi_writeback structure. We will use this to decide whether wb does any IO and so we can estimate its writeback throughput. In principle we could use number of pages under writeback (WB_WRITEBACK counter) for this however normal percpu counter reads are too inaccurate for our purposes and summing the counter is too expensive. Link: https://lkml.kernel.org/r/20210713104519.16394-1-jack@suse.cz Link: https://lkml.kernel.org/r/20210713104716.22868-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Michael Stapelberg <stapelberg+linux@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
5ed964f8 |
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09-Aug-2021 |
Christoph Hellwig <hch@lst.de> |
mm: hide laptop_mode_wb_timer entirely behind the BDI API Don't leak the detaÑ–ls of the timer into the block layer, instead initialize the timer in bdi_alloc and delete it in bdi_unregister. Note that this means the timer is initialized (but not armed) for non-block queues as well now. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210809141744.1203023-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
3af3d772 |
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12-Mar-2021 |
zhangyi (F) <yi.zhang@huawei.com> |
block_dump: remove block_dump feature We have already delete block_dump feature in mark_inode_dirty() because it can be replaced by tracepoints, now we also remove the part in submit_bio() for the same reason. The part of block dump feature in submit_bio() dump the write process, write region and sectors on the target disk into kernel message. it can be replaced by block_bio_queue tracepoint in submit_bio_checks(), so we do not need block_dump anymore, remove the whole block_dump feature. Signed-off-by: zhangyi (F) <yi.zhang@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210313030146.2882027-3-yi.zhang@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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b82a96c9 |
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28-Jun-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
fs: remove noop_set_page_dirty() Use __set_page_dirty_no_writeback() instead. This will set the dirty bit on the page, which will be used to avoid calling set_page_dirty() in the future. It will have no effect on actually writing the page back, as the pages are not on any LRU lists. [akpm@linux-foundation.org: export __set_page_dirty_no_writeback() to modules] Link: https://lkml.kernel.org/r/20210615162342.1669332-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2f18be36 |
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28-Jun-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: use __set_page_dirty in __set_page_dirty_nobuffers This is fundamentally the same code, so just call it instead of duplicating it. Link: https://lkml.kernel.org/r/20210615162342.1669332-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6e1cae88 |
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28-Jun-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: move __set_page_dirty() to core mm Patch series "Further set_page_dirty cleanups". Prompted by Christoph's recent patches, here are some more patches to improve the state of set_page_dirty(). They're all from the folio tree, so they've been tested to a certain extent. This patch (of 6): Nothing in __set_page_dirty() is specific to buffer_head, so move it to mm/page-writeback.c. That removes the only caller of account_page_dirtied() outside of page-writeback.c, so make it static. Link: https://lkml.kernel.org/r/20210615162342.1669332-1-willy@infradead.org Link: https://lkml.kernel.org/r/20210615162342.1669332-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0af57378 |
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28-Jun-2021 |
Christoph Hellwig <hch@lst.de> |
mm: require ->set_page_dirty to be explicitly wired up Remove the CONFIG_BLOCK default to __set_page_dirty_buffers and just wire that method up for the missing instances. [hch@lst.de: ecryptfs: add a ->set_page_dirty cludge] Link: https://lkml.kernel.org/r/20210624125250.536369-1-hch@lst.de Link: https://lkml.kernel.org/r/20210614061512.3966143-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Tyler Hicks <code@tyhicks.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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87e37897 |
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28-Jun-2021 |
Chi Wu <wuchi.zero@gmail.com> |
mm/page-writeback: use __this_cpu_inc() in account_page_dirtied() As account_page_dirtied() was always protected by xa_lock_irqsave(), so using __this_cpu_inc() is better. Link: https://lkml.kernel.org/r/20210512144742.4764-1-wuchi.zero@gmail.com Signed-off-by: Chi Wu <wuchi.zero@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Howard Cochran <hcochran@kernelspring.com> Cc: Miklos Szeredi <mszeredi@redhat.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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03231554 |
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28-Jun-2021 |
Chi Wu <wuchi.zero@gmail.com> |
mm/page-writeback: update the comment of Dirty position control As the value of pos_ratio_polynom() clamp between 0 and 2LL << RATELIMIT_CALC_SHIFT, the global control line should be consistent with it. Link: https://lkml.kernel.org/r/20210511103606.3732-1-wuchi.zero@gmail.com Signed-off-by: Chi Wu <wuchi.zero@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@fb.com> Cc: Howard Cochran <hcochran@kernelspring.com> Cc: Miklos Szeredi <mszeredi@redhat.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ab19939a |
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28-Jun-2021 |
Chi Wu <wuchi.zero@gmail.com> |
mm/page-writeback: Fix performance when BDI's share of ratio is 0. Fix performance when BDI's share of ratio is 0. The issue is similar to commit 74d369443325 ("writeback: Fix performance regression in wb_over_bg_thresh()"). Balance_dirty_pages and the writeback worker will also disagree on whether writeback when a BDI uses BDI_CAP_STRICTLIMIT and BDI's share of the thresh ratio is zero. For example, A thread on cpu0 writes 32 pages and then balance_dirty_pages, it will wake up background writeback and pauses because wb_dirty > wb->wb_thresh = 0 (share of thresh ratio is zero). A thread may runs on cpu0 again because scheduler prefers pre_cpu. Then writeback worker may runs on other cpus(1,2..) which causes the value of wb_stat(wb, WB_RECLAIMABLE) in wb_over_bg_thresh is 0 and does not writeback and returns. Thus, balance_dirty_pages keeps looping, sleeping and then waking up the worker who will do nothing. It remains stuck in this state until the writeback worker hit the right dirty cpu or the dirty pages expire. The fix that we should get the wb_stat_sum radically when thresh is low. Link: https://lkml.kernel.org/r/20210428225046.16301-1-wuchi.zero@gmail.com Signed-off-by: Chi Wu <wuchi.zero@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Miklos Szeredi <mszeredi@redhat.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5defd497 |
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28-Jun-2021 |
Kefeng Wang <wangkefeng.wang@huawei.com> |
mm: page-writeback: kill get_writeback_state() comments The get_writeback_state() has gone since 2006, kill related comments. Link: https://lkml.kernel.org/r/20210508125026.56600-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f0953a1b |
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06-May-2021 |
Ingo Molnar <mingo@kernel.org> |
mm: fix typos in comments Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c824a68 |
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29-Apr-2021 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: page-writeback: simplify memcg handling in test_clear_page_writeback() Page writeback doesn't hold a page reference, which allows truncate to free a page the second PageWriteback is cleared. This used to require special attention in test_clear_page_writeback(), where we had to be careful not to rely on the unstable page->memcg binding and look up all the necessary information before clearing the writeback flag. Since commit 073861ed77b6 ("mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback)") test_clear_page_writeback() is called with an explicit reference on the page, and this dance is no longer needed. Use unlock_page_memcg() and dec_lruvec_page_state() directly. This removes the last user of the lock_page_memcg() return value, change it to void. Touch up the comments in there as well. This also removes the last extern user of __unlock_page_memcg(), make it static. Further, it removes the last user of dec_lruvec_state(), delete it, along with a few other unused helpers. Link: https://lkml.kernel.org/r/YCQbYAWg4nvBFL6h@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hugh Dickins <hughd@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e5dbd332 |
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19-Mar-2021 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/writeback: Add wait_on_page_writeback_killable This is the killable version of wait_on_page_writeback. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: kafs-testing@auristor.com cc: linux-afs@lists.infradead.org cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/20210320054104.1300774-3-willy@infradead.org
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c2407cf7 |
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05-Jan-2021 |
Linus Torvalds <torvalds@linux-foundation.org> |
mm: make wait_on_page_writeback() wait for multiple pending writebacks Ever since commit 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") we've had some very occasional reports of BUG_ON(PageWriteback) in write_cache_pages(), which we thought we already fixed in commit 073861ed77b6 ("mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback)"). But syzbot just reported another one, even with that commit in place. And it turns out that there's a simpler way to trigger the BUG_ON() than the one Hugh found with page re-use. It all boils down to the fact that the page writeback is ostensibly serialized by the page lock, but that isn't actually really true. Yes, the people _setting_ writeback all do so under the page lock, but the actual clearing of the bit - and waking up any waiters - happens without any page lock. This gives us this fairly simple race condition: CPU1 = end previous writeback CPU2 = start new writeback under page lock CPU3 = write_cache_pages() CPU1 CPU2 CPU3 ---- ---- ---- end_page_writeback() test_clear_page_writeback(page) ... delayed... lock_page(); set_page_writeback() unlock_page() lock_page() wait_on_page_writeback(); wake_up_page(page, PG_writeback); .. wakes up CPU3 .. BUG_ON(PageWriteback(page)); where the BUG_ON() happens because we woke up the PG_writeback bit becasue of the _previous_ writeback, but a new one had already been started because the clearing of the bit wasn't actually atomic wrt the actual wakeup or serialized by the page lock. The reason this didn't use to happen was that the old logic in waiting on a page bit would just loop if it ever saw the bit set again. The nice proper fix would probably be to get rid of the whole "wait for writeback to clear, and then set it" logic in the writeback path, and replace it with an atomic "wait-to-set" (ie the same as we have for page locking: we set the page lock bit with a single "lock_page()", not with "wait for lock bit to clear and then set it"). However, out current model for writeback is that the waiting for the writeback bit is done by the generic VFS code (ie write_cache_pages()), but the actual setting of the writeback bit is done much later by the filesystem ".writepages()" function. IOW, to make the writeback bit have that same kind of "wait-to-set" behavior as we have for page locking, we'd have to change our roughly ~50 different writeback functions. Painful. Instead, just make "wait_on_page_writeback()" loop on the very unlikely situation that the PG_writeback bit is still set, basically re-instating the old behavior. This is very non-optimal in case of contention, but since we only ever set the bit under the page lock, that situation is controlled. Reported-by: syzbot+2fc0712f8f8b8b8fa0ef@syzkaller.appspotmail.com Fixes: 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") Acked-by: Hugh Dickins <hughd@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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073861ed |
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24-Nov-2020 |
Hugh Dickins <hughd@google.com> |
mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback) Twice now, when exercising ext4 looped on shmem huge pages, I have crashed on the PF_ONLY_HEAD check inside PageWaiters(): ext4_finish_bio() calling end_page_writeback() calling wake_up_page() on tail of a shmem huge page, no longer an ext4 page at all. The problem is that PageWriteback is not accompanied by a page reference (as the NOTE at the end of test_clear_page_writeback() acknowledges): as soon as TestClearPageWriteback has been done, that page could be removed from page cache, freed, and reused for something else by the time that wake_up_page() is reached. https://lore.kernel.org/linux-mm/20200827122019.GC14765@casper.infradead.org/ Matthew Wilcox suggested avoiding or weakening the PageWaiters() tail check; but I'm paranoid about even looking at an unreferenced struct page, lest its memory might itself have already been reused or hotremoved (and wake_up_page_bit() may modify that memory with its ClearPageWaiters()). Then on crashing a second time, realized there's a stronger reason against that approach. If my testing just occasionally crashes on that check, when the page is reused for part of a compound page, wouldn't it be much more common for the page to get reused as an order-0 page before reaching wake_up_page()? And on rare occasions, might that reused page already be marked PageWriteback by its new user, and already be waited upon? What would that look like? It would look like BUG_ON(PageWriteback) after wait_on_page_writeback() in write_cache_pages() (though I have never seen that crash myself). Matthew Wilcox explaining this to himself: "page is allocated, added to page cache, dirtied, writeback starts, --- thread A --- filesystem calls end_page_writeback() test_clear_page_writeback() --- context switch to thread B --- truncate_inode_pages_range() finds the page, it doesn't have writeback set, we delete it from the page cache. Page gets reallocated, dirtied, writeback starts again. Then we call write_cache_pages(), see PageWriteback() set, call wait_on_page_writeback() --- context switch back to thread A --- wake_up_page(page, PG_writeback); ... thread B is woken, but because the wakeup was for the old use of the page, PageWriteback is still set. Devious" And prior to 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") this would have been much less likely: before that, wake_page_function()'s non-exclusive case would stop walking and not wake if it found Writeback already set again; whereas now the non-exclusive case proceeds to wake. I have not thought of a fix that does not add a little overhead: the simplest fix is for end_page_writeback() to get_page() before calling test_clear_page_writeback(), then put_page() after wake_up_page(). Was there a chance of missed wakeups before, since a page freed before reaching wake_up_page() would have PageWaiters cleared? I think not, because each waiter does hold a reference on the page. This bug comes when the old use of the page, the one we do TestClearPageWriteback on, had *no* waiters, so no additional page reference beyond the page cache (and whoever racily freed it). The reuse of the page has a waiter holding a reference, and its own PageWriteback set; but the belated wake_up_page() has woken the reuse to hit that BUG_ON(PageWriteback). Reported-by: syzbot+3622cea378100f45d59f@syzkaller.appspotmail.com Reported-by: Qian Cai <cai@lca.pw> Fixes: 2a9127fcf229 ("mm: rewrite wait_on_page_bit_common() logic") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org # v5.8+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8854a6a7 |
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15-Oct-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/page-writeback: support tail pages in wait_for_stable_page page->mapping is undefined for tail pages, so operate exclusively on the head page. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: SeongJae Park <sjpark@amazon.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Link: https://lkml.kernel.org/r/20200908195539.25896-11-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f56753ac |
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24-Sep-2020 |
Christoph Hellwig <hch@lst.de> |
bdi: replace BDI_CAP_NO_{WRITEBACK,ACCT_DIRTY} with a single flag Replace the two negative flags that are always used together with a single positive flag that indicates the writeback capability instead of two related non-capabilities. Also remove the pointless wrappers to just check the flag. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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823423ef |
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24-Sep-2020 |
Christoph Hellwig <hch@lst.de> |
bdi: invert BDI_CAP_NO_ACCT_WB Replace BDI_CAP_NO_ACCT_WB with a positive BDI_CAP_WRITEBACK_ACCT to make the checks more obvious. Also remove the pointless bdi_cap_account_writeback wrapper that just obsfucates the check. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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1cb039f3 |
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24-Sep-2020 |
Christoph Hellwig <hch@lst.de> |
bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag The BDI_CAP_STABLE_WRITES is one of the few bits of information in the backing_dev_info shared between the block drivers and the writeback code. To help untangling the dependency replace it with a queue flag and a superblock flag derived from it. This also helps with the case of e.g. a file system requiring stable writes due to its own checksumming, but not forcing it on other users of the block device like the swap code. One downside is that we an't support the stable_pages_required bdi attribute in sysfs anymore. It is replaced with a queue attribute which also is writable for easier testing. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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0a18e607 |
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07-Aug-2020 |
David Hildenbrand <david@redhat.com> |
mm: remove vm_total_pages The global variable "vm_total_pages" is a relic from older days. There is only a single user that reads the variable - build_all_zonelists() - and the first thing it does is update it. Use a local variable in build_all_zonelists() instead and remove the global variable. Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/20200619132410.23859-2-david@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e0857cf5 |
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04-Jun-2020 |
Ethon Paul <ethp@qq.com> |
mm/page-writeback: fix a typo in comment "effictive"->"effective" There is a typo in comment, fix it. Signed-off-by: Ethon Paul <ethp@qq.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200411003513.14613-1-ethp@qq.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8d92890b |
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01-Jun-2020 |
NeilBrown <neilb@suse.de> |
mm/writeback: discard NR_UNSTABLE_NFS, use NR_WRITEBACK instead After an NFS page has been written it is considered "unstable" until a COMMIT request succeeds. If the COMMIT fails, the page will be re-written. These "unstable" pages are currently accounted as "reclaimable", either in WB_RECLAIMABLE, or in NR_UNSTABLE_NFS which is included in a 'reclaimable' count. This might have made sense when sending the COMMIT required a separate action by the VFS/MM (e.g. releasepage() used to send a COMMIT). However now that all writes generated by ->writepages() will automatically be followed by a COMMIT (since commit 919e3bd9a875 ("NFS: Ensure we commit after writeback is complete")) it makes more sense to treat them as writeback pages. So this patch removes NR_UNSTABLE_NFS and accounts unstable pages in NR_WRITEBACK and WB_WRITEBACK. A particular effect of this change is that when wb_check_background_flush() calls wb_over_bg_threshold(), the latter will report 'true' a lot less often as the 'unstable' pages are no longer considered 'dirty' (as there is nothing that writeback can do about them anyway). Currently wb_check_background_flush() will trigger writeback to NFS even when there are relatively few dirty pages (if there are lots of unstable pages), this can result in small writes going to the server (10s of Kilobytes rather than a Megabyte) which hurts throughput. With this patch, there are fewer writes which are each larger on average. Where the NR_UNSTABLE_NFS count was included in statistics virtual-files, the entry is retained, but the value is hard-coded as zero. static trace points and warning printks which mentioned this counter no longer report it. [akpm@linux-foundation.org: re-layout comment] [akpm@linux-foundation.org: fix printk warning] Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Trond Myklebust <trond.myklebust@hammerspace.com> Acked-by: Michal Hocko <mhocko@suse.com> [mm] Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Link: http://lkml.kernel.org/r/87d06j7gqa.fsf@notabene.neil.brown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a37b0715 |
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01-Jun-2020 |
NeilBrown <neilb@suse.de> |
mm/writeback: replace PF_LESS_THROTTLE with PF_LOCAL_THROTTLE PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a daemon needs to write to one bdi (the final bdi) in order to free up writes queued to another bdi (the client bdi). The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty pages, so that it can still dirty pages after other processses have been throttled. The purpose of this is to avoid deadlock that happen when the PF_LESS_THROTTLE process must write for any dirty pages to be freed, but it is being thottled and cannot write. This approach was designed when all threads were blocked equally, independently on which device they were writing to, or how fast it was. Since that time the writeback algorithm has changed substantially with different threads getting different allowances based on non-trivial heuristics. This means the simple "add 25%" heuristic is no longer reliable. The important issue is not that the daemon needs a *larger* dirty page allowance, but that it needs a *private* dirty page allowance, so that dirty pages for the "client" bdi that it is helping to clear (the bdi for an NFS filesystem or loop block device etc) do not affect the throttling of the daemon writing to the "final" bdi. This patch changes the heuristic so that the task is not throttled when the bdi it is writing to has a dirty page count below below (or equal to) the free-run threshold for that bdi. This ensures it will always be able to have some pages in flight, and so will not deadlock. In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might still be throttled by global threshold, but that is acceptable as it is only the deadlock state that is interesting for this flag. This approach of "only throttle when target bdi is busy" is consistent with the other use of PF_LESS_THROTTLE in current_may_throttle(), were it causes attention to be focussed only on the target bdi. So this patch - renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE, - removes the 25% bonus that that flag gives, and - If PF_LOCAL_THROTTLE is set, don't delay at all unless the global and the local free-run thresholds are exceeded. Note that previously realtime threads were treated the same as PF_LESS_THROTTLE threads. This patch does *not* change the behvaiour for real-time threads, so it is now different from the behaviour of nfsd and loop tasks. I don't know what is wanted for realtime. [akpm@linux-foundation.org: coding style fixes] Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Chuck Lever <chuck.lever@oracle.com> [nfsd] Cc: Christoph Hellwig <hch@lst.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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28659cc8 |
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01-Jun-2020 |
Chao Yu <chao@kernel.org> |
mm/page-writeback.c: remove unused variable Commit 64081362e8ff ("mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock") left unused variable, remove it. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Link: http://lkml.kernel.org/r/20200528033740.17269-1-yuchao0@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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32927393 |
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24-Apr-2020 |
Christoph Hellwig <hch@lst.de> |
sysctl: pass kernel pointers to ->proc_handler Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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f28d4363 |
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01-Apr-2020 |
Claudio Imbrenda <imbrenda@linux.ibm.com> |
mm/gup/writeback: add callbacks for inaccessible pages With the introduction of protected KVM guests on s390 there is now a concept of inaccessible pages. These pages need to be made accessible before the host can access them. While cpu accesses will trigger a fault that can be resolved, I/O accesses will just fail. We need to add a callback into architecture code for places that will do I/O, namely when writeback is started or when a page reference is taken. This is not only to enable paging, file backing etc, it is also necessary to protect the host against a malicious user space. For example a bad QEMU could simply start direct I/O on such protected memory. We do not want userspace to be able to trigger I/O errors and thus the logic is "whenever somebody accesses that page (gup) or does I/O, make sure that this page can be accessed". When the guest tries to access that page we will wait in the page fault handler for writeback to have finished and for the page_ref to be the expected value. On s390x the function is not supposed to fail, so it is ok to use a WARN_ON on failure. If we ever need some more finegrained handling we can tackle this when we know the details. Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Will Deacon <will@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200306132537.783769-3-imbrenda@linux.ibm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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184b4fef |
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01-Apr-2020 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm/page-writeback.c: use VM_BUG_ON_PAGE in clear_page_dirty_for_io Dumping the page information in this circumstance helps for debugging. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/20200318140253.6141-7-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cc7b8f62 |
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01-Apr-2020 |
Mauricio Faria de Oliveira <mfo@canonical.com> |
mm/page-writeback.c: write_cache_pages(): deduplicate identical checks There used to be a 'retry' label in between the two (identical) checks when first introduced in commit f446daaea9d4 ("mm: implement writeback livelock avoidance using page tagging"), and later modified/updated in commit 6e6938b6d313 ("writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage"). The label has been removed in commit 64081362e8ff ("mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock"), and the (identical) checks are now present / performed immediately one after another. So, remove/deduplicate the latter check, moving tag_pages_for_writeback() into the former check before the 'tag' variable assignment, so it's clear that it's not used in this (similarly-named) function call but only later in pagevec_lookup_range_tag(). Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Link: http://lkml.kernel.org/r/20200218221716.1648-1-mfo@canonical.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0a5d1a7f |
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13-Jan-2020 |
Wen Yang <wenyang@linux.alibaba.com> |
mm/page-writeback.c: improve arithmetic divisions Use div64_ul() instead of do_div() if the divisor is unsigned long, to avoid truncation to 32-bit on 64-bit platforms. Link: http://lkml.kernel.org/r/20200102081442.8273-4-wenyang@linux.alibaba.com Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Qian Cai <cai@lca.pw> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d3ac946e |
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13-Jan-2020 |
Wen Yang <wenyang@linux.alibaba.com> |
mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide The two variables 'numerator' and 'denominator', though they are declared as long, they should actually be unsigned long (according to the implementation of the fprop_fraction_percpu() function) And do_div() does a 64-by-32 division, while the divisor 'denominator' is unsigned long, thus 64-bit on 64-bit platforms. Hence the proper function to call is div64_ul(). Link: http://lkml.kernel.org/r/20200102081442.8273-3-wenyang@linux.alibaba.com Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Qian Cai <cai@lca.pw> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6d9e8c65 |
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13-Jan-2020 |
Wen Yang <wenyang@linux.alibaba.com> |
mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() Patch series "use div64_ul() instead of div_u64() if the divisor is unsigned long". We were first inspired by commit b0ab99e7736a ("sched: Fix possible divide by zero in avg_atom () calculation"), then refer to the recently analyzed mm code, we found this suspicious place. 201 if (min) { 202 min *= this_bw; 203 do_div(min, tot_bw); 204 } And we also disassembled and confirmed it: /usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 201 0xffffffff811c37da <__wb_calc_thresh+234>: xor %r10d,%r10d 0xffffffff811c37dd <__wb_calc_thresh+237>: test %rax,%rax 0xffffffff811c37e0 <__wb_calc_thresh+240>: je 0xffffffff811c3800 <__wb_calc_thresh+272> /usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 202 0xffffffff811c37e2 <__wb_calc_thresh+242>: imul %r8,%rax /usr/src/debug/kernel-4.9.168-016.ali3000/linux-4.9.168-016.ali3000.alios7.x86_64/mm/page-writeback.c: 203 0xffffffff811c37e6 <__wb_calc_thresh+246>: mov %r9d,%r10d ---> truncates it to 32 bits here 0xffffffff811c37e9 <__wb_calc_thresh+249>: xor %edx,%edx 0xffffffff811c37eb <__wb_calc_thresh+251>: div %r10 0xffffffff811c37ee <__wb_calc_thresh+254>: imul %rbx,%rax 0xffffffff811c37f2 <__wb_calc_thresh+258>: shr $0x2,%rax 0xffffffff811c37f6 <__wb_calc_thresh+262>: mul %rcx 0xffffffff811c37f9 <__wb_calc_thresh+265>: shr $0x2,%rdx 0xffffffff811c37fd <__wb_calc_thresh+269>: mov %rdx,%r10 This series uses div64_ul() instead of div_u64() if the divisor is unsigned long, to avoid truncation to 32-bit on 64-bit platforms. This patch (of 3): The variables 'min' and 'max' are unsigned long and do_div truncates them to 32 bits, which means it can test non-zero and be truncated to zero for division. Fix this issue by using div64_ul() instead. Link: http://lkml.kernel.org/r/20200102081442.8273-2-wenyang@linux.alibaba.com Fixes: 693108a8a667 ("writeback: make bdi->min/max_ratio handling cgroup writeback aware") Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Qian Cai <cai@lca.pw> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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97b27821 |
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26-Aug-2019 |
Tejun Heo <tj@kernel.org> |
writeback, memcg: Implement foreign dirty flushing There's an inherent mismatch between memcg and writeback. The former trackes ownership per-page while the latter per-inode. This was a deliberate design decision because honoring per-page ownership in the writeback path is complicated, may lead to higher CPU and IO overheads and deemed unnecessary given that write-sharing an inode across different cgroups isn't a common use-case. Combined with inode majority-writer ownership switching, this works well enough in most cases but there are some pathological cases. For example, let's say there are two cgroups A and B which keep writing to different but confined parts of the same inode. B owns the inode and A's memory is limited far below B's. A's dirty ratio can rise enough to trigger balance_dirty_pages() sleeps but B's can be low enough to avoid triggering background writeback. A will be slowed down without a way to make writeback of the dirty pages happen. This patch implements foreign dirty recording and foreign mechanism so that when a memcg encounters a condition as above it can trigger flushes on bdi_writebacks which can clean its pages. Please see the comment on top of mem_cgroup_track_foreign_dirty_slowpath() for details. A reproducer follows. write-range.c:: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <sys/types.h> static const char *usage = "write-range FILE START SIZE\n"; int main(int argc, char **argv) { int fd; unsigned long start, size, end, pos; char *endp; char buf[4096]; if (argc < 4) { fprintf(stderr, usage); return 1; } fd = open(argv[1], O_WRONLY); if (fd < 0) { perror("open"); return 1; } start = strtoul(argv[2], &endp, 0); if (*endp != '\0') { fprintf(stderr, usage); return 1; } size = strtoul(argv[3], &endp, 0); if (*endp != '\0') { fprintf(stderr, usage); return 1; } end = start + size; while (1) { for (pos = start; pos < end; ) { long bread, bwritten = 0; if (lseek(fd, pos, SEEK_SET) < 0) { perror("lseek"); return 1; } bread = read(0, buf, sizeof(buf) < end - pos ? sizeof(buf) : end - pos); if (bread < 0) { perror("read"); return 1; } if (bread == 0) return 0; while (bwritten < bread) { long this; this = write(fd, buf + bwritten, bread - bwritten); if (this < 0) { perror("write"); return 1; } bwritten += this; pos += bwritten; } } } } repro.sh:: #!/bin/bash set -e set -x sysctl -w vm.dirty_expire_centisecs=300000 sysctl -w vm.dirty_writeback_centisecs=300000 sysctl -w vm.dirtytime_expire_seconds=300000 echo 3 > /proc/sys/vm/drop_caches TEST=/sys/fs/cgroup/test A=$TEST/A B=$TEST/B mkdir -p $A $B echo "+memory +io" > $TEST/cgroup.subtree_control echo $((1<<30)) > $A/memory.high echo $((32<<30)) > $B/memory.high rm -f testfile touch testfile fallocate -l 4G testfile echo "Starting B" (echo $BASHPID > $B/cgroup.procs pv -q --rate-limit 70M < /dev/urandom | ./write-range testfile $((2<<30)) $((2<<30))) & echo "Waiting 10s to ensure B claims the testfile inode" sleep 5 sync sleep 5 sync echo "Starting A" (echo $BASHPID > $A/cgroup.procs pv < /dev/urandom | ./write-range testfile 0 $((2<<30))) v2: Added comments explaining why the specific intervals are being used. v3: Use 0 @nr when calling cgroup_writeback_by_id() to use best-effort flushing while avoding possible livelocks. v4: Use get_jiffies_64() and time_before/after64() instead of raw jiffies_64 and arthimetic comparisons as suggested by Jan. Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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ac1c3e49 |
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11-Jul-2019 |
Christoph Hellwig <hch@lst.de> |
mm: remove the account_page_dirtied export account_page_dirtied() is only used by our set_page_dirty() helpers and should not be used anywhere else. Link: http://lkml.kernel.org/r/20190605183702.30572-1-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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457c8996 |
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19-May-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Add SPDX license identifier for missed files Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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19343b5b |
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13-May-2019 |
Yafang Shao <laoar.shao@gmail.com> |
mm/page-writeback: introduce tracepoint for wait_on_page_writeback() Recently there have been some hung tasks on our server due to wait_on_page_writeback(), and we want to know the details of this PG_writeback, i.e. this page is writing back to which device. But it is not so convenient to get the details. I think it would be better to introduce a tracepoint for diagnosing the writeback details. Link: http://lkml.kernel.org/r/1556274402-19018-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a862f68a |
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05-Mar-2019 |
Mike Rapoport <rppt@kernel.org> |
docs/core-api/mm: fix return value descriptions in mm/ Many kernel-doc comments in mm/ have the return value descriptions either misformatted or omitted at all which makes kernel-doc script unhappy: $ make V=1 htmldocs ... ./mm/util.c:36: info: Scanning doc for kstrdup ./mm/util.c:41: warning: No description found for return value of 'kstrdup' ./mm/util.c:57: info: Scanning doc for kstrdup_const ./mm/util.c:66: warning: No description found for return value of 'kstrdup_const' ./mm/util.c:75: info: Scanning doc for kstrndup ./mm/util.c:83: warning: No description found for return value of 'kstrndup' ... Fixing the formatting and adding the missing return value descriptions eliminates ~100 such warnings. Link: http://lkml.kernel.org/r/1549549644-4903-4-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3fa750dc |
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28-Dec-2018 |
Brian Foster <bfoster@redhat.com> |
mm/page-writeback.c: don't break integrity writeback on ->writepage() error write_cache_pages() is used in both background and integrity writeback scenarios by various filesystems. Background writeback is mostly concerned with cleaning a certain number of dirty pages based on various mm heuristics. It may not write the full set of dirty pages or wait for I/O to complete. Integrity writeback is responsible for persisting a set of dirty pages before the writeback job completes. For example, an fsync() call must perform integrity writeback to ensure data is on disk before the call returns. write_cache_pages() unconditionally breaks out of its processing loop in the event of a ->writepage() error. This is fine for background writeback, which had no strict requirements and will eventually come around again. This can cause problems for integrity writeback on filesystems that might need to clean up state associated with failed page writeouts. For example, XFS performs internal delayed allocation accounting before returning a ->writepage() error, where applicable. If the current writeback happens to be associated with an unmount and write_cache_pages() completes the writeback prematurely due to error, the filesystem is unmounted in an inconsistent state if dirty+delalloc pages still exist. To handle this problem, update write_cache_pages() to always process the full set of pages for integrity writeback regardless of ->writepage() errors. Save the first encountered error and return it to the caller once complete. This facilitates XFS (or any other fs that expects integrity writeback to process the entire set of dirty pages) to clean up its internal state completely in the event of persistent mapping errors. Background writeback continues to exit on the first error encountered. [akpm@linux-foundation.org: fix typo in comment] Link: http://lkml.kernel.org/r/20181116134304.32440-1-bfoster@redhat.com Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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64081362 |
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26-Oct-2018 |
Dave Chinner <dchinner@redhat.com> |
mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock We've recently seen a workload on XFS filesystems with a repeatable deadlock between background writeback and a multi-process application doing concurrent writes and fsyncs to a small range of a file. range_cyclic writeback Process 1 Process 2 xfs_vm_writepages write_cache_pages writeback_index = 2 cycled = 0 .... find page 2 dirty lock Page 2 ->writepage page 2 writeback page 2 clean page 2 added to bio no more pages write() locks page 1 dirties page 1 locks page 2 dirties page 1 fsync() .... xfs_vm_writepages write_cache_pages start index 0 find page 1 towrite lock Page 1 ->writepage page 1 writeback page 1 clean page 1 added to bio find page 2 towrite lock Page 2 page 2 is writeback <blocks> write() locks page 1 dirties page 1 fsync() .... xfs_vm_writepages write_cache_pages start index 0 !done && !cycled sets index to 0, restarts lookup find page 1 dirty find page 1 towrite lock Page 1 page 1 is writeback <blocks> lock Page 1 <blocks> DEADLOCK because: - process 1 needs page 2 writeback to complete to make enough progress to issue IO pending for page 1 - writeback needs page 1 writeback to complete so process 2 can progress and unlock the page it is blocked on, then it can issue the IO pending for page 2 - process 2 can't make progress until process 1 issues IO for page 1 The underlying cause of the problem here is that range_cyclic writeback is processing pages in descending index order as we hold higher index pages in a structure controlled from above write_cache_pages(). The write_cache_pages() caller needs to be able to submit these pages for IO before write_cache_pages restarts writeback at mapping index 0 to avoid wcp inverting the page lock/writeback wait order. generic_writepages() is not susceptible to this bug as it has no private context held across write_cache_pages() - filesystems using this infrastructure always submit pages in ->writepage immediately and so there is no problem with range_cyclic going back to mapping index 0. However: mpage_writepages() has a private bio context, exofs_writepages() has page_collect fuse_writepages() has fuse_fill_wb_data nfs_writepages() has nfs_pageio_descriptor xfs_vm_writepages() has xfs_writepage_ctx All of these ->writepages implementations can hold pages under writeback in their private structures until write_cache_pages() returns, and hence they are all susceptible to this deadlock. Also worth noting is that ext4 has it's own bastardised version of write_cache_pages() and so it /may/ have an equivalent deadlock. I looked at the code long enough to understand that it has a similar retry loop for range_cyclic writeback reaching the end of the file and then promptly ran away before my eyes bled too much. I'll leave it for the ext4 developers to determine if their code is actually has this deadlock and how to fix it if it has. There's a few ways I can see avoid this deadlock. There's probably more, but these are the first I've though of: 1. get rid of range_cyclic altogether 2. range_cyclic always stops at EOF, and we start again from writeback index 0 on the next call into write_cache_pages() 2a. wcp also returns EAGAIN to ->writepages implementations to indicate range cyclic has hit EOF. writepages implementations can then flush the current context and call wpc again to continue. i.e. lift the retry into the ->writepages implementation 3. range_cyclic uses trylock_page() rather than lock_page(), and it skips pages it can't lock without blocking. It will already do this for pages under writeback, so this seems like a no-brainer 3a. all non-WB_SYNC_ALL writeback uses trylock_page() to avoid blocking as per pages under writeback. I don't think #1 is an option - range_cyclic prevents frequently dirtied lower file offset from starving background writeback of rarely touched higher file offsets. #2 is simple, and I don't think it will have any impact on performance as going back to the start of the file implies an immediate seek. We'll have exactly the same number of seeks if we switch writeback to another inode, and then come back to this one later and restart from index 0. #2a is pretty much "status quo without the deadlock". Moving the retry loop up into the wcp caller means we can issue IO on the pending pages before calling wcp again, and so avoid locking or waiting on pages in the wrong order. I'm not convinced we need to do this given that we get the same thing from #2 on the next writeback call from the writeback infrastructure. #3 is really just a band-aid - it doesn't fix the access/wait inversion problem, just prevents it from becoming a deadlock situation. I'd prefer we fix the inversion, not sweep it under the carpet like this. #3a is really an optimisation that just so happens to include the band-aid fix of #3. So it seems that the simplest way to fix this issue is to implement solution #2 Link: http://lkml.kernel.org/r/20181005054526.21507-1-david@fromorbit.com Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Jan Kara <jack@suse.de> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ff9c745b |
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22-Nov-2017 |
Matthew Wilcox <willy@infradead.org> |
mm: Convert page-writeback to XArray Includes moving mapping_tagged() to fs.h as a static inline, and changing it to return bool. Signed-off-by: Matthew Wilcox <willy@infradead.org>
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#
13ba17be |
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24-Aug-2018 |
Mukesh Ojha <mojha@codeaurora.org> |
notifier: Remove notifier header file wherever not used The conversion of the hotplug notifiers to a state machine left the notifier.h includes around in some places. Remove them. Signed-off-by: Mukesh Ojha <mojha@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1535114033-4605-1-git-send-email-mojha@codeaurora.org
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#
dcfe4df3 |
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17-Aug-2018 |
Greg Thelen <gthelen@google.com> |
mm/page-writeback.c: update stale account_page_redirty() comment Commit 93f78d882865 ("writeback: move backing_dev_info->bdi_stat[] into bdi_writeback") replaced BDI_DIRTIED with WB_DIRTIED in account_page_redirty(). Update comment to track that change. BDI_DIRTIED => WB_DIRTIED BDI_WRITTEN => WB_WRITTEN Link: http://lkml.kernel.org/r/20180625171526.173483-1-gthelen@google.com Signed-off-by: Greg Thelen <gthelen@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2e898e4c |
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20-Apr-2018 |
Greg Thelen <gthelen@google.com> |
writeback: safer lock nesting lock_page_memcg()/unlock_page_memcg() use spin_lock_irqsave/restore() if the page's memcg is undergoing move accounting, which occurs when a process leaves its memcg for a new one that has memory.move_charge_at_immigrate set. unlocked_inode_to_wb_begin,end() use spin_lock_irq/spin_unlock_irq() if the given inode is switching writeback domains. Switches occur when enough writes are issued from a new domain. This existing pattern is thus suspicious: lock_page_memcg(page); unlocked_inode_to_wb_begin(inode, &locked); ... unlocked_inode_to_wb_end(inode, locked); unlock_page_memcg(page); If both inode switch and process memcg migration are both in-flight then unlocked_inode_to_wb_end() will unconditionally enable interrupts while still holding the lock_page_memcg() irq spinlock. This suggests the possibility of deadlock if an interrupt occurs before unlock_page_memcg(). truncate __cancel_dirty_page lock_page_memcg unlocked_inode_to_wb_begin unlocked_inode_to_wb_end <interrupts mistakenly enabled> <interrupt> end_page_writeback test_clear_page_writeback lock_page_memcg <deadlock> unlock_page_memcg Due to configuration limitations this deadlock is not currently possible because we don't mix cgroup writeback (a cgroupv2 feature) and memory.move_charge_at_immigrate (a cgroupv1 feature). If the kernel is hacked to always claim inode switching and memcg moving_account, then this script triggers lockup in less than a minute: cd /mnt/cgroup/memory mkdir a b echo 1 > a/memory.move_charge_at_immigrate echo 1 > b/memory.move_charge_at_immigrate ( echo $BASHPID > a/cgroup.procs while true; do dd if=/dev/zero of=/mnt/big bs=1M count=256 done ) & while true; do sync done & sleep 1h & SLEEP=$! while true; do echo $SLEEP > a/cgroup.procs echo $SLEEP > b/cgroup.procs done The deadlock does not seem possible, so it's debatable if there's any reason to modify the kernel. I suggest we should to prevent future surprises. And Wang Long said "this deadlock occurs three times in our environment", so there's more reason to apply this, even to stable. Stable 4.4 has minor conflicts applying this patch. For a clean 4.4 patch see "[PATCH for-4.4] writeback: safer lock nesting" https://lkml.org/lkml/2018/4/11/146 Wang Long said "this deadlock occurs three times in our environment" [gthelen@google.com: v4] Link: http://lkml.kernel.org/r/20180411084653.254724-1-gthelen@google.com [akpm@linux-foundation.org: comment tweaks, struct initialization simplification] Change-Id: Ibb773e8045852978f6207074491d262f1b3fb613 Link: http://lkml.kernel.org/r/20180410005908.167976-1-gthelen@google.com Fixes: 682aa8e1a6a1 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates") Signed-off-by: Greg Thelen <gthelen@google.com> Reported-by: Wang Long <wanglong19@meituan.com> Acked-by: Wang Long <wanglong19@meituan.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: <stable@vger.kernel.org> [v4.2+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b93b0163 |
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10-Apr-2018 |
Matthew Wilcox <willy@infradead.org> |
page cache: use xa_lock Remove the address_space ->tree_lock and use the xa_lock newly added to the radix_tree_root. Rename the address_space ->page_tree to ->i_pages, since we don't really care that it's a tree. [willy@infradead.org: fix nds32, fs/dax.c] Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Jeff Layton <jlayton@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
90daf306 |
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29-Nov-2017 |
Michal Hocko <mhocko@suse.com> |
Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical" This reverts commit 0f6d24f87856 ("mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical") because it causes false positive warnings during OOM situations as noticed by Tetsuo Handa: Node 0 active_anon:3525940kB inactive_anon:8372kB active_file:216kB inactive_file:1872kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:2504kB dirty:52kB writeback:0kB shmem:8660kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 636928kB writeback_tmp:0kB unstable:0kB all_unreclaimable? yes Node 0 DMA free:14848kB min:284kB low:352kB high:420kB active_anon:992kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15988kB managed:15904kB mlocked:0kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 2687 3645 3645 Node 0 DMA32 free:53004kB min:49608kB low:62008kB high:74408kB active_anon:2712648kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:3129216kB managed:2773132kB mlocked:0kB kernel_stack:96kB pagetables:5096kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 0 958 958 Node 0 Normal free:17140kB min:17684kB low:22104kB high:26524kB active_anon:812300kB inactive_anon:8372kB active_file:1228kB inactive_file:1868kB unevictable:0kB writepending:52kB present:1048576kB managed:981224kB mlocked:0kB kernel_stack:3520kB pagetables:8552kB bounce:0kB free_pcp:120kB local_pcp:120kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 [...] Out of memory: Kill process 8459 (a.out) score 999 or sacrifice child Killed process 8459 (a.out) total-vm:4180kB, anon-rss:88kB, file-rss:0kB, shmem-rss:0kB oom_reaper: reaped process 8459 (a.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB vm direct limit must be set greater than background limit. The problem is that both thresh and bg_thresh will be 0 if available_memory is less than 4 pages when evaluating global_dirtyable_memory. While this might be worked around the whole point of the warning is dubious at best. We do rely on admins to do sensible things when changing tunable knobs. Dirty memory writeback knobs are not any special in that regards so revert the warning rather than adding more hacks to work this around. Debugged by Yafang Shao. Link: http://lkml.kernel.org/r/20171127091939.tahb77nznytcxw55@dhcp22.suse.cz Fixes: 0f6d24f87856 ("mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bca237a5 |
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28-Aug-2017 |
Kees Cook <keescook@chromium.org> |
block/laptop_mode: Convert timers to use timer_setup() In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: Jens Axboe <axboe@kernel.dk> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Jeff Layton <jlayton@redhat.com> Cc: linux-block@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Kees Cook <keescook@chromium.org>
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2bce774e |
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15-Nov-2017 |
Wang Long <wanglong19@meituan.com> |
writeback: remove unused function parameter The parameter `struct bdi_writeback *wb` is not been used in the function body. Remove it. Link: http://lkml.kernel.org/r/1509685485-15278-1-git-send-email-wanglong19@meituan.com Signed-off-by: Wang Long <wanglong19@meituan.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
86679820 |
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15-Nov-2017 |
Mel Gorman <mgorman@techsingularity.net> |
mm, pagevec: remove cold parameter for pagevecs Every pagevec_init user claims the pages being released are hot even in cases where it is unlikely the pages are hot. As no one cares about the hotness of pages being released to the allocator, just ditch the parameter. No performance impact is expected as the overhead is marginal. The parameter is removed simply because it is a bit stupid to have a useless parameter copied everywhere. Link: http://lkml.kernel.org/r/20171018075952.10627-6-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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736304f3 |
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15-Nov-2017 |
Jan Kara <jack@suse.cz> |
mm: speed up cancel_dirty_page() for clean pages Patch series "Speed up page cache truncation", v1. When rebasing our enterprise distro to a newer kernel (from 4.4 to 4.12) we have noticed a regression in bonnie++ benchmark when deleting files. Eventually we have tracked this down to a fact that page cache truncation got slower by about 10%. There were both gains and losses in the above interval of kernels but we have been able to identify that commit 83929372f629 ("filemap: prepare find and delete operations for huge pages") caused about 10% regression on its own. After some investigation it didn't seem easily possible to fix the regression while maintaining the THP in page cache functionality so we've decided to optimize the page cache truncation path instead to make up for the change. This series is a result of that effort. Patch 1 is an easy speedup of cancel_dirty_page(). Patches 2-6 refactor page cache truncation code so that it is easier to batch radix tree operations. Patch 7 implements batching of deletes from the radix tree which more than makes up for the original regression. This patch (of 7): cancel_dirty_page() does quite some work even for clean pages (fetching of mapping, locking of memcg, atomic bit op on page flags) so it accounts for ~2.5% of cost of truncation of a clean page. That is not much but still dumb for something we don't need at all. Check whether a page is actually dirty and avoid any work if not. Link: http://lkml.kernel.org/r/20171010151937.26984-2-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9823e51b |
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15-Nov-2017 |
Kees Cook <keescook@chromium.org> |
mm/page-writeback.c: convert timers to use timer_setup() In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Link: http://lkml.kernel.org/r/20171016225913.GA99214@beast Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Jeff Layton <jlayton@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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67fd707f |
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15-Nov-2017 |
Jan Kara <jack@suse.cz> |
mm: remove nr_pages argument from pagevec_lookup_{,range}_tag() All users of pagevec_lookup() and pagevec_lookup_range() now pass PAGEVEC_SIZE as a desired number of pages. Just drop the argument. Link: http://lkml.kernel.org/r/20171009151359.31984-15-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2b9775ae |
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15-Nov-2017 |
Jan Kara <jack@suse.cz> |
mm: use pagevec_lookup_range_tag() in write_cache_pages() Use pagevec_lookup_range_tag() in write_cache_pages() as it is interested only in pages from given range. Remove unnecessary code resulting from this. Link: http://lkml.kernel.org/r/20171009151359.31984-12-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0f6d24f8 |
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15-Nov-2017 |
Yafang Shao <laoar.shao@gmail.com> |
mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical The vm direct limit setting must be set greater than vm background limit setting. Otherwise print a warning to help the operator to figure out that the vm dirtiness settings is in illogical state. Link: http://lkml.kernel.org/r/1506592464-30962-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4c578dce |
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15-Nov-2017 |
Tahsin Erdogan <tahsin@google.com> |
mm/page-writeback.c: remove unused parameter from balance_dirty_pages() "mapping" parameter to balance_dirty_pages() is not used anymore. Fixes: dfb8ae567835 ("writeback: let balance_dirty_pages() work on the matching cgroup bdi_writeback") Link: http://lkml.kernel.org/r/20170927221311.23263-1-tahsin@google.com Signed-off-by: Tahsin Erdogan <tahsin@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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515c24c1 |
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14-Oct-2017 |
Yafang Shao <laoar.shao@gmail.com> |
mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately This patch is the followup of the prvious patch: [writeback: schedule periodic writeback with sysctl]. There's another issue to fix. For example, - When the tunable was set to one hour and is reset to one second, the new setting will not take effect for up to one hour. Kicking the flusher threads immediately fixes it. Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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94af5846 |
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09-Oct-2017 |
Yafang Shao <laoar.shao@gmail.com> |
writeback: schedule periodic writeback with sysctl After disable periodic writeback by writing 0 to dirty_writeback_centisecs, the handler wb_workfn() will not be entered again until the dirty background limit reaches or sync syscall is executed or no enough free memory available or vmscan is triggered. So the periodic writeback can't be enabled by writing a non-zero value to dirty_writeback_centisecs. As it can be disabled by sysctl, it should be able to enable by sysctl as well. Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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0ab29fd0 |
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28-Sep-2017 |
Jens Axboe <axboe@kernel.dk> |
writeback: pass in '0' for nr_pages writeback in laptop mode Laptop mode really wants to writeback the number of dirty pages and inodes. Instead of calculating this in the caller, just pass in 0 and let wakeup_flusher_threads() handle it. Use the new wakeup_flusher_threads_bdi() instead of rolling our own. Acked-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Chris Mason <clm@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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47410d88 |
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28-Sep-2017 |
Jens Axboe <axboe@kernel.dk> |
writeback: remove 'range_cyclic' argument for wb_start_writeback() All the callers pass in 'true' for range_cyclic, so kill the argument. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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c41f012a |
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06-Sep-2017 |
Michal Hocko <mhocko@suse.com> |
mm: rename global_page_state to global_zone_page_state global_page_state is error prone as a recent bug report pointed out [1]. It only returns proper values for zone based counters as the enum it gets suggests. We already have global_node_page_state so let's rename global_page_state to global_zone_page_state to be more explicit here. All existing users seems to be correct: $ git grep "global_page_state(NR_" | sed 's@.*(\(NR_[A-Z_]*\)).*@\1@' | sort | uniq -c 2 NR_BOUNCE 2 NR_FREE_CMA_PAGES 11 NR_FREE_PAGES 1 NR_KERNEL_STACK_KB 1 NR_MLOCK 2 NR_PAGETABLE This patch shouldn't introduce any functional change. [1] http://lkml.kernel.org/r/201707260628.v6Q6SmaS030814@www262.sakura.ne.jp Link: http://lkml.kernel.org/r/20170801134256.5400-2-hannes@cmpxchg.org Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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739f79fc |
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18-Aug-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: fix NULL pointer crash in test_clear_page_writeback() Jaegeuk and Brad report a NULL pointer crash when writeback ending tries to update the memcg stats: BUG: unable to handle kernel NULL pointer dereference at 00000000000003b0 IP: test_clear_page_writeback+0x12e/0x2c0 [...] RIP: 0010:test_clear_page_writeback+0x12e/0x2c0 Call Trace: <IRQ> end_page_writeback+0x47/0x70 f2fs_write_end_io+0x76/0x180 [f2fs] bio_endio+0x9f/0x120 blk_update_request+0xa8/0x2f0 scsi_end_request+0x39/0x1d0 scsi_io_completion+0x211/0x690 scsi_finish_command+0xd9/0x120 scsi_softirq_done+0x127/0x150 __blk_mq_complete_request_remote+0x13/0x20 flush_smp_call_function_queue+0x56/0x110 generic_smp_call_function_single_interrupt+0x13/0x30 smp_call_function_single_interrupt+0x27/0x40 call_function_single_interrupt+0x89/0x90 RIP: 0010:native_safe_halt+0x6/0x10 (gdb) l *(test_clear_page_writeback+0x12e) 0xffffffff811bae3e is in test_clear_page_writeback (./include/linux/memcontrol.h:619). 614 mod_node_page_state(page_pgdat(page), idx, val); 615 if (mem_cgroup_disabled() || !page->mem_cgroup) 616 return; 617 mod_memcg_state(page->mem_cgroup, idx, val); 618 pn = page->mem_cgroup->nodeinfo[page_to_nid(page)]; 619 this_cpu_add(pn->lruvec_stat->count[idx], val); 620 } 621 622 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, 623 gfp_t gfp_mask, The issue is that writeback doesn't hold a page reference and the page might get freed after PG_writeback is cleared (and the mapping is unlocked) in test_clear_page_writeback(). The stat functions looking up the page's node or zone are safe, as those attributes are static across allocation and free cycles. But page->mem_cgroup is not, and it will get cleared if we race with truncation or migration. It appears this race window has been around for a while, but less likely to trigger when the memcg stats were updated first thing after PG_writeback is cleared. Recent changes reshuffled this code to update the global node stats before the memcg ones, though, stretching the race window out to an extent where people can reproduce the problem. Update test_clear_page_writeback() to look up and pin page->mem_cgroup before clearing PG_writeback, then not use that pointer afterward. It is a partial revert of 62cccb8c8e7a ("mm: simplify lock_page_memcg()") but leaves the pageref-holding callsites that aren't affected alone. Link: http://lkml.kernel.org/r/20170809183825.GA26387@cmpxchg.org Fixes: 62cccb8c8e7a ("mm: simplify lock_page_memcg()") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Jaegeuk Kim <jaegeuk@kernel.org> Tested-by: Jaegeuk Kim <jaegeuk@kernel.org> Reported-by: Bradley Bolen <bradleybolen@gmail.com> Tested-by: Brad Bolen <bradleybolen@gmail.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> [4.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3e8f399d |
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12-Jul-2017 |
Nikolay Borisov <nborisov@suse.com> |
writeback: rework wb_[dec|inc]_stat family of functions Currently the writeback statistics code uses a percpu counters to hold various statistics. Furthermore we have 2 families of functions - those which disable local irq and those which doesn't and whose names begin with double underscore. However, they both end up calling __add_wb_stats which in turn calls percpu_counter_add_batch which is already irq-safe. Exploiting this fact allows to eliminated the __wb_* functions since they don't add any further protection than we already have. Furthermore, refactor the wb_* function to call __add_wb_stat directly without the irq-disabling dance. This will likely result in better runtime of code which deals with modifying the stat counters. While at it also document why percpu_counter_add_batch is in fact preempt and irq-safe since at least 3 people got confused. Link: http://lkml.kernel.org/r/1498029937-27293-1-git-send-email-nborisov@suse.com Signed-off-by: Nikolay Borisov <nborisov@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Josef Bacik <jbacik@fb.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Jeff Layton <jlayton@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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00f3ca2c |
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06-Jul-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: per-lruvec stats infrastructure lruvecs are at the intersection of the NUMA node and memcg, which is the scope for most paging activity. Introduce a convenient accounting infrastructure that maintains statistics per node, per memcg, and the lruvec itself. Then convert over accounting sites for statistics that are already tracked in both nodes and memcgs and can be easily switched. [hannes@cmpxchg.org: fix crash in the new cgroup stat keeping code] Link: http://lkml.kernel.org/r/20170531171450.GA10481@cmpxchg.org [hannes@cmpxchg.org: don't track uncharged pages at all Link: http://lkml.kernel.org/r/20170605175254.GA8547@cmpxchg.org [hannes@cmpxchg.org: add missing free_percpu()] Link: http://lkml.kernel.org/r/20170605175354.GB8547@cmpxchg.org [linux@roeck-us.net: hexagon: fix build error caused by include file order] Link: http://lkml.kernel.org/r/20170617153721.GA4382@roeck-us.net Link: http://lkml.kernel.org/r/20170530181724.27197-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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37e51a76 |
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05-Jul-2017 |
Jeff Layton <jlayton@kernel.org> |
mm: clean up error handling in write_one_page Don't try to check PageError since that's potentially racy and not necessarily going to be set after writepage errors out. Instead, check the mapping for an error after writepage returns. That should also help us detect errors that occurred if the VM tried to clean the page earlier due to memory pressure. Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz>
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2b69c828 |
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05-Jul-2017 |
Jeff Layton <jlayton@kernel.org> |
mm: drop "wait" parameter from write_one_page() The callers all set it to 1. Also, make it clear that this function will not set any sort of AS_* error, and that the caller must do so if necessary. No existing caller uses this on normal files, so none of them need it. Also, add __must_check here since, in general, the callers need to handle an error here in some fashion. Link: http://lkml.kernel.org/r/20170525103303.6524-1-jlayton@redhat.com Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ccda7f43 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: use node page state naming scheme for memcg The memory controllers stat function names are awkwardly long and arbitrarily different from the zone and node stat functions. The current interface is named: mem_cgroup_read_stat() mem_cgroup_update_stat() mem_cgroup_inc_stat() mem_cgroup_dec_stat() mem_cgroup_update_page_stat() mem_cgroup_inc_page_stat() mem_cgroup_dec_page_stat() This patch renames it to match the corresponding node stat functions: memcg_page_state() [node_page_state()] mod_memcg_state() [mod_node_state()] inc_memcg_state() [inc_node_state()] dec_memcg_state() [dec_node_state()] mod_memcg_page_state() [mod_node_page_state()] inc_memcg_page_state() [inc_node_page_state()] dec_memcg_page_state() [dec_node_page_state()] Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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71cd3113 |
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03-May-2017 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: re-use node VM page state enum The current duplication is a high-maintenance mess, and it's painful to add new items or query memcg state from the rest of the VM. This increases the size of the stat array marginally, but we should aim to track all these stats on a per-cgroup level anyway. Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0a372d09 |
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03-May-2017 |
Geliang Tang <geliangtang@gmail.com> |
mm/page-writeback.c: use setup_deferrable_timer Use setup_deferrable_timer() instead of init_timer_deferrable() to simplify the code. Link: http://lkml.kernel.org/r/e8e3d4280a34facbc007346f31df833cec28801e.1488070291.git.geliangtang@gmail.com Signed-off-by: Geliang Tang <geliangtang@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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80a2ea9f |
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28-Apr-2017 |
Theodore Ts'o <tytso@mit.edu> |
mm: retry writepages() on ENOMEM when doing an data integrity writeback Currently, file system's writepages() function must not fail with an ENOMEM, since if they do, it's possible for buffered data to be lost. This is because on a data integrity writeback writepages() gets called but once, and if it returns ENOMEM, if you're lucky the error will get reflected back to the userspace process calling fsync(). If you aren't lucky, the user is unmounting the file system, and the dirty pages will simply be lost. For this reason, file system code generally will use GFP_NOFS, and in some cases, will retry the allocation in a loop, on the theory that "kernel livelocks are temporary; data loss is forever". Unfortunately, this can indeed cause livelocks, since inside the writepages() call, the file system is holding various mutexes, and these mutexes may prevent the OOM killer from killing its targetted victim if it is also holding on to those mutexes. A better solution would be to allow writepages() to call the memory allocator with flags that give greater latitude to the allocator to fail, and then release its locks and return ENOMEM, and in the case of background writeback, the writes can be retried at a later time. In the case of data-integrity writeback retry after waiting a brief amount of time. Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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f361bf4a |
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03-Feb-2017 |
Ingo Molnar <mingo@kernel.org> |
sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency Instead of including the full <linux/signal.h>, we are going to include the types-only <linux/signal_types.h> header in <linux/sched.h>, to further decouple the scheduler header from the signal headers. This means that various files which relied on the full <linux/signal.h> need to be updated to gain an explicit dependency on it. Update the code that relies on sched.h's inclusion of the <linux/signal.h> header. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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3f8b6fb7 |
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27-Feb-2017 |
Masahiro Yamada <yamada.masahiro@socionext.com> |
scripts/spelling.txt: add "comsume(r)" pattern and fix typo instances Fix typos and add the following to the scripts/spelling.txt: comsume||consume comsumer||consumer comsuming||consuming I see some variable names with this pattern, but this commit is only touching comment blocks to avoid unexpected impact. Link: http://lkml.kernel.org/r/1481573103-11329-19-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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517663ed |
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24-Feb-2017 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
mm/page-writeback.c: place "not" inside of unlikely() statement in wb_domain_writeout_inc() The likely/unlikely profiler noticed that the unlikely statement in wb_domain_writeout_inc() is constantly wrong. This is due to the "not" (!) being outside the unlikely statement. It is likely that dom->period_time will be set, but unlikely that it wont be. Move the not into the unlikely statement. Link: http://lkml.kernel.org/r/20170206120035.3c2e2b91@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dc3b17cc |
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02-Feb-2017 |
Jan Kara <jack@suse.cz> |
block: Use pointer to backing_dev_info from request_queue We will want to have struct backing_dev_info allocated separately from struct request_queue. As the first step add pointer to backing_dev_info to request_queue and convert all users touching it. No functional changes in this patch. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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268f42de |
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14-Dec-2016 |
Matthew Wilcox <willy@infradead.org> |
radix-tree: delete radix_tree_range_tag_if_tagged() This is an exceptionally complicated function with just one caller (tag_pages_for_writeback). We devote a large portion of the runtime of the test suite to testing this one function which has one caller. By introducing the new function radix_tree_iter_tag_set(), we can eliminate all of the complexity while keeping the performance. The caller can now use a fairly standard radix_tree_for_each() loop, and it doesn't need to worry about tricksy things like 'start' wrapping. The test suite continues to spend a large amount of time investigating this function, but now it's testing the underlying primitives such as radix_tree_iter_resume() and the radix_tree_for_each_tagged() iterator which are also used by other parts of the kernel. Link: http://lkml.kernel.org/r/1480369871-5271-57-git-send-email-mawilcox@linuxonhyperv.com Signed-off-by: Matthew Wilcox <willy@infradead.org> Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b57d74af |
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01-Sep-2016 |
Jens Axboe <axboe@fb.com> |
writeback: track if we're sleeping on progress in balance_dirty_pages() Note in the bdi_writeback structure whenever a task ends up sleeping waiting for progress. We can use that information in the lower layers to increase the priority of writes. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Jan Kara <jack@suse.cz>
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371a096e |
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07-Oct-2016 |
Huang Ying <ying.huang@intel.com> |
mm: don't use radix tree writeback tags for pages in swap cache File pages use a set of radix tree tags (DIRTY, TOWRITE, WRITEBACK, etc.) to accelerate finding the pages with a specific tag in the radix tree during inode writeback. But for anonymous pages in the swap cache, there is no inode writeback. So there is no need to find the pages with some writeback tags in the radix tree. It is not necessary to touch radix tree writeback tags for pages in the swap cache. Per Rik van Riel's suggestion, a new flag AS_NO_WRITEBACK_TAGS is introduced for address spaces which don't need to update the writeback tags. The flag is set for swap caches. It may be used for DAX file systems, etc. With this patch, the swap out bandwidth improved 22.3% (from ~1.2GB/s to ~1.48GBps) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. The improvement comes from the reduced contention on the swap cache radix tree lock. To test sequential swapping out, the test case uses 8 processes, which sequentially allocate and write to the anonymous pages until RAM and part of the swap device is used up. Details of comparison is as follow, base base+patch ---------------- -------------------------- %stddev %change %stddev \ | \ 2506952 ± 2% +28.1% 3212076 ± 7% vm-scalability.throughput 1207402 ± 7% +22.3% 1476578 ± 6% vmstat.swap.so 10.86 ± 12% -23.4% 8.31 ± 16% perf-profile.cycles-pp._raw_spin_lock_irq.__add_to_swap_cache.add_to_swap_cache.add_to_swap.shrink_page_list 10.82 ± 13% -33.1% 7.24 ± 14% perf-profile.cycles-pp._raw_spin_lock_irqsave.__remove_mapping.shrink_page_list.shrink_inactive_list.shrink_zone_memcg 10.36 ± 11% -100.0% 0.00 ± -1% perf-profile.cycles-pp._raw_spin_lock_irqsave.__test_set_page_writeback.bdev_write_page.__swap_writepage.swap_writepage 10.52 ± 12% -100.0% 0.00 ± -1% perf-profile.cycles-pp._raw_spin_lock_irqsave.test_clear_page_writeback.end_page_writeback.page_endio.pmem_rw_page Link: http://lkml.kernel.org/r/1472578089-5560-1-git-send-email-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bf484383 |
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07-Oct-2016 |
Michal Hocko <mhocko@suse.com> |
mm, vmscan: get rid of throttle_vm_writeout throttle_vm_writeout() was introduced back in 2005 to fix OOMs caused by excessive pageout activity during the reclaim. Too many pages could be put under writeback therefore LRUs would be full of unreclaimable pages until the IO completes and in turn the OOM killer could be invoked. There have been some important changes introduced since then in the reclaim path though. Writers are throttled by balance_dirty_pages when initiating the buffered IO and later during the memory pressure, the direct reclaim is throttled by wait_iff_congested if the node is considered congested by dirty pages on LRUs and the underlying bdi is congested by the queued IO. The kswapd is throttled as well if it encounters pages marked for immediate reclaim or under writeback which signals that that there are too many pages under writeback already. Finally should_reclaim_retry does congestion_wait if the reclaim cannot make any progress and there are too many dirty/writeback pages. Another important aspect is that we do not issue any IO from the direct reclaim context anymore. In a heavy parallel load this could queue a lot of IO which would be very scattered and thus unefficient which would just make the problem worse. This three mechanisms should throttle and keep the amount of IO in a steady state even under heavy IO and memory pressure so yet another throttling point doesn't really seem helpful. Quite contrary, Mikulas Patocka has reported that swap backed by dm-crypt doesn't work properly because the swapout IO cannot make sufficient progress as the writeout path depends on dm_crypt worker which has to allocate memory to perform the encryption. In order to guarantee a forward progress it relies on the mempool allocator. mempool_alloc(), however, prefers to use the underlying (usually page) allocator before it grabs objects from the pool. Such an allocation can dive into the memory reclaim and consequently to throttle_vm_writeout. If there are too many dirty or pages under writeback it will get throttled even though it is in fact a flusher to clear pending pages. kworker/u4:0 D ffff88003df7f438 10488 6 2 0x00000000 Workqueue: kcryptd kcryptd_crypt [dm_crypt] Call Trace: schedule+0x3c/0x90 schedule_timeout+0x1d8/0x360 io_schedule_timeout+0xa4/0x110 congestion_wait+0x86/0x1f0 throttle_vm_writeout+0x44/0xd0 shrink_zone_memcg+0x613/0x720 shrink_zone+0xe0/0x300 do_try_to_free_pages+0x1ad/0x450 try_to_free_pages+0xef/0x300 __alloc_pages_nodemask+0x879/0x1210 alloc_pages_current+0xa1/0x1f0 new_slab+0x2d7/0x6a0 ___slab_alloc+0x3fb/0x5c0 __slab_alloc+0x51/0x90 kmem_cache_alloc+0x27b/0x310 mempool_alloc_slab+0x1d/0x30 mempool_alloc+0x91/0x230 bio_alloc_bioset+0xbd/0x260 kcryptd_crypt+0x114/0x3b0 [dm_crypt] Let's just drop throttle_vm_writeout altogether. It is not very much helpful anymore. I have tried to test a potential writeback IO runaway similar to the one described in the original patch which has introduced that [1]. Small virtual machine (512MB RAM, 4 CPUs, 2G of swap space and disk image on a rather slow NFS in a sync mode on the host) with 8 parallel writers each writing 1G worth of data. As soon as the pagecache fills up and the direct reclaim hits then I start anon memory consumer in a loop (allocating 300M and exiting after populating it) in the background to make the memory pressure even stronger as well as to disrupt the steady state for the IO. The direct reclaim is throttled because of the congestion as well as kswapd hitting congestion_wait due to nr_immediate but throttle_vm_writeout doesn't ever trigger the sleep throughout the test. Dirty+writeback are close to nr_dirty_threshold with some fluctuations caused by the anon consumer. [1] https://www2.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc1/2.6.9-rc1-mm3/broken-out/vm-pageout-throttling.patch Link: http://lkml.kernel.org/r/1471171473-21418-1-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Mikulas Patocka <mpatocka@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: NeilBrown <neilb@suse.com> Cc: Ondrej Kozina <okozina@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1d7ac6ae |
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18-Aug-2016 |
Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
mm/writeback: Convert to hotplug state machine Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jens Axboe <axboe@fb.com> Cc: linux-mm@kvack.org Cc: rt@linutronix.de Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20160818125731.27256-6-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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5a1c84b4 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: remove reclaim and compaction retry approximations If per-zone LRU accounting is available then there is no point approximating whether reclaim and compaction should retry based on pgdat statistics. This is effectively a revert of "mm, vmstat: remove zone and node double accounting by approximating retries" with the difference that inactive/active stats are still available. This preserves the history of why the approximation was retried and why it had to be reverted to handle OOM kills on 32-bit systems. Link: http://lkml.kernel.org/r/1469110261-7365-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bb4cc2be |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: remove highmem_file_pages With the reintroduction of per-zone LRU stats, highmem_file_pages is redundant so remove it. [mgorman@techsingularity.net: wrong stat is being accumulated in highmem_dirtyable_memory] Link: http://lkml.kernel.org/r/20160725092324.GM10438@techsingularity.netLink: http://lkml.kernel.org/r/1469110261-7365-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9cb937e2 |
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28-Jul-2016 |
Minchan Kim <minchan@kernel.org> |
mm, page_alloc: fix dirtyable highmem calculation When I tested vmscale in mmtest in 32bit, I found the benchmark was slow down 0.5 times. base node 1 global-1 User 12.98 16.04 System 147.61 166.42 Elapsed 26.48 38.08 With vmstat, I found IO wait avg is much increased compared to base. The reason was highmem_dirtyable_memory accumulates free pages and highmem_file_pages from HIGHMEM to MOVABLE zones which was wrong. With that, dirth_thresh in throtlle_vm_write is always 0 so that it calls congestion_wait frequently if writeback starts. With this patch, it is much recovered. base node fi 1 global-1 fix User 12.98 16.04 13.78 System 147.61 166.42 143.92 Elapsed 26.48 38.08 29.64 Link: http://lkml.kernel.org/r/1468404004-5085-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bca67592 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmstat: remove zone and node double accounting by approximating retries The number of LRU pages, dirty pages and writeback pages must be accounted for on both zones and nodes because of the reclaim retry logic, compaction retry logic and highmem calculations all depending on per-zone stats. Many lowmem allocations are immune from OOM kill due to a check in __alloc_pages_may_oom for (ac->high_zoneidx < ZONE_NORMAL) since commit 03668b3ceb0c ("oom: avoid oom killer for lowmem allocations"). The exception is costly high-order allocations or allocations that cannot fail. If the __alloc_pages_may_oom avoids OOM-kill for low-order lowmem allocations then it would fall through to __alloc_pages_direct_compact. This patch will blindly retry reclaim for zone-constrained allocations in should_reclaim_retry up to MAX_RECLAIM_RETRIES. This is not ideal but without per-zone stats there are not many alternatives. The impact it that zone-constrained allocations may delay before considering the OOM killer. As there is no guarantee enough memory can ever be freed to satisfy compaction, this patch avoids retrying compaction for zone-contrained allocations. In combination, that means that the per-node stats can be used when deciding whether to continue reclaim using a rough approximation. While it is possible this will make the wrong decision on occasion, it will not infinite loop as the number of reclaim attempts is capped by MAX_RECLAIM_RETRIES. The final step is calculating the number of dirtyable highmem pages. As those calculations only care about the global count of file pages in highmem. This patch uses a global counter used instead of per-zone stats as it is sufficient. In combination, this allows the per-zone LRU and dirty state counters to be removed. [mgorman@techsingularity.net: fix acct_highmem_file_pages()] Link: http://lkml.kernel.org/r/1468853426-12858-4-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-35-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Suggested by: Michal Hocko <mhocko@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c4a25635 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: move vmscan writes and file write accounting to the node As reclaim is now node-based, it follows that page write activity due to page reclaim should also be accounted for on the node. For consistency, also account page writes and page dirtying on a per-node basis. After this patch, there are a few remaining zone counters that may appear strange but are fine. NUMA stats are still per-zone as this is a user-space interface that tools consume. NR_MLOCK, NR_SLAB_*, NR_PAGETABLE, NR_KERNEL_STACK and NR_BOUNCE are all allocations that potentially pin low memory and cannot trivially be reclaimed on demand. This information is still useful for debugging a page allocation failure warning. Link: http://lkml.kernel.org/r/1467970510-21195-21-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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11fb9989 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm: move most file-based accounting to the node There are now a number of accounting oddities such as mapped file pages being accounted for on the node while the total number of file pages are accounted on the zone. This can be coped with to some extent but it's confusing so this patch moves the relevant file-based accounted. Due to throttling logic in the page allocator for reliable OOM detection, it is still necessary to track dirty and writeback pages on a per-zone basis. [mgorman@techsingularity.net: fix NR_ZONE_WRITE_PENDING accounting] Link: http://lkml.kernel.org/r/1468404004-5085-5-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-20-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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281e3726 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, page_alloc: consider dirtyable memory in terms of nodes Historically dirty pages were spread among zones but now that LRUs are per-node it is more appropriate to consider dirty pages in a node. Link: http://lkml.kernel.org/r/1467970510-21195-17-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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599d0c95 |
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28-Jul-2016 |
Mel Gorman <mgorman@techsingularity.net> |
mm, vmscan: move LRU lists to node This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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800d8c63 |
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26-Jul-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
shmem: add huge pages support Here's basic implementation of huge pages support for shmem/tmpfs. It's all pretty streight-forward: - shmem_getpage() allcoates huge page if it can and try to inserd into radix tree with shmem_add_to_page_cache(); - shmem_add_to_page_cache() puts the page onto radix-tree if there's space for it; - shmem_undo_range() removes huge pages, if it fully within range. Partial truncate of huge pages zero out this part of THP. This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE) behaviour. As we don't really create hole in this case, lseek(SEEK_HOLE) may have inconsistent results depending what pages happened to be allocated. - no need to change shmem_fault: core-mm will map an compound page as huge if VMA is suitable; Link: http://lkml.kernel.org/r/1466021202-61880-30-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6c60d2b5 |
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26-Jul-2016 |
Dave Chinner <dchinner@redhat.com> |
fs/fs-writeback.c: add a new writeback list for sync wait_sb_inodes() currently does a walk of all inodes in the filesystem to find dirty one to wait on during sync. This is highly inefficient and wastes a lot of CPU when there are lots of clean cached inodes that we don't need to wait on. To avoid this "all inode" walk, we need to track inodes that are currently under writeback that we need to wait for. We do this by adding inodes to a writeback list on the sb when the mapping is first tagged as having pages under writeback. wait_sb_inodes() can then walk this list of "inodes under IO" and wait specifically just for the inodes that the current sync(2) needs to wait for. Define a couple helpers to add/remove an inode from the writeback list and call them when the overall mapping is tagged for or cleared from writeback. Update wait_sb_inodes() to walk only the inodes under writeback due to the sync. With this change, filesystem sync times are significantly reduced for fs' with largely populated inode caches and otherwise no other work to do. For example, on a 16xcpu 2GHz x86-64 server, 10TB XFS filesystem with a ~10m entry inode cache, sync times are reduced from ~7.3s to less than 0.1s when the filesystem is fully clean. Link: http://lkml.kernel.org/r/1466594593-6757-2-git-send-email-bfoster@redhat.com Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Tested-by: Holger Hoffstätte <holger.hoffstaette@applied-asynchrony.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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62a584fe |
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27-May-2016 |
Tejun Heo <tj@kernel.org> |
writeback: use higher precision calculation in domain_dirty_limits() As vm.dirty_[background_]bytes can't be applied verbatim to multiple cgroup writeback domains, they get converted to percentages in domain_dirty_limits() and applied the same way as vm.dirty_[background]ratio. However, if the specified bytes is lower than 1% of available memory, the calculated ratios become zero and the writeback domain gets throttled constantly. Fix it by using per-PAGE_SIZE instead of percentage for ratio calculations. Also, the updated DIV_ROUND_UP() usages now should yield 1/4096 (0.0244%) as the minimum ratio as long as the specified bytes are above zero. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Miao Xie <miaoxie@huawei.com> Link: http://lkml.kernel.org/g/57333E75.3080309@huawei.com Cc: stable@vger.kernel.org # v4.2+ Fixes: 9fc3a43e1757 ("writeback: separate out domain_dirty_limits()") Reviewed-by: Jan Kara <jack@suse.cz> Adjusted comment based on Jan's suggestion. Signed-off-by: Jens Axboe <axboe@fb.com>
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a53eaff8 |
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20-May-2016 |
NeilBrown <neilb@suse.com> |
MM: increase safety margin provided by PF_LESS_THROTTLE When nfsd is exporting a filesystem over NFS which is then NFS-mounted on the local machine there is a risk of deadlock. This happens when there are lots of dirty pages in the NFS filesystem and they cause NFSD to be throttled, either in throttle_vm_writeout() or in balance_dirty_pages(). To avoid this problem the PF_LESS_THROTTLE flag is set for NFSD threads and it provides a 25% increase to the limits that affect NFSD. Any process writing to an NFS filesystem will be throttled well before the number of dirty NFS pages reaches the limit imposed on NFSD, so NFSD will not deadlock on pages that it needs to write out. At least it shouldn't. All processes are allowed a small excess margin to avoid performing too many calculations: ratelimit_pages. ratelimit_pages is set so that if a thread on every CPU uses the entire margin, the total will only go 3% over the limit, and this is much less than the 25% bonus that PF_LESS_THROTTLE provides, so this margin shouldn't be a problem. But it is. The "total memory" that these 3% and 25% are calculated against are not really total memory but are "global_dirtyable_memory()" which doesn't include anonymous memory, just free memory and page-cache memory. The "ratelimit_pages" number is based on whatever the global_dirtyable_memory was on the last CPU hot-plug, which might not be what you expect, but is probably close to the total freeable memory. The throttle threshold uses the global_dirtable_memory at the moment when the throttling happens, which could be much less than at the last CPU hotplug. So if lots of anonymous memory has been allocated, thus pushing out lots of page-cache pages, then NFSD might end up being throttled due to dirty NFS pages because the "25%" bonus it gets is calculated against a rather small amount of dirtyable memory, while the "3%" margin that other processes are allowed to dirty without penalty is calculated against a much larger number. To remove this possibility of deadlock we need to make sure that the margin granted to PF_LESS_THROTTLE exceeds that rate-limit margin. Simply adding ratelimit_pages isn't enough as that should be multiplied by the number of cpus. So add "global_wb_domain.dirty_limit / 32" as that more accurately reflects the current total over-shoot margin. This ensures that the number of dirty NFS pages never gets so high that nfsd will be throttled waiting for them to be written. Link: http://lkml.kernel.org/r/87futgowwv.fsf@notabene.neil.brown.name Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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09b4ab3c |
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19-May-2016 |
Joonsoo Kim <iamjoonsoo.kim@lge.com> |
mm/writeback: correct dirty page calculation for highmem ZONE_MOVABLE could be treated as highmem so we need to consider it for accurate calculation of dirty pages. And, in following patches, ZONE_CMA will be introduced and it can be treated as highmem, too. So, instead of manually adding stat of ZONE_MOVABLE, looping all zones and check whether the zone is highmem or not and add stat of the zone which can be treated as highmem. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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74d36944 |
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09-Mar-2016 |
Howard Cochran <hcochran@kernelspring.com> |
writeback: Fix performance regression in wb_over_bg_thresh() Commit 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") unintentionally changed this function's meaning from "are there more dirty pages than the background writeback threshold" to "are there more dirty pages than the writeback threshold". The background writeback threshold is typically half of the writeback threshold, so this had the effect of raising the number of dirty pages required to cause a writeback worker to perform background writeout. This can cause a very severe performance regression when a BDI uses BDI_CAP_STRICTLIMIT because balance_dirty_pages() and the writeback worker can now disagree on whether writeback should be initiated. For example, in a system having 1GB of RAM, a single spinning disk, and a "pass-through" FUSE filesystem mounted over the disk, application code mmapped a 128MB file on the disk and was randomly dirtying pages in that mapping. Because FUSE uses strictlimit and has a default max_ratio of only 1%, in balance_dirty_pages, thresh is ~200, bg_thresh is ~100, and the dirty_freerun_ceiling is the average of those, ~150. So, it pauses the dirtying processes when we have 151 dirty pages and wakes up a background writeback worker. But the worker tests the wrong threshold (200 instead of 100), so it does not initiate writeback and just returns. Thus, balance_dirty_pages keeps looping, sleeping and then waking up the worker who will do nothing. It remains stuck in this state until the few dirty pages that we have finally expire and we write them back for that reason. Then the whole process repeats, resulting in near-zero throughput through the FUSE BDI. The fix is to call the parameterized variant of wb_calc_thresh, so that the worker will do writeback if the bg_thresh is exceeded which was the behavior before the referenced commit. Fixes: 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") Signed-off-by: Howard Cochran <hcochran@kernelspring.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org> # v4.2+ Tested-by Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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81b76485 |
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09-Mar-2016 |
Howard Cochran <hcochran@kernelspring.com> |
writeback: Fix performance regression in wb_over_bg_thresh() Commit 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") unintentionally changed this function's meaning from "are there more dirty pages than the background writeback threshold" to "are there more dirty pages than the writeback threshold". The background writeback threshold is typically half of the writeback threshold, so this had the effect of raising the number of dirty pages required to cause a writeback worker to perform background writeout. This can cause a very severe performance regression when a BDI uses BDI_CAP_STRICTLIMIT because balance_dirty_pages() and the writeback worker can now disagree on whether writeback should be initiated. For example, in a system having 1GB of RAM, a single spinning disk, and a "pass-through" FUSE filesystem mounted over the disk, application code mmapped a 128MB file on the disk and was randomly dirtying pages in that mapping. Because FUSE uses strictlimit and has a default max_ratio of only 1%, in balance_dirty_pages, thresh is ~200, bg_thresh is ~100, and the dirty_freerun_ceiling is the average of those, ~150. So, it pauses the dirtying processes when we have 151 dirty pages and wakes up a background writeback worker. But the worker tests the wrong threshold (200 instead of 100), so it does not initiate writeback and just returns. Thus, balance_dirty_pages keeps looping, sleeping and then waking up the worker who will do nothing. It remains stuck in this state until the few dirty pages that we have finally expire and we write them back for that reason. Then the whole process repeats, resulting in near-zero throughput through the FUSE BDI. The fix is to call the parameterized variant of wb_calc_thresh, so that the worker will do writeback if the bg_thresh is exceeded which was the bahavior before the referenced commit. Fixes: 947e9762a8dd ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations") Signed-off-by: Howard Cochran <hcochran@kernelspring.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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09cbfeaf |
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01-Apr-2016 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fdf1cdb9 |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: remove unnecessary uses of lock_page_memcg() There are several users that nest lock_page_memcg() inside lock_page() to prevent page->mem_cgroup from changing. But the page lock prevents pages from moving between cgroups, so that is unnecessary overhead. Remove lock_page_memcg() in contexts with locked contexts and fix the debug code in the page stat functions to be okay with the page lock. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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62cccb8c |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: simplify lock_page_memcg() Now that migration doesn't clear page->mem_cgroup of live pages anymore, it's safe to make lock_page_memcg() and the memcg stat functions take pages, and spare the callers from memcg objects. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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81f8c3a4 |
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15-Mar-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: generalize locking for the page->mem_cgroup binding These patches tag the page cache radix tree eviction entries with the memcg an evicted page belonged to, thus making per-cgroup LRU reclaim work properly and be as adaptive to new cache workingsets as global reclaim already is. This should have been part of the original thrash detection patch series, but was deferred due to the complexity of those patches. This patch (of 5): So far the only sites that needed to exclude charge migration to stabilize page->mem_cgroup have been per-cgroup page statistics, hence the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection will add another site that needs to ensure page->mem_cgroup lifetime. Rename these locking functions to the more generic lock_page_memcg() and unlock_page_memcg(). Since charge migration is a cgroup1 feature only, we might be able to delete it at some point, and these now easy to identify locking sites along with it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d59b1087 |
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15-Mar-2016 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
mm/page-writeback: fix dirty_ratelimit calculation Calculation of dirty_ratelimit sometimes is not correct. E.g. initial values of dirty_ratelimit == INIT_BW and step == 0, lead to the following result: UBSAN: Undefined behaviour in ../mm/page-writeback.c:1286:7 shift exponent 25600 is too large for 64-bit type 'long unsigned int' The fix is straightforward - make step 0 if the shift exponent is too big. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a8d01437 |
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14-Jan-2016 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: page_alloc: generalize the dirty balance reserve The dirty balance reserve that dirty throttling has to consider is merely memory not available to userspace allocations. There is nothing writeback-specific about it. Generalize the name so that it's reusable outside of that context. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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90eec103 |
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16-Nov-2015 |
Peter Zijlstra <peterz@infradead.org> |
treewide: Remove old email address There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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50e55bf6 |
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20-Nov-2015 |
Yang Shi <yang.shi@linaro.org> |
mm/page-writeback.c: initialize m_dirty to avoid compile warning When building kernel with gcc 5.2, the below warning is raised: mm/page-writeback.c: In function 'balance_dirty_pages.isra.10': mm/page-writeback.c:1545:17: warning: 'm_dirty' may be used uninitialized in this function [-Wmaybe-uninitialized] unsigned long m_dirty, m_thresh, m_bg_thresh; The m_dirty{thresh, bg_thresh} are initialized in the block of "if (mdtc)", so if mdts is null, they won't be initialized before being used. Initialize m_dirty to zero, also initialize m_thresh and m_bg_thresh to keep consistency. They are used later by if condition: !mdtc || m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh) If mdtc is null, dirty_freerun_ceiling will not be called at all, so the initialization will not change any behavior other than just ceasing the compile warning. (akpm: the patch actually reduces .text size by ~20 bytes on gcc-4.x.y) [akpm@linux-foundation.org: add comment] Signed-off-by: Yang Shi <yang.shi@linaro.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c5edf9cd |
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29-Sep-2015 |
Tejun Heo <tj@kernel.org> |
writeback: fix incorrect calculation of available memory for memcg domains For memcg domains, the amount of available memory was calculated as min(the amount currently in use + headroom according to memcg, total clean memory) This isn't quite correct as what should be capped by the amount of clean memory is the headroom, not the sum of memory in use and headroom. For example, if a memcg domain has a significant amount of dirty memory, the above can lead to a value which is lower than the current amount in use which doesn't make much sense. In most circumstances, the above leads to a number which is somewhat but not drastically lower. As the amount of memory which can be readily allocated to the memcg domain is capped by the amount of system-wide clean memory which is not already assigned to the memcg itself, the number we want is the amount currently in use + min(headroom according to memcg, clean memory elsewhere in the system) This patch updates mem_cgroup_wb_stats() to return the number of filepages and headroom instead of the calculated available pages. mdtc_cap_avail() is renamed to mdtc_calc_avail() and performs the above calculation from file, headroom, dirty and globally clean pages. v2: Dummy mem_cgroup_wb_stats() implementation wasn't updated leading to build failure when !CGROUP_WRITEBACK. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: c2aa723a6093 ("writeback: implement memcg writeback domain based throttling") Signed-off-by: Jens Axboe <axboe@fb.com>
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#
d60d1bdd |
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28-Sep-2015 |
Tejun Heo <tj@kernel.org> |
writeback: memcg dirty_throttle_control should be initialized with wb->memcg_completions MDTC_INIT() is used to initialize dirty_throttle_control for memcg domains. It used DTC_INIT_COMMON() to initialized mdtc->wb and ->wb_completions which is incorrect as DTC_INIT_COMMON() sets the latter to wb->completions instead of wb->memcg_completions. This can lead to wildly incorrect results when calculating the proportion of dirty memory the memcg domain should get. Remove DTC_INIT_COMMON() and update MDTC_INIT() to initialize mdtc->wb_completions to wb->memcg_completions. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: c2aa723a6093 ("writeback: implement memcg writeback domain based throttling") Signed-off-by: Jens Axboe <axboe@fb.com>
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b817525a |
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02-Oct-2015 |
Tejun Heo <tj@kernel.org> |
writeback: bdi_writeback iteration must not skip dying ones bdi_for_each_wb() is used in several places to wake up or issue writeback work items to all wb's (bdi_writeback's) on a given bdi. The iteration is performed by walking bdi->cgwb_tree; however, the tree only indexes wb's which are currently active. For example, when a memcg gets associated with a different blkcg, the old wb is removed from the tree so that the new one can be indexed. The old wb starts dying from then on but will linger till all its inodes are drained. As these dying wb's may still host dirty inodes, writeback operations which affect all wb's must include them. bdi_for_each_wb() skipping dying wb's led to sync(2) missing and failing to sync the inodes belonging to those wb's. This patch adds a RCU protected @bdi->wb_list which lists all wb's beloinging to that bdi. wb's are added on creation and removed on release rather than on the start of destruction. bdi_for_each_wb() usages are replaced with list_for_each[_continue]_rcu() iterations over @bdi->wb_list and bdi_for_each_wb() and its helpers are removed. v2: Updated as per Jan. last_wb ref leak in bdi_split_work_to_wbs() fixed and unnecessary list head severing in cgwb_bdi_destroy() removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Artem Bityutskiy <dedekind1@gmail.com> Fixes: ebe41ab0c79d ("writeback: implement bdi_for_each_wb()") Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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9ad18ab9 |
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28-Sep-2015 |
Tejun Heo <tj@kernel.org> |
writeback: laptop_mode_timer_fn() needs rcu_read_lock() around bdi_writeback iteration laptop_mode_timer_fn() was using bdi_for_each_wb() without the required RCU locking leading to the following warning. WARNING: CPU: 0 PID: 0 at include/linux/backing-dev.h:415 laptop_mode_timer_fn+0x106/0x170() ... Call Trace: <IRQ> [<ffffffff81480cdc>] dump_stack+0x4e/0x82 [<ffffffff81051912>] warn_slowpath_common+0x82/0xc0 [<ffffffff81051a0a>] warn_slowpath_null+0x1a/0x20 [<ffffffff8115f0e6>] laptop_mode_timer_fn+0x106/0x170 [<ffffffff810ca8e3>] call_timer_fn+0xb3/0x2f0 [<ffffffff810cad25>] run_timer_softirq+0x205/0x370 [<ffffffff81056854>] __do_softirq+0xd4/0x460 [<ffffffff81056d69>] irq_exit+0x89/0xa0 [<ffffffff8185a892>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff81858a44>] apic_timer_interrupt+0x84/0x90 ... Fix it by adding rcu_read_lock() around the iteration. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: a06fd6b10228 ("writeback: make laptop_mode_timer_fn() handle multiple bdi_writeback's") Reviewed-by: Jan Kara <jack@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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5634cc2a |
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18-Aug-2015 |
Tejun Heo <tj@kernel.org> |
writeback: update writeback tracepoints to report cgroup The following tracepoints are updated to report the cgroup used during cgroup writeback. * writeback_write_inode[_start] * writeback_queue * writeback_exec * writeback_start * writeback_written * writeback_wait * writeback_nowork * writeback_wake_background * wbc_writepage * writeback_queue_io * bdi_dirty_ratelimit * balance_dirty_pages * writeback_sb_inodes_requeue * writeback_single_inode[_start] Note that writeback_bdi_register is separated out from writeback_class as reporting cgroup doesn't make sense to it. Tracepoints which take bdi are updated to take bdi_writeback instead. Signed-off-by: Tejun Heo <tj@kernel.org> Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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a50fcb51 |
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06-Aug-2015 |
Rabin Vincent <rabin.vincent@axis.com> |
writeback: fix initial dirty limit The initial value of global_wb_domain.dirty_limit set by writeback_set_ratelimit() is zeroed out by the memset in wb_domain_init(). Signed-off-by: Rabin Vincent <rabin.vincent@axis.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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682aa8e1 |
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28-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement unlocked_inode_to_wb transaction and use it for stat updates The mechanism for detecting whether an inode should switch its wb (bdi_writeback) association is now in place. This patch build the framework for the actual switching. This patch adds a new inode flag I_WB_SWITCHING, which has two functions. First, the easy one, it ensures that there's only one switching in progress for a give inode. Second, it's used as a mechanism to synchronize wb stat updates. The two stats, WB_RECLAIMABLE and WB_WRITEBACK, aren't event counters but track the current number of dirty pages and pages under writeback respectively. As such, when an inode is moved from one wb to another, the inode's portion of those stats have to be transferred together; unfortunately, this is a bit tricky as those stat updates are percpu operations which are performed without holding any lock in some places. This patch solves the problem in a similar way as memcg. Each such lockless stat updates are wrapped in transaction surrounded by unlocked_inode_to_wb_begin/end(). During normal operation, they map to rcu_read_lock/unlock(); however, if I_WB_SWITCHING is asserted, mapping->tree_lock is grabbed across the transaction. In turn, the switching path sets I_WB_SWITCHING and waits for a RCU grace period to pass before actually starting to switch, which guarantees that all stat update paths are synchronizing against mapping->tree_lock. This patch still doesn't implement the actual switching. v3: Updated on top of the recent cancel_dirty_page() updates. unlocked_inode_to_wb_begin() now nests inside mem_cgroup_begin_page_stat() to match the locking order. v2: The i_wb access transaction will be used for !stat accesses too. Function names and comments updated accordingly. s/inode_wb_stat_unlocked_{begin|end}/unlocked_inode_to_wb_{begin|end}/ s/switch_wb/switch_wbs/ Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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c2aa723a |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement memcg writeback domain based throttling While cgroup writeback support now connects memcg and blkcg so that writeback IOs are properly attributed and controlled, the IO back pressure propagation mechanism implemented in balance_dirty_pages() and its subroutines wasn't aware of cgroup writeback. Processes belonging to a memcg may have access to only subset of total memory available in the system and not factoring this into dirty throttling rendered it completely ineffective for processes under memcg limits and memcg ended up building a separate ad-hoc degenerate mechanism directly into vmscan code to limit page dirtying. The previous patches updated balance_dirty_pages() and its subroutines so that they can deal with multiple wb_domain's (writeback domains) and defined per-memcg wb_domain. Processes belonging to a non-root memcg are bound to two wb_domains, global wb_domain and memcg wb_domain, and should be throttled according to IO pressures from both domains. This patch updates dirty throttling code so that it repeats similar calculations for the two domains - the differences between the two are few and minor - and applies the lower of the two sets of resulting constraints. wb_over_bg_thresh(), which controls when background writeback terminates, is also updated to consider both global and memcg wb_domains. It returns true if dirty is over bg_thresh for either domain. This makes the dirty throttling mechanism operational for memcg domains including writeback-bandwidth-proportional dirty page distribution inside them but the ad-hoc memcg throttling mechanism in vmscan is still in place. The next patch will rip it out. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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841710aa |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement memcg wb_domain Dirtyable memory is distributed to a wb (bdi_writeback) according to the relative bandwidth the wb is writing out in the whole system. This distribution is global - each wb is measured against all other wb's and gets the proportinately sized portion of the memory in the whole system. For cgroup writeback, the amount of dirtyable memory is scoped by memcg and thus each wb would need to be measured and controlled in its memcg. IOW, a wb will belong to two writeback domains - the global and memcg domains. The previous patches laid the groundwork to support the two wb_domains and this patch implements memcg wb_domain. memcg->cgwb_domain is initialized on css online and destroyed on css release, wb->memcg_completions is added, and __wb_writeout_inc() is updated to increment completions against both global and memcg wb_domains. The following patches will update balance_dirty_pages() and its subroutines to actually consider memcg wb_domain for throttling. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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947e9762 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: update wb_over_bg_thresh() to use wb_domain aware operations wb_over_bg_thresh() currently uses global_dirty_limits() and wb_dirty_limit() both of which are wrappers around operations which take dirty_throttle_control. For cgroup writeback support, the function will be updated to also consider memcg wb_domains which requires the context information carried in dirty_throttle_control. This patch updates wb_over_bg_thresh() so that it uses the underlying wb_domain aware operations directly and builds the global dirty_throttle_control in the process. This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
aa661bbe |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: move over_bground_thresh() to mm/page-writeback.c and rename it to wb_over_bg_thresh(). The function is closely tied to the dirty throttling mechanism implemented in page-writeback.c. This relocation will allow future updates necessary for cgroup writeback support. While at it, add function comment. This is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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9fc3a43e |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: separate out domain_dirty_limits() global_dirty_limits() calculates thresh and bg_thresh (confusingly called *pdirty and *pbackground in the function) assuming global_wb_domain; however, cgroup writeback support requires considering per-memcg wb_domain too. This patch separates out domain_dirty_limits() which takes dirty_throttle_control out of global_dirty_limits(). As thresh and bg_thresh calculation needs the amount of dirtyable memory in the domain, dirty_throttle_control->avail is added. The new function calculates the two thresholds and store them directly in the dirty_throttle_control. Also, as memcg domains can't follow vm_dirty_bytes and dirty_background_bytes settings directly. If those are set and domain_dirty_limits() is invoked for a !global domain, the settings are translated to ratios by scaling them against globally available memory. dirty_throttle_control->gdtc is added to enable this when CONFIG_CGROUP_WRITEBACK. global_dirty_limits() is now a thin wrapper around domain_dirty_limits() and balance_dirty_pages() is updated to use the new function too. This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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c7981433 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make __wb_writeout_inc() and hard_dirty_limit() take wb_domaas a parameter Currently __wb_writeout_inc() and hard_dirty_limit() assume global_wb_domain; however, cgroup writeback support requires considering per-memcg wb_domain too. This patch separates out domain-specific part of __wb_writeout_inc() into wb_domain_writeout_inc() which takes wb_domain as a parameter and adds the parameter to hard_dirty_limit(). This will allow these two functions to handle per-memcg wb_domains. This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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e9f07dfd |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: add dirty_throttle_control->dom Currently all dirty throttle operations use global_wb_domain; however, cgroup writeback support requires considering per-memcg wb_domain too. This patch adds dirty_throttle_control->dom and updates functions which are directly using globabl_wb_domain to use it instead. As this makes global_update_bandwidth() a misnomer, the function is renamed to domain_update_bandwidth(). This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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e9770b34 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: add dirty_throttle_control->wb_completions wb->completions measures the wb's proportional write bandwidth in global_wb_domain and thus naturally tied to the wb_domain. This patch adds dirty_throttle_control->wb_completions which is initialized to wb->completions by GDTC_INIT() and updates __wb_dirty_limits() to use it instead of dereferencing wb->completions directly. This will allow dirty_throttle_control to represent different wb_domains and the matching wb completions. This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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daddfa3c |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: add dirty_throttle_control->pos_ratio wb_position_ratio() is used to calculate pos_ratio, which is used for two purposes. wb_update_dirty_ratelimit() uses it to adjust wb->[balanced_]dirty_ratelimit gradually and balance_dirty_pages() to immediately adjust dirty_ratelimit right before applying it to determine pause duration. While wb_update_dirty_ratelimit() is separately rate limited from balance_dirty_pages(), on the run where the ratelimit is updated, we end up calculating pos_ratio twice with the same parameters. This patch adds dirty_throttle_control->pos_ratio. balance_dirty_pages() calculates it once per run and wb_update_dirty_ratelimit() uses the value stored in dirty_throttle_control. This removes the duplicate calculation and also will help implementing memcg wb_domain. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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b1cbc6d4 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make __wb_calc_thresh() take dirty_throttle_control wb_calc_thresh() calculates wb_thresh by scaling thresh according to the wb's portion in the system-wide write bandwidth. cgroup writeback support would need to calculate wb_thresh against memcg domain too. This patch renames wb_calc_thresh() to __wb_calc_thresh() and makes it take dirty_throttle_control so that the function can later be updated to calculate against different domains according to dirty_throttle_control. wb_calc_thresh() is now a thin wrapper around __wb_calc_thresh(). v2: The original version was incorrectly scaling dtc->dirty instead of dtc->thresh. This was due to the extremely confusing function and variable names. Added a rename patch and fixed this one. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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970fb01a |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: add dirty_throttle_control->wb_bg_thresh wb_bg_thresh is currently treated as a second-class citizen. It's only used when BDI_CAP_STRICTLIMIT is set and balance_dirty_pages() doesn't calculate it unless the cap is set. When the cap is set, the calculated value is not passed around but instead recalculated whenever it's used. wb_position_ratio() calculates it by scaling wb_thresh proportional to bg_thresh / thresh. wb_update_dirty_ratelimit() uses wb_dirty_limit() on bg_thresh, which should generally lead to a similar result as the proportional scaling but can also be way off in the presence of max/min_ratio settings. Avoiding wb_bg_thresh calculation saves us one u64 multiplication and divsion when BDI_CAP_STRICTLIMIT is not set. Given that balance_dirty_pages() is already ratelimited, this doesn't justify the incurred extra complexity. This patch adds wb_bg_thresh to dirty_throttle_control and makes wb_dirty_limits() always calculate it and updates the users to use the pre-calculated value. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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2bc00aef |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: consolidate dirty throttle parameters into dirty_throttle_control Dirty throttling implemented in balance_dirty_pages() and its subroutines makes use of a number of parameters which are passed around individually. This renders these functions somewhat unwieldy and makes it difficult to add or change the involved parameters. Also some functions use different or conflicting naming schemes for the same parameters making the code confusing to follow. This patch consolidates the main parameters into struct dirty_throttle_control so that they can be passed around easily and adding new paramters isn't painful. This also unifies how a given parameter is named and accessed. The drawback of using this type of control structure rather than explicit paramters is that it isn't immediately obvious which function accesses and modifies what; however, it's fairly clear that the benefits outweigh in this case. GDTC_INIT() macro is provided to ease initializing dirty_throttle_control for the global_wb_domain and balance_dirty_pages() uses a separate pointer to point to its global dirty_throttle_control. This is to make it uniform with memcg domain handling which will be added later. This patch doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
dcc25ae7 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: move global_dirty_limit into wb_domain This patch is a part of the series to define wb_domain which represents a domain that wb's (bdi_writeback's) belong to and are measured against each other in. This will enable IO backpressure propagation for cgroup writeback. global_dirty_limit exists to regulate the global dirty threshold which is a property of the wb_domain. This patch moves hard_dirty_limit, dirty_lock, and update_time into wb_domain. This is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
380c27ca |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement wb_domain Dirtyable memory is distributed to a wb (bdi_writeback) according to the relative bandwidth the wb is writing out in the whole system. This distribution is global - each wb is measured against all other wb's and gets the proportinately sized portion of the memory in the whole system. For cgroup writeback, the amount of dirtyable memory is scoped by memcg and thus each wb would need to be measured and controlled in its memcg. IOW, a wb will belong to two writeback domains - the global and memcg domains. Currently, what constitutes the global writeback domain are scattered across a number of global states. This patch starts collecting them into struct wb_domain. * fprop_global which serves as the basis for proportional bandwidth measurement and its period timer are moved into struct wb_domain. * global_wb_domain hosts the states for the global domain. * While at it, flatten wb_writeout_fraction() into its callers. This thin wrapper doesn't provide any actual benefits while getting in the way. This is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
8a731799 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: reorganize [__]wb_update_bandwidth() __wb_update_bandwidth() is called from two places - fs/fs-writeback.c::balance_dirty_pages() and mm/page-writeback.c::wb_writeback(). The latter updates only the write bandwidth while the former also deals with the dirty ratelimit. The two callsites are distinguished by whether @thresh parameter is zero or not, which is cryptic. In addition, the two files define their own different versions of wb_update_bandwidth() on top of __wb_update_bandwidth(), which is confusing to say the least. This patch cleans up [__]wb_update_bandwidth() in the following ways. * __wb_update_bandwidth() now takes explicit @update_ratelimit parameter to gate dirty ratelimit handling. * mm/page-writeback.c::wb_update_bandwidth() is flattened into its caller - balance_dirty_pages(). * fs/fs-writeback.c::wb_update_bandwidth() is moved to mm/page-writeback.c and __wb_update_bandwidth() is made static. * While at it, add a lockdep assertion to __wb_update_bandwidth(). Except for the lockdep addition, this is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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0d960a38 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: clean up wb_dirty_limit() The function name wb_dirty_limit(), its argument @dirty and the local variable @wb_dirty are mortally confusing given that the function calculates per-wb threshold value not dirty pages, especially given that @dirty and @wb_dirty are used elsewhere for dirty pages. Let's rename the function to wb_calc_thresh() and wb_dirty to wb_thresh. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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9ecf4866 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make bdi_start_background_writeback() take bdi_writeback instead of backing_dev_info bdi_start_background_writeback() currently takes @bdi and kicks the root wb (bdi_writeback). In preparation for cgroup writeback support, make it take wb instead. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
bc05873d |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make writeback_in_progress() take bdi_writeback instead of backing_dev_info writeback_in_progress() currently takes @bdi and returns whether writeback is in progress on its root wb (bdi_writeback). In preparation for cgroup writeback support, make it take wb instead. While at it, make it an inline function. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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a06fd6b1 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make laptop_mode_timer_fn() handle multiple bdi_writeback's For cgroup writeback support, all bdi-wide operations should be distributed to all its wb's (bdi_writeback's). This patch updates laptop_mode_timer_fn() so that it invokes wb_start_writeback() on all wb's rather than just the root one. As the intent is writing out all dirty data, there's no reason to split the number of pages to write. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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c00ddad3 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: remove bdi_start_writeback() bdi_start_writeback() is a thin wrapper on top of __wb_start_writeback() which is used only by laptop_mode_timer_fn(). This patches removes bdi_start_writeback(), renames __wb_start_writeback() to wb_start_writeback() and makes laptop_mode_timer_fn() use it instead. This doesn't cause any functional difference and will ease making laptop_mode_timer_fn() cgroup writeback aware. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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693108a8 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make bdi->min/max_ratio handling cgroup writeback aware bdi->min/max_ratio are user-configurable per-bdi knobs which regulate dirty limit of each bdi. For cgroup writeback, they need to be further distributed across wb's (bdi_writeback's) belonging to the configured bdi. This patch introduces wb_min_max_ratio() which distributes bdi->min/max_ratio according to a wb's proportion in the total active bandwidth of its bdi. v2: Update wb_min_max_ratio() to fix a bug where both min and max were assigned the min value and avoid calculations when possible. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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95a46c65 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make bdi_has_dirty_io() take multiple bdi_writeback's into account bdi_has_dirty_io() used to only reflect whether the root wb (bdi_writeback) has dirty inodes. For cgroup writeback support, it needs to take all active wb's into account. If any wb on the bdi has dirty inodes, bdi_has_dirty_io() should return true. To achieve that, as inode_wb_list_{move|del}_locked() now keep track of the dirty state transition of each wb, the number of dirty wbs can be counted in the bdi; however, bdi is already aggregating wb->avg_write_bandwidth which can easily be guaranteed to be > 0 when there are any dirty inodes by ensuring wb->avg_write_bandwidth can't dip below 1. bdi_has_dirty_io() can simply test whether bdi->tot_write_bandwidth is zero or not. While this bumps the value of wb->avg_write_bandwidth to one when it used to be zero, this shouldn't cause any meaningful behavior difference. bdi_has_dirty_io() is made an inline function which tests whether ->tot_write_bandwidth is non-zero. Also, WARN_ON_ONCE()'s on its value are added to inode_wb_list_{move|del}_locked(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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766a9d6e |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: implement backing_dev_info->tot_write_bandwidth cgroup writeback support needs to keep track of the sum of avg_write_bandwidth of all wb's (bdi_writeback's) with dirty inodes to distribute write workload. This patch adds bdi->tot_write_bandwidth and updates inode_wb_list_move_locked(), inode_wb_list_del_locked() and wb_update_write_bandwidth() to adjust it as wb's gain and lose dirty inodes and its avg_write_bandwidth gets updated. As the update events are not synchronized with each other, bdi->tot_write_bandwidth is an atomic_long_t. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
dfb8ae56 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: let balance_dirty_pages() work on the matching cgroup bdi_writeback Currently, balance_dirty_pages() always work on bdi->wb. This patch updates it to work on the wb (bdi_writeback) matching memcg and blkcg of the current task as that's what the inode is being dirtied against. balance_dirty_pages_ratelimited() now pins the current wb and passes it to balance_dirty_pages(). As no filesystem has FS_CGROUP_WRITEBACK yet, this doesn't lead to visible behavior differences. v2: Updated for per-inode wb association. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
91018134 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: attribute stats to the matching per-cgroup bdi_writeback Until now, all WB_* stats were accounted against the root wb (bdi_writeback), now that multiple wb (bdi_writeback) support is in place, let's attributes the stats to the respective per-cgroup wb's. As no filesystem has FS_CGROUP_WRITEBACK yet, this doesn't lead to visible behavior differences. v2: Updated for per-inode wb association. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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52ebea74 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: make backing_dev_info host cgroup-specific bdi_writebacks For the planned cgroup writeback support, on each bdi (backing_dev_info), each memcg will be served by a separate wb (bdi_writeback). This patch updates bdi so that a bdi can host multiple wbs (bdi_writebacks). On the default hierarchy, blkcg implicitly enables memcg. This allows using memcg's page ownership for attributing writeback IOs, and every memcg - blkcg combination can be served by its own wb by assigning a dedicated wb to each memcg. This means that there may be multiple wb's of a bdi mapped to the same blkcg. As congested state is per blkcg - bdi combination, those wb's should share the same congested state. This is achieved by tracking congested state via bdi_writeback_congested structs which are keyed by blkcg. bdi->wb remains unchanged and will keep serving the root cgroup. cgwb's (cgroup wb's) for non-root cgroups are created on-demand or looked up while dirtying an inode according to the memcg of the page being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree by its memcg id. Once an inode is associated with its wb, it can be retrieved using inode_to_wb(). Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all pages will keep being associated with bdi->wb. v3: inode_attach_wb() in account_page_dirtied() moved inside mapping_cap_account_dirty() block where it's known to be !NULL. Also, an unnecessary NULL check before kfree() removed. Both detected by the kbuild bot. v2: Updated so that wb association is per inode and wb is per memcg rather than blkcg. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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de1fff37 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: s/bdi/wb/ in mm/page-writeback.c Writeback operations will now be per wb (bdi_writeback) instead of bdi. Replace the relevant bdi references in symbol names and comments with wb. This patch is purely cosmetic and doesn't make any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@fb.com>
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a88a341a |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: move bandwidth related fields from backing_dev_info into bdi_writeback Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback) and the role of the separation is unclear. For cgroup support for writeback IOs, a bdi will be updated to host multiple wb's where each wb serves writeback IOs of a different cgroup on the bdi. To achieve that, a wb should carry all states necessary for servicing writeback IOs for a cgroup independently. This patch moves bandwidth related fields from backing_dev_info into bdi_writeback. * The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp, write_bandwidth, avg_write_bandwidth, dirty_ratelimit, balanced_dirty_ratelimit, completions and dirty_exceeded. * writeback_chunk_size() and over_bground_thresh() now take @wb instead of @bdi. * bdi_writeout_fraction(bdi, ...) -> wb_writeout_fraction(wb, ...) bdi_dirty_limit(bdi, ...) -> wb_dirty_limit(wb, ...) bdi_position_ration(bdi, ...) -> wb_position_ratio(wb, ...) bdi_update_writebandwidth(bdi, ...) -> wb_update_write_bandwidth(wb, ...) [__]bdi_update_bandwidth(bdi, ...) -> [__]wb_update_bandwidth(wb, ...) bdi_{max|min}_pause(bdi, ...) -> wb_{max|min}_pause(wb, ...) bdi_dirty_limits(bdi, ...) -> wb_dirty_limits(wb, ...) * Init/exits of the relocated fields are moved to bdi_wb_init/exit() respectively. Note that explicit zeroing is dropped in the process as wb's are cleared in entirety anyway. * As there's still only one bdi_writeback per backing_dev_info, all uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[] introducing no behavior changes. v2: Typo in description fixed as suggested by Jan. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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93f78d88 |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
writeback: move backing_dev_info->bdi_stat[] into bdi_writeback Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback) and the role of the separation is unclear. For cgroup support for writeback IOs, a bdi will be updated to host multiple wb's where each wb serves writeback IOs of a different cgroup on the bdi. To achieve that, a wb should carry all states necessary for servicing writeback IOs for a cgroup independently. This patch moves bdi->bdi_stat[] into wb. * enum bdi_stat_item is renamed to wb_stat_item and the prefix of all enums is changed from BDI_ to WB_. * BDI_STAT_BATCH() -> WB_STAT_BATCH() * [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...) * bdi_stat[_error]() -> wb_stat[_error]() * bdi_writeout_inc() -> wb_writeout_inc() * stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and frees stat. * As there's still only one bdi_writeback per backing_dev_info, all uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[] introducing no behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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c4843a75 |
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22-May-2015 |
Greg Thelen <gthelen@google.com> |
memcg: add per cgroup dirty page accounting When modifying PG_Dirty on cached file pages, update the new MEM_CGROUP_STAT_DIRTY counter. This is done in the same places where global NR_FILE_DIRTY is managed. The new memcg stat is visible in the per memcg memory.stat cgroupfs file. The most recent past attempt at this was http://thread.gmane.org/gmane.linux.kernel.cgroups/8632 The new accounting supports future efforts to add per cgroup dirty page throttling and writeback. It also helps an administrator break down a container's memory usage and provides evidence to understand memcg oom kills (the new dirty count is included in memcg oom kill messages). The ability to move page accounting between memcg (memory.move_charge_at_immigrate) makes this accounting more complicated than the global counter. The existing mem_cgroup_{begin,end}_page_stat() lock is used to serialize move accounting with stat updates. Typical update operation: memcg = mem_cgroup_begin_page_stat(page) if (TestSetPageDirty()) { [...] mem_cgroup_update_page_stat(memcg) } mem_cgroup_end_page_stat(memcg) Summary of mem_cgroup_end_page_stat() overhead: - Without CONFIG_MEMCG it's a no-op - With CONFIG_MEMCG and no inter memcg task movement, it's just rcu_read_lock() - With CONFIG_MEMCG and inter memcg task movement, it's rcu_read_lock() + spin_lock_irqsave() A memcg parameter is added to several routines because their callers now grab mem_cgroup_begin_page_stat() which returns the memcg later needed by for mem_cgroup_update_page_stat(). Because mem_cgroup_begin_page_stat() may disable interrupts, some adjustments are needed: - move __mark_inode_dirty() from __set_page_dirty() to its caller. __mark_inode_dirty() locking does not want interrupts disabled. - use spin_lock_irqsave(tree_lock) rather than spin_lock_irq() in __delete_from_page_cache(), replace_page_cache_page(), invalidate_complete_page2(), and __remove_mapping(). text data bss dec hex filename 8925147 1774832 1785856 12485835 be84cb vmlinux-!CONFIG_MEMCG-before 8925339 1774832 1785856 12486027 be858b vmlinux-!CONFIG_MEMCG-after +192 text bytes 8965977 1784992 1785856 12536825 bf4bf9 vmlinux-CONFIG_MEMCG-before 8966750 1784992 1785856 12537598 bf4efe vmlinux-CONFIG_MEMCG-after +773 text bytes Performance tests run on v4.0-rc1-36-g4f671fe2f952. Lower is better for all metrics, they're all wall clock or cycle counts. The read and write fault benchmarks just measure fault time, they do not include I/O time. * CONFIG_MEMCG not set: baseline patched kbuild 1m25.030000(+-0.088% 3 samples) 1m25.426667(+-0.120% 3 samples) dd write 100 MiB 0.859211561 +-15.10% 0.874162885 +-15.03% dd write 200 MiB 1.670653105 +-17.87% 1.669384764 +-11.99% dd write 1000 MiB 8.434691190 +-14.15% 8.474733215 +-14.77% read fault cycles 254.0(+-0.000% 10 samples) 253.0(+-0.000% 10 samples) write fault cycles 2021.2(+-3.070% 10 samples) 1984.5(+-1.036% 10 samples) * CONFIG_MEMCG=y root_memcg: baseline patched kbuild 1m25.716667(+-0.105% 3 samples) 1m25.686667(+-0.153% 3 samples) dd write 100 MiB 0.855650830 +-14.90% 0.887557919 +-14.90% dd write 200 MiB 1.688322953 +-12.72% 1.667682724 +-13.33% dd write 1000 MiB 8.418601605 +-14.30% 8.673532299 +-15.00% read fault cycles 266.0(+-0.000% 10 samples) 266.0(+-0.000% 10 samples) write fault cycles 2051.7(+-1.349% 10 samples) 2049.6(+-1.686% 10 samples) * CONFIG_MEMCG=y non-root_memcg: baseline patched kbuild 1m26.120000(+-0.273% 3 samples) 1m25.763333(+-0.127% 3 samples) dd write 100 MiB 0.861723964 +-15.25% 0.818129350 +-14.82% dd write 200 MiB 1.669887569 +-13.30% 1.698645885 +-13.27% dd write 1000 MiB 8.383191730 +-14.65% 8.351742280 +-14.52% read fault cycles 265.7(+-0.172% 10 samples) 267.0(+-0.000% 10 samples) write fault cycles 2070.6(+-1.512% 10 samples) 2084.4(+-2.148% 10 samples) As expected anon page faults are not affected by this patch. tj: Updated to apply on top of the recent cancel_dirty_page() changes. Signed-off-by: Sha Zhengju <handai.szj@gmail.com> Signed-off-by: Greg Thelen <gthelen@google.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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11f81bec |
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22-May-2015 |
Tejun Heo <tj@kernel.org> |
page_writeback: revive cancel_dirty_page() in a restricted form cancel_dirty_page() had some issues and b9ea25152e56 ("page_writeback: clean up mess around cancel_dirty_page()") replaced it with account_page_cleaned() which makes the caller responsible for clearing the dirty bit; unfortunately, the planned changes for cgroup writeback support requires synchronization between dirty bit manipulation and stat updates. While we can open-code such synchronization in each account_page_cleaned() callsite, that's gonna be unnecessarily awkward and verbose. This patch revives cancel_dirty_page() but in a more restricted form. All it does is TestClearPageDirty() followed by account_page_cleaned() invocation if the page was dirty. This helper covers all account_page_cleaned() usages except for __delete_from_page_cache() which is a special case anyway and left alone. As this leaves no module user for account_page_cleaned(), EXPORT_SYMBOL() is dropped from it. This patch just revives cancel_dirty_page() as a trivial wrapper to replace equivalent usages and doesn't introduce any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@fb.com>
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464d1387 |
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21-Apr-2015 |
Tejun Heo <tj@kernel.org> |
writeback: use |1 instead of +1 to protect against div by zero mm/page-writeback.c has several places where 1 is added to the divisor to prevent division by zero exceptions; however, if the original divisor is equivalent to -1, adding 1 leads to division by zero. There are three places where +1 is used for this purpose - one in pos_ratio_polynom() and two in bdi_position_ratio(). The second one in bdi_position_ratio() actually triggered div-by-zero oops on a machine running a 3.10 kernel. The divisor is x_intercept - bdi_setpoint + 1 == span + 1 span is confirmed to be (u32)-1. It isn't clear how it ended up that but it could be from write bandwidth calculation underflow fixed by c72efb658f7c ("writeback: fix possible underflow in write bandwidth calculation"). At any rate, +1 isn't a proper protection against div-by-zero. This patch converts all +1 protections to |1. Note that bdi_update_dirty_ratelimit() was already using |1 before this patch. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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a4bb3ecd |
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15-Apr-2015 |
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
mm/page-writeback: check-before-clear PageReclaim With the page flag sanitization patchset, an invalid usage of ClearPageReclaim() is detected in set_page_dirty(). This can be called from __unmap_hugepage_range(), so let's check PageReclaim() before trying to clear it to avoid the misuse. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b9ea2515 |
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14-Apr-2015 |
Konstantin Khlebnikov <koct9i@gmail.com> |
page_writeback: clean up mess around cancel_dirty_page() This patch replaces cancel_dirty_page() with a helper function account_page_cleaned() which only updates counters. It's called from truncate_complete_page() and from try_to_free_buffers() (hack for ext3). Page is locked in both cases, page-lock protects against concurrent dirtiers: see commit 2d6d7f982846 ("mm: protect set_page_dirty() from ongoing truncation"). Delete_from_page_cache() shouldn't be called for dirty pages, they must be handled by caller (either written or truncated). This patch treats final dirty accounting fixup at the end of __delete_from_page_cache() as a debug check and adds WARN_ON_ONCE() around it. If something removes dirty pages without proper handling that might be a bug and unwritten data might be lost. Hugetlbfs has no dirty pages accounting, ClearPageDirty() is enough here. cancel_dirty_page() in nfs_wb_page_cancel() is redundant. This is helper for nfs_invalidate_page() and it's called only in case complete invalidation. The mess was started in v2.6.20 after commits 46d2277c796f ("Clean up and make try_to_free_buffers() not race with dirty pages") and 3e67c0987d75 ("truncate: clear page dirtiness before running try_to_free_buffers()") first was reverted right in v2.6.20 in commit ecdfc9787fe5 ("Resurrect 'try_to_free_buffers()' VM hackery"), second in v2.6.25 commit a2b345642f53 ("Fix dirty page accounting leak with ext3 data=journal"). Custom fixes were introduced between these points. NFS in v2.6.23, commit 1b3b4a1a2deb ("NFS: Fix a write request leak in nfs_invalidate_page()"). Kludge in __delete_from_page_cache() in v2.6.24, commit 3a6927906f1b ("Do dirty page accounting when removing a page from the page cache"). Since v2.6.25 all of them are redundant. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Tejun Heo <tj@kernel.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c72efb65 |
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22-Mar-2015 |
Tejun Heo <tj@kernel.org> |
writeback: fix possible underflow in write bandwidth calculation From 1ebf33901ecc75d9496862dceb1ef0377980587c Mon Sep 17 00:00:00 2001 From: Tejun Heo <tj@kernel.org> Date: Mon, 23 Mar 2015 00:08:19 -0400 2f800fbd777b ("writeback: fix dirtied pages accounting on redirty") introduced account_page_redirty() which reverts stat updates for a redirtied page, making BDI_DIRTIED no longer monotonically increasing. bdi_update_write_bandwidth() uses the delta in BDI_DIRTIED as the basis for bandwidth calculation. While unlikely, since the above patch, the newer value may be lower than the recorded past value and underflow the bandwidth calculation leading to a wild result. Fix it by subtracing min of the old and new values when calculating delta. AFAIK, there hasn't been any report of it happening but the resulting erratic behavior would be non-critical and temporary, so it's possible that the issue is happening without being reported. The risk of the fix is very low, so tagged for -stable. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Fixes: 2f800fbd777b ("writeback: fix dirtied pages accounting on redirty") Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
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7d70e154 |
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04-Mar-2015 |
Tejun Heo <tj@kernel.org> |
writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() global_update_bandwidth() uses static variable update_time as the timestamp for the last update but forgets to initialize it to INITIALIZE_JIFFIES. This means that global_dirty_limit will be 5 mins into the future on 32bit and some large amount jiffies into the past on 64bit. This isn't critical as the only effect is that global_dirty_limit won't be updated for the first 5 mins after booting on 32bit machines, especially given the auxiliary nature of global_dirty_limit's role - protecting against global dirty threshold's sudden dips; however, it does lead to unintended suboptimal behavior. Fix it. Fixes: c42843f2f0bb ("writeback: introduce smoothed global dirty limit") Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
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8d38633c |
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11-Feb-2015 |
Konstantin Khlebnikov <koct9i@gmail.com> |
page_writeback: put account_page_redirty() after set_page_dirty() Helper account_page_redirty() fixes dirty pages counter for redirtied pages. This patch puts it after dirtying and prevents temporary underflows of dirtied pages counters on zone/bdi and current->nr_dirtied. Signed-off-by: Konstantin Khebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6de22619 |
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11-Feb-2015 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: track move_lock state internally The complexity of memcg page stat synchronization is currently leaking into the callsites, forcing them to keep track of the move_lock state and the IRQ flags. Simplify the API by tracking it in the memcg. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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de1414a6 |
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14-Jan-2015 |
Christoph Hellwig <hch@lst.de> |
fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info Now that we got rid of the bdi abuse on character devices we can always use sb->s_bdi to get at the backing_dev_info for a file, except for the block device special case. Export inode_to_bdi and replace uses of mapping->backing_dev_info with it to prepare for the removal of mapping->backing_dev_info. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
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2d6d7f98 |
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08-Jan-2015 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: protect set_page_dirty() from ongoing truncation Tejun, while reviewing the code, spotted the following race condition between the dirtying and truncation of a page: __set_page_dirty_nobuffers() __delete_from_page_cache() if (TestSetPageDirty(page)) page->mapping = NULL if (PageDirty()) dec_zone_page_state(page, NR_FILE_DIRTY); dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); if (page->mapping) account_page_dirtied(page) __inc_zone_page_state(page, NR_FILE_DIRTY); __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); which results in an imbalance of NR_FILE_DIRTY and BDI_RECLAIMABLE. Dirtiers usually lock out truncation, either by holding the page lock directly, or in case of zap_pte_range(), by pinning the mapcount with the page table lock held. The notable exception to this rule, though, is do_wp_page(), for which this race exists. However, do_wp_page() already waits for a locked page to unlock before setting the dirty bit, in order to prevent a race where clear_page_dirty() misses the page bit in the presence of dirty ptes. Upgrade that wait to a fully locked set_page_dirty() to also cover the situation explained above. Afterwards, the code in set_page_dirty() dealing with a truncation race is no longer needed. Remove it. Reported-by: Tejun Heo <tj@kernel.org> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e4bd6a02 |
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10-Dec-2014 |
Michal Hocko <mhocko@suse.cz> |
mm, memcg: fix potential undefined behaviour in page stat accounting Since commit d7365e783edb ("mm: memcontrol: fix missed end-writeback page accounting") mem_cgroup_end_page_stat consumes locked and flags variables directly rather than via pointers which might trigger C undefined behavior as those variables are initialized only in the slow path of mem_cgroup_begin_page_stat. Although mem_cgroup_end_page_stat handles parameters correctly and touches them only when they hold a sensible value it is caller which loads a potentially uninitialized value which then might allow compiler to do crazy things. I haven't seen any warning from gcc and it seems that the current version (4.9) doesn't exploit this type undefined behavior but Sasha has reported the following: UBSan: Undefined behaviour in mm/rmap.c:1084:2 load of value 255 is not a valid value for type '_Bool' CPU: 4 PID: 8304 Comm: rngd Not tainted 3.18.0-rc2-next-20141029-sasha-00039-g77ed13d-dirty #1427 Call Trace: dump_stack (lib/dump_stack.c:52) ubsan_epilogue (lib/ubsan.c:159) __ubsan_handle_load_invalid_value (lib/ubsan.c:482) page_remove_rmap (mm/rmap.c:1084 mm/rmap.c:1096) unmap_page_range (./arch/x86/include/asm/atomic.h:27 include/linux/mm.h:463 mm/memory.c:1146 mm/memory.c:1258 mm/memory.c:1279 mm/memory.c:1303) unmap_single_vma (mm/memory.c:1348) unmap_vmas (mm/memory.c:1377 (discriminator 3)) exit_mmap (mm/mmap.c:2837) mmput (kernel/fork.c:659) do_exit (./arch/x86/include/asm/thread_info.h:168 kernel/exit.c:462 kernel/exit.c:747) do_group_exit (include/linux/sched.h:775 kernel/exit.c:873) SyS_exit_group (kernel/exit.c:901) tracesys_phase2 (arch/x86/kernel/entry_64.S:529) Fix this by using pointer parameters for both locked and flags and be more robust for future compiler changes even though the current code is implemented correctly. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d7365e78 |
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29-Oct-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: memcontrol: fix missed end-writeback page accounting Commit 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API") changed page migration to uncharge the old page right away. The page is locked, unmapped, truncated, and off the LRU, but it could race with writeback ending, which then doesn't unaccount the page properly: test_clear_page_writeback() migration wait_on_page_writeback() TestClearPageWriteback() mem_cgroup_migrate() clear PCG_USED mem_cgroup_update_page_stat() if (PageCgroupUsed(pc)) decrease memcg pages under writeback release pc->mem_cgroup->move_lock The per-page statistics interface is heavily optimized to avoid a function call and a lookup_page_cgroup() in the file unmap fast path, which means it doesn't verify whether a page is still charged before clearing PageWriteback() and it has to do it in the stat update later. Rework it so that it looks up the page's memcg once at the beginning of the transaction and then uses it throughout. The charge will be verified before clearing PageWriteback() and migration can't uncharge the page as long as that is still set. The RCU lock will protect the memcg past uncharge. As far as losing the optimization goes, the following test results are from a microbenchmark that maps, faults, and unmaps a 4GB sparse file three times in a nested fashion, so that there are two negative passes that don't account but still go through the new transaction overhead. There is no actual difference: old: 33.195102545 seconds time elapsed ( +- 0.01% ) new: 33.199231369 seconds time elapsed ( +- 0.03% ) The time spent in page_remove_rmap()'s callees still adds up to the same, but the time spent in the function itself seems reduced: # Children Self Command Shared Object Symbol old: 0.12% 0.11% filemapstress [kernel.kallsyms] [k] page_remove_rmap new: 0.12% 0.08% filemapstress [kernel.kallsyms] [k] page_remove_rmap Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: <stable@vger.kernel.org> [3.17.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3a3c02ec |
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29-Oct-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: page-writeback: inline account_page_dirtied() into single caller A follow-up patch would have changed the call signature. To save the trouble, just fold it instead. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: <stable@vger.kernel.org> [3.17.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7c809968 |
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09-Oct-2014 |
Mark Rustad <mark.d.rustad@intel.com> |
mm/page-writeback.c: use min3/max3 macros to avoid shadow warnings Nested calls to min/max functions result in shadow warnings in W=2 builds. Avoid the warning by using the min3 and max3 macros to get the min/max of 3 values instead of nested calls. Signed-off-by: Mark Rustad <mark.d.rustad@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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20ae0079 |
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07-Sep-2014 |
Tejun Heo <tj@kernel.org> |
proportions: add @gfp to init functions Percpu allocator now supports allocation mask. Add @gfp to [flex_]proportions init functions so that !GFP_KERNEL allocation masks can be used with them too. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org>
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9ef0a0ff |
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06-Aug-2014 |
David Rientjes <rientjes@google.com> |
mm, writeback: prevent race when calculating dirty limits Setting vm_dirty_bytes and dirty_background_bytes is not protected by any serialization. Therefore, it's possible for either variable to change value after the test in global_dirty_limits() to determine whether available_memory needs to be initialized or not. Always ensure that available_memory is properly initialized. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f6789593 |
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30-Jul-2014 |
Maxim Patlasov <MPatlasov@parallels.com> |
mm/page-writeback.c: fix divide by zero in bdi_dirty_limits() Under memory pressure, it is possible for dirty_thresh, calculated by global_dirty_limits() in balance_dirty_pages(), to equal zero. Then, if strictlimit is true, bdi_dirty_limits() tries to resolve the proportion: bdi_bg_thresh : bdi_thresh = background_thresh : dirty_thresh by dividing by zero. Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cccad5b9 |
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06-Jun-2014 |
Joe Perches <joe@perches.com> |
mm: convert use of typedef ctl_table to struct ctl_table This typedef is unnecessary and should just be removed. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d2f31028 |
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04-Jun-2014 |
Jianyu Zhan <nasa4836@gmail.com> |
mm/page-writeback.c: remove outdated comment There is an orphaned prehistoric comment , which used to be against get_dirty_limits(), the dawn of global_dirtyable_memory(). Back then, the implementation of get_dirty_limits() is complicated and full of magic numbers, so this comment is necessary. But we now use the clear and neat global_dirtyable_memory(), which renders this comment ambiguous and useless. Remove it. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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7c8e0181 |
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04-Jun-2014 |
Christoph Lameter <cl@linux.com> |
mm: replace __get_cpu_var uses with this_cpu_ptr Replace places where __get_cpu_var() is used for an address calculation with this_cpu_ptr(). Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1c8349a1 |
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12-May-2014 |
Namjae Jeon <namjae.jeon@samsung.com> |
ext4: fix data integrity sync in ordered mode When we perform a data integrity sync we tag all the dirty pages with PAGECACHE_TAG_TOWRITE at start of ext4_da_writepages. Later we check for this tag in write_cache_pages_da and creates a struct mpage_da_data containing contiguously indexed pages tagged with this tag and sync these pages with a call to mpage_da_map_and_submit. This process is done in while loop until all the PAGECACHE_TAG_TOWRITE pages are synced. We also do journal start and stop in each iteration. journal_stop could initiate journal commit which would call ext4_writepage which in turn will call ext4_bio_write_page even for delayed OR unwritten buffers. When ext4_bio_write_page is called for such buffers, even though it does not sync them but it clears the PAGECACHE_TAG_TOWRITE of the corresponding page and hence these pages are also not synced by the currently running data integrity sync. We will end up with dirty pages although sync is completed. This could cause a potential data loss when the sync call is followed by a truncate_pagecache call, which is exactly the case in collapse_range. (It will cause generic/127 failure in xfstests) To avoid this issue, we can use set_page_writeback_keepwrite instead of set_page_writeback, which doesn't clear TOWRITE tag. Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
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d5c9fde3 |
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06-May-2014 |
Rik van Riel <riel@redhat.com> |
mm/page-writeback.c: fix divide by zero in pos_ratio_polynom It is possible for "limit - setpoint + 1" to equal zero, after getting truncated to a 32 bit variable, and resulting in a divide by zero error. Using the fully 64 bit divide functions avoids this problem. It also will cause pos_ratio_polynom() to return the correct value when (setpoint - limit) exceeds 2^32. Also uninline pos_ratio_polynom, at Andrew's request. Signed-off-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ed6d7c8e |
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07-Apr-2014 |
Miklos Szeredi <mszeredi@suse.cz> |
mm: remove unused arg of set_page_dirty_balance() There's only one caller of set_page_dirty_balance() and that will call it with page_mkwrite == 0. The page_mkwrite argument was unused since commit b827e496c893 "mm: close page_mkwrite races". Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a85d9df1 |
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06-Feb-2014 |
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> |
mm: __set_page_dirty_nobuffers() uses spin_lock_irqsave() instead of spin_lock_irq() During aio stress test, we observed the following lockdep warning. This mean AIO+numa_balancing is currently deadlockable. The problem is, aio_migratepage disable interrupt, but __set_page_dirty_nobuffers unintentionally enable it again. Generally, all helper function should use spin_lock_irqsave() instead of spin_lock_irq() because they don't know caller at all. other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&ctx->completion_lock)->rlock); <Interrupt> lock(&(&ctx->completion_lock)->rlock); *** DEADLOCK *** dump_stack+0x19/0x1b print_usage_bug+0x1f7/0x208 mark_lock+0x21d/0x2a0 mark_held_locks+0xb9/0x140 trace_hardirqs_on_caller+0x105/0x1d0 trace_hardirqs_on+0xd/0x10 _raw_spin_unlock_irq+0x2c/0x50 __set_page_dirty_nobuffers+0x8c/0xf0 migrate_page_copy+0x434/0x540 aio_migratepage+0xb1/0x140 move_to_new_page+0x7d/0x230 migrate_pages+0x5e5/0x700 migrate_misplaced_page+0xbc/0xf0 do_numa_page+0x102/0x190 handle_pte_fault+0x241/0x970 handle_mm_fault+0x265/0x370 __do_page_fault+0x172/0x5a0 do_page_fault+0x1a/0x70 page_fault+0x28/0x30 Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <jweiner@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a1c3bfb2 |
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29-Jan-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm/page-writeback.c: do not count anon pages as dirtyable memory The VM is currently heavily tuned to avoid swapping. Whether that is good or bad is a separate discussion, but as long as the VM won't swap to make room for dirty cache, we can not consider anonymous pages when calculating the amount of dirtyable memory, the baseline to which dirty_background_ratio and dirty_ratio are applied. A simple workload that occupies a significant size (40+%, depending on memory layout, storage speeds etc.) of memory with anon/tmpfs pages and uses the remainder for a streaming writer demonstrates this problem. In that case, the actual cache pages are a small fraction of what is considered dirtyable overall, which results in an relatively large portion of the cache pages to be dirtied. As kswapd starts rotating these, random tasks enter direct reclaim and stall on IO. Only consider free pages and file pages dirtyable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a804552b |
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29-Jan-2014 |
Johannes Weiner <hannes@cmpxchg.org> |
mm/page-writeback.c: fix dirty_balance_reserve subtraction from dirtyable memory Tejun reported stuttering and latency spikes on a system where random tasks would enter direct reclaim and get stuck on dirty pages. Around 50% of memory was occupied by tmpfs backed by an SSD, and another disk (rotating) was reading and writing at max speed to shrink a partition. : The problem was pretty ridiculous. It's a 8gig machine w/ one ssd and 10k : rpm harddrive and I could reliably reproduce constant stuttering every : several seconds for as long as buffered IO was going on on the hard drive : either with tmpfs occupying somewhere above 4gig or a test program which : allocates about the same amount of anon memory. Although swap usage was : zero, turning off swap also made the problem go away too. : : The trigger conditions seem quite plausible - high anon memory usage w/ : heavy buffered IO and swap configured - and it's highly likely that this : is happening in the wild too. (this can happen with copying large files : to usb sticks too, right?) This patch (of 2): The dirty_balance_reserve is an approximation of the fraction of free pages that the page allocator does not make available for page cache allocations. As a result, it has to be taken into account when calculating the amount of "dirtyable memory", the baseline to which dirty_background_ratio and dirty_ratio are applied. However, currently the reserve is subtracted from the sum of free and reclaimable pages, which is non-sensical and leads to erroneous results when the system is dominated by unreclaimable pages and the dirty_balance_reserve is bigger than free+reclaimable. In that case, at least the already allocated cache should be considered dirtyable. Fix the calculation by subtracting the reserve from the amount of free pages, then adding the reclaimable pages on top. [akpm@linux-foundation.org: fix CONFIG_HIGHMEM build] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e3b6c655 |
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16-Oct-2013 |
Fengguang Wu <fengguang.wu@intel.com> |
writeback: fix negative bdi max pause Toralf runs trinity on UML/i386. After some time it hangs and the last message line is BUG: soft lockup - CPU#0 stuck for 22s! [trinity-child0:1521] It's found that pages_dirtied becomes very large. More than 1000000000 pages in this case: period = HZ * pages_dirtied / task_ratelimit; BUG_ON(pages_dirtied > 2000000000); BUG_ON(pages_dirtied > 1000000000); <--------- UML debug printf shows that we got negative pause here: ick: pause : -984 ick: pages_dirtied : 0 ick: task_ratelimit: 0 pause: + if (pause < 0) { + extern int printf(char *, ...); + printf("ick : pause : %li\n", pause); + printf("ick: pages_dirtied : %lu\n", pages_dirtied); + printf("ick: task_ratelimit: %lu\n", task_ratelimit); + BUG_ON(1); + } trace_balance_dirty_pages(bdi, Since pause is bounded by [min_pause, max_pause] where min_pause is also bounded by max_pause. It's suspected and demonstrated that the max_pause calculation goes wrong: ick: pause : -717 ick: min_pause : -177 ick: max_pause : -717 ick: pages_dirtied : 14 ick: task_ratelimit: 0 The problem lies in the two "long = unsigned long" assignments in bdi_max_pause() which might go negative if the highest bit is 1, and the min_t(long, ...) check failed to protect it falling under 0. Fix all of them by using "unsigned long" throughout the function. Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Reported-by: Toralf Förster <toralf.foerster@gmx.de> Tested-by: Toralf Förster <toralf.foerster@gmx.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Richard Weinberger <richard@nod.at> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3ea67d06 |
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12-Sep-2013 |
Sha Zhengju <handai.szj@taobao.com> |
memcg: add per cgroup writeback pages accounting Add memcg routines to count writeback pages, later dirty pages will also be accounted. After Kame's commit 89c06bd52fb9 ("memcg: use new logic for page stat accounting"), we can use 'struct page' flag to test page state instead of per page_cgroup flag. But memcg has a feature to move a page from a cgroup to another one and may have race between "move" and "page stat accounting". So in order to avoid the race we have designed a new lock: mem_cgroup_begin_update_page_stat() modify page information -->(a) mem_cgroup_update_page_stat() -->(b) mem_cgroup_end_update_page_stat() It requires both (a) and (b)(writeback pages accounting) to be pretected in mem_cgroup_{begin/end}_update_page_stat(). It's full no-op for !CONFIG_MEMCG, almost no-op if memcg is disabled (but compiled in), rcu read lock in the most cases (no task is moving), and spin_lock_irqsave on top in the slow path. There're two writeback interfaces to modify: test_{clear/set}_page_writeback(). And the lock order is: --> memcg->move_lock --> mapping->tree_lock Signed-off-by: Sha Zhengju <handai.szj@taobao.com> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Greg Thelen <gthelen@google.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a537485 |
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11-Sep-2013 |
Maxim Patlasov <mpatlasov@parallels.com> |
mm/page-writeback.c: add strictlimit feature The feature prevents mistrusted filesystems (ie: FUSE mounts created by unprivileged users) to grow a large number of dirty pages before throttling. For such filesystems balance_dirty_pages always check bdi counters against bdi limits. I.e. even if global "nr_dirty" is under "freerun", it's not allowed to skip bdi checks. The only use case for now is fuse: it sets bdi max_ratio to 1% by default and system administrators are supposed to expect that this limit won't be exceeded. The feature is on if a BDI is marked by BDI_CAP_STRICTLIMIT flag. A filesystem may set the flag when it initializes its BDI. The problematic scenario comes from the fact that nobody pays attention to the NR_WRITEBACK_TEMP counter (i.e. number of pages under fuse writeback). The implementation of fuse writeback releases original page (by calling end_page_writeback) almost immediately. A fuse request queued for real processing bears a copy of original page. Hence, if userspace fuse daemon doesn't finalize write requests in timely manner, an aggressive mmap writer can pollute virtually all memory by those temporary fuse page copies. They are carefully accounted in NR_WRITEBACK_TEMP, but nobody cares. To make further explanations shorter, let me use "NR_WRITEBACK_TEMP problem" as a shortcut for "a possibility of uncontrolled grow of amount of RAM consumed by temporary pages allocated by kernel fuse to process writeback". The problem was very easy to reproduce. There is a trivial example filesystem implementation in fuse userspace distribution: fusexmp_fh.c. I added "sleep(1);" to the write methods, then recompiled and mounted it. Then created a huge file on the mount point and run a simple program which mmap-ed the file to a memory region, then wrote a data to the region. An hour later I observed almost all RAM consumed by fuse writeback. Since then some unrelated changes in kernel fuse made it more difficult to reproduce, but it is still possible now. Putting this theoretical happens-in-the-lab thing aside, there is another thing that really hurts real world (FUSE) users. This is write-through page cache policy FUSE currently uses. I.e. handling write(2), kernel fuse populates page cache and flushes user data to the server synchronously. This is excessively suboptimal. Pavel Emelyanov's patches ("writeback cache policy") solve the problem, but they also make resolving NR_WRITEBACK_TEMP problem absolutely necessary. Otherwise, simply copying a huge file to a fuse mount would result in memory starvation. Miklos, the maintainer of FUSE, believes strictlimit feature the way to go. And eventually putting FUSE topics aside, there is one more use-case for strictlimit feature. Using a slow USB stick (mass storage) in a machine with huge amount of RAM installed is a well-known pain. Let's make simple computations. Assuming 64GB of RAM installed, existing implementation of balance_dirty_pages will start throttling only after 9.6GB of RAM becomes dirty (freerun == 15% of total RAM). So, the command "cp 9GB_file /media/my-usb-storage/" may return in a few seconds, but subsequent "umount /media/my-usb-storage/" will take more than two hours if effective throughput of the storage is, to say, 1MB/sec. After inclusion of strictlimit feature, it will be trivial to add a knob (e.g. /sys/devices/virtual/bdi/x:y/strictlimit) to enable it on demand. Manually or via udev rule. May be I'm wrong, but it seems to be quite a natural desire to limit the amount of dirty memory for some devices we are not fully trust (in the sense of sustainable throughput). [akpm@linux-foundation.org: fix warning in page-writeback.c] Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com> Cc: Jan Kara <jack@suse.cz> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6e543d57 |
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11-Sep-2013 |
Lisa Du <cldu@marvell.com> |
mm: vmscan: fix do_try_to_free_pages() livelock This patch is based on KOSAKI's work and I add a little more description, please refer https://lkml.org/lkml/2012/6/14/74. Currently, I found system can enter a state that there are lots of free pages in a zone but only order-0 and order-1 pages which means the zone is heavily fragmented, then high order allocation could make direct reclaim path's long stall(ex, 60 seconds) especially in no swap and no compaciton enviroment. This problem happened on v3.4, but it seems issue still lives in current tree, the reason is do_try_to_free_pages enter live lock: kswapd will go to sleep if the zones have been fully scanned and are still not balanced. As kswapd thinks there's little point trying all over again to avoid infinite loop. Instead it changes order from high-order to 0-order because kswapd think order-0 is the most important. Look at 73ce02e9 in detail. If watermarks are ok, kswapd will go back to sleep and may leave zone->all_unreclaimable =3D 0. It assume high-order users can still perform direct reclaim if they wish. Direct reclaim continue to reclaim for a high order which is not a COSTLY_ORDER without oom-killer until kswapd turn on zone->all_unreclaimble= . This is because to avoid too early oom-kill. So it means direct_reclaim depends on kswapd to break this loop. In worst case, direct-reclaim may continue to page reclaim forever when kswapd sleeps forever until someone like watchdog detect and finally kill the process. As described in: http://thread.gmane.org/gmane.linux.kernel.mm/103737 We can't turn on zone->all_unreclaimable from direct reclaim path because direct reclaim path don't take any lock and this way is racy. Thus this patch removes zone->all_unreclaimable field completely and recalculates zone reclaimable state every time. Note: we can't take the idea that direct-reclaim see zone->pages_scanned directly and kswapd continue to use zone->all_unreclaimable. Because, it is racy. commit 929bea7c71 (vmscan: all_unreclaimable() use zone->all_unreclaimable as a name) describes the detail. [akpm@linux-foundation.org: uninline zone_reclaimable_pages() and zone_reclaimable()] Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Nick Piggin <npiggin@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Bob Liu <lliubbo@gmail.com> Cc: Neil Zhang <zhangwm@marvell.com> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Lisa Du <cldu@marvell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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72457c0a |
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11-Sep-2013 |
Johannes Weiner <hannes@cmpxchg.org> |
mm: revert "page-writeback.c: subtract min_free_kbytes from dirtyable memory" This reverts commit 75f7ad8e043d. It was the result of a problem observed with a 3.2 kernel and merged in 3.9, while the issue had been resolved upstream in 3.3 (commit ab8fabd46f81: "mm: exclude reserved pages from dirtyable memory"). The "reserved pages" are a superset of min_free_kbytes, thus this change is redundant and confusing. Revert it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Paul Szabo <psz@maths.usyd.edu.au> Cc: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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0db0628d |
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19-Jun-2013 |
Paul Gortmaker <paul.gortmaker@windriver.com> |
kernel: delete __cpuinit usage from all core kernel files The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the uses of the __cpuinit macros from C files in the core kernel directories (kernel, init, lib, mm, and include) that don't really have a specific maintainer. [1] https://lkml.org/lkml/2013/5/20/589 Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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713685111 |
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29-Apr-2013 |
Darrick J. Wong <darrick.wong@oracle.com> |
mm: make snapshotting pages for stable writes a per-bio operation Walking a bio's page mappings has proved problematic, so create a new bio flag to indicate that a bio's data needs to be snapshotted in order to guarantee stable pages during writeback. Next, for the one user (ext3/jbd) of snapshotting, hook all the places where writes can be initiated without PG_writeback set, and set BIO_SNAP_STABLE there. We must also flag journal "metadata" bios for stable writeout, since file data can be written through the journal. Finally, the MS_SNAP_STABLE mount flag (only used by ext3) is now superfluous, so get rid of it. [akpm@linux-foundation.org: rename _submit_bh()'s `flags' to `bio_flags', delobotomize the _submit_bh declaration] [akpm@linux-foundation.org: teeny cleanup] Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Artem Bityutskiy <dedekind1@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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75f7ad8e |
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22-Feb-2013 |
Paul Szabo <psz@maths.usyd.edu.au> |
page-writeback.c: subtract min_free_kbytes from dirtyable memory When calculating amount of dirtyable memory, min_free_kbytes should be subtracted because it is not intended for dirty pages. Addresses http://bugs.debian.org/695182 [akpm@linux-foundation.org: fix up min_free_kbytes extern declarations] [akpm@linux-foundation.org: fix min() warning] Signed-off-by: Paul Szabo <psz@maths.usyd.edu.au> Acked-by: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ffecfd1a |
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21-Feb-2013 |
Darrick J. Wong <darrick.wong@oracle.com> |
block: optionally snapshot page contents to provide stable pages during write This provides a band-aid to provide stable page writes on jbd without needing to backport the fixed locking and page writeback bit handling schemes of jbd2. The band-aid works by using bounce buffers to snapshot page contents instead of waiting. For those wondering about the ext3 bandage -- fixing the jbd locking (which was done as part of ext4dev years ago) is a lot of surgery, and setting PG_writeback on data pages when we actually hold the page lock dropped ext3 performance by nearly an order of magnitude. If we're going to migrate iscsi and raid to use stable page writes, the complaints about high latency will likely return. We might as well centralize their page snapshotting thing to one place. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Artem Bityutskiy <dedekind1@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Ron Minnich <rminnich@sandia.gov> Cc: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1d1d1a76 |
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21-Feb-2013 |
Darrick J. Wong <darrick.wong@oracle.com> |
mm: only enforce stable page writes if the backing device requires it Create a helper function to check if a backing device requires stable page writes and, if so, performs the necessary wait. Then, make it so that all points in the memory manager that handle making pages writable use the helper function. This should provide stable page write support to most filesystems, while eliminating unnecessary waiting for devices that don't require the feature. Before this patchset, all filesystems would block, regardless of whether or not it was necessary. ext3 would wait, but still generate occasional checksum errors. The network filesystems were left to do their own thing, so they'd wait too. After this patchset, all the disk filesystems except ext3 and btrfs will wait only if the hardware requires it. ext3 (if necessary) snapshots pages instead of blocking, and btrfs provides its own bdi so the mm will never wait. Network filesystems haven't been touched, so either they provide their own stable page guarantees or they don't block at all. The blocking behavior is back to what it was before 3.0 if you don't have a disk requiring stable page writes. Here's the result of using dbench to test latency on ext2: 3.8.0-rc3: Operation Count AvgLat MaxLat ---------------------------------------- WriteX 109347 0.028 59.817 ReadX 347180 0.004 3.391 Flush 15514 29.828 287.283 Throughput 57.429 MB/sec 4 clients 4 procs max_latency=287.290 ms 3.8.0-rc3 + patches: WriteX 105556 0.029 4.273 ReadX 335004 0.005 4.112 Flush 14982 30.540 298.634 Throughput 55.4496 MB/sec 4 clients 4 procs max_latency=298.650 ms As you can see, the maximum write latency drops considerably with this patch enabled. The other filesystems (ext3/ext4/xfs/btrfs) behave similarly, but see the cover letter for those results. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Acked-by: Steven Whitehouse <swhiteho@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Ron Minnich <rminnich@sandia.gov> Cc: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8bd75c77 |
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07-Feb-2013 |
Clark Williams <williams@redhat.com> |
sched/rt: Move rt specific bits into new header file Move rt scheduler definitions out of include/linux/sched.h into new file include/linux/sched/rt.h Signed-off-by: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
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ed84825b |
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19-Jan-2013 |
paul.szabo@sydney.edu.au <paul.szabo@sydney.edu.au> |
Negative (setpoint-dirty) in bdi_position_ratio() In bdi_position_ratio(), get difference (setpoint-dirty) right even when negative. Both setpoint and dirty are unsigned long, the difference was zero-padded thus wrongly sign-extended to s64. This issue affects all 32-bit architectures, does not affect 64-bit architectures where long and s64 are equivalent. In this function, dirty is between freerun and limit, the pseudo-float x is between [-1,1], expected to be negative about half the time. With zero-padding, instead of a small negative x we obtained a large positive one so bdi_position_ratio() returned garbage. Casting the difference to s64 also prevents overflow with left-shift; though normally these numbers are small and I never observed a 32-bit overflow there. (This patch does not solve the PAE OOM issue.) Paul Szabo psz@maths.usyd.edu.au http://www.maths.usyd.edu.au/u/psz/ School of Mathematics and Statistics University of Sydney Australia Reviewed-by: Jan Kara <jack@suse.cz> Reported-by: Paul Szabo <psz@maths.usyd.edu.au> Reference: http://bugs.debian.org/695182 Signed-off-by: Paul Szabo <psz@maths.usyd.edu.au> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
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9fb0a7da |
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11-Jan-2013 |
Tejun Heo <tj@kernel.org> |
writeback: add more tracepoints Add tracepoints for page dirtying, writeback_single_inode start, inode dirtying and writeback. For the latter two inode events, a pair of events are defined to denote start and end of the operations (the starting one has _start suffix and the one w/o suffix happens after the operation is complete). These inode ops are FS specific and can be non-trivial and having enclosing tracepoints is useful for external tracers. This is part of tracepoint additions to improve visiblity into dirtying / writeback operations for io tracer and userland. v2: writeback_dirty_inode[_start] TPs may be called for files on pseudo FSes w/ unregistered bdi. Check whether bdi->dev is %NULL before dereferencing. v3: buffer dirtying moved to a block TP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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c8b74c2f |
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20-Dec-2012 |
Sonny Rao <sonnyrao@chromium.org> |
mm: fix calculation of dirtyable memory The system uses global_dirtyable_memory() to calculate number of dirtyable pages/pages that can be allocated to the page cache. A bug causes an underflow thus making the page count look like a big unsigned number. This in turn confuses the dirty writeback throttling to aggressively write back pages as they become dirty (usually 1 page at a time). This generally only affects systems with highmem because the underflowed count gets subtracted from the global count of dirtyable memory. The problem was introduced with v3.2-4896-gab8fabd Fix is to ensure we don't get an underflowed total of either highmem or global dirtyable memory. Signed-off-by: Sonny Rao <sonnyrao@chromium.org> Signed-off-by: Puneet Kumar <puneetster@chromium.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Damien Wyart <damien.wyart@free.fr> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d0e1d66b |
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11-Dec-2012 |
Namjae Jeon <linkinjeon@gmail.com> |
writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr() There is no reason to pass the nr_pages_dirtied argument, because nr_pages_dirtied value from the caller is unused in balance_dirty_pages_ratelimited_nr(). Signed-off-by: Namjae Jeon <linkinjeon@gmail.com> Signed-off-by: Vivek Trivedi <vtrivedi018@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2f60d628 |
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28-Sep-2012 |
Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> |
CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug The CPU hotplug callback related to writeback calls writeback_set_ratelimit() during every state change in the hotplug sequence. This is unnecessary since num_online_cpus() changes only once during the entire hotplug operation. So invoke the function only once per hotplug, thereby avoiding the unnecessary repetition of those costly calculations. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
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f0cd2dbb |
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25-Jul-2012 |
Artem Bityutskiy <artem.bityutskiy@linux.intel.com> |
vfs: kill write_super and sync_supers Finally we can kill the 'sync_supers' kernel thread along with the '->write_super()' superblock operation because all the users are gone. Now every file-system is supposed to self-manage own superblock and its dirty state. The nice thing about killing this thread is that it improves power management. Indeed, 'sync_supers' is a source of monotonic system wake-ups - it woke up every 5 seconds no matter what - even if there were no dirty superblocks and even if there were no file-systems using this service (e.g., btrfs and journalled ext4 do not need it). So it was wasting power most of the time. And because the thread was in the core of the kernel, all systems had to have it. So I am quite happy to make it go away. Interestingly, this thread is a left-over from the pdflush kernel thread which was a self-forking kernel thread responsible for all the write-back in old Linux kernels. It was turned into per-block device BDI threads, and 'sync_supers' was a left-over. Thus, R.I.P, pdflush as well. Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
331cbdee |
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08-Jun-2012 |
Wanpeng Li <liwp@linux.vnet.ibm.com> |
writeback: Fix some comment errors Signed-off-by: Wanpeng Li <liwp@linux.vnet.ibm.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
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#
eb608e3a |
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24-May-2012 |
Jan Kara <jack@suse.cz> |
block: Convert BDI proportion calculations to flexible proportions Convert calculations of proportion of writeback each bdi does to new flexible proportion code. That allows us to use aging period of fixed wallclock time which gives better proportion estimates given the hugely varying throughput of different devices. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
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#
68809c71 |
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05-May-2012 |
Fengguang Wu <fengguang.wu@intel.com> |
writeback: initialize global_dirty_limit This prevents global_dirty_limit from remaining 0 (the initial value) for long time, since it's only updated in update_dirty_limit() when above the dirty freerun area. It will avoid unexpected consequences when some random code use it as a convenient approximation of the global dirty threshold. Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
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#
18cf8cf8 |
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12-Apr-2012 |
H Hartley Sweeten <hartleys@visionengravers.com> |
mm: page-writeback.c: local functions should not be exposed globally The function global_dirtyable_memory is only referenced in this file and should be marked static to prevent it from being exposed globally. This quiets the sparse warning: warning: symbol 'global_dirtyable_memory' was not declared. Should it be static? Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
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#
91913a29 |
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21-Mar-2012 |
Artem Bityutskiy <artem.bityutskiy@linux.intel.com> |
mm: export dirty_writeback_interval Export 'dirty_writeback_interval' to make it visible to file-systems. We are going to push superblock management down to file-systems and get rid of the 'sync_supers' kernel thread completly. Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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#
47a13333 |
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21-Mar-2012 |
Fengguang Wu <fengguang.wu@intel.com> |
mm: use global_dirty_limit in throttle_vm_writeout() When starting a memory hog task, a desktop box w/o swap is found to go unresponsive for a long time. It's solely caused by lots of congestion waits in throttle_vm_writeout(): gnome-system-mo-4201 553.073384: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 gnome-system-mo-4201 553.073386: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 gtali-4237 553.080377: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 gtali-4237 553.080378: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 Xorg-3483 553.103375: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 Xorg-3483 553.103377: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 The root cause is, the dirty threshold is knocked down a lot by the memory hog task. Fixed by using global_dirty_limit which decreases gradually on such events and can guarantee we stay above (the also decreasing) nr_dirty in the progress of following down to the new dirty threshold. Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jan Kara <jack@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Ying Han <yinghan@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a756cf59 |
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10-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: try to distribute dirty pages fairly across zones The maximum number of dirty pages that exist in the system at any time is determined by a number of pages considered dirtyable and a user-configured percentage of those, or an absolute number in bytes. This number of dirtyable pages is the sum of memory provided by all the zones in the system minus their lowmem reserves and high watermarks, so that the system can retain a healthy number of free pages without having to reclaim dirty pages. But there is a flaw in that we have a zoned page allocator which does not care about the global state but rather the state of individual memory zones. And right now there is nothing that prevents one zone from filling up with dirty pages while other zones are spared, which frequently leads to situations where kswapd, in order to restore the watermark of free pages, does indeed have to write pages from that zone's LRU list. This can interfere so badly with IO from the flusher threads that major filesystems (btrfs, xfs, ext4) mostly ignore write requests from reclaim already, taking away the VM's only possibility to keep such a zone balanced, aside from hoping the flushers will soon clean pages from that zone. Enter per-zone dirty limits. They are to a zone's dirtyable memory what the global limit is to the global amount of dirtyable memory, and try to make sure that no single zone receives more than its fair share of the globally allowed dirty pages in the first place. As the number of pages considered dirtyable excludes the zones' lowmem reserves and high watermarks, the maximum number of dirty pages in a zone is such that the zone can always be balanced without requiring page cleaning. As this is a placement decision in the page allocator and pages are dirtied only after the allocation, this patch allows allocators to pass __GFP_WRITE when they know in advance that the page will be written to and become dirty soon. The page allocator will then attempt to allocate from the first zone of the zonelist - which on NUMA is determined by the task's NUMA memory policy - that has not exceeded its dirty limit. At first glance, it would appear that the diversion to lower zones can increase pressure on them, but this is not the case. With a full high zone, allocations will be diverted to lower zones eventually, so it is more of a shift in timing of the lower zone allocations. Workloads that previously could fit their dirty pages completely in the higher zone may be forced to allocate from lower zones, but the amount of pages that "spill over" are limited themselves by the lower zones' dirty constraints, and thus unlikely to become a problem. For now, the problem of unfair dirty page distribution remains for NUMA configurations where the zones allowed for allocation are in sum not big enough to trigger the global dirty limits, wake up the flusher threads and remedy the situation. Because of this, an allocation that could not succeed on any of the considered zones is allowed to ignore the dirty limits before going into direct reclaim or even failing the allocation, until a future patch changes the global dirty throttling and flusher thread activation so that they take individual zone states into account. Test results 15M DMA + 3246M DMA32 + 504 Normal = 3765M memory 40% dirty ratio 16G USB thumb drive 10 runs of dd if=/dev/zero of=disk/zeroes bs=32k count=$((10 << 15)) seconds nr_vmscan_write (stddev) min| median| max xfs vanilla: 549.747( 3.492) 0.000| 0.000| 0.000 patched: 550.996( 3.802) 0.000| 0.000| 0.000 fuse-ntfs vanilla: 1183.094(53.178) 54349.000| 59341.000| 65163.000 patched: 558.049(17.914) 0.000| 0.000| 43.000 btrfs vanilla: 573.679(14.015) 156657.000| 460178.000| 606926.000 patched: 563.365(11.368) 0.000| 0.000| 1362.000 ext4 vanilla: 561.197(15.782) 0.000|2725438.000|4143837.000 patched: 568.806(17.496) 0.000| 0.000| 0.000 Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Tested-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ccafa287 |
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10-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: writeback: cleanups in preparation for per-zone dirty limits The next patch will introduce per-zone dirty limiting functions in addition to the traditional global dirty limiting. Rename determine_dirtyable_memory() to global_dirtyable_memory() before adding the zone-specific version, and fix up its documentation. Also, move the functions to determine the dirtyable memory and the function to calculate the dirty limit based on that together so that their relationship is more apparent and that they can be commented on as a group. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Mel Gorman <mel@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ab8fabd4 |
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10-Jan-2012 |
Johannes Weiner <jweiner@redhat.com> |
mm: exclude reserved pages from dirtyable memory Per-zone dirty limits try to distribute page cache pages allocated for writing across zones in proportion to the individual zone sizes, to reduce the likelihood of reclaim having to write back individual pages from the LRU lists in order to make progress. This patch: The amount of dirtyable pages should not include the full number of free pages: there is a number of reserved pages that the page allocator and kswapd always try to keep free. The closer (reclaimable pages - dirty pages) is to the number of reserved pages, the more likely it becomes for reclaim to run into dirty pages: +----------+ --- | anon | | +----------+ | | | | | | -- dirty limit new -- flusher new | file | | | | | | | | | -- dirty limit old -- flusher old | | | +----------+ --- reclaim | reserved | +----------+ | kernel | +----------+ This patch introduces a per-zone dirty reserve that takes both the lowmem reserve as well as the high watermark of the zone into account, and a global sum of those per-zone values that is subtracted from the global amount of dirtyable pages. The lowmem reserve is unavailable to page cache allocations and kswapd tries to keep the high watermark free. We don't want to end up in a situation where reclaim has to clean pages in order to balance zones. Not treating reserved pages as dirtyable on a global level is only a conceptual fix. In reality, dirty pages are not distributed equally across zones and reclaim runs into dirty pages on a regular basis. But it is important to get this right before tackling the problem on a per-zone level, where the distance between reclaim and the dirty pages is mostly much smaller in absolute numbers. [akpm@linux-foundation.org: fix highmem build] Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1edf2234 |
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10-Jan-2012 |
Johannes Weiner <hannes@cmpxchg.org> |
mm/page-writeback.c: make determine_dirtyable_memory static again The tracing ring-buffer used this function briefly, but not anymore. Make it local to the writeback code again. Also, move the function so that no forward declaration needs to be reintroduced. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
ff01bb48 |
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16-Sep-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
fs: move code out of buffer.c Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export kill_bdev as well, so brd doesn't have to open code it. Reduce buffer_head.h requirement accordingly. Removed a rather large comment from invalidate_bdev, as it looked a bit obsolete to bother moving. The small comment replacing it says enough. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
bdaac490 |
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03-Aug-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: balanced_rate cannot exceed write bandwidth Add an upper limit to balanced_rate according to the below inequality. This filters out some rare but huge singular points, which at least enables more readable gnuplot figures. When there are N dd dirtiers, balanced_dirty_ratelimit = write_bw / N So it holds that balanced_dirty_ratelimit <= write_bw The singular points originate from dirty_rate in the below formular: balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate where dirty_rate = (number of page dirties in the past 200ms) / 200ms In the extreme case, if all dd tasks suddenly get blocked on something else and hence no pages are dirtied at all, dirty_rate will be 0 and balanced_dirty_ratelimit will be inf. This could happen in reality. Note that these huge singular points are not a real threat, since they are _guaranteed_ to be filtered out by the min(balanced_dirty_ratelimit, task_ratelimit) line in bdi_update_dirty_ratelimit(). task_ratelimit is based on the number of dirty pages, which will never _suddenly_ fly away like balanced_dirty_ratelimit. So any weirdly large balanced_dirty_ratelimit will be cut down to the level of task_ratelimit. There won't be tiny singular points though, as long as the dirty pages lie inside the dirty throttling region (above the freerun region). Because there the dd tasks will be throttled by balanced_dirty_pages() and won't be able to suddenly dirty much more pages than average. Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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82791940 |
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03-Dec-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: do strict bdi dirty_exceeded This helps to reduce dirty throttling polls and hence CPU overheads. bdi->dirty_exceeded typically only helps when suddenly starting 100+ dd's on a disk, in which case the dd's may need to poll balance_dirty_pages() earlier than tsk->nr_dirtied_pause. CC: Jan Kara <jack@suse.cz> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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5b9b3574 |
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06-Dec-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: avoid tiny dirty poll intervals The LKP tests see big 56% regression for the case fio_mmap_randwrite_64k. Shaohua manages to root cause it to be the much smaller dirty pause times and hence much more frequent invocations to the IO-less balance_dirty_pages(). Since fio_mmap_randwrite_64k effectively contains both reads and writes, the more frequent pauses triggered more idling in the cfq IO scheduler. The solution is to increase pause time all the way up to the max 200ms in this case, which is found to restore most performance. This will help reduce CPU overheads in other cases, too. Note that I don't expect many performance critical workloads to run this access pattern: the mmap read-on-write is rather inefficient and could be avoided by doing normal writes syscalls. CC: Jan Kara <jack@suse.cz> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: Li Shaohua <shaohua.li@intel.com> Tested-by: Li Shaohua <shaohua.li@intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
7ccb9ad5 |
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30-Nov-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: max, min and target dirty pause time Control the pause time and the call intervals to balance_dirty_pages() with three parameters: 1) max_pause, limited by bdi_dirty and MAX_PAUSE 2) the target pause time, grows with the number of dd tasks and is normally limited by max_pause/2 3) the minimal pause, set to half the target pause and is used to skip short sleeps and accumulate them into bigger ones The typical behaviors after patch: - if ever task_ratelimit is far below dirty_ratelimit, the pause time will remain constant at max_pause and nr_dirtied_pause will be fluctuating with task_ratelimit - in the normal cases, nr_dirtied_pause will remain stable (keep in the same pace with dirty_ratelimit) and the pause time will be fluctuating with task_ratelimit In summary, someone has to fluctuate with task_ratelimit, because task_ratelimit = nr_dirtied_pause / pause We normally prefer a stable nr_dirtied_pause, until reaching max_pause. The notable behavior changes are: - in stable workloads, there will no longer be sudden big trajectory switching of nr_dirtied_pause as concerned by Peter. It will be as smooth as dirty_ratelimit and changing proportionally with it (as always, assuming bdi bandwidth does not fluctuate across 2^N lines, otherwise nr_dirtied_pause will show up in 2+ parallel trajectories) - in the rare cases when something keeps task_ratelimit far below dirty_ratelimit, the smoothness can no longer be retained and nr_dirtied_pause will be "dancing" with task_ratelimit. This fixes a (not that destructive but still not good) bug that dirty_ratelimit gets brought down undesirably <= balanced_dirty_ratelimit is under estimated <= weakly executed task_ratelimit <= pause goes too large and gets trimmed down to max_pause <= nr_dirtied_pause (based on dirty_ratelimit) is set too large <= dirty_ratelimit being much larger than task_ratelimit - introduce min_pause to avoid small pause sleeps - when pause is trimmed down to max_pause, try to compensate it at the next pause time The "refactor" type of changes are: The max_pause equation is slightly transformed to make it slightly more efficient. We now scale target_pause by (N * 10ms) on 2^N concurrent tasks, which is effectively equal to the original scaling max_pause by (N * 20ms) because the original code does implicit target_pause ~= max_pause / 2. Based on the same implicit ratio, target_pause starts with 10ms on 1 dd. CC: Jan Kara <jack@suse.cz> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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83712358 |
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11-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: dirty ratelimit - think time compensation Compensate the task's think time when computing the final pause time, so that ->dirty_ratelimit can be executed accurately. think time := time spend outside of balance_dirty_pages() In the rare case that the task slept longer than the 200ms period time (result in negative pause time), the sleep time will be compensated in the following periods, too, if it's less than 1 second. Accumulated errors are carefully avoided as long as the max pause area is not hitted. Pseudo code: period = pages_dirtied / task_ratelimit; think = jiffies - dirty_paused_when; pause = period - think; 1) normal case: period > think pause = period - think dirty_paused_when = jiffies + pause nr_dirtied = 0 period time |===============================>| think time pause time |===============>|==============>| ------|----------------|---------------|------------------------ dirty_paused_when jiffies 2) no pause case: period <= think don't pause; reduce future pause time by: dirty_paused_when += period nr_dirtied = 0 period time |===============================>| think time |===================================================>| ------|--------------------------------+-------------------|---- dirty_paused_when jiffies Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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2f800fbd |
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08-Aug-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: fix dirtied pages accounting on redirty De-account the accumulative dirty counters on page redirty. Page redirties (very common in ext4) will introduce mismatch between counters (a) and (b) a) NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied b) NR_WRITTEN, BDI_WRITTEN This will introduce systematic errors in balanced_rate and result in dirty page position errors (ie. the dirty pages are no longer balanced around the global/bdi setpoints). Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
d3bc1fef |
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14-Apr-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: fix dirtied pages accounting on sub-page writes When dd in 512bytes, generic_perform_write() calls balance_dirty_pages_ratelimited() 8 times for the same page, but obviously the page is only dirtied once. Fix it by accounting tsk->nr_dirtied and bdp_ratelimits at page dirty time. Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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54848d73 |
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05-Apr-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: charge leaked page dirties to active tasks It's a years long problem that a large number of short-lived dirtiers (eg. gcc instances in a fast kernel build) may starve long-run dirtiers (eg. dd) as well as pushing the dirty pages to the global hard limit. The solution is to charge the pages dirtied by the exited gcc to the other random dirtying tasks. It sounds not perfect, however should behave good enough in practice, seeing as that throttled tasks aren't actually running so those that are running are more likely to pick it up and get throttled, therefore promoting an equal spread. Randy: fix compile error: 'dirty_throttle_leaks' undeclared in exit.c Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
82e230a0 |
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02-Dec-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: set max_pause to lowest value on zero bdi_dirty Some trace shows lots of bdi_dirty=0 lines where it's actually some small value if w/o the accounting errors in the per-cpu bdi stats. In this case the max pause time should really be set to the smallest (non-zero) value to avoid IO queue underrun and improve throughput. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
c5c6343c |
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02-Dec-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: permit through good bdi even when global dirty exceeded On a system with 1 local mount and 1 NFS mount, if the NFS server becomes not responding when dd to the NFS mount, the NFS dirty pages may exceed the global dirty limit and _every_ task involving writing will be blocked. The whole system appears unresponsive. The workaround is to permit through the bdi's that only has a small number of dirty pages. The number chosen (bdi_stat_error pages) is not enough to enable the local disk to run in optimal throughput, however is enough to make the system responsive on a broken NFS mount. The user can then kill the dirtiers on the NFS mount and increase the global dirty limit to bring up the local disk's throughput. It risks allowing dirty pages to grow much larger than the global dirty limit when there are 1000+ mounts, however that's very unlikely to happen, especially in low memory profiles. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
aed21ad2 |
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23-Nov-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: comment on the bdi dirty threshold We do "floating proportions" to let active devices to grow its target share of dirty pages and stalled/inactive devices to decrease its target share over time. It works well except in the case of "an inactive disk suddenly goes busy", where the initial target share may be too small. To mitigate this, bdi_position_ratio() has the below line to raise a small bdi_thresh when it's safe to do so, so that the disk be feed with enough dirty pages for efficient IO and in turn fast rampup of bdi_thresh: bdi_thresh = max(bdi_thresh, (limit - dirty) / 8); balance_dirty_pages() normally does negative feedback control which adjusts ratelimit to balance the bdi dirty pages around the target. In some extreme cases when that is not enough, it will have to block the tasks completely until the bdi dirty pages drop below bdi_thresh. Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
468e6a20 |
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07-Sep-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: remove vm_dirties and task->dirties They are not used any more. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
1df64719 |
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13-Nov-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: hard throttle 1000+ dd on a slow USB stick The sleep based balance_dirty_pages() can pause at most MAX_PAUSE=200ms on every 1 4KB-page, which means it cannot throttle a task under 4KB/200ms=20KB/s. So when there are more than 512 dd writing to a 10MB/s USB stick, its bdi dirty pages could grow out of control. Even if we can increase MAX_PAUSE, the minimal (task_ratelimit = 1) means a limit of 4KB/s. They can eventually be safeguarded by the global limit check (nr_dirty < dirty_thresh). However if someone is also writing to an HDD at the same time, it'll get poor HDD write performance. We at least want to maintain good write performance for other devices when one device is attacked by some "massive parallel" workload, or suffers from slow write bandwidth, or somehow get stalled due to some error condition (eg. NFS server not responding). For a stalled device, we need to completely block its dirtiers, too, before its bdi dirty pages grow all the way up to the global limit and leave no space for the other functional devices. So change the loop exit condition to /* * Always enforce global dirty limit; also enforce bdi dirty limit * if the normal max_pause sleeps cannot keep things under control. */ if (nr_dirty < dirty_thresh && (bdi_dirty < bdi_thresh || bdi->dirty_ratelimit > 1)) break; which can be further simplified to if (task_ratelimit) break; Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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499d05ec |
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16-Nov-2011 |
Jan Kara <jack@suse.cz> |
mm: Make task in balance_dirty_pages() killable There is no reason why task in balance_dirty_pages() shouldn't be killable and it helps in recovering from some error conditions (like when filesystem goes in error state and cannot accept writeback anymore but we still want to kill processes using it to be able to unmount it). There will be follow up patches to further abort the generic_perform_write() and other filesystem write loops, to avoid large write + SIGKILL combination exceeding the dirty limit and possibly strange OOM. Reported-by: Kazuya Mio <k-mio@sx.jp.nec.com> Tested-by: Kazuya Mio <k-mio@sx.jp.nec.com> Reviewed-by: Neil Brown <neilb@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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3a73dbbc |
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07-Nov-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: fix uninitialized task_ratelimit In balance_dirty_pages() task_ratelimit may be not initialized (initialization skiped by goto pause), and then used when calling tracing hook. Fix it by moving the task_ratelimit assignment before goto pause. Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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d08c429b |
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31-Oct-2011 |
Johannes Weiner <jweiner@redhat.com> |
mm/page-writeback.c: document bdi_min_ratio Looks like someone got distracted after adding the comment characters. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b95f1b31 |
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16-Oct-2011 |
Paul Gortmaker <paul.gortmaker@windriver.com> |
mm: Map most files to use export.h instead of module.h The files changed within are only using the EXPORT_SYMBOL macro variants. They are not using core modular infrastructure and hence don't need module.h but only the export.h header. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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0e175a18 |
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07-Oct-2011 |
Curt Wohlgemuth <curtw@google.com> |
writeback: Add a 'reason' to wb_writeback_work This creates a new 'reason' field in a wb_writeback_work structure, which unambiguously identifies who initiates writeback activity. A 'wb_reason' enumeration has been added to writeback.h, to enumerate the possible reasons. The 'writeback_work_class' and tracepoint event class and 'writeback_queue_io' tracepoints are updated to include the symbolic 'reason' in all trace events. And the 'writeback_inodes_sbXXX' family of routines has had a wb_stats parameter added to them, so callers can specify why writeback is being started. Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Curt Wohlgemuth <curtw@google.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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ece13ac3 |
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29-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: trace event balance_dirty_pages Useful for analyzing the dynamics of the throttling algorithms and debugging user reported problems. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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b48c104d |
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02-Mar-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: trace event bdi_dirty_ratelimit It helps understand how various throttle bandwidths are updated. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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50657fc4 |
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11-Oct-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: fix ppc compile warnings on do_div(long long, unsigned long) Fix powerpc compile warnings mm/page-writeback.c: In function 'bdi_position_ratio': mm/page-writeback.c:622:3: warning: comparison of distinct pointer types lacks a cast [enabled by default] page-writeback.c:635:4: warning: comparison of distinct pointer types lacks a cast [enabled by default] Also fix gcc "uninitialized var" warnings. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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8927f66c |
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04-Aug-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: dirty position control - bdi reserve area Keep a minimal pool of dirty pages for each bdi, so that the disk IO queues won't underrun. Also gently increase a small bdi_thresh to avoid it stuck in 0 for some light dirtied bdi. It's particularly useful for JBOD and small memory system. It may result in (pos_ratio > 1) at the setpoint and push the dirty pages high. This is more or less intended because the bdi is in the danger of IO queue underflow. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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57fc978c |
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11-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: control dirty pause time The dirty pause time shall ultimately be controlled by adjusting nr_dirtied_pause, since there is relationship pause = pages_dirtied / task_ratelimit Assuming pages_dirtied ~= nr_dirtied_pause task_ratelimit ~= dirty_ratelimit We get nr_dirtied_pause ~= dirty_ratelimit * desired_pause Here dirty_ratelimit is preferred over task_ratelimit because it's more stable. It's also important to limit possible large transitional errors: - bw is changing quickly - pages_dirtied << nr_dirtied_pause on entering dirty exceeded area - pages_dirtied >> nr_dirtied_pause on btrfs (to be improved by a separate fix, but still expect non-trivial errors) So we end up using the above formula inside clamp_val(). The best test case for this code is to run 100 "dd bs=4M" tasks on btrfs and check its pause time distribution. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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c8462cc9 |
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11-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: limit max dirty pause time Apply two policies to scale down the max pause time for 1) small number of concurrent dirtiers 2) small memory system (comparing to storage bandwidth) MAX_PAUSE=200ms may only be suitable for high end servers with lots of concurrent dirtiers, where the large pause time can reduce much overheads. Otherwise, smaller pause time is desirable whenever possible, so as to get good responsiveness and smooth user experiences. It's actually required for good disk utilization in the case when all the dirty pages can be synced to disk within MAX_PAUSE=200ms. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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143dfe86 |
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27-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: IO-less balance_dirty_pages() As proposed by Chris, Dave and Jan, don't start foreground writeback IO inside balance_dirty_pages(). Instead, simply let it idle sleep for some time to throttle the dirtying task. In the mean while, kick off the per-bdi flusher thread to do background writeback IO. RATIONALS ========= - disk seeks on concurrent writeback of multiple inodes (Dave Chinner) If every thread doing writes and being throttled start foreground writeback, it leads to N IO submitters from at least N different inodes at the same time, end up with N different sets of IO being issued with potentially zero locality to each other, resulting in much lower elevator sort/merge efficiency and hence we seek the disk all over the place to service the different sets of IO. OTOH, if there is only one submission thread, it doesn't jump between inodes in the same way when congestion clears - it keeps writing to the same inode, resulting in large related chunks of sequential IOs being issued to the disk. This is more efficient than the above foreground writeback because the elevator works better and the disk seeks less. - lock contention and cache bouncing on concurrent IO submitters (Dave Chinner) With this patchset, the fs_mark benchmark on a 12-drive software RAID0 goes from CPU bound to IO bound, freeing "3-4 CPUs worth of spinlock contention". * "CPU usage has dropped by ~55%", "it certainly appears that most of the CPU time saving comes from the removal of contention on the inode_wb_list_lock" (IMHO at least 10% comes from the reduction of cacheline bouncing, because the new code is able to call much less frequently into balance_dirty_pages() and hence access the global page states) * the user space "App overhead" is reduced by 20%, by avoiding the cacheline pollution by the complex writeback code path * "for a ~5% throughput reduction", "the number of write IOs have dropped by ~25%", and the elapsed time reduced from 41:42.17 to 40:53.23. * On a simple test of 100 dd, it reduces the CPU %system time from 30% to 3%, and improves IO throughput from 38MB/s to 42MB/s. - IO size too small for fast arrays and too large for slow USB sticks The write_chunk used by current balance_dirty_pages() cannot be directly set to some large value (eg. 128MB) for better IO efficiency. Because it could lead to more than 1 second user perceivable stalls. Even the current 4MB write size may be too large for slow USB sticks. The fact that balance_dirty_pages() starts IO on itself couples the IO size to wait time, which makes it hard to do suitable IO size while keeping the wait time under control. Now it's possible to increase writeback chunk size proportional to the disk bandwidth. In a simple test of 50 dd's on XFS, 1-HDD, 3GB ram, the larger writeback size dramatically reduces the seek count to 1/10 (far beyond my expectation) and improves the write throughput by 24%. - long block time in balance_dirty_pages() hurts desktop responsiveness Many of us may have the experience: it often takes a couple of seconds or even long time to stop a heavy writing dd/cp/tar command with Ctrl-C or "kill -9". - IO pipeline broken by bumpy write() progress There are a broad class of "loop {read(buf); write(buf);}" applications whose read() pipeline will be under-utilized or even come to a stop if the write()s have long latencies _or_ don't progress in a constant rate. The current threshold based throttling inherently transfers the large low level IO completion fluctuations to bumpy application write()s, and further deteriorates with increasing number of dirtiers and/or bdi's. For example, when doing 50 dd's + 1 remote rsync to an XFS partition, the rsync progresses very bumpy in legacy kernel, and throughput is improved by 67% by this patchset. (plus the larger write chunk size, it will be 93% speedup). The new rate based throttling can support 1000+ dd's with excellent smoothness, low latency and low overheads. For the above reasons, it's much better to do IO-less and low latency pauses in balance_dirty_pages(). Jan Kara, Dave Chinner and me explored the scheme to let balance_dirty_pages() wait for enough writeback IO completions to safeguard the dirty limit. However it's found to have two problems: - in large NUMA systems, the per-cpu counters may have big accounting errors, leading to big throttle wait time and jitters. - NFS may kill large amount of unstable pages with one single COMMIT. Because NFS server serves COMMIT with expensive fsync() IOs, it is desirable to delay and reduce the number of COMMITs. So it's not likely to optimize away such kind of bursty IO completions, and the resulted large (and tiny) stall times in IO completion based throttling. So here is a pause time oriented approach, which tries to control the pause time in each balance_dirty_pages() invocations, by controlling the number of pages dirtied before calling balance_dirty_pages(), for smooth and efficient dirty throttling: - avoid useless (eg. zero pause time) balance_dirty_pages() calls - avoid too small pause time (less than 4ms, which burns CPU power) - avoid too large pause time (more than 200ms, which hurts responsiveness) - avoid big fluctuations of pause times It can control pause times at will. The default policy (in a followup patch) will be to do ~10ms pauses in 1-dd case, and increase to ~100ms in 1000-dd case. BEHAVIOR CHANGE =============== (1) dirty threshold Users will notice that the applications will get throttled once crossing the global (background + dirty)/2=15% threshold, and then balanced around 17.5%. Before patch, the behavior is to just throttle it at 20% dirtyable memory in 1-dd case. Since the task will be soft throttled earlier than before, it may be perceived by end users as performance "slow down" if his application happens to dirty more than 15% dirtyable memory. (2) smoothness/responsiveness Users will notice a more responsive system during heavy writeback. "killall dd" will take effect instantly. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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9d823e8f |
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11-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: per task dirty rate limit Add two fields to task_struct. 1) account dirtied pages in the individual tasks, for accuracy 2) per-task balance_dirty_pages() call intervals, for flexibility The balance_dirty_pages() call interval (ie. nr_dirtied_pause) will scale near-sqrt to the safety gap between dirty pages and threshold. The main problem of per-task nr_dirtied is, if 1k+ tasks start dirtying pages at exactly the same time, each task will be assigned a large initial nr_dirtied_pause, so that the dirty threshold will be exceeded long before each task reached its nr_dirtied_pause and hence call balance_dirty_pages(). The solution is to watch for the number of pages dirtied on each CPU in between the calls into balance_dirty_pages(). If it exceeds ratelimit_pages (3% dirty threshold), force call balance_dirty_pages() for a chance to set bdi->dirty_exceeded. In normal situations, this safeguarding condition is not expected to trigger at all. On the sqrt in dirty_poll_interval(): It will serve as an initial guess when dirty pages are still in the freerun area. When dirty pages are floating inside the dirty control scope [freerun, limit], a followup patch will use some refined dirty poll interval to get the desired pause time. thresh-dirty (MB) sqrt 1 16 2 22 4 32 8 45 16 64 32 90 64 128 128 181 256 256 512 362 1024 512 The above table means, given 1MB (or 1GB) gap and the dd tasks polling balance_dirty_pages() on every 16 (or 512) pages, the dirty limit won't be exceeded as long as there are less than 16 (or 512) concurrent dd's. So sqrt naturally leads to less overheads and more safe concurrent tasks for large memory servers, which have large (thresh-freerun) gaps. peter: keep the per-CPU ratelimit for safeguarding the 1k+ tasks case CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Andrea Righi <andrea@betterlinux.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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7381131c |
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26-Aug-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: stabilize bdi->dirty_ratelimit There are some imperfections in balanced_dirty_ratelimit. 1) large fluctuations The dirty_rate used for computing balanced_dirty_ratelimit is merely averaged in the past 200ms (very small comparing to the 3s estimation period for write_bw), which makes rather dispersed distribution of balanced_dirty_ratelimit. It's pretty hard to average out the singular points by increasing the estimation period. Considering that the averaging technique will introduce very undesirable time lags, I give it up totally. (btw, the 3s write_bw averaging time lag is much more acceptable because its impact is one-way and therefore won't lead to oscillations.) The more practical way is filtering -- most singular balanced_dirty_ratelimit points can be filtered out by remembering some prev_balanced_rate and prev_prev_balanced_rate. However the more reliable way is to guard balanced_dirty_ratelimit with task_ratelimit. 2) due to truncates and fs redirties, the (write_bw <=> dirty_rate) match could become unbalanced, which may lead to large systematical errors in balanced_dirty_ratelimit. The truncates, due to its possibly bumpy nature, can hardly be compensated smoothly. So let's face it. When some over-estimated balanced_dirty_ratelimit brings dirty_ratelimit high, dirty pages will go higher than the setpoint. task_ratelimit will in turn become lower than dirty_ratelimit. So if we consider both balanced_dirty_ratelimit and task_ratelimit and update dirty_ratelimit only when they are on the same side of dirty_ratelimit, the systematical errors in balanced_dirty_ratelimit won't be able to bring dirty_ratelimit far away. The balanced_dirty_ratelimit estimation may also be inaccurate near @limit or @freerun, however is less an issue. 3) since we ultimately want to - keep the fluctuations of task ratelimit as small as possible - keep the dirty pages around the setpoint as long time as possible the update policy used for (2) also serves the above goals nicely: if for some reason the dirty pages are high (task_ratelimit < dirty_ratelimit), and dirty_ratelimit is low (dirty_ratelimit < balanced_dirty_ratelimit), there is no point to bring up dirty_ratelimit in a hurry only to hurt both the above two goals. So, we make use of task_ratelimit to limit the update of dirty_ratelimit in two ways: 1) avoid changing dirty rate when it's against the position control target (the adjusted rate will slow down the progress of dirty pages going back to setpoint). 2) limit the step size. task_ratelimit is changing values step by step, leaving a consistent trace comparing to the randomly jumping balanced_dirty_ratelimit. task_ratelimit also has the nice smaller errors in stable state and typically larger errors when there are big errors in rate. So it's a pretty good limiting factor for the step size of dirty_ratelimit. Note that bdi->dirty_ratelimit is always tracking balanced_dirty_ratelimit. task_ratelimit is merely used as a limiting factor. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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be3ffa27 |
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12-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: dirty rate control It's all about bdi->dirty_ratelimit, which aims to be (write_bw / N) when there are N dd tasks. On write() syscall, use bdi->dirty_ratelimit ============================================ balance_dirty_pages(pages_dirtied) { task_ratelimit = bdi->dirty_ratelimit * bdi_position_ratio(); pause = pages_dirtied / task_ratelimit; sleep(pause); } On every 200ms, update bdi->dirty_ratelimit =========================================== bdi_update_dirty_ratelimit() { task_ratelimit = bdi->dirty_ratelimit * bdi_position_ratio(); balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate; bdi->dirty_ratelimit = balanced_dirty_ratelimit } Estimation of balanced bdi->dirty_ratelimit =========================================== balanced task_ratelimit ----------------------- balance_dirty_pages() needs to throttle tasks dirtying pages such that the total amount of dirty pages stays below the specified dirty limit in order to avoid memory deadlocks. Furthermore we desire fairness in that tasks get throttled proportionally to the amount of pages they dirty. IOW we want to throttle tasks such that we match the dirty rate to the writeout bandwidth, this yields a stable amount of dirty pages: dirty_rate == write_bw (1) The fairness requirement gives us: task_ratelimit = balanced_dirty_ratelimit == write_bw / N (2) where N is the number of dd tasks. We don't know N beforehand, but still can estimate balanced_dirty_ratelimit within 200ms. Start by throttling each dd task at rate task_ratelimit = task_ratelimit_0 (3) (any non-zero initial value is OK) After 200ms, we measured dirty_rate = # of pages dirtied by all dd's / 200ms write_bw = # of pages written to the disk / 200ms For the aggressive dd dirtiers, the equality holds dirty_rate == N * task_rate == N * task_ratelimit_0 (4) Or task_ratelimit_0 == dirty_rate / N (5) Now we conclude that the balanced task ratelimit can be estimated by write_bw balanced_dirty_ratelimit = task_ratelimit_0 * ---------- (6) dirty_rate Because with (4) and (5) we can get the desired equality (1): write_bw balanced_dirty_ratelimit == (dirty_rate / N) * ---------- dirty_rate == write_bw / N Then using the balanced task ratelimit we can compute task pause times like: task_pause = task->nr_dirtied / task_ratelimit task_ratelimit with position control ------------------------------------ However, while the above gives us means of matching the dirty rate to the writeout bandwidth, it at best provides us with a stable dirty page count (assuming a static system). In order to control the dirty page count such that it is high enough to provide performance, but does not exceed the specified limit we need another control. The dirty position control works by extending (2) to task_ratelimit = balanced_dirty_ratelimit * pos_ratio (7) where pos_ratio is a negative feedback function that subjects to 1) f(setpoint) = 1.0 2) df/dx < 0 That is, if the dirty pages are ABOVE the setpoint, we throttle each task a bit more HEAVY than balanced_dirty_ratelimit, so that the dirty pages are created less fast than they are cleaned, thus DROP to the setpoints (and the reverse). Based on (7) and the assumption that both dirty_ratelimit and pos_ratio remains CONSTANT for the past 200ms, we get task_ratelimit_0 = balanced_dirty_ratelimit * pos_ratio (8) Putting (8) into (6), we get the formula used in bdi_update_dirty_ratelimit(): write_bw balanced_dirty_ratelimit *= pos_ratio * ---------- (9) dirty_rate Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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af6a3113 |
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03-Oct-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: add bg_threshold parameter to __bdi_update_bandwidth() No behavior change. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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6c14ae1e |
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02-Mar-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: dirty position control bdi_position_ratio() provides a scale factor to bdi->dirty_ratelimit, so that the resulted task rate limit can drive the dirty pages back to the global/bdi setpoints. Old scheme is, | free run area | throttle area ----------------------------------------+----------------------------> thresh^ dirty pages New scheme is, ^ task rate limit | | * | * | * |[free run] * [smooth throttled] | * | * | * ..bdi->dirty_ratelimit..........* | . * | . * | . * | . * | . * +-------------------------------.-----------------------*------------> setpoint^ limit^ dirty pages The slope of the bdi control line should be 1) large enough to pull the dirty pages to setpoint reasonably fast 2) small enough to avoid big fluctuations in the resulted pos_ratio and hence task ratelimit Since the fluctuation range of the bdi dirty pages is typically observed to be within 1-second worth of data, the bdi control line's slope is selected to be a linear function of bdi write bandwidth, so that it can adapt to slow/fast storage devices well. Assume the bdi control line pos_ratio = 1.0 + k * (dirty - bdi_setpoint) where k is the negative slope. If targeting for 12.5% fluctuation range in pos_ratio when dirty pages are fluctuating in range [bdi_setpoint - write_bw/2, bdi_setpoint + write_bw/2], we get slope k = - 1 / (8 * write_bw) Let pos_ratio(x_intercept) = 0, we get the parameter used in code: x_intercept = bdi_setpoint + 8 * write_bw The global/bdi slopes are nicely complementing each other when the system has only one major bdi (indicated by bdi_thresh ~= thresh): 1) slope of global control line => scaling to the control scope size 2) slope of main bdi control line => scaling to the writeout bandwidth so that - in memory tight systems, (1) becomes strong enough to squeeze dirty pages inside the control scope - in large memory systems where the "gravity" of (1) for pulling the dirty pages to setpoint is too weak, (2) can back (1) up and drive dirty pages to bdi_setpoint ~= setpoint reasonably fast. Unfortunately in JBOD setups, the fluctuation range of bdi threshold is related to memory size due to the interferences between disks. In this case, the bdi slope will be weighted sum of write_bw and bdi_thresh. Given equations span = x_intercept - bdi_setpoint k = df/dx = - 1 / span and the extremum values span = bdi_thresh dx = bdi_thresh we get df = - dx / span = - 1.0 That means, when bdi_dirty deviates bdi_thresh up, pos_ratio and hence task ratelimit will fluctuate by -100%. peter: use 3rd order polynomial for the global control line CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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c8e28ce0 |
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23-Jan-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: account per-bdi accumulated dirtied pages Introduce the BDI_DIRTIED counter. It will be used for estimating the bdi's dirty bandwidth. CC: Jan Kara <jack@suse.cz> CC: Michael Rubin <mrubin@google.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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bb082295 |
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16-Aug-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
squeeze max-pause area and drop pass-good area Revert the pass-good area introduced in ffd1f609ab10 ("writeback: introduce max-pause and pass-good dirty limits") and make the max-pause area smaller and safe. This fixes ~30% performance regression in the ext3 data=writeback fio_mmap_randwrite_64k/fio_mmap_randrw_64k test cases, where there are 12 JBOD disks, on each disk runs 8 concurrent tasks doing reads+writes. Using deadline scheduler also has a regression, but not that big as CFQ, so this suggests we have some write starvation. The test logs show that - the disks are sometimes under utilized - global dirty pages sometimes rush high to the pass-good area for several hundred seconds, while in the mean time some bdi dirty pages drop to very low value (bdi_dirty << bdi_thresh). Then suddenly the global dirty pages dropped under global dirty threshold and bdi_dirty rush very high (for example, 2 times higher than bdi_thresh). During which time balance_dirty_pages() is not called at all. So the problems are 1) The random writes progress so slow that they break the assumption of the max-pause logic that "8 pages per 200ms is typically more than enough to curb heavy dirtiers". 2) The max-pause logic ignored task_bdi_thresh and thus opens the possibility for some bdi's to over dirty pages, leading to (bdi_dirty >> bdi_thresh) and then (bdi_thresh >> bdi_dirty) for others. 3) The higher max-pause/pass-good thresholds somehow leads to the bad swing of dirty pages. The fix is to allow the task to slightly dirty over task_bdi_thresh, but no way to exceed bdi_dirty and/or global dirty_thresh. Tests show that it fixed the JBOD regression completely (both behavior and performance), while still being able to cut down large pause times in balance_dirty_pages() for single-disk cases. Reported-by: Li Shaohua <shaohua.li@intel.com> Tested-by: Li Shaohua <shaohua.li@intel.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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99b12e3d |
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25-Jul-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: account NR_WRITTEN at IO completion time NR_WRITTEN is now accounted at block IO enqueue time, which is not very accurate as to common understanding. This moves NR_WRITTEN accounting to the IO completion time and makes it more consistent with BDI_WRITTEN, which is used for bandwidth estimation. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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72c47832 |
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25-Jul-2011 |
Konstantin Khlebnikov <khlebnikov@openvz.org> |
mm: remove useless rcu lock-unlock from mapping_tagged() radix_tree_tagged() is lockless - it reads from a member of the raid-tree root node. It does not require any protection. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bcff25fc |
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01-Jul-2011 |
Jan Kara <jack@suse.cz> |
mm: properly reflect task dirty limits in dirty_exceeded logic We set bdi->dirty_exceeded (and thus ratelimiting code starts to call balance_dirty_pages() every 8 pages) when a per-bdi limit is exceeded or global limit is exceeded. But per-bdi limit also depends on the task. Thus different tasks reach the limit on that bdi at different levels of dirty pages. The result is that with current code bdi->dirty_exceeded ping-ponged between 1 and 0 depending on which task just got into balance_dirty_pages(). We fix the issue by clearing bdi->dirty_exceeded only when per-bdi amount of dirty pages drops below the threshold (7/8 * bdi_dirty_limit) where task limits already do not have any influence. Impact: The end result is, the dirty pages are kept more tightly under control, with the average number slightly lowered than before. This reduces the risk to throttle light dirtiers and hence more responsive. However it may add overheads by enforcing balance_dirty_pages() calls on every 8 pages when there are 2+ heavy dirtiers. CC: Andrew Morton <akpm@linux-foundation.org> CC: Christoph Hellwig <hch@infradead.org> CC: Dave Chinner <david@fromorbit.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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e1cbe236 |
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06-Dec-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: trace global_dirty_state Add trace event balance_dirty_state for showing the global dirty page counts and thresholds at each global_dirty_limits() invocation. This will cover the callers throttle_vm_writeout(), over_bground_thresh() and each balance_dirty_pages() loop. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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ffd1f609 |
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19-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: introduce max-pause and pass-good dirty limits The max-pause limit helps to keep the sleep time inside balance_dirty_pages() within MAX_PAUSE=200ms. The 200ms max sleep means per task rate limit of 8pages/200ms=160KB/s when dirty exceeded, which normally is enough to stop dirtiers from continue pushing the dirty pages high, unless there are a sufficient large number of slow dirtiers (eg. 500 tasks doing 160KB/s will still sum up to 80MB/s, exceeding the write bandwidth of a slow disk and hence accumulating more and more dirty pages). The pass-good limit helps to let go of the good bdi's in the presence of a blocked bdi (ie. NFS server not responding) or slow USB disk which for some reason build up a large number of initial dirty pages that refuse to go away anytime soon. For example, given two bdi's A and B and the initial state bdi_thresh_A = dirty_thresh / 2 bdi_thresh_B = dirty_thresh / 2 bdi_dirty_A = dirty_thresh / 2 bdi_dirty_B = dirty_thresh / 2 Then A get blocked, after a dozen seconds bdi_thresh_A = 0 bdi_thresh_B = dirty_thresh bdi_dirty_A = dirty_thresh / 2 bdi_dirty_B = dirty_thresh / 2 The (bdi_dirty_B < bdi_thresh_B) test is now useless and the dirty pages will be effectively throttled by condition (nr_dirty < dirty_thresh). This has two problems: (1) we lose the protections for light dirtiers (2) balance_dirty_pages() effectively becomes IO-less because the (bdi_nr_reclaimable > bdi_thresh) test won't be true. This is good for IO, but balance_dirty_pages() loses an important way to break out of the loop which leads to more spread out throttle delays. DIRTY_PASSGOOD_AREA can eliminate the above issues. The only problem is, DIRTY_PASSGOOD_AREA needs to be defined as 2 to fully cover the above example while this patch uses the more conservative value 8 so as not to surprise people with too many dirty pages than expected. The max-pause limit won't noticeably impact the speed dirty pages are knocked down when there is a sudden drop of global/bdi dirty thresholds. Because the heavy dirties will be throttled below 160KB/s which is slow enough. It does help to avoid long dirty throttle delays and especially will make light dirtiers more responsive. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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c42843f2 |
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02-Mar-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: introduce smoothed global dirty limit The start of a heavy weight application (ie. KVM) may instantly knock down determine_dirtyable_memory() if the swap is not enabled or full. global_dirty_limits() and bdi_dirty_limit() will in turn get global/bdi dirty thresholds that are _much_ lower than the global/bdi dirty pages. balance_dirty_pages() will then heavily throttle all dirtiers including the light ones, until the dirty pages drop below the new dirty thresholds. During this _deep_ dirty-exceeded state, the system may appear rather unresponsive to the users. About "deep" dirty-exceeded: task_dirty_limit() assigns 1/8 lower dirty threshold to heavy dirtiers than light ones, and the dirty pages will be throttled around the heavy dirtiers' dirty threshold and reasonably below the light dirtiers' dirty threshold. In this state, only the heavy dirtiers will be throttled and the dirty pages are carefully controlled to not exceed the light dirtiers' dirty threshold. However if the threshold itself suddenly drops below the number of dirty pages, the light dirtiers will get heavily throttled. So introduce global_dirty_limit for tracking the global dirty threshold with policies - follow downwards slowly - follow up in one shot global_dirty_limit can effectively mask out the impact of sudden drop of dirtyable memory. It will be used in the next patch for two new type of dirty limits. Note that the new dirty limits are not going to avoid throttling the light dirtiers, but could limit their sleep time to 200ms. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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7762741e |
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12-Sep-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: consolidate variable names in balance_dirty_pages() Introduce nr_dirty = NR_FILE_DIRTY + NR_WRITEBACK + NR_UNSTABLE_NFS in order to simplify many tests in the following patches. balance_dirty_pages() will eventually care only about the dirty sums besides nr_writeback. Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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e98be2d5 |
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29-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: bdi write bandwidth estimation The estimation value will start from 100MB/s and adapt to the real bandwidth in seconds. It tries to update the bandwidth only when disk is fully utilized. Any inactive period of more than one second will be skipped. The estimated bandwidth will be reflecting how fast the device can writeout when _fully utilized_, and won't drop to 0 when it goes idle. The value will remain constant at disk idle time. At busy write time, if not considering fluctuations, it will also remain high unless be knocked down by possible concurrent reads that compete for the disk time and bandwidth with async writes. The estimation is not done purely in the flusher because there is no guarantee for write_cache_pages() to return timely to update bandwidth. The bdi->avg_write_bandwidth smoothing is very effective for filtering out sudden spikes, however may be a little biased in long term. The overheads are low because the bdi bandwidth update only occurs at 200ms intervals. The 200ms update interval is suitable, because it's not possible to get the real bandwidth for the instance at all, due to large fluctuations. The NFS commits can be as large as seconds worth of data. One XFS completion may be as large as half second worth of data if we are going to increase the write chunk to half second worth of data. In ext4, fluctuations with time period of around 5 seconds is observed. And there is another pattern of irregular periods of up to 20 seconds on SSD tests. That's why we are not only doing the estimation at 200ms intervals, but also averaging them over a period of 3 seconds and then go further to do another level of smoothing in avg_write_bandwidth. CC: Li Shaohua <shaohua.li@intel.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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f7d2b1ec |
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08-Dec-2010 |
Jan Kara <jack@suse.cz> |
writeback: account per-bdi accumulated written pages Introduce the BDI_WRITTEN counter. It will be used for estimating the bdi's write bandwidth. Peter Zijlstra <a.p.zijlstra@chello.nl>: Move BDI_WRITTEN accounting into __bdi_writeout_inc(). This will cover and fix fuse, which only calls bdi_writeout_inc(). CC: Michael Rubin <mrubin@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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d46db3d5 |
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04-May-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: make writeback_control.nr_to_write straight Pass struct wb_writeback_work all the way down to writeback_sb_inodes(), and initialize the struct writeback_control there. struct writeback_control is basically designed to control writeback of a single file, but we keep abuse it for writing multiple files in writeback_sb_inodes() and its callers. It immediately clean things up, e.g. suddenly wbc.nr_to_write vs work->nr_pages starts to make sense, and instead of saving and restoring pages_skipped in writeback_sb_inodes it can always start with a clean zero value. It also makes a neat IO pattern change: large dirty files are now written in the full 4MB writeback chunk size, rather than whatever remained quota in wbc->nr_to_write. Acked-by: Jan Kara <jack@suse.cz> Proposed-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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36715cef |
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11-Jun-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: skip tmpfs early in balance_dirty_pages_ratelimited_nr() This helps prevent tmpfs dirtiers from skewing the per-cpu bdp_ratelimits. Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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3efaf0fa |
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16-Dec-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: skip balance_dirty_pages() for in-memory fs This avoids unnecessary checks and dirty throttling on tmpfs/ramfs. Notes about the tmpfs/ramfs behavior changes: As for 2.6.36 and older kernels, the tmpfs writes will sleep inside balance_dirty_pages() as long as we are over the (dirty+background)/2 global throttle threshold. This is because both the dirty pages and threshold will be 0 for tmpfs/ramfs. Hence this test will always evaluate to TRUE: dirty_exceeded = (bdi_nr_reclaimable + bdi_nr_writeback >= bdi_thresh) || (nr_reclaimable + nr_writeback >= dirty_thresh); For 2.6.37, someone complained that the current logic does not allow the users to set vm.dirty_ratio=0. So commit 4cbec4c8b9 changed the test to dirty_exceeded = (bdi_nr_reclaimable + bdi_nr_writeback > bdi_thresh) || (nr_reclaimable + nr_writeback > dirty_thresh); So 2.6.37 will behave differently for tmpfs/ramfs: it will never get throttled unless the global dirty threshold is exceeded (which is very unlikely to happen; once happen, will block many tasks). I'd say that the 2.6.36 behavior is very bad for tmpfs/ramfs. It means for a busy writing server, tmpfs write()s may get livelocked! The "inadvertent" throttling can hardly bring help to any workload because of its "either no throttling, or get throttled to death" property. So based on 2.6.37, this patch won't bring more noticeable changes. CC: Hugh Dickins <hughd@google.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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6f718656 |
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02-Mar-2011 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: add bdi_dirty_limit() kernel-doc Clarify the bdi_dirty_limit() comment. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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#
6e6938b6 |
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06-Jun-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage sync(2) is performed in two stages: the WB_SYNC_NONE sync and the WB_SYNC_ALL sync. Identify the first stage with .tagged_writepages and do livelock prevention for it, too. Jan's commit f446daaea9 ("mm: implement writeback livelock avoidance using page tagging") is a partial fix in that it only fixed the WB_SYNC_ALL phase livelock. Although ext4 is tested to no longer livelock with commit f446daaea9, it may due to some "redirty_tail() after pages_skipped" effect which is by no means a guarantee for _all_ the file systems. Note that writeback_inodes_sb() is called by not only sync(), they are treated the same because the other callers also need livelock prevention. Impact: It changes the order in which pages/inodes are synced to disk. Now in the WB_SYNC_NONE stage, it won't proceed to write the next inode until finished with the current inode. Acked-by: Jan Kara <jack@suse.cz> CC: Dave Chinner <david@fromorbit.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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cf15b07c |
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22-Mar-2011 |
Jun'ichi Nomura <j-nomura@ce.jp.nec.com> |
writeback: make mapping->writeback_index to point to the last written page For range-cyclic writeback (e.g. kupdate), the writeback code sets a continuation point of the next writeback to mapping->writeback_index which is set the page after the last written page. This happens so that we evenly write the whole file even if pages in it get continuously redirtied. However, in some cases, sequential writer is writing in the middle of the page and it just redirties the last written page by continuing from that. For example with an application which uses a file as a big ring buffer we see: [1st writeback session] ... flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898514 + 8 flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898522 + 8 flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898530 + 8 flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898538 + 8 flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898546 + 8 kworker/0:1-11 4571: block_rq_issue: 8,0 W 0 () 94898514 + 40 >> flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898554 + 8 >> flush-8:0-2743 4571: block_rq_issue: 8,0 W 0 () 94898554 + 8 [2nd writeback session after 35sec] flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898562 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898570 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898578 + 8 ... kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94898562 + 640 kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94899202 + 72 ... flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899962 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899970 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899978 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899986 + 8 flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899994 + 8 kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94899962 + 40 >> flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898554 + 8 >> flush-8:0-2743 4606: block_rq_issue: 8,0 W 0 () 94898554 + 8 So we seeked back to 94898554 after we wrote all the pages at the end of the file. This extra seek seems unnecessary. If we continue writeback from the last written page, we can avoid it and do not cause harm to other cases. The original intent of even writeout over the whole file is preserved and if the page does not get redirtied pagevec_lookup_tag() just skips it. As an exceptional case, when I/O error happens, set done_index to the next page as the comment in the code suggests. Tested-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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278df9f4 |
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22-Mar-2011 |
Minchan Kim <minchan.kim@gmail.com> |
mm: reclaim invalidated page ASAP invalidate_mapping_pages is very big hint to reclaimer. It means user doesn't want to use the page any more. So in order to prevent working set page eviction, this patch move the page into tail of inactive list by PG_reclaim. Please, remember that pages in inactive list are working set as well as active list. If we don't move pages into inactive list's tail, pages near by tail of inactive list can be evicted although we have a big clue about useless pages. It's totally bad. Now PG_readahead/PG_reclaim is shared. fe3cba17 added ClearPageReclaim into clear_page_dirty_for_io for preventing fast reclaiming readahead marker page. In this series, PG_reclaim is used by invalidated page, too. If VM find the page is invalidated and it's dirty, it sets PG_reclaim to reclaim asap. Then, when the dirty page will be writeback, clear_page_dirty_for_io will clear PG_reclaim unconditionally. It disturbs this serie's goal. I think it's okay to clear PG_readahead when the page is dirty, not writeback time. So this patch moves ClearPageReadahead. In v4, ClearPageReadahead in set_page_dirty has a problem which is reported by Steven Barrett. It's due to compound page. Some driver(ex, audio) calls set_page_dirty with compound page which isn't on LRU. but my patch does ClearPageRelcaim on compound page. In non-CONFIG_PAGEFLAGS_EXTENDED, it breaks PageTail flag. I think it doesn't affect THP and pass my test with THP enabling but Cced Andrea for double check. Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Reported-by: Steven Barrett <damentz@liquorix.net> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9b6096a6 |
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17-Mar-2011 |
Shaohua Li <shaohua.li@intel.com> |
mm: make generic_writepages() use plugging This recovers a performance regression caused by the removal of the per-device plugging. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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7eaceacc |
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10-Mar-2011 |
Jens Axboe <jaxboe@fusionio.com> |
block: remove per-queue plugging Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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240c879f |
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13-Jan-2011 |
Minchan Kim <minchan.kim@gmail.com> |
writeback: avoid unnecessary determine_dirtyable_memory call I think determine_dirtyable_memory() is a rather costly function since it need many atomic reads for gathering zone/global page state. But when we use vm_dirty_bytes && dirty_background_bytes, we don't need that costly calculation. This patch eliminates such unnecessary overhead. NOTE : newly added if condition might add overhead in normal path. But it should be _really_ small because anyway we need the access both vm_dirty_bytes and dirty_background_bytes so it is likely to hit the cache. [akpm@linux-foundation.org: fix used-uninitialised warning] Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c3f0da63 |
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13-Jan-2011 |
Bob Liu <lliubbo@gmail.com> |
mm/page-writeback.c: fix __set_page_dirty_no_writeback() return value __set_page_dirty_no_writeback() should return true if it actually transitioned the page from a clean to dirty state although it seems nobody uses its return value at present. Signed-off-by: Bob Liu <lliubbo@gmail.com> Acked-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ebd1373d |
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03-Jan-2011 |
Minchan Kim <minchan.kim@gmail.com> |
writeback: fix global_dirty_limits comment runtime -> real-time Change runtime with real-time Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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d153ba64 |
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21-Dec-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: do uninterruptible sleep in balance_dirty_pages() Using TASK_INTERRUPTIBLE in balance_dirty_pages() seems wrong. If it's going to do that then it must break out if signal_pending(), otherwise it's pretty much guaranteed to degenerate into a busywait loop. Plus we *do* want these processes to appear in D state and to contribute to load average. So it should be TASK_UNINTERRUPTIBLE. -- Andrew Morton Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4cbec4c8 |
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26-Oct-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: remove the internal 5% low bound on dirty_ratio The dirty_ratio was silently limited in global_dirty_limits() to >= 5%. This is not a user expected behavior. And it's inconsistent with calc_period_shift(), which uses the plain vm_dirty_ratio value. Let's remove the internal bound. At the same time, fix balance_dirty_pages() to work with the dirty_thresh=0 case. This allows applications to proceed when dirty+writeback pages are all cleaned. And ">" fits with the name "exceeded" better than ">=" does. Neil thinks it is an aesthetic improvement as well as a functional one :) Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Proposed-by: Con Kolivas <kernel@kolivas.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Neil Brown <neilb@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ea941f0e |
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26-Oct-2010 |
Michael Rubin <mrubin@google.com> |
writeback: add nr_dirtied and nr_written to /proc/vmstat To help developers and applications gain visibility into writeback behaviour adding two entries to vm_stat_items and /proc/vmstat. This will allow us to track the "written" and "dirtied" counts. # grep nr_dirtied /proc/vmstat nr_dirtied 3747 # grep nr_written /proc/vmstat nr_written 3618 Signed-off-by: Michael Rubin <mrubin@google.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f629d1c9 |
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26-Oct-2010 |
Michael Rubin <mrubin@google.com> |
mm: add account_page_writeback() To help developers and applications gain visibility into writeback behaviour this patch adds two counters to /proc/vmstat. # grep nr_dirtied /proc/vmstat nr_dirtied 3747 # grep nr_written /proc/vmstat nr_written 3618 These entries allow user apps to understand writeback behaviour over time and learn how it is impacting their performance. Currently there is no way to inspect dirty and writeback speed over time. It's not possible for nr_dirty/nr_writeback. These entries are necessary to give visibility into writeback behaviour. We have /proc/diskstats which lets us understand the io in the block layer. We have blktrace for more in depth understanding. We have e2fsprogs and debugsfs to give insight into the file systems behaviour, but we don't offer our users the ability understand what writeback is doing. There is no way to know how active it is over the whole system, if it's falling behind or to quantify it's efforts. With these values exported users can easily see how much data applications are sending through writeback and also at what rates writeback is processing this data. Comparing the rates of change between the two allow developers to see when writeback is not able to keep up with incoming traffic and the rate of dirty memory being sent to the IO back end. This allows folks to understand their io workloads and track kernel issues. Non kernel engineers at Google often use these counters to solve puzzling performance problems. Patch #4 adds a pernode vmstat file with nr_dirtied and nr_written Patch #5 add writeback thresholds to /proc/vmstat Currently these values are in debugfs. But they should be promoted to /proc since they are useful for developers who are writing databases and file servers and are not debugging the kernel. The output is as below: # grep threshold /proc/vmstat nr_pages_dirty_threshold 409111 nr_pages_dirty_background_threshold 818223 This patch: This allows code outside of the mm core to safely manipulate page writeback state and not worry about the other accounting. Not using these routines means that some code will lose track of the accounting and we get bugs. Modify nilfs2 to use interface. Signed-off-by: Michael Rubin <mrubin@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Cc: Jiro SEKIBA <jir@unicus.jp> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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546a1924 |
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23-Aug-2010 |
Dave Chinner <dchinner@redhat.com> |
writeback: write_cache_pages doesn't terminate at nr_to_write <= 0 I noticed XFS writeback in 2.6.36-rc1 was much slower than it should have been. Enabling writeback tracing showed: flush-253:16-8516 [007] 1342952.351608: wbc_writepage: bdi 253:16: towrt=1024 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [007] 1342952.351654: wbc_writepage: bdi 253:16: towrt=1023 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369520: wbc_writepage: bdi 253:16: towrt=0 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369542: wbc_writepage: bdi 253:16: towrt=-1 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369549: wbc_writepage: bdi 253:16: towrt=-2 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 Writeback is not terminating in background writeback if ->writepage is returning with wbc->nr_to_write == 0, resulting in sub-optimal single page writeback on XFS. Fix the write_cache_pages loop to terminate correctly when this situation occurs and so prevent this sub-optimal background writeback pattern. This improves sustained sequential buffered write performance from around 250MB/s to 750MB/s for a 100GB file on an XFS filesystem on my 8p test VM. Cc:<stable@kernel.org> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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#
679ceace |
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20-Aug-2010 |
Michael Rubin <mrubin@google.com> |
mm: exporting account_page_dirty This allows code outside of the mm core to safely manipulate page state and not worry about the other accounting. Not using these routines means that some code will lose track of the accounting and we get bugs. This has happened once already. Signed-off-by: Michael Rubin <mrubin@google.com> Signed-off-by: Sage Weil <sage@newdream.net>
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#
d5ed3a4a |
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19-Aug-2010 |
Jan Kara <jack@suse.cz> |
lib/radix-tree.c: fix overflow in radix_tree_range_tag_if_tagged() When radix_tree_maxindex() is ~0UL, it can happen that scanning overflows index and tree traversal code goes astray reading memory until it hits unreadable memory. Check for overflow and exit in that case. Signed-off-by: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
03ab450f |
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14-Aug-2010 |
Randy Dunlap <randy.dunlap@oracle.com> |
mm/page-writeback: fix non-kernel-doc function comments Remove leading /** from non-kernel-doc function comments to prevent kernel-doc warnings. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1babe183 |
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11-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: add comment to the dirty limit functions Document global_dirty_limits() and bdi_dirty_limit(). Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
16c4042f |
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11-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: avoid unnecessary calculation of bdi dirty thresholds Split get_dirty_limits() into global_dirty_limits()+bdi_dirty_limit(), so that the latter can be avoided when under global dirty background threshold (which is the normal state for most systems). Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e50e3720 |
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11-Aug-2010 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: balance_dirty_pages(): reduce calls to global_page_state Reducing the number of times balance_dirty_pages calls global_page_state reduces the cache references and so improves write performance on a variety of workloads. 'perf stats' of simple fio write tests shows the reduction in cache access. Where the test is fio 'write,mmap,600Mb,pre_read' on AMD AthlonX2 with 3Gb memory (dirty_threshold approx 600 Mb) running each test 10 times, dropping the fasted & slowest values then taking the average & standard deviation average (s.d.) in millions (10^6) 2.6.31-rc8 648.6 (14.6) +patch 620.1 (16.5) Achieving this reduction is by dropping clip_bdi_dirty_limit as it rereads the counters to apply the dirty_threshold and moving this check up into balance_dirty_pages where it has already read the counters. Also by rearrange the for loop to only contain one copy of the limit tests allows the pdflush test after the loop to use the local copies of the counters rather than rereading them. In the common case with no throttling it now calls global_page_state 5 fewer times and bdi_stat 2 fewer. Fengguang: This patch slightly changes behavior by replacing clip_bdi_dirty_limit() with the explicit check (nr_reclaimable + nr_writeback >= dirty_thresh) to avoid exceeding the dirty limit. Since the bdi dirty limit is mostly accurate we don't need to do routinely clip. A simple dirty limit check would be enough. The check is necessary because, in principle we should throttle everything calling balance_dirty_pages() when we're over the total limit, as said by Peter. We now set and clear dirty_exceeded not only based on bdi dirty limits, but also on the global dirty limit. The global limit check is added in place of clip_bdi_dirty_limit() for safety and not intended as a behavior change. The bdi limits should be tight enough to keep all dirty pages under the global limit at most time; occasional small exceeding should be OK though. The change makes the logic more obvious: the global limit is the ultimate goal and shall be always imposed. We may now start background writeback work based on outdated conditions. That's safe because the bdi flush thread will (and have to) double check the states. It reduces overall overheads because the test based on old states still have good chance to be right. [akpm@linux-foundation.org] fix uninitialized dirty_exceeded Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3c111a07 |
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11-Aug-2010 |
Randy Dunlap <randy.dunlap@oracle.com> |
mm: fix fatal kernel-doc error Fix a fatal kernel-doc error due to a #define coming between a function's kernel-doc notation and the function signature. (kernel-doc cannot handle this) Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f446daae |
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09-Aug-2010 |
Jan Kara <jack@suse.cz> |
mm: implement writeback livelock avoidance using page tagging We try to avoid livelocks of writeback when some steadily creates dirty pages in a mapping we are writing out. For memory-cleaning writeback, using nr_to_write works reasonably well but we cannot really use it for data integrity writeback. This patch tries to solve the problem. The idea is simple: Tag all pages that should be written back with a special tag (TOWRITE) in the radix tree. This can be done rather quickly and thus livelocks should not happen in practice. Then we start doing the hard work of locking pages and sending them to disk only for those pages that have TOWRITE tag set. Note: Adding new radix tree tag grows radix tree node from 288 to 296 bytes for 32-bit archs and from 552 to 560 bytes for 64-bit archs. However, the number of slab/slub items per page remains the same (13 and 7 respectively). Signed-off-by: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Chris Mason <chris.mason@oracle.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
9e094383 |
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06-Jul-2010 |
Dave Chinner <dchinner@redhat.com> |
writeback: Add tracing to write_cache_pages Add a trace event to the ->writepage loop in write_cache_pages to give visibility into how the ->writepage call is changing variables within the writeback control structure. Of most interest is how wbc->nr_to_write changes from call to call, especially with filesystems that write multiple pages in ->writepage. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
028c2dd1 |
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06-Jul-2010 |
Dave Chinner <dchinner@redhat.com> |
writeback: Add tracing to balance_dirty_pages Tracing high level background writeback events is good, but it doesn't give the entire picture. Add visibility into write throttling to catch IO dispatched by foreground throttling of processing dirtying lots of pages. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
9c3a8ee8 |
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09-Jun-2010 |
Christoph Hellwig <hch@lst.de> |
writeback: remove writeback_inodes_wbc This was just an odd wrapper around writeback_inodes_wb. Removing this also allows to get rid of the bdi member of struct writeback_control which was rather out of place there. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
c5444198 |
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08-Jun-2010 |
Christoph Hellwig <hch@lst.de> |
writeback: simplify and split bdi_start_writeback bdi_start_writeback now never gets a superblock passed, so we can just remove that case. And to further untangle the code and flatten the call stack split it into two trivial helpers for it's two callers. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
d87815cb |
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08-Jun-2010 |
Dave Chinner <dchinner@redhat.com> |
writeback: limit write_cache_pages integrity scanning to current EOF sync can currently take a really long time if a concurrent writer is extending a file. The problem is that the dirty pages on the address space grow in the same direction as write_cache_pages scans, so if the writer keeps ahead of writeback, the writeback will not terminate until the writer stops adding dirty pages. For a data integrity sync, we only need to write the pages dirty at the time we start the writeback, so we can stop scanning once we get to the page that was at the end of the file at the time the scan started. This will prevent operations like copying a large file preventing sync from completing as it will not write back pages that were dirtied after the sync was started. This does not impact the existing integrity guarantees, as any dirty page (old or new) within the EOF range at the start of the scan will still be captured. This patch will not prevent sync from blocking on large writes into holes. That requires more complex intervention while this patch only addresses the common append-case of this sync holdoff. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0b564927 |
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08-Jun-2010 |
Dave Chinner <dchinner@redhat.com> |
writeback: pay attention to wbc->nr_to_write in write_cache_pages If a filesystem writes more than one page in ->writepage, write_cache_pages fails to notice this and continues to attempt writeback when wbc->nr_to_write has gone negative - this trace was captured from XFS: wbc_writeback_start: towrt=1024 wbc_writepage: towrt=1024 wbc_writepage: towrt=0 wbc_writepage: towrt=-1 wbc_writepage: towrt=-5 wbc_writepage: towrt=-21 wbc_writepage: towrt=-85 This has adverse effects on filesystem writeback behaviour. write_cache_pages() needs to terminate after a certain number of pages are written, not after a certain number of calls to ->writepage are made. This is a regression introduced by 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 ("vfs: Add no_nrwrite_index_update writeback control flag"), but cannot be reverted directly due to subsequent bug fixes that have gone in on top of it. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0e3c9a22 |
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01-Jun-2010 |
Jens Axboe <jaxboe@fusionio.com> |
Revert "writeback: fix WB_SYNC_NONE writeback from umount" This reverts commit e913fc825dc685a444cb4c1d0f9d32f372f59861. We are investigating a hang associated with the WB_SYNC_NONE changes, so revert them for now. Conflicts: fs/fs-writeback.c mm/page-writeback.c Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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#
df96e96f |
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21-May-2010 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: fix mixed up arguments to bdi_start_writeback() The laptop mode timer had the nr_pages and sb_locked arguments mixed up. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
c2c4986e |
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20-May-2010 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: fix problem with !CONFIG_BLOCK compilation When CONFIG_BLOCK isn't enabled: mm/page-writeback.c: In function 'laptop_mode_timer_fn': mm/page-writeback.c:708: error: dereferencing pointer to incomplete type mm/page-writeback.c:709: error: dereferencing pointer to incomplete type Fix this by essentially eliminating the laptop sync handlers when CONFIG_BLOCK isn't set, as most are only used from the block layer code. The exception is laptop_sync_completion() which is used from sys_sync(), make that an empty declaration in that case. Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
6423104b |
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21-May-2010 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: fixups for !dirty_writeback_centisecs Commit 69b62d01 fixed up most of the places where we would enter busy schedule() spins when disabling the periodic background writeback. This fixes up the sb timer so that it doesn't get hammered on with the delay disabled, and ensures that it gets rearmed if needed when /proc/sys/vm/dirty_writeback_centisecs gets modified. bdi_forker_task() also needs to check for !dirty_writeback_centisecs and use schedule() appropriately, fix that up too. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
e913fc82 |
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16-May-2010 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: fix WB_SYNC_NONE writeback from umount When umount calls sync_filesystem(), we first do a WB_SYNC_NONE writeback to kick off writeback of pending dirty inodes, then follow that up with a WB_SYNC_ALL to wait for it. Since umount already holds the sb s_umount mutex, WB_SYNC_NONE ends up doing nothing and all writeback happens as WB_SYNC_ALL. This can greatly slow down umount, since WB_SYNC_ALL writeback is a data integrity operation and thus a bigger hammer than simple WB_SYNC_NONE. For barrier aware file systems it's a lot slower. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
31373d09 |
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06-Apr-2010 |
Matthew Garrett <mjg@redhat.com> |
laptop-mode: Make flushes per-device One of the features of laptop-mode is that it forces a writeout of dirty pages if something else triggers a physical read or write from a device. The current implementation flushes pages on all devices, rather than only the one that triggered the flush. This patch alters the behaviour so that only the recently accessed block device is flushed, preventing other disks being spun up for no terribly good reason. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
0d99519e |
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03-Dec-2009 |
Wu Fengguang <fengguang.wu@gmail.com> |
writeback: remove unused nonblocking and congestion checks - no one is calling wb_writeback and write_cache_pages with wbc.nonblocking=1 any more - lumpy pageout will want to do nonblocking writeback without the congestion wait So remove the congestion checks as suggested by Chris. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Evgeniy Polyakov <zbr@ioremap.net> Cc: Alex Elder <aelder@sgi.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
d25105e8 |
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08-Oct-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: account IO throttling wait as iowait It makes sense to do IOWAIT when someone is blocked due to IO throttle, as suggested by Kame and Peter. There is an old comment for not doing IOWAIT on throttle, however it has been mismatching the code for a long time. If we stop accounting IOWAIT for 2.6.32, it could be an undesirable behavior change. So restore the io_schedule. CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
a72bfd4d |
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25-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: pass in super_block to bdi_start_writeback() Sometimes we only want to write pages from a specific super_block, so allow that to be passed in. This fixes a problem with commit 56a131dcf7ed36c3c6e36bea448b674ea85ed5bb causing writeback on all super_blocks on a bdi, where we only really want to sync a specific sb from writeback_inodes_sb(). Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
5b0830cb |
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23-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: get rid to incorrect references to pdflush in comments Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
d3ddec76 |
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23-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: stop background writeback when below background threshold Treat bdi_start_writeback(0) as a special request to do background write, and stop such work when we are below the background dirty threshold. Also simplify the (nr_pages <= 0) checks. Since we already pass in nr_pages=LONG_MAX for WB_SYNC_ALL and background writes, we don't need to worry about it being decreased to zero. Reported-by: Richard Kennedy <richard@rsk.demon.co.uk> CC: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
3a2e9a5a |
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23-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: balance_dirty_pages() shall write more than dirtied pages Some filesystem may choose to write much more than ratelimit_pages before calling balance_dirty_pages_ratelimited_nr(). So it is safer to determine number to write based on real number of dirtied pages. Otherwise it is possible that loop { btrfs_file_write(): dirty 1024 pages balance_dirty_pages(): write up to 48 pages (= ratelimit_pages * 1.5) } in which the writeback rate cannot keep up with dirty rate, and the dirty pages go all the way beyond dirty_thresh. The increased write_chunk may make the dirtier more bumpy. So filesystems shall be take care not to dirty too much at a time (eg. > 4MB) without checking the ratelimit. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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8d65af78 |
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23-Sep-2009 |
Alexey Dobriyan <adobriyan@gmail.com> |
sysctl: remove "struct file *" argument of ->proc_handler It's unused. It isn't needed -- read or write flag is already passed and sysctl shouldn't care about the rest. It _was_ used in two places at arch/frv for some reason. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
adea02a1 |
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21-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
mm: count only reclaimable lru pages global_lru_pages() / zone_lru_pages() can be used in two ways: - to estimate max reclaimable pages in determine_dirtyable_memory() - to calculate the slab scan ratio When swap is full or not present, the anon lru lists are not reclaimable and also won't be scanned. So the anon pages shall not be counted in both usage scenarios. Also rename to _reclaimable_pages: now they are counting the possibly reclaimable lru pages. It can greatly (and correctly) increase the slab scan rate under high memory pressure (when most file pages have been reclaimed and swap is full/absent), thus reduce false OOM kills. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Howells <dhowells@redhat.com> Cc: "Li, Ming Chun" <macli@brc.ubc.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
87c6a9b2 |
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17-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: make balance_dirty_pages() gradually back more off Currently it just sleeps for a very short time, just 1 jiffy. If we keep looping in there, continually delay for a little longer of up to 100msec in total. That was the old limit for congestion wait. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
3542a5c0 |
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17-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: don't use schedule_timeout() without setting runstate Just use schedule_timeout_interruptible(), saves a call to set_current_state(). Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
b6e51316 |
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16-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: separate starting of sync vs opportunistic writeback bdi_start_writeback() is currently split into two paths, one for WB_SYNC_NONE and one for WB_SYNC_ALL. Add bdi_sync_writeback() for WB_SYNC_ALL writeback and let bdi_start_writeback() handle only WB_SYNC_NONE. Push down the writeback_control allocation and only accept the parameters that make sense for each function. This cleans up the API considerably. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
cfc4ba53 |
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14-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: use RCU to protect bdi_list Now that bdi_writeback_all() no longer handles integrity writeback, it doesn't have to block anymore. This means that we can switch bdi_list reader side protection to RCU. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
1fe06ad8 |
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15-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: get rid of wbc->for_writepages It's only set, it's never checked. Kill it. Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
6746aff7 |
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16-Sep-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
HWPOISON: shmem: call set_page_dirty() with locked page The dirtying of page and set_page_dirty() can be moved into the page lock. - In shmem_write_end(), the page was dirtied while the page lock was held, but it's being marked dirty just after dropping the page lock. - In shmem_symlink(), both dirtying and marking can be moved into page lock. It's valuable for the hwpoison code to know whether one bad page can be dropped without losing data. It mainly judges by testing the PG_dirty bit after taking the page lock. So it becomes important that the dirtying of page and the marking of dirtiness are both done inside the page lock. Which is a common practice, but sadly not a rule. The noticeable exceptions are - mapped pages - pages with buffer_heads The above pages could go dirty at any time. Fortunately the hwpoison will unmap the page and release the buffer_heads beforehand anyway. Many other types of pages (eg. metadata pages) can also be dirtied at will by their owners, the hwpoison code cannot do meaningful things to them anyway. Only the dirtiness of pagecache pages owned by regular files are interested. v2: AK: Add comment about set_page_dirty rules (suggested by Peter Zijlstra) Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
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#
03ba3782 |
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09-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: switch to per-bdi threads for flushing data This gets rid of pdflush for bdi writeout and kupdated style cleaning. pdflush writeout suffers from lack of locality and also requires more threads to handle the same workload, since it has to work in a non-blocking fashion against each queue. This also introduces lumpy behaviour and potential request starvation, since pdflush can be starved for queue access if others are accessing it. A sample ffsb workload that does random writes to files is about 8% faster here on a simple SATA drive during the benchmark phase. File layout also seems a LOT more smooth in vmstat: r b swpd free buff cache si so bi bo in cs us sy id wa 0 1 0 608848 2652 375372 0 0 0 71024 604 24 1 10 48 42 0 1 0 549644 2712 433736 0 0 0 60692 505 27 1 8 48 44 1 0 0 476928 2784 505192 0 0 4 29540 553 24 0 9 53 37 0 1 0 457972 2808 524008 0 0 0 54876 331 16 0 4 38 58 0 1 0 366128 2928 614284 0 0 4 92168 710 58 0 13 53 34 0 1 0 295092 3000 684140 0 0 0 62924 572 23 0 9 53 37 0 1 0 236592 3064 741704 0 0 4 58256 523 17 0 8 48 44 0 1 0 165608 3132 811464 0 0 0 57460 560 21 0 8 54 38 0 1 0 102952 3200 873164 0 0 4 74748 540 29 1 10 48 41 0 1 0 48604 3252 926472 0 0 0 53248 469 29 0 7 47 45 where vanilla tends to fluctuate a lot in the creation phase: r b swpd free buff cache si so bi bo in cs us sy id wa 1 1 0 678716 5792 303380 0 0 0 74064 565 50 1 11 52 36 1 0 0 662488 5864 319396 0 0 4 352 302 329 0 2 47 51 0 1 0 599312 5924 381468 0 0 0 78164 516 55 0 9 51 40 0 1 0 519952 6008 459516 0 0 4 78156 622 56 1 11 52 37 1 1 0 436640 6092 541632 0 0 0 82244 622 54 0 11 48 41 0 1 0 436640 6092 541660 0 0 0 8 152 39 0 0 51 49 0 1 0 332224 6200 644252 0 0 4 102800 728 46 1 13 49 36 1 0 0 274492 6260 701056 0 0 4 12328 459 49 0 7 50 43 0 1 0 211220 6324 763356 0 0 0 106940 515 37 1 10 51 39 1 0 0 160412 6376 813468 0 0 0 8224 415 43 0 6 49 45 1 1 0 85980 6452 886556 0 0 4 113516 575 39 1 11 54 34 0 2 0 85968 6452 886620 0 0 0 1640 158 211 0 0 46 54 A 10 disk test with btrfs performs 26% faster with per-bdi flushing. A SSD based writeback test on XFS performs over 20% better as well, with the throughput being very stable around 1GB/sec, where pdflush only manages 750MB/sec and fluctuates wildly while doing so. Random buffered writes to many files behave a lot better as well, as does random mmap'ed writes. A separate thread is added to sync the super blocks. In the long term, adding sync_supers_bdi() functionality could get rid of this thread again. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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#
66f3b8e2 |
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02-Sep-2009 |
Jens Axboe <jens.axboe@oracle.com> |
writeback: move dirty inodes from super_block to backing_dev_info This is a first step at introducing per-bdi flusher threads. We should have no change in behaviour, although sb_has_dirty_inodes() is now ridiculously expensive, as there's no easy way to answer that question. Not a huge problem, since it'll be deleted in subsequent patches. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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8aa7e847 |
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09-Jul-2009 |
Jens Axboe <jens.axboe@oracle.com> |
Fix congestion_wait() sync/async vs read/write confusion Commit 1faa16d22877f4839bd433547d770c676d1d964c accidentally broke the bdi congestion wait queue logic, causing us to wait on congestion for WRITE (== 1) when we really wanted BLK_RW_ASYNC (== 0) instead. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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d7831a0b |
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30-Jun-2009 |
Richard Kennedy <richard@rsk.demon.co.uk> |
mm: prevent balance_dirty_pages() from doing too much work balance_dirty_pages can overreact and move all of the dirty pages to writeback unnecessarily. balance_dirty_pages makes its decision to throttle based on the number of dirty plus writeback pages that are over the calculated limit,so it will continue to move pages even when there are plenty of pages in writeback and less than the threshold still dirty. This allows it to overshoot its limits and move all the dirty pages to writeback while waiting for the drives to catch up and empty the writeback list. A simple fio test easily demonstrates this problem. fio --name=f1 --directory=/disk1 --size=2G -rw=write --name=f2 --directory=/disk2 --size=1G --rw=write --startdelay=10 This is the simplest fix I could find, but I'm not entirely sure that it alone will be enough for all cases. But it certainly is an improvement on my desktop machine writing to 2 disks. Do we need something more for machines with large arrays where bdi_threshold * number_of_drives is greater than the dirty_ratio ? Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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245b2e70 |
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24-Jun-2009 |
Tejun Heo <tj@kernel.org> |
percpu: clean up percpu variable definitions Percpu variable definition is about to be updated such that all percpu symbols including the static ones must be unique. Update percpu variable definitions accordingly. * as,cfq: rename ioc_count uniquely * cpufreq: rename cpu_dbs_info uniquely * xen: move nesting_count out of xen_evtchn_do_upcall() and rename it * mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and rename it * ipv4,6: rename cookie_scratch uniquely * x86 perf_counter: rename prev_left to pmc_prev_left, irq_entry to pmc_irq_entry and nmi_entry to pmc_nmi_entry * perf_counter: rename disable_count to perf_disable_count * ftrace: rename test_event_disable to ftrace_test_event_disable * kmemleak: rename test_pointer to kmemleak_test_pointer * mce: rename next_interval to mce_next_interval [ Impact: percpu usage cleanups, no duplicate static percpu var names ] Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Dave Jones <davej@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: linux-mm <linux-mm@kvack.org> Cc: David S. Miller <davem@davemloft.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andi Kleen <andi@firstfloor.org>
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dcf975d5 |
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16-Jun-2009 |
H Hartley Sweeten <hartleys@visionengravers.com> |
mm/page-writeback.c: dirty limit type should be unsigned long get_dirty_limits() calls clip_bdi_dirty_limit() and task_dirty_limit() with variable pbdi_dirty as one of the arguments. This variable is an unsigned long * but both functions expect it to be a long *. This causes the following sparse warnings: warning: incorrect type in argument 3 (different signedness) expected long *pbdi_dirty got unsigned long *pbdi_dirty warning: incorrect type in argument 2 (different signedness) expected long *pdirty got unsigned long *pbdi_dirty Fix the warnings by changing the long * to unsigned long * in both functions. Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
22ef37ee |
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16-May-2009 |
Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> |
page-writeback: fix the calculation of the oldest_jif in wb_kupdate() wb_kupdate() function has a bug on linux-2.6.30-rc5. This bug causes generic_sync_sb_inodes() to start to write inodes back much earlier than our expectations because it miscalculates oldest_jif in wb_kupdate(). This bug was introduced in 704503d836042d4a4c7685b7036e7de0418fbc0f ('mm: fix proc_dointvec_userhz_jiffies "breakage"'). Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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704503d8 |
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31-Mar-2009 |
Alexey Dobriyan <adobriyan@gmail.com> |
mm: fix proc_dointvec_userhz_jiffies "breakage" Addresses http://bugzilla.kernel.org/show_bug.cgi?id=9838 On i386, HZ=1000, jiffies_to_clock_t() converts time in a somewhat strange way from the user's point of view: # echo 500 >/proc/sys/vm/dirty_writeback_centisecs # cat /proc/sys/vm/dirty_writeback_centisecs 499 So, we have 5000 jiffies converted to only 499 clock ticks and reported back. TICK_NSEC = 999848 ACTHZ = 256039 Keeping in-kernel variable in units passed from userspace will fix issue of course, but this probably won't be right for every sysctl. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e3a7cca1 |
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31-Mar-2009 |
Edward Shishkin <edward.shishkin@gmail.com> |
vfs: add/use account_page_dirtied() Add a helper function account_page_dirtied(). Use that from two callsites. reiser4 adds a function which adds a third callsite. Signed-off-by: Edward Shishkin<edward.shishkin@gmail.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1b5e62b4 |
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22-Mar-2009 |
Wu Fengguang <fengguang.wu@intel.com> |
writeback: double the dirty thresholds Enlarge default dirty ratios from 5/10 to 10/20. This fixes [Bug #12809] iozone regression with 2.6.29-rc6. The iozone benchmarks are performed on a 1200M file, with 8GB ram. iozone -i 0 -i 1 -i 2 -i 3 -i 4 -r 4k -s 64k -s 512m -s 1200m -b tmp.xls iozone -B -r 4k -s 64k -s 512m -s 1200m -b tmp.xls The performance regression is triggered by commit 1cf6e7d83bf3(mm: task dirty accounting fix), which makes more correct/thorough dirty accounting. The default 5/10 dirty ratios were picked (a) with the old dirty logic and (b) largely at random and (c) designed to be aggressive. In particular, that (a) means that having fixed some of the dirty accounting, maybe the real bug is now that it was always too aggressive, just hidden by an accounting issue. The enlarged 10/20 dirty ratios are just about enough to fix the regression. [ We will have to look at how this affects the old fsync() latency issue, but that probably will need independent work. - Linus ] Cc: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: "Lin, Ming M" <ming.m.lin@intel.com> Tested-by: "Lin, Ming M" <ming.m.lin@intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1cf6e7d8 |
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18-Feb-2009 |
Nick Piggin <npiggin@suse.de> |
mm: task dirty accounting fix YAMAMOTO-san noticed that task_dirty_inc doesn't seem to be called properly for cases where set_page_dirty is not used to dirty a page (eg. mark_buffer_dirty). Additionally, there is some inconsistency about when task_dirty_inc is called. It is used for dirty balancing, however it even gets called for __set_page_dirty_no_writeback. So rather than increment it in a set_page_dirty wrapper, move it down to exactly where the dirty page accounting stats are incremented. Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3a4c6800 |
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11-Feb-2009 |
Nick Piggin <npiggin@suse.de> |
Fix page writeback thinko, causing Berkeley DB slowdown A bug was introduced into write_cache_pages cyclic writeout by commit 31a12666d8f0c22235297e1c1575f82061480029 ("mm: write_cache_pages cyclic fix"). The intention (and comments) is that we should cycle back and look for more dirty pages at the beginning of the file if there is no more work to be done. But the !done condition was dropped from the test. This means that any time the page writeout loop breaks (eg. due to nr_to_write == 0), we will set index to 0, then goto again. This will set done_index to index, then find done is set, so will proceed to the end of the function. When updating mapping->writeback_index for cyclic writeout, we now use done_index == 0, so we're always cycling back to 0. This seemed to be causing random mmap writes (slapadd and iozone) to start writing more pages from the LRU and writeout would slowdown, and caused bugzilla entry http://bugzilla.kernel.org/show_bug.cgi?id=12604 about Berkeley DB slowing down dramatically. With this patch, iozone random write performance is increased nearly 5x on my system (iozone -B -r 4k -s 64k -s 512m -s 1200m on ext2). Signed-off-by: Nick Piggin <npiggin@suse.de> Reported-and-tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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89e12190 |
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11-Feb-2009 |
Federico Cuello <fedux@lugmen.org.ar> |
writeback: fix break condition Commit dcf6a79dda5cc2a2bec183e50d829030c0972aaa ("write-back: fix nr_to_write counter") fixed nr_to_write counter, but didn't set the break condition properly. If nr_to_write == 0 after being decremented it will loop one more time before setting done = 1 and breaking the loop. [akpm@linux-foundation.org: coding-style fixes] Cc: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fc3501d4 |
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11-Feb-2009 |
Sven Wegener <sven.wegener@stealer.net> |
mm: fix dirty_bytes/dirty_background_bytes sysctls on 64bit arches We need to pass an unsigned long as the minimum, because it gets casted to an unsigned long in the sysctl handler. If we pass an int, we'll access four more bytes on 64bit arches, resulting in a random minimum value. [rientjes@google.com: fix type of `old_bytes'] Signed-off-by: Sven Wegener <sven.wegener@stealer.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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dcf6a79d |
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02-Feb-2009 |
Artem Bityutskiy <Artem.Bityutskiy@nokia.com> |
write-back: fix nr_to_write counter Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some @wbc->nr_to_write breakage. It made the following changes: 1. Decrement wbc->nr_to_write instead of nr_to_write 2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE 3. If synced nr_to_write pages, stop only if if wbc->sync_mode == WB_SYNC_NONE, otherwise keep going. However, according to the commit message, the intention was to only make change 3. Change 1 is a bug. Change 2 does not seem to be necessary, and it breaks UBIFS expectations, so if needed, it should be done separately later. And change 2 does not seem to be documented in the commit message. This patch does the following: 1. Undo changes 1 and 2 2. Add a comment explaining change 3 (it very useful to have comments in _code_, not only in the commit). Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Acked-by: Nick Piggin <npiggin@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2da02997 |
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06-Jan-2009 |
David Rientjes <rientjes@google.com> |
mm: add dirty_background_bytes and dirty_bytes sysctls This change introduces two new sysctls to /proc/sys/vm: dirty_background_bytes and dirty_bytes. dirty_background_bytes is the counterpart to dirty_background_ratio and dirty_bytes is the counterpart to dirty_ratio. With growing memory capacities of individual machines, it's no longer sufficient to specify dirty thresholds as a percentage of the amount of dirtyable memory over the entire system. dirty_background_bytes and dirty_bytes specify quantities of memory, in bytes, that represent the dirty limits for the entire system. If either of these values is set, its value represents the amount of dirty memory that is needed to commence either background or direct writeback. When a `bytes' or `ratio' file is written, its counterpart becomes a function of the written value. For example, if dirty_bytes is written to be 8096, 8K of memory is required to commence direct writeback. dirty_ratio is then functionally equivalent to 8K / the amount of dirtyable memory: dirtyable_memory = free pages + mapped pages + file cache dirty_background_bytes = dirty_background_ratio * dirtyable_memory -or- dirty_background_ratio = dirty_background_bytes / dirtyable_memory AND dirty_bytes = dirty_ratio * dirtyable_memory -or- dirty_ratio = dirty_bytes / dirtyable_memory Only one of dirty_background_bytes and dirty_background_ratio may be specified at a time, and only one of dirty_bytes and dirty_ratio may be specified. When one sysctl is written, the other appears as 0 when read. The `bytes' files operate on a page size granularity since dirty limits are compared with ZVC values, which are in page units. Prior to this change, the minimum dirty_ratio was 5 as implemented by get_dirty_limits() although /proc/sys/vm/dirty_ratio would show any user written value between 0 and 100. This restriction is maintained, but dirty_bytes has a lower limit of only one page. Also prior to this change, the dirty_background_ratio could not equal or exceed dirty_ratio. This restriction is maintained in addition to restricting dirty_background_bytes. If either background threshold equals or exceeds that of the dirty threshold, it is implicitly set to half the dirty threshold. Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Cc: Andrea Righi <righi.andrea@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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364aeb28 |
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06-Jan-2009 |
David Rientjes <rientjes@google.com> |
mm: change dirty limit type specifiers to unsigned long The background dirty and dirty limits are better defined with type specifiers of unsigned long since negative writeback thresholds are not possible. These values, as returned by get_dirty_limits(), are normally compared with ZVC values to determine whether writeback shall commence or be throttled. Such page counts cannot be negative, so declaring the page limits as signed is unnecessary. Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Cc: Andrea Righi <righi.andrea@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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82fd1a9a |
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06-Jan-2009 |
Andrew Morton <akpm@linux-foundation.org> |
mm: write_cache_pages more terminate quickly Now that we have the early-termination logic in place, it makes sense to bail out early in all other cases where done is set to 1. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d5482cdf |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages terminate quickly Terminate the write_cache_pages loop upon encountering the first page past end, without locking the page. Pages cannot have their index change when we have a reference on them (truncate, eg truncate_inode_pages_range performs the same check without the page lock). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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515f4a03 |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages optimise page cleaning In write_cache_pages, if we get stuck behind another process that is cleaning pages, we will be forced to wait for them to finish, then perform our own writeout (if it was redirtied during the long wait), then wait for that. If a page under writeout is still clean, we can skip waiting for it (if we're part of a data integrity sync, we'll be waiting for all writeout pages afterwards, so we'll still be waiting for the other guy's write that's cleaned the page). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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5a3d5c98 |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages cleanups Get rid of some complex expressions from flow control statements, add a comment, remove some duplicate code. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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05fe478d |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages integrity fix In write_cache_pages, nr_to_write is heeded even for data-integrity syncs, so the function will return success after writing out nr_to_write pages, even if that was not sufficient to guarantee data integrity. The callers tend to set it to values that could break data interity semantics easily in practice. For example, nr_to_write can be set to mapping->nr_pages * 2, however if a file has a single, dirty page, then fsync is called, subsequent pages might be concurrently added and dirtied, then write_cache_pages might writeout two of these newly dirty pages, while not writing out the old page that should have been written out. Fix this by ignoring nr_to_write if it is a data integrity sync. This is a data integrity bug. The reason this has been done in the past is to avoid stalling sync operations behind page dirtiers. "If a file has one dirty page at offset 1000000000000000 then someone does an fsync() and someone else gets in first and starts madly writing pages at offset 0, we want to write that page at 1000000000000000. Somehow." What we do today is return success after an arbitrary amount of pages are written, whether or not we have provided the data-integrity semantics that the caller has asked for. Even this doesn't actually fix all stall cases completely: in the above situation, if the file has a huge number of pages in pagecache (but not dirty), then mapping->nrpages is going to be huge, even if pages are being dirtied. This change does indeed make the possibility of long stalls lager, and that's not a good thing, but lying about data integrity is even worse. We have to either perform the sync, or return -ELINUXISLAME so at least the caller knows what has happened. There are subsequent competing approaches in the works to solve the stall problems properly, without compromising data integrity. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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00266770 |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages writepage error fix In write_cache_pages, if ret signals a real error, but we still have some pages left in the pagevec, done would be set to 1, but the remaining pages would continue to be processed and ret will be overwritten in the process. It could easily be overwritten with success, and thus success will be returned even if there is an error. Thus the caller is told all writes succeeded, wheras in reality some did not. Fix this by bailing immediately if there is an error, and retaining the first error code. This is a data integrity bug. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bd19e012 |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages early loop termination We'd like to break out of the loop early in many situations, however the existing code has been setting mapping->writeback_index past the final page in the pagevec lookup for cyclic writeback. This is a problem if we don't process all pages up to the final page. Currently the code mostly keeps writeback_index reasonable and hacked around this by not breaking out of the loop or writing pages outside the range in these cases. Keep track of a real "done index" that enables us to terminate the loop in a much more flexible manner. Needed by the subsequent patch to preserve writepage errors, and then further patches to break out of the loop early for other reasons. However there are no functional changes with this patch alone. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
31a12666 |
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06-Jan-2009 |
Nick Piggin <npiggin@suse.de> |
mm: write_cache_pages cyclic fix In write_cache_pages, scanned == 1 is supposed to mean that cyclic writeback has circled through zero, thus we should not circle again. However it gets set to 1 after the first successful pagevec lookup. This leads to cases where not enough data gets written. Counterexample: file with first 10 pages dirty, writeback_index == 5, nr_to_write == 10. Then the 5 last pages will be found, and scanned will be set to 1, after writing those out, we will not cycle back to get the first 5. Rework this logic, now we'll always cycle unless we started off from index 0. When cycling, only write out as far as 1 page before the start page from the first cycle (so we don't write parts of the file twice). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4f98a2fe |
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18-Oct-2008 |
Rik van Riel <riel@redhat.com> |
vmscan: split LRU lists into anon & file sets Split the LRU lists in two, one set for pages that are backed by real file systems ("file") and one for pages that are backed by memory and swap ("anon"). The latter includes tmpfs. The advantage of doing this is that the VM will not have to scan over lots of anonymous pages (which we generally do not want to swap out), just to find the page cache pages that it should evict. This patch has the infrastructure and a basic policy to balance how much we scan the anon lists and how much we scan the file lists. The big policy changes are in separate patches. [lee.schermerhorn@hp.com: collect lru meminfo statistics from correct offset] [kosaki.motohiro@jp.fujitsu.com: prevent incorrect oom under split_lru] [kosaki.motohiro@jp.fujitsu.com: fix pagevec_move_tail() doesn't treat unevictable page] [hugh@veritas.com: memcg swapbacked pages active] [hugh@veritas.com: splitlru: BDI_CAP_SWAP_BACKED] [akpm@linux-foundation.org: fix /proc/vmstat units] [nishimura@mxp.nes.nec.co.jp: memcg: fix handling of shmem migration] [kosaki.motohiro@jp.fujitsu.com: adjust Quicklists field of /proc/meminfo] [kosaki.motohiro@jp.fujitsu.com: fix style issue of get_scan_ratio()] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e1f8e874 |
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15-Oct-2008 |
Francois Cami <francois.cami@free.fr> |
Remove Andrew Morton's old email accounts People can use the real name an an index into MAINTAINERS to find the current email address. Signed-off-by: Francois Cami <francois.cami@free.fr> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
17bc6c30 |
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16-Oct-2008 |
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
vfs: Add no_nrwrite_index_update writeback control flag If no_nrwrite_index_update is set we don't update nr_to_write and address space writeback_index in write_cache_pages. This change enables a file system to skip these updates in write_cache_pages and do them in the writepages() callback. This patch will be followed by an ext4 patch that make use of these new flags. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> CC: linux-fsdevel@vger.kernel.org
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#
74baaaae |
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14-Oct-2008 |
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
vfs: Remove the range_cont writeback mode. Ext4 was the only user of range_cont writeback mode and ext4 switched to a different method. So remove the range_cont mode which is not used in the kernel. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> CC: linux-fsdevel@vger.kernel.org
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#
19fd6231 |
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25-Jul-2008 |
Nick Piggin <npiggin@suse.de> |
mm: spinlock tree_lock mapping->tree_lock has no read lockers. convert the lock from an rwlock to a spinlock. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
06d6cf69 |
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11-Jul-2008 |
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> |
mm: Add range_cont mode for writeback Filesystems like ext4 needs to start a new transaction in the writepages for block allocation. This happens with delayed allocation and there is limit to how many credits we can request from the journal layer. So we call write_cache_pages multiple times with wbc->nr_to_write set to the maximum possible value limitted by the max journal credits available. Add a new mode to writeback that enables us to handle this behaviour. In the new mode we update the wbc->range_start to point to the new offset to be written. Next call to call to write_cache_pages will start writeout from specified range_start offset. In the new mode we also limit writing to the specified wbc->range_end. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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#
3eefae99 |
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12-May-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: limit trace entries Currently there is no protection from the root user to use up all of memory for trace buffers. If the root user allocates too many entries, the OOM killer might start kill off all tasks. This patch adds an algorith to check the following condition: pages_requested > (freeable_memory + current_trace_buffer_pages) / 4 If the above is met then the allocation fails. The above prevents more than 1/4th of freeable memory from being used by trace buffers. To determine the freeable_memory, I made determine_dirtyable_memory in mm/page-writeback.c global. Special thanks goes to Peter Zijlstra for suggesting the above calculation. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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#
fc3ba692 |
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30-Apr-2008 |
Miklos Szeredi <mszeredi@suse.cz> |
mm: Add NR_WRITEBACK_TEMP counter Fuse will use temporary buffers to write back dirty data from memory mappings (normal writes are done synchronously). This is needed, because there cannot be any guarantee about the time in which a write will complete. By using temporary buffers, from the MM's point if view the page is written back immediately. If the writeout was due to memory pressure, this effectively migrates data from a full zone to a less full zone. This patch adds a new counter (NR_WRITEBACK_TEMP) for the number of pages used as temporary buffers. [Lee.Schermerhorn@hp.com: add vmstat_text for NR_WRITEBACK_TEMP] Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
dd5656e5 |
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30-Apr-2008 |
Miklos Szeredi <mszeredi@suse.cz> |
mm: bdi: export bdi_writeout_inc() Fuse needs this for writable mmap support. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e4ad08fe |
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30-Apr-2008 |
Miklos Szeredi <mszeredi@suse.cz> |
mm: bdi: add separate writeback accounting capability Add a new BDI capability flag: BDI_CAP_NO_ACCT_WB. If this flag is set, then don't update the per-bdi writeback stats from test_set_page_writeback() and test_clear_page_writeback(). Misc cleanups: - convert bdi_cap_writeback_dirty() and friends to static inline functions - create a flag that includes all three dirty/writeback related flags, since almst all users will want to have them toghether Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a42dde04 |
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30-Apr-2008 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: bdi: allow setting a maximum for the bdi dirty limit Add "max_ratio" to /sys/class/bdi. This indicates the maximum percentage of the global dirty threshold allocated to this bdi. [mszeredi@suse.cz] - fix parsing in max_ratio_store(). - export bdi_set_max_ratio() to modules - limit bdi_dirty with bdi->max_ratio - document new sysfs attribute Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
189d3c4a |
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30-Apr-2008 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: bdi: allow setting a minimum for the bdi dirty limit Under normal circumstances each device is given a part of the total write-back cache that relates to its current avg writeout speed in relation to the other devices. min_ratio - allows one to assign a minimum portion of the write-back cache to a particular device. This is useful in situations where you might want to provide a minimum QoS. (One request for this feature came from flash based storage people who wanted to avoid writing out at all costs - they of course needed some pdflush hacks as well) max_ratio - allows one to assign a maximum portion of the dirty limit to a particular device. This is useful in situations where you want to avoid one device taking all or most of the write-back cache. Eg. an NFS mount that is prone to get stuck, or a FUSE mount which you don't trust to play fair. Add "min_ratio" to /sys/class/bdi. This indicates the minimum percentage of the global dirty threshold allocated to this bdi. [mszeredi@suse.cz] - fix parsing in min_ratio_store() - document new sysfs attribute Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
cf0ca9fe |
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30-Apr-2008 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: bdi: export BDI attributes in sysfs Provide a place in sysfs (/sys/class/bdi) for the backing_dev_info object. This allows us to see and set the various BDI specific variables. In particular this properly exposes the read-ahead window for all relevant users and /sys/block/<block>/queue/read_ahead_kb should be deprecated. With patient help from Kay Sievers and Greg KH [mszeredi@suse.cz] - split off NFS and FUSE changes into separate patches - document new sysfs attributes under Documentation/ABI - do bdi_class_init as a core_initcall, otherwise the "default" BDI won't be initialized - remove bdi_init_fmt macro, it's not used very much [akpm@linux-foundation.org: fix ia64 warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Kay Sievers <kay.sievers@vrfy.org> Acked-by: Greg KH <greg@kroah.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8bc3be27 |
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04-Feb-2008 |
Fengguang Wu <wfg@mail.ustc.edu.cn> |
writeback: speed up writeback of big dirty files After making dirty a 100M file, the normal behavior is to start the writeback for all data after 30s delays. But sometimes the following happens instead: - after 30s: ~4M - after 5s: ~4M - after 5s: all remaining 92M Some analyze shows that the internal io dispatch queues goes like this: s_io s_more_io ------------------------- 1) 100M,1K 0 2) 1K 96M 3) 0 96M 1) initial state with a 100M file and a 1K file 2) 4M written, nr_to_write <= 0, so write more 3) 1K written, nr_to_write > 0, no more writes(BUG) nr_to_write > 0 in (3) fools the upper layer to think that data have all been written out. The big dirty file is actually still sitting in s_more_io. We cannot simply splice s_more_io back to s_io as soon as s_io becomes empty, and let the loop in generic_sync_sb_inodes() continue: this may starve newly expired inodes in s_dirty. It is also not an option to draw inodes from both s_more_io and s_dirty, an let the loop go on: this might lead to live locks, and might also starve other superblocks in sync time(well kupdate may still starve some superblocks, that's another bug). We have to return when a full scan of s_io completes. So nr_to_write > 0 does not necessarily mean that "all data are written". This patch introduces a flag writeback_control.more_io to indicate that more io should be done. With it the big dirty file no longer has to wait for the next kupdate invokation 5s later. In sync_sb_inodes() we only set more_io on super_blocks we actually visited. This avoids the interaction between two pdflush deamons. Also in __sync_single_inode() we don't blindly keep requeuing the io if the filesystem cannot progress. Failing to do so may lead to 100% iowait. Tested-by: Mike Snitzer <snitzer@gmail.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
920c7a5d |
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04-Feb-2008 |
Harvey Harrison <harvey.harrison@gmail.com> |
mm: remove fastcall from mm/ fastcall is always defined to be empty, remove it [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
195cf453 |
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04-Feb-2008 |
Bron Gondwana <brong@fastmail.fm> |
mm/page-writeback: highmem_is_dirtyable option Add vm.highmem_is_dirtyable toggle A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of approximately 2Gb size which contains a hash format that is written randomly by the dbclean process. On 2.6.16 this process took a few minutes. With lowmem only accounting of dirty ratios, this takes about 12 hours of 100% disk IO, all random writes. Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to add the highmem back to the total available memory count. [akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build] Signed-off-by: Bron Gondwana <brong@fastmail.fm> Cc: Ethan Solomita <solo@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: WU Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
f61eaf9f |
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04-Feb-2008 |
Adrian Bunk <bunk@kernel.org> |
mm/page-writeback.c: make a function static task_dirty_limit() can become static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c23f72ca |
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14-Jan-2008 |
Linus Torvalds <torvalds@woody.linux-foundation.org> |
Revert "writeback: introduce writeback_control.more_io to indicate more io" This reverts commit 2e6883bdf49abd0e7f0d9b6297fc3be7ebb2250b, as requested by Fengguang Wu. It's not quite fully baked yet, and while there are patches around to fix the problems it caused, they should get more testing. Says Fengguang: "I'll resend them both for -mm later on, in a more complete patchset". See http://bugzilla.kernel.org/show_bug.cgi?id=9738 for some of this discussion. Requested-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
8c086340 |
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15-Nov-2007 |
Linus Torvalds <torvalds@woody.linux-foundation.org> |
dirty page balancing: Get rid of broken unmapped_ratio logic This code harks back to the days when we didn't count dirty mapped pages, which led us to try to balance the number of dirty unmapped pages by how much unmapped memory there was in the system. That makes no sense any more, since now the dirty counts include the mapped pages. Not to mention that the math doesn't work with HIGHMEM machines anyway, and causes the unmapped_ratio to potentially turn negative (which we do catch thanks to clamping it at a minimum value, but I mention that as an indication of how broken the code is). The code also was written at a time when the default dirty ratio was much larger, and the unmapped_ratio logic effectively capped that large dirty ratio a bit. Again, we've since lowered the dirty ratio rather aggressively, further lessening the point of that code. Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
5fce25a9 |
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14-Nov-2007 |
Peter Zijlstra <peterz@infradead.org> |
mm: speed up writeback ramp-up on clean systems We allow violation of bdi limits if there is a lot of room on the system. Once we hit half the total limit we start enforcing bdi limits and bdi ramp-up should happen. Doing it this way avoids many small writeouts on an otherwise idle system and should also speed up the ramp-up. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
183ff22b |
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19-Oct-2007 |
Simon Arlott <simon@fire.lp0.eux> |
spelling fixes: mm/ Spelling fixes in mm/. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Signed-off-by: Adrian Bunk <bunk@kernel.org>
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#
369f2389 |
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17-Oct-2007 |
Fengguang Wu <wfg@mail.ustc.edu.cn> |
writeback: remove unnecessary wait in throttle_vm_writeout() We don't want to introduce pointless delays in throttle_vm_writeout() when the writeback limits are not yet exceeded, do we? Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Kumar Gala <galak@kernel.crashing.org> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: Greg KH <greg@kroah.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1c0eeaf5 |
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17-Oct-2007 |
Joern Engel <joern@wohnheim.fh-wedel.de> |
introduce I_SYNC I_LOCK was used for several unrelated purposes, which caused deadlock situations in certain filesystems as a side effect. One of the purposes now uses the new I_SYNC bit. Also document the various bits and change their order from historical to logical. [bunk@stusta.de: make fs/inode.c:wake_up_inode() static] Signed-off-by: Joern Engel <joern@wohnheim.fh-wedel.de> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: David Chinner <dgc@sgi.com> Cc: Anton Altaparmakov <aia21@cam.ac.uk> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2e6883bd |
|
17-Oct-2007 |
Fengguang Wu <wfg@mail.ustc.edu.cn> |
writeback: introduce writeback_control.more_io to indicate more io After making dirty a 100M file, the normal behavior is to start the writeback for all data after 30s delays. But sometimes the following happens instead: - after 30s: ~4M - after 5s: ~4M - after 5s: all remaining 92M Some analyze shows that the internal io dispatch queues goes like this: s_io s_more_io ------------------------- 1) 100M,1K 0 2) 1K 96M 3) 0 96M 1) initial state with a 100M file and a 1K file 2) 4M written, nr_to_write <= 0, so write more 3) 1K written, nr_to_write > 0, no more writes(BUG) nr_to_write > 0 in (3) fools the upper layer to think that data have all been written out. The big dirty file is actually still sitting in s_more_io. We cannot simply splice s_more_io back to s_io as soon as s_io becomes empty, and let the loop in generic_sync_sb_inodes() continue: this may starve newly expired inodes in s_dirty. It is also not an option to draw inodes from both s_more_io and s_dirty, an let the loop go on: this might lead to live locks, and might also starve other superblocks in sync time(well kupdate may still starve some superblocks, that's another bug). We have to return when a full scan of s_io completes. So nr_to_write > 0 does not necessarily mean that "all data are written". This patch introduces a flag writeback_control.more_io to indicate this situation. With it the big dirty file no longer has to wait for the next kupdate invocation 5s later. Cc: David Chinner <dgc@sgi.com> Cc: Ken Chen <kenchen@google.com> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e4230030 |
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17-Oct-2007 |
Andrew Morton <akpm@linux-foundation.org> |
writeback: don't propagate AOP_WRITEPAGE_ACTIVATE This is a writeback-internal marker but we're propagating it all the way back to userspace!. Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3e26c149 |
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17-Oct-2007 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: dirty balancing for tasks Based on ideas of Andrew: http://marc.info/?l=linux-kernel&m=102912915020543&w=2 Scale the bdi dirty limit inversly with the tasks dirty rate. This makes heavy writers have a lower dirty limit than the occasional writer. Andrea proposed something similar: http://lwn.net/Articles/152277/ The main disadvantage to his patch is that he uses an unrelated quantity to measure time, which leaves him with a workload dependant tunable. Other than that the two approaches appear quite similar. [akpm@linux-foundation.org: fix warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
04fbfdc1 |
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17-Oct-2007 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: per device dirty threshold Scale writeback cache per backing device, proportional to its writeout speed. By decoupling the BDI dirty thresholds a number of problems we currently have will go away, namely: - mutual interference starvation (for any number of BDIs); - deadlocks with stacked BDIs (loop, FUSE and local NFS mounts). It might be that all dirty pages are for a single BDI while other BDIs are idling. By giving each BDI a 'fair' share of the dirty limit, each one can have dirty pages outstanding and make progress. A global threshold also creates a deadlock for stacked BDIs; when A writes to B, and A generates enough dirty pages to get throttled, B will never start writeback until the dirty pages go away. Again, by giving each BDI its own 'independent' dirty limit, this problem is avoided. So the problem is to determine how to distribute the total dirty limit across the BDIs fairly and efficiently. A DBI that has a large dirty limit but does not have any dirty pages outstanding is a waste. What is done is to keep a floating proportion between the DBIs based on writeback completions. This way faster/more active devices get a larger share than slower/idle devices. [akpm@linux-foundation.org: fix warnings] [hugh@veritas.com: Fix occasional hang when a task couldn't get out of balance_dirty_pages] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
69cb51d1 |
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17-Oct-2007 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: count writeback pages per BDI Count per BDI writeback pages. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
c9e51e41 |
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17-Oct-2007 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
mm: count reclaimable pages per BDI Count per BDI reclaimable pages; nr_reclaimable = nr_dirty + nr_unstable. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
37b07e41 |
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16-Oct-2007 |
Lee Schermerhorn <Lee.Schermerhorn@hp.com> |
memoryless nodes: fixup uses of node_online_map in generic code Here's a cut at fixing up uses of the online node map in generic code. mm/shmem.c:shmem_parse_mpol() Ensure nodelist is subset of nodes with memory. Use node_states[N_HIGH_MEMORY] as default for missing nodelist for interleave policy. mm/shmem.c:shmem_fill_super() initialize policy_nodes to node_states[N_HIGH_MEMORY] mm/page-writeback.c:highmem_dirtyable_memory() sum over nodes with memory mm/page_alloc.c:zlc_setup() allowednodes - use nodes with memory. mm/page_alloc.c:default_zonelist_order() average over nodes with memory. mm/page_alloc.c:find_next_best_node() skip nodes w/o memory. N_HIGH_MEMORY state mask may not be initialized at this time, unless we want to depend on early_calculate_totalpages() [see below]. Will ZONE_MOVABLE ever be configurable? mm/page_alloc.c:find_zone_movable_pfns_for_nodes() spread kernelcore over nodes with memory. This required calling early_calculate_totalpages() unconditionally, and populating N_HIGH_MEMORY node state therein from nodes in the early_node_map[]. If we can depend on this, we can eliminate the population of N_HIGH_MEMORY mask from __build_all_zonelists() and use the N_HIGH_MEMORY mask in find_next_best_node(). mm/mempolicy.c:mpol_check_policy() Ensure nodes specified for policy are subset of nodes with memory. [akpm@linux-foundation.org: fix warnings] Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Cc: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
00128188 |
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16-Oct-2007 |
Nick Piggin <npiggin@suse.de> |
mm: use lockless radix-tree probe Probing pages and radix_tree_tagged are lockless operations with the lockless radix-tree. Convert these users to RCU locking rather than using tree_lock. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
a200ee18 |
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08-Oct-2007 |
Peter Zijlstra <peterz@infradead.org> |
mm: set_page_dirty_balance() vs ->page_mkwrite() All the current page_mkwrite() implementations also set the page dirty. Which results in the set_page_dirty_balance() call to _not_ call balance, because the page is already found dirty. This allows us to dirty a _lot_ of pages without ever hitting balance_dirty_pages(). Not good (tm). Force a balance call if ->page_mkwrite() was successful. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
d688abf5 |
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19-Jul-2007 |
Andrew Morton <akpm@osdl.org> |
move page writeback acounting out of macros page-writeback accounting is presently performed in the page-flags macros. This is inconsistent and a bit ugly and makes it awkward to implement per-backing_dev under-writeback page accounting. So move this accounting down to the callsite(s). Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
fe3cba17 |
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19-Jul-2007 |
Fengguang Wu <wfg@mail.ustc.edu.cn> |
mm: share PG_readahead and PG_reclaim Share the same page flag bit for PG_readahead and PG_reclaim. One is used only on file reads, another is only for emergency writes. One is used mostly for fresh/young pages, another is for old pages. Combinations of possible interactions are: a) clear PG_reclaim => implicit clear of PG_readahead it will delay an asynchronous readahead into a synchronous one it actually does _good_ for readahead: the pages will be reclaimed soon, it's readahead thrashing! in this case, synchronous readahead makes more sense. b) clear PG_readahead => implicit clear of PG_reclaim one(and only one) page will not be reclaimed in time it can be avoided by checking PageWriteback(page) in readahead first c) set PG_reclaim => implicit set of PG_readahead will confuse readahead and make it restart the size rampup process it's a trivial problem, and can mostly be avoided by checking PageWriteback(page) first in readahead d) set PG_readahead => implicit set of PG_reclaim PG_readahead will never be set on already cached pages. PG_reclaim will always be cleared on dirtying a page. so not a problem. In summary, a) we get better behavior b,d) possible interactions can be avoided c) racy condition exists that might affect readahead, but the chance is _really_ low, and the hurt on readahead is trivial. Compound pages also use PG_reclaim, but for now they do not interact with reclaim/readahead code. Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
79352894 |
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19-Jul-2007 |
Nick Piggin <npiggin@suse.de> |
mm: fix clear_page_dirty_for_io vs fault race Fix msync data loss and (less importantly) dirty page accounting inaccuracies due to the race remaining in clear_page_dirty_for_io(). The deleted comment explains what the race was, and the added comments explain how it is fixed. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
787d2214 |
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17-Jul-2007 |
Nick Piggin <npiggin@suse.de> |
fs: introduce some page/buffer invariants It is a bug to set a page dirty if it is not uptodate unless it has buffers. If the page has buffers, then the page may be dirty (some buffers dirty) but not uptodate (some buffers not uptodate). The exception to this rule is if the set_page_dirty caller is racing with truncate or invalidate. A buffer can not be set dirty if it is not uptodate. If either of these situations occurs, it indicates there could be some data loss problem. Some of these warnings could be a harmless one where the page or buffer is set uptodate immediately after it is dirtied, however we should fix those up, and enforce this ordering. Bring the order of operations for truncate into line with those of invalidate. This will prevent a page from being able to go !uptodate while we're holding the tree_lock, which is probably a good thing anyway. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3e733f07 |
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16-Jul-2007 |
Andrew Morton <akpm@linux-foundation.org> |
dirty_writeback_centisecs_handler() cleanup Repair indenting bustage. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
0ea97180 |
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10-May-2007 |
Miklos Szeredi <mszeredi@suse.cz> |
consolidate generic_writepages and mpage_writepages Clean up massive code duplication between mpage_writepages() and generic_writepages(). The new generic function, write_cache_pages() takes a function pointer argument, which will be called for each page to be written. Maybe cifs_writepages() too can use this infrastructure, but I'm not touching that with a ten-foot pole. The upcoming page writeback support in fuse will also want this. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
3e9f45bd |
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08-May-2007 |
Guillaume Chazarain <guichaz@yahoo.fr> |
Factor outstanding I/O error handling Cleanup: setting an outstanding error on a mapping was open coded too many times. Factor it out in mapping_set_error(). Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
1b424464 |
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06-May-2007 |
Christoph Lameter <clameter@sgi.com> |
Use ZVC counters to establish exact size of dirtyable pages We can use the global ZVC counters to establish the exact size of the LRU and the free pages. This allows a more accurate determination of the dirty ratio. This patch will fix the broken ratio calculations if large amounts of memory are allocated to huge pags or other consumers that do not put the pages on to the LRU. Notes: - I did not add NR_SLAB_RECLAIMABLE to the calculation of the dirtyable pages. Those may be reclaimable but they are at this point not dirtyable. If NR_SLAB_RECLAIMABLE would be considered then a huge number of reclaimable pages would stop writeback from occurring. - This patch used to be in mm as the last one in a series of patches. It was removed when Linus updated the treatment of highmem because there was a conflict. I updated the patch to follow Linus' approach. This patch is neede to fulfill the claims made in the beginning of the patchset that is now in Linus' tree. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
07db59bd |
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27-Apr-2007 |
Linus Torvalds <torvalds@woody.linux-foundation.org> |
Change default dirty-writeback limits Do this really early in the 2.6.22-rc series, so that we'll get feedback. And don't change by half measures. Just cut the default dirty limit to a quarter of what it was, and see if anybody even notices. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
232ea4d6 |
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28-Feb-2007 |
Andrew Morton <akpm@linux-foundation.org> |
[PATCH] throttle_vm_writeout(): don't loop on GFP_NOFS and GFP_NOIO allocations throttle_vm_writeout() is designed to wait for the dirty levels to subside. But if the caller holds IO or FS locks, we might be holding up that writeout. So change it to take a single nap to give other devices a chance to clean some memory, then return. Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Kumar Gala <galak@kernel.crashing.org> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
aa0f0303 |
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10-Feb-2007 |
Paul E. McKenney <paulmck@kernel.org> |
[PATCH] Change constant zero to NOTIFY_DONE in ratelimit_handler() Change a hard-coded constant 0 to the symbolic equivalent NOTIFY_DONE in the ratelimit_handler() CPU notifier handler function. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
72fd4a35 |
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10-Feb-2007 |
Robert P. J. Day <rpjday@mindspring.com> |
[PATCH] Numerous fixes to kernel-doc info in source files. A variety of (mostly) innocuous fixes to the embedded kernel-doc content in source files, including: * make multi-line initial descriptions single line * denote some function names, constants and structs as such * change erroneous opening '/*' to '/**' in a few places * reword some text for clarity Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
76719325 |
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10-Feb-2007 |
Ken Chen <kenchen@google.com> |
[PATCH] simplify shmem_aops.set_page_dirty() method shmem backed file does not have page writeback, nor it participates in backing device's dirty or writeback accounting. So using generic __set_page_dirty_nobuffers() for its .set_page_dirty aops method is a bit overkill. It unnecessarily prolongs shm unmap latency. For example, on a densely populated large shm segment (sevearl GBs), the unmapping operation becomes painfully long. Because at unmap, kernel transfers dirty bit in PTE into page struct and to the radix tree tag. The operation of tagging the radix tree is particularly expensive because it has to traverse the tree from the root to the leaf node on every dirty page. What's bothering is that radix tree tag is used for page write back. However, shmem is memory backed and there is no page write back for such file system. And in the end, we spend all that time tagging radix tree and none of that fancy tagging will be used. So let's simplify it by introduce a new aops __set_page_dirty_no_writeback and this will speed up shm unmap. Signed-off-by: Ken Chen <kenchen@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
dc6e29da |
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29-Jan-2007 |
Linus Torvalds <torvalds@woody.linux-foundation.org> |
Fix balance_dirty_page() calculations with CONFIG_HIGHMEM This makes balance_dirty_page() always base its calculations on the amount of non-highmem memory in the machine, rather than try to base it on total memory and then falling back on non-highmem memory if the mapping it was writing wasn't highmem capable. This not only fixes a situation where two different writers can have wildly different notions about what is a "balanced" dirty state, but it also means that people with highmem machines don't run into an OOM situation when regular memory fills up with dirty pages. We used to try to handle the latter case by scaling down the dirty_ratio if the machine had a lot of highmem pages in page_writeback_init(), but it wasn't aggressive enough for some situations, and since basing the dirty ratio on highmem memory was broken in the first place, let's just stop doing so. (A variation of this theme fixed Justin Piszcz's OOM problem when copying an 18GB file on a RAID setup). Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Justin Piszcz <jpiszcz@lucidpixels.com> Cc: Andrew Morton <akpm@osdl.org> Cc: Neil Brown <neilb@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Christoph Lameter <clameter@sgi.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
7658cc28 |
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29-Dec-2006 |
Linus Torvalds <torvalds@macmini.osdl.org> |
VM: Fix nasty and subtle race in shared mmap'ed page writeback The VM layer (on the face of it, fairly reasonably) expected that when it does a ->writepage() call to the filesystem, it would write out the full page at that point in time. Especially since it had earlier marked the whole page dirty with "set_page_dirty()". But that isn't actually the case: ->writepage() does not actually write a page, it writes the parts of the page that have been explicitly marked dirty before, *and* that had not got written out for other reasons since the last time we told it they were dirty. That last caveat is the important one. Which _most_ of the time ends up being the whole page (since we had called "set_page_dirty()" on the page earlier), but if the filesystem had done any dirty flushing of its own (for example, to honor some internal write ordering guarantees), it might end up doing only a partial page IO (or none at all) when ->writepage() is actually called. That is the correct thing in general (since we actually often _want_ only the known-dirty parts of the page to be written out), but the shared dirty page handling had implicitly forgotten about these details, and had a number of cases where it was doing just the "->writepage()" part, without telling the low-level filesystem that the whole page might have been re-dirtied as part of being mapped writably into user space. Since most of the time the FS did actually write out the full page, we didn't notice this for a loong time, and this needed some really odd patterns to trigger. But it caused occasional corruption with rtorrent and with the Debian "apt" database, because both use shared mmaps to update the end result. This fixes it. Finally. After way too much hair-pulling. Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: Martin J. Bligh <mbligh@google.com> Acked-by: Martin Michlmayr <tbm@cyrius.com> Acked-by: Martin Johansson <martin@fatbob.nu> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Andrei Popa <andrei.popa@i-neo.ro> Cc: High Dickins <hugh@veritas.com> Cc: Andrew Morton <akpm@osdl.org>, Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Guillaume Chazarain <guichaz@yahoo.fr> Cc: Theodore Tso <tytso@mit.edu> Cc: Kenneth Cheng <kenneth.w.chen@intel.com> Cc: Tobias Diedrich <ranma@tdiedrich.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
fba2591b |
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20-Dec-2006 |
Linus Torvalds <torvalds@woody.osdl.org> |
VM: Remove "clear_page_dirty()" and "test_clear_page_dirty()" functions They were horribly easy to mis-use because of their tempting naming, and they also did way more than any users of them generally wanted them to do. A dirty page can become clean under two circumstances: (a) when we write it out. We have "clear_page_dirty_for_io()" for this, and that function remains unchanged. In the "for IO" case it is not sufficient to just clear the dirty bit, you also have to mark the page as being under writeback etc. (b) when we actually remove a page due to it becoming inaccessible to users, notably because it was truncate()'d away or the file (or metadata) no longer exists, and we thus want to cancel any outstanding dirty state. For the (b) case, we now introduce "cancel_dirty_page()", which only touches the page state itself, and verifies that the page is not mapped (since cancelling writes on a mapped page would be actively wrong as it is still accessible to users). Some filesystems need to be fixed up for this: CIFS, FUSE, JFS, ReiserFS, XFS all use the old confusing functions, and will be fixed separately in subsequent commits (with some of them just removing the offending logic, and others using clear_page_dirty_for_io()). This was confirmed by Martin Michlmayr to fix the apt database corruption on ARM. Cc: Martin Michlmayr <tbm@cyrius.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrei Popa <andrei.popa@i-neo.ro> Cc: Andrew Morton <akpm@osdl.org> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
55e829af |
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10-Dec-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] io-accounting: write accounting Accounting writes is fairly simple: whenever a process flips a page from clean to dirty, we accuse it of having caused a write to underlying storage of PAGE_CACHE_SIZE bytes. This may overestimate the amount of writing: the page-dirtying may cause only one buffer_head's worth of writeout. Fixing that is possible, but probably a bit messy and isn't obviously important. Cc: Jay Lan <jlan@sgi.com> Cc: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Chris Sturtivant <csturtiv@sgi.com> Cc: Tony Ernst <tee@sgi.com> Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net> Cc: David Wright <daw@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
8c08540f |
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10-Dec-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] clean up __set_page_dirty_nobuffers() Save a tabstop in __set_page_dirty_nobuffers() and __set_page_dirty_buffers() and a few other places. No functional changes. Cc: Jay Lan <jlan@sgi.com> Cc: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Chris Sturtivant <csturtiv@sgi.com> Cc: Tony Ernst <tee@sgi.com> Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net> Cc: David Wright <daw@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
3fcfab16 |
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20-Oct-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] separate bdi congestion functions from queue congestion functions Separate out the concept of "queue congestion" from "backing-dev congestion". Congestion is a backing-dev concept, not a queue concept. The blk_* congestion functions are retained, as wrappers around the core backing-dev congestion functions. This proper layering is needed so that NFS can cleanly use the congestion functions, and so that CONFIG_BLOCK=n actually links. Cc: "Thomas Maier" <balagi@justmail.de> Cc: "Jens Axboe" <jens.axboe@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Howells <dhowells@redhat.com> Cc: Peter Osterlund <petero2@telia.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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#
f30c2269 |
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03-Oct-2006 |
Uwe Zeisberger <Uwe_Zeisberger@digi.com> |
fix file specification in comments Many files include the filename at the beginning, serveral used a wrong one. Signed-off-by: Uwe Zeisberger <Uwe_Zeisberger@digi.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
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#
9361401e |
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30-Sep-2006 |
David Howells <dhowells@redhat.com> |
[PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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811d736f |
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29-Aug-2006 |
David Howells <dhowells@redhat.com> |
[PATCH] BLOCK: Dissociate generic_writepages() from mpage stuff [try #6] Dissociate the generic_writepages() function from the mpage stuff, moving its declaration to linux/mm.h and actually emitting a full implementation into mm/page-writeback.c. The implementation is a partial duplicate of mpage_writepages() with all BIO references removed. It is used by NFS to do writeback. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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cf9a2ae8 |
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29-Aug-2006 |
David Howells <dhowells@redhat.com> |
[PATCH] BLOCK: Move functions out of buffer code [try #6] Move some functions out of the buffering code that aren't strictly buffering specific. This is a precursor to being able to disable the block layer. (*) Moved some stuff out of fs/buffer.c: (*) The file sync and general sync stuff moved to fs/sync.c. (*) The superblock sync stuff moved to fs/super.c. (*) do_invalidatepage() moved to mm/truncate.c. (*) try_to_release_page() moved to mm/filemap.c. (*) Moved some related declarations between header files: (*) declarations for do_invalidatepage() and try_to_release_page() moved to linux/mm.h. (*) __set_page_dirty_buffers() moved to linux/buffer_head.h. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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2d1d43f6 |
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29-Sep-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added ratelimit_pages in page-writeback.c is recalculated (in set_ratelimit()) every time a CPU is hot-added/removed. But this value is not recalculated when new pages are hot-added. This patch fixes that problem by calling set_ratelimit() when new pages are hot-added. [akpm@osdl.org: cleanups] Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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40c99aae |
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29-Sep-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] remove static variable mm/page-writeback.c:total_pages page-writeback.c has a static local variable "total_pages", which is the total number of pages in the system. There is a global variable "vm_total_pages", which is the total number of pages the VM controls. Both are assigned from the return value of nr_free_pagecache_pages(). This patch removes the local variable and uses the global variable in that place. One more issue with the local static variable "total_pages" is that it is not updated when new pages are hot-added. Since vm_total_pages is updated when new pages are hot-added, this patch fixes that problem too. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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db37648c |
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26-Sep-2006 |
Nick Piggin <npiggin@suse.de> |
[PATCH] mm: non syncing lock_page() lock_page needs the caller to have a reference on the page->mapping inode due to sync_page, ergo set_page_dirty_lock is obviously buggy according to its comments. Solve it by introducing a new lock_page_nosync which does not do a sync_page. akpm: unpleasant solution to an unpleasant problem. If it goes wrong it could cause great slowdowns while the lock_page() caller waits for kblockd to perform the unplug. And if a filesystem has special sync_page() requirements (none presently do), permanent hangs are possible. otoh, set_page_dirty_lock() is usually (always?) called against userspace pages. They are always up-to-date, so there shouldn't be any pending read I/O against these pages. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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edc79b2a |
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26-Sep-2006 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
[PATCH] mm: balance dirty pages Now that we can detect writers of shared mappings, throttle them. Avoids OOM by surprise. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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d08b3851 |
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26-Sep-2006 |
Peter Zijlstra <a.p.zijlstra@chello.nl> |
[PATCH] mm: tracking shared dirty pages Tracking of dirty pages in shared writeable mmap()s. The idea is simple: write protect clean shared writeable pages, catch the write-fault, make writeable and set dirty. On page write-back clean all the PTE dirty bits and write protect them once again. The implementation is a tad harder, mainly because the default backing_dev_info capabilities were too loosely maintained. Hence it is not enough to test the backing_dev_info for cap_account_dirty. The current heuristic is as follows, a VMA is eligible when: - its shared writeable (vm_flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED) - it is not a 'special' mapping (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) == 0 - the backing_dev_info is cap_account_dirty mapping_cap_account_dirty(vma->vm_file->f_mapping) - f_op->mmap() didn't change the default page protection Page from remap_pfn_range() are explicitly excluded because their COW semantics are already horrid enough (see vm_normal_page() in do_wp_page()) and because they don't have a backing store anyway. mprotect() is taught about the new behaviour as well. However it overrides the last condition. Cleaning the pages on write-back is done with page_mkclean() a new rmap call. It can be called on any page, but is currently only implemented for mapped pages, if the page is found the be of a VMA that accounts dirty pages it will also wrprotect the PTE. Finally, in fs/buffers.c:try_to_free_buffers(); remove clear_page_dirty() from under ->private_lock. This seems to be safe, since ->private_lock is used to serialize access to the buffers, not the page itself. This is needed because clear_page_dirty() will call into page_mkclean() and would thereby violate locking order. [dhowells@redhat.com: Provide a page_mkclean() implementation for NOMMU] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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275a082f |
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22-Aug-2006 |
Trond Myklebust <Trond.Myklebust@netapp.com> |
Add a real API for dealing with blk_congestion_wait() Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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c24f21bd |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: remove useless struct wbs Remove writeback state We can remove some functions now that were needed to calculate the page state for writeback control since these statistics are now directly available. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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fd39fc85 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: conversion of nr_unstable to per zone counter Conversion of nr_unstable to a per zone counter We need to do some special modifications to the nfs code since there are multiple cases of disposition and we need to have a page ref for proper accounting. This converts the last critical page state of the VM and therefore we need to remove several functions that were depending on GET_PAGE_STATE_LAST in order to make the kernel compile again. We are only left with event type counters in page state. [akpm@osdl.org: bugfixes] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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ce866b34 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: conversion of nr_writeback to per zone counter Conversion of nr_writeback to per zone counter. This removes the last page_state counter from arch/i386/mm/pgtable.c so we drop the page_state from there. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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b1e7a8fd |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: conversion of nr_dirty to per zone counter This makes nr_dirty a per zone counter. Looping over all processors is avoided during writeback state determination. The counter aggregation for nr_dirty had to be undone in the NFS layer since we summed up the page counts from multiple zones. Someone more familiar with NFS should probably review what I have done. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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f3dbd344 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: split NR_ANON_PAGES off from NR_FILE_MAPPED The current NR_FILE_MAPPED is used by zone reclaim and the dirty load calculation as the number of mapped pagecache pages. However, that is not true. NR_FILE_MAPPED includes the mapped anonymous pages. This patch separates those and therefore allows an accurate tracking of the anonymous pages per zone. It then becomes possible to determine the number of unmapped pages per zone and we can avoid scanning for unmapped pages if there are none. Also it may now be possible to determine the mapped/unmapped ratio in get_dirty_limit. Isnt the number of anonymous pages irrelevant in that calculation? Note that this will change the meaning of the number of mapped pages reported in /proc/vmstat /proc/meminfo and in the per node statistics. This may affect user space tools that monitor these counters! NR_FILE_MAPPED works like NR_FILE_DIRTY. It is only valid for pagecache pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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65ba55f5 |
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30-Jun-2006 |
Christoph Lameter <clameter@sgi.com> |
[PATCH] zoned vm counters: convert nr_mapped to per zone counter nr_mapped is important because it allows a determination of how many pages of a zone are not mapped, which would allow a more efficient means of determining when we need to reclaim memory in a zone. We take the nr_mapped field out of the page state structure and define a new per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off from NR_MAPPED in the next patch). We replace the use of nr_mapped in various kernel locations. This avoids the looping over all processors in try_to_free_pages(), writeback, reclaim (swap + zone reclaim). [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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26c2143b |
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27-Jun-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] cpu hotplug: make cpu_notifier related notifier calls __cpuinit only Make notifier_calls associated with cpu_notifier as __cpuinit. __cpuinit makes sure that the function is init time only unless CONFIG_HOTPLUG_CPU is defined. [akpm@osdl.org: section fix] Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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74b85f37 |
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27-Jun-2006 |
Chandra Seetharaman <sekharan@us.ibm.com> |
[PATCH] cpu hotplug: make cpu_notifier related notifier blocks __cpuinit only Make notifier_blocks associated with cpu_notifier as __cpuinitdata. __cpuinitdata makes sure that the data is init time only unless CONFIG_HOTPLUG_CPU is defined. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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111ebb6e |
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23-Jun-2006 |
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> |
[PATCH] writeback: fix range handling When a writeback_control's `start' and `end' fields are used to indicate a one-byte-range starting at file offset zero, the required values of .start=0,.end=0 mean that the ->writepages() implementation has no way of telling that it is being asked to perform a range request. Because we're currently overloading (start == 0 && end == 0) to mean "this is not a write-a-range request". To make all this sane, the patch changes range of writeback_control. So caller does: If it is calling ->writepages() to write pages, it sets range (range_start/end or range_cyclic) always. And if range_cyclic is true, ->writepages() thinks the range is cyclic, otherwise it just uses range_start and range_end. This patch does, - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h -1 is usually ok for range_end (type is long long). But, if someone did, range_end += val; range_end is "val - 1" u64val = range_end >> bits; u64val is "~(0ULL)" or something, they are wrong. So, this adds LLONG_MAX to avoid nasty things, and uses LLONG_MAX for range_end. - All callers of ->writepages() sets range_start/end or range_cyclic. - Fix updates of ->writeback_index. It seems already bit strange. If it starts at 0 and ended by check of nr_to_write, this last index may reduce chance to scan end of file. So, this updates ->writeback_index only if range_cyclic is true or whole-file is scanned. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Nathan Scott <nathans@sgi.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Steven French <sfrench@us.ibm.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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fd5403c7 |
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10-Apr-2006 |
Coywolf Qi Hunt <coywolf@gmail.com> |
[PATCH] page-writeback comment fixes Signed-off-by: Coywolf Qi Hunt <qiyong@fc-cn.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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a580290c |
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02-Apr-2006 |
Martin Waitz <tali@admingilde.org> |
Documentation: fix minor kernel-doc warnings This patch updates the comments to match the actual code. Signed-off-by: Martin Waitz <tali@admingilde.org> Signed-off-by: Adrian Bunk <bunk@stusta.de>
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4741c9fd |
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24-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] set_page_dirty() return value fixes We need set_page_dirty() to return true if it actually transitioned the page from a clean to dirty state. This wasn't right in a couple of places. Do a kernel-wide audit, fix things up. This leaves open the possibility of returning a negative errno from set_page_dirty() sometime in the future. But we don't do that at present. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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fa5a734e |
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24-Mar-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] balance_dirty_pages_ratelimited: take nr_pages arg Modify balance_dirty_pages_ratelimited() so that it can take a number-of-pages-which-I-just-dirtied argument. For msync(). Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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ed5b43f1 |
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24-Mar-2006 |
Bart Samwel <bart@samwel.tk> |
[PATCH] Represent laptop_mode as jiffies internally Make that the internal value for /proc/sys/vm/laptop_mode is stored as jiffies instead of seconds. Let the sysctl interface do the conversions, instead of doing on-the-fly conversions every time the value is used. Add a description of the fact that laptop_mode doubles as a flag and a timeout to the comment above the laptop_mode variable. Signed-off-by: Bart Samwel <bart@samwel.tk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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f6ef9438 |
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24-Mar-2006 |
Bart Samwel <bart@samwel.tk> |
[PATCH] Represent dirty_*_centisecs as jiffies internally Make that the internal values for: /proc/sys/vm/dirty_writeback_centisecs /proc/sys/vm/dirty_expire_centisecs are stored as jiffies instead of centiseconds. Let the sysctl interface do the conversions with full precision using clock_t_to_jiffies, instead of doing overflow-sensitive on-the-fly conversions every time the values are used. Cons: apparent precision loss if HZ is not a multiple of 100, because of conversion back and forth. This is a common problem for all sysctl values that use proc_dointvec_userhz_jiffies. (There is only one other in-tree use, in net/core/neighbour.c.) Signed-off-by: Bart Samwel <bart@samwel.tk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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e236a166 |
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18-Jan-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] mm: dirty_exceeded speedup Ravikiran reports that this variable is bouncing all around nodes on NUMA machines, causing measurable performance problems. Fix that up by only writing to it when it actually changed. And put it in a new cacheline to prevent it sharing with other things (this happened). Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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22905f77 |
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16-Nov-2005 |
Andrew Morton <akpm@osdl.org> |
identify multipage ->writepages() calls NFS needs to be able to distinguish between single-page ->writepage() calls and multipage ->writepages() calls. For the single-page writepage calls NFS can kick off the I/O within the context of ->writepage(). For multipage ->writepages calls, nfs_writepage() will leave the I/O pending and nfs_writepages() will kick off the I/O when it all has been queued up within NFS. Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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58bb01a9 |
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18-Nov-2005 |
Hans Reiser <reiser@namesys.com> |
[PATCH] re-export clear_page_dirty_for_io() 2.6.14 has this exported, and reiser4 (at least) uses it. Put things back the way they were. Signed-off-by: Vladimir V. Saveliev <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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e6a7e0e7 |
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07-Nov-2005 |
Adrian Bunk <bunk@stusta.de> |
[PATCH] unexport clear_page_dirty_for_io I didn't find any possible modular usage in the kernel. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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8d06afab |
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09-Sep-2005 |
Ingo Molnar <mingo@elte.hu> |
[PATCH] timer initialization cleanup: DEFINE_TIMER Clean up timer initialization by introducing DEFINE_TIMER a'la DEFINE_SPINLOCK. Build and boot-tested on x86. A similar patch has been been in the -RT tree for some time. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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687a21ce |
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28-Jun-2005 |
Pekka J Enberg <penberg@cs.Helsinki.FI> |
[PATCH] rename wakeup_bdflush to wakeup_pdflush Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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67be2dd1 |
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01-May-2005 |
Martin Waitz <tali@admingilde.org> |
[PATCH] DocBook: fix some descriptions Some KernelDoc descriptions are updated to match the current code. No code changes. Signed-off-by: Martin Waitz <tali@admingilde.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1da177e4 |
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16-Apr-2005 |
Linus Torvalds <torvalds@ppc970.osdl.org> |
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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