highmem: add kernel-doc for memcpy_*_folio()

This was inadvertently skipped when adding the new functions.

Link: https://lkml.kernel.org/r/20240124181217.1761674-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add folio_fill_tail() and use it in iomap

The iomap code was limited to PAGE_SIZE bytes; generalise it to cover
an arbitrary-sized folio, and move it to be a common helper.

[akpm@linux-foundation.org: fix folio_fill_tail(), per Andreas Gruenbacher]
Link: https://lkml.kernel.org/r/20231107212643.3490372-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add folio_zero_tail() and use it in ext4

Patch series "Add folio_zero_tail() and folio_fill_tail()".

I'm trying to make it easier for filesystems with tailpacking / stuffing /
inline data to use folios. The primary function here is
folio_fill_tail(). You give it a pointer to memory where the data
currently is, and it takes care of copying it into the folio at that
offset. That works for gfs2 & iomap. Then There's Ext4. Rather than gin
up some kind of specialist "Here's a two pointers to two blocks of memory"
routine, just let it do its current thing, and let it call
folio_zero_tail(), which is also called by folio_fill_tail().

Other filesystems can be converted later; these ones seemed like good
examples as they're already partly or completely converted to folios.


This patch (of 3):

Instead of unmapping the folio after copying the data to it, then mapping
it again to zero the tail, provide folio_zero_tail() to zero the tail of
an already-mapped folio.

[akpm@linux-foundation.org: fix kerneldoc argument ordering]
Link: https://lkml.kernel.org/r/20231107212643.3490372-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231107212643.3490372-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: fix a memory copy problem in memcpy_from_folio

Clang static checker complains that value stored to 'from' is never read.
And memcpy_from_folio() only copy the last chunk memory from folio to
destination. Use 'to += chunk' to replace 'from += chunk' to fix this
typo problem.

Link: https://lkml.kernel.org/r/20231130034017.1210429-1-suhui@nfschina.com
Fixes: b23d03ef7af5 ("highmem: add memcpy_to_folio() and memcpy_from_folio()")
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: Add folio_release_kmap()

This is the folio equivalent of unmap_and_put_page(), which remains as
a wrapper for it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230921200746.3303942-1-willy@infradead.org>

highmem: add memcpy_to_folio() and memcpy_from_folio()

Patch series "More filesystem folio conversions for 6.6".

Remove the only spots in affs which actually use a struct page; there
are a few places where one is mentioned, but it's part of the interface.

The rest of this is removing the remaining calls to set_bh_page(),
and then removing the function before any new users show up.


This patch (of 7):

These are the folio equivalent of memcpy_to_page() and memcpy_from_page().

[agruenba@redhat.com: use correct chunk size in memcpy()]
Link: https://lkml.kernel.org/r/20230802144354.1023099-1-agruenba@redhat.com
Link: https://lkml.kernel.org/r/20230713035512.4139457-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20230713035512.4139457-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Jan Kara <jack@suse.com>
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: Rename put_and_unmap_page() to unmap_and_put_page()

With commit 849ad04cf562a ("new helper: put_and_unmap_page()"), Al Viro
introduced the put_and_unmap_page() to use in those many places where we
have a common pattern consisting of calls to kunmap_local() +
put_page().

Obviously, first we unmap and then we put pages. Instead, the original
name of this helper seems to imply that we first put and then unmap.

Therefore, rename the helper and change the only known upstreamed user
(i.e., fs/sysv) before this helper enters common use and might become
difficult to find all call sites and instead easy to break the builds.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Message-Id: <20230602103307.5637-1-fmdefrancesco@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

mm/hwpoison: introduce copy_mc_highpage

Similar to how copy_mc_user_highpage is implemented for copy_user_highpage
on #MC supported architecture, introduce the #MC handled version of
copy_highpage.

This helper has immediate usage when khugepaged wants to copy file-backed
memory pages and tolerate #MC.

Link: https://lkml.kernel.org/r/20230329151121.949896-3-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: David Stevens <stevensd@chromium.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Tong Tiangen <tongtiangen@huawei.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: call clear_page with a match-all tag instead of changing page tag

Instead of changing the page's tag solely in order to obtain a pointer
with a match-all tag and then changing it back again, just convert the
pointer that we get from kmap_atomic() into one with a match-all tag
before passing it to clear_page().

On a certain microarchitecture, this has been observed to cause a
measurable improvement in microbenchmark performance, presumably as a
result of being able to avoid the atomic operations on the page tag.

Link: https://lkml.kernel.org/r/20230216195924.3287772-1-pcc@google.com
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I0249822cc29097ca7a04ad48e8eb14871f80e711
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

new helper: put_and_unmap_page()

kunmap_local() + put_page(), as done by e.g. ext2 directory handling.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

mm: fix memcpy_from_file_folio() integer underflow

If we have a HIGHMEM system with a large folio, 'offset' may be larger
than PAGE_SIZE, and so min_t will cap at 'len' instead of the intended
end-of-page. That can overflow into the next page which is likely to be
unmapped and fault, but could theoretically copy the wrong data.

Link: https://lkml.kernel.org/r/Y919vmSrtAgsf6K3@casper.infradead.org
Fixes: 00cdf76012ab ("mm: add memcpy_from_file_folio()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add memcpy_from_file_folio()

This is the equivalent of memcpy_from_page(). It differs in that it takes
the position in a file instead of offset in a folio, it accepts the total
number of bytes to be copied (instead of the number of bytes to be copied
from this folio) and it returns how many bytes were copied from the folio,
rather than making the caller calculate that and then checking if the
caller got it right.

[akpm@linux-foundation.org: fix typo in comment]
Link: https://lkml.kernel.org/r/20230126201552.1681588-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add vma_alloc_zeroed_movable_folio()

Replace alloc_zeroed_user_highpage_movable(). The main difference is
returning a folio containing a single page instead of returning the page,
but take the opportunity to rename the function to match other allocation
functions a little better and rewrite the documentation to place more
emphasis on the zeroing rather than the highmem aspect.

Link: https://lkml.kernel.org/r/20230116191813.2145215-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix spelling mistake in highmem.h

Substitute "higmem" with "highmem" in highmem.h.

Link: https://lkml.kernel.org/r/20230105121305.30714-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove an ambiguous sentence from kmap_local_folio() kdocs

In the kdocs of kmap_local_folio() there is a an ambiguous sentence which
suggests to use this API "only when really necessary".

On the contrary, since kmap() and kmap_atomic() are deprecated, both
kmap_local_folio(), as well as kmap_local_page(), must be preferred to the
previous ones.

Therefore, remove the above-mentioned sentence exactly how it has
previously been done for the kmap_local_page() kdocs in commit
72f1c55adf70 ("highmem: delete a sentence from kmap_local_page() kdocs").

Link: https://lkml.kernel.org/r/20230105120424.30055-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, hwpoison: try to recover from copy-on write faults

Patch series "Copy-on-write poison recovery", v3.

Part 1 deals with the process that triggered the copy on write fault with
a store to a shared read-only page. That process is send a SIGBUS with
the usual machine check decoration to specify the virtual address of the
lost page, together with the scope.

Part 2 sets up to asynchronously take the page with the uncorrected error
offline to prevent additional machine check faults. H/t to Miaohe Lin
<linmiaohe@huawei.com> and Shuai Xue <xueshuai@linux.alibaba.com> for
pointing me to the existing function to queue a call to memory_failure().

On x86 there is some duplicate reporting (because the error is also
signalled by the memory controller as well as by the core that triggered
the machine check). Console logs look like this:


This patch (of 2):

If the kernel is copying a page as the result of a copy-on-write
fault and runs into an uncorrectable error, Linux will crash because
it does not have recovery code for this case where poison is consumed
by the kernel.

It is easy to set up a test case. Just inject an error into a private
page, fork(2), and have the child process write to the page.

I wrapped that neatly into a test at:

git://git.kernel.org/pub/scm/linux/kernel/git/aegl/ras-tools.git

just enable ACPI error injection and run:

# ./einj_mem-uc -f copy-on-write

Add a new copy_user_highpage_mc() function that uses copy_mc_to_kernel()
on architectures where that is available (currently x86 and powerpc).
When an error is detected during the page copy, return VM_FAULT_HWPOISON
to caller of wp_page_copy(). This propagates up the call stack. Both x86
and powerpc have code in their fault handler to deal with this code by
sending a SIGBUS to the application.

Note that this patch avoids a system crash and signals the process that
triggered the copy-on-write action. It does not take any action for the
memory error that is still in the shared page. To handle that a call to
memory_failure() is needed. But this cannot be done from wp_page_copy()
because it holds mmap_lock(). Perhaps the architecture fault handlers
can deal with this loose end in a subsequent patch?

On Intel/x86 this loose end will often be handled automatically because
the memory controller provides an additional notification of the h/w
poison in memory, the handler for this will call memory_failure(). This
isn't a 100% solution. If there are multiple errors, not all may be
logged in this way.

[tony.luck@intel.com: add call to kmsan_unpoison_memory(), per Miaohe Lin]
Link: https://lkml.kernel.org/r/20221031201029.102123-2-tony.luck@intel.com
Link: https://lkml.kernel.org/r/20221021200120.175753-1-tony.luck@intel.com
Link: https://lkml.kernel.org/r/20221021200120.175753-2-tony.luck@intel.com
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Shuai Xue <xueshuai@linux.alibaba.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: kmsan: maintain KMSAN metadata for page operations

Insert KMSAN hooks that make the necessary bookkeeping changes:
- poison page shadow and origins in alloc_pages()/free_page();
- clear page shadow and origins in clear_page(), copy_user_highpage();
- copy page metadata in copy_highpage(), wp_page_copy();
- handle vmap()/vunmap()/iounmap();

Link: https://lkml.kernel.org/r/20220915150417.722975-15-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: delete a sentence from kmap_local_page() kdocs

kmap_local_page() should always be preferred in place of kmap() and
kmap_atomic(). "Only use when really necessary." is not consistent with
the Documentation/mm/highmem.rst and these kdocs it embeds.

Therefore, delete the above-mentioned sentence from kdocs.

Link: https://lkml.kernel.org/r/20220728154844.10874-7-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: specify that kmap_local_page() is callable from interrupts

In a recent thread about converting kmap() to kmap_local_page(), the
safety of calling kmap_local_page() was questioned.[1]

"any context" should probably be enough detail for users who want to know
whether or not kmap_local_page() can be called from interrupts. However,
Linux still has kmap_atomic() which might make users think they must use
the latter in interrupts.

Add "including interrupts" for better clarity.

[1] https://lore.kernel.org/lkml/3187836.aeNJFYEL58@opensuse/

Link: https://lkml.kernel.org/r/20220728154844.10874-3-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

highmem: remove unneeded spaces in kmap_local_page() kdocs

Patch series "highmem: Extend kmap_local_page() documentation", v2.

The Highmem interface is evolving and the current documentation does not
reflect the intended uses of each of the calls. Furthermore, after a
recent series of reworks, the differences of the calls can still be
confusing and may lead to the expanded use of calls which are deprecated.

This series is the second round of changes towards an enhanced
documentation of the Highmem's interface; at this stage the patches are
only focused to kmap_local_page().

In addition it also contains some minor clean ups.


This patch (of 7):

In the kdocs of kmap_local_page(), the description of @page starts after
several unnecessary spaces.

Therefore, remove those spaces.

Link: https://lkml.kernel.org/r/20220728154844.10874-1-fmdefrancesco@gmail.com
Link: https://lkml.kernel.org/r/20220728154844.10874-2-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: introduce clear_highpage_kasan_tagged

Add a clear_highpage_kasan_tagged() helper that does clear_highpage() on a
page potentially tagged by KASAN.

This helper is used by the following patch.

Link: https://lkml.kernel.org/r/4471979b46b2c487787ddcd08b9dc5fedd1b6ffd.1654798516.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/highmem: delete memmove_page()

Matthew Wilcox reported that, while he was looking at memmove_page(), he
realized that it can't actually work.

The reasons are hidden in its implementation, which makes use of memmove()
on logical addresses provided by kmap_local_page(). memmove() does the
wrong thing when it tests "if (dest <= src)".

Therefore, delete memmove_page().

No need to change any other code because we have no call sites of
memmove_page() across the whole kernel.

Link: https://lkml.kernel.org/r/20220606141533.555-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reported-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation: highmem: use literal block for code example in highmem.h comment

When building htmldocs on Linus's tree, there are inline emphasis warnings
on include/linux/highmem.h:

Documentation/vm/highmem:166: ./include/linux/highmem.h:154: WARNING: Inline emphasis start-string without end-string.
Documentation/vm/highmem:166: ./include/linux/highmem.h:157: WARNING: Inline emphasis start-string without end-string.

These warnings above are due to comments in code example at the mentioned
lines above are enclosed by double dash (--), which confuses Sphinx as
inline markup delimiters instead.

Fix these warnings by indenting the code example with literal block
indentation and making the comments C comments.

Link: https://lkml.kernel.org/r/20220622084546.17745-1-bagasdotme@gmail.com
Fixes: 85a85e7601263f ("Documentation/vm: move "Using kmap-atomic" to highmem.h")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/vm: move "Using kmap-atomic" to highmem.h

The use of kmap_atomic() is new code is being deprecated in favor of
kmap_local_page(). For this reason the "Using kmap_atomic" section in
highmem.rst is obsolete and unnecessary, but it can still help developers
if it were moved to kdocs in highmem.h.

Therefore, move the relevant parts of this section from highmem.rst and
merge them with the kdocs in highmem.h.

Link: https://lkml.kernel.org/r/20220428212455.892-4-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/highmem: fix kernel-doc warnings in highmem*.h

Patch series "Extend and reorganize Highmem's documentation", v4.

This series has the purpose to extend and reorganize Highmem's
documentation.

This is a work in progress because some information should still be moved
from highmem.rst to highmem.h and highmem-internal.h. Specifically I'm
talking about moving the "how to" information to the relevant headers, as
it as been suggested by Ira Weiny (Intel).

Also, this is a work in progress because some kdocs in highmem.h and
highmem-internal.h should be improved.


This patch (of 4):

`scripts/kernel-doc -v -none include/linux/highmem*` reports the following
warnings:

include/linux/highmem.h:160: warning: expecting prototype for kunmap_atomic(). Prototype was for nr_free_highpages() instead
include/linux/highmem.h:204: warning: No description found for return value of 'alloc_zeroed_user_highpage_movable'
include/linux/highmem-internal.h:256: warning: Function parameter or member '__addr' not described in 'kunmap_atomic'
include/linux/highmem-internal.h:256: warning: Excess function parameter 'addr' description in 'kunmap_atomic'

Fix these warnings by (1) moving the kernel-doc comments from highmem.h to
highmem-internal.h (which is the file were the kunmap_atomic() macro is
actually defined), (2) extending and merging it with the comment which was
already in highmem-internal.h, and (3) using correct parameter names (4)
correcting a few technical inaccuracies in comments, and (5) adding a
deprecation notice in kunmap_atomic() for consistency with kmap_atomic().

Link: https://lkml.kernel.org/r/20220428212455.892-1-fmdefrancesco@gmail.com
Link: https://lkml.kernel.org/r/20220428212455.892-2-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE

Add VM_BUG_ON() bounds checking to make sure that, if "offset + len>
PAGE_SIZE", memset() does not corrupt data in adjacent pages.

Mainly to match all the similar functions in highmem.h.

Link: https://lkml.kernel.org/r/20220426193020.8710-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: Add functions to zero portions of a folio

These functions are wrappers around zero_user_segments(), which means
that zero_user_segments() can now be called for compound pages even when
CONFIG_TRANSPARENT_HUGEPAGE is disabled.

Use 'xend' as the name of the parameter to indicate that this is an
excluded end, not the more usual included end. Excluding the end makes
more sense to the callers, but can cause confusion to readers who are
more used to seeing included ends.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Add linux/cacheflush.h

Many architectures do not include asm-generic/cacheflush.h, so turn
the includes on their head and add linux/cacheflush.h which includes
asm/cacheflush.h.

Move the flush_dcache_folio() declaration from asm-generic/cacheflush.h
to linux/cacheflush.h and change linux/highmem.h to include
linux/cacheflush.h instead of asm/cacheflush.h so that all necessary
places will see flush_dcache_folio().

More functions should have their default implementations moved in the
future, but those are for follow-on patches. This fixes csky, sparc and
sparc64 which were missed in the commit which added flush_dcache_folio().

Fixes: 08b0b0059bf1 ("mm: Add flush_dcache_folio()")
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

mm/highmem: remove deprecated kmap_atomic

kmap_atomic() is being deprecated in favor of kmap_local_page().

Replace the uses of kmap_atomic() within the highmem code.

On profiling clear_huge_page() using ftrace an improvement of 62% was
observed on the below setup.

Setup:-
Below data has been collected on Qualcomm's SM7250 SoC THP enabled
(kernel v4.19.113) with only CPU-0(Cortex-A55) and CPU-7(Cortex-A76)
switched on and set to max frequency, also DDR set to perf governor.

FTRACE Data:-

Base data:-
Number of iterations: 48
Mean of allocation time: 349.5 us
std deviation: 74.5 us

v4 data:-
Number of iterations: 48
Mean of allocation time: 131 us
std deviation: 32.7 us

The following simple userspace experiment to allocate
100MB(BUF_SZ) of pages and writing to it gave us a good insight,
we observed an improvement of 42% in allocation and writing timings.
-------------------------------------------------------------
Test code snippet
-------------------------------------------------------------
clock_start();
buf = malloc(BUF_SZ); /* Allocate 100 MB of memory */

for(i=0; i < BUF_SZ_PAGES; i++)
{
*((int *)(buf + (i*PAGE_SIZE))) = 1;
}
clock_end();
-------------------------------------------------------------

Malloc test timings for 100MB anon allocation:-

Base data:-
Number of iterations: 100
Mean of allocation time: 31831 us
std deviation: 4286 us

v4 data:-
Number of iterations: 100
Mean of allocation time: 18193 us
std deviation: 4915 us

[willy@infradead.org: fix zero_user_segments()]
Link: https://lkml.kernel.org/r/YYVhHCJcm2DM2G9u@casper.infradead.org

Link: https://lkml.kernel.org/r/20210204073255.20769-2-prathu.baronia@oneplus.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Prathu Baronia <prathu.baronia@oneplus.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: Add kmap_local_folio()

This allows us to map a portion of a folio. Callers can only expect
to access up to the next page boundary.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

mm: remove flush_kernel_dcache_page

flush_kernel_dcache_page is a rather confusing interface that implements a
subset of flush_dcache_page by not being able to properly handle page
cache mapped pages.

The only callers left are in the exec code as all other previous callers
were incorrect as they could have dealt with page cache pages. Replace
the calls to flush_kernel_dcache_page with calls to flush_dcache_page,
which for all architectures does either exactly the same thing, can
contains one or more of the following:

1) an optimization to defer the cache flush for page cache pages not
mapped into userspace
2) additional flushing for mapped page cache pages if cache aliases
are possible

Link: https://lkml.kernel.org/r/20210712060928.4161649-7-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: use kmap_local_page in memzero_page

The commit message introducing the global memzero_page explicitly
mentions switching to kmap_local_page in the commit log but doesn't
actually do that.

Link: https://lkml.kernel.org/r/20210713055231.137602-3-hch@lst.de
Fixes: 28961998f858 ("iov_iter: lift memzero_page() to highmem.h")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: call flush_dcache_page() in memcpy_to_page() and memzero_page()

memcpy_to_page and memzero_page can write to arbitrary pages, which
could be in the page cache or in high memory, so call
flush_kernel_dcache_pages to flush the dcache.

This is a problem when using these helpers on dcache challeneged
architectures. Right now there are just a few users, chances are no one
used the PC floppy driver, the aha1542 driver for an ISA SCSI HBA, and a
few advanced and optional btrfs and ext4 features on those platforms yet
since the conversion.

Link: https://lkml.kernel.org/r/20210713055231.137602-2-hch@lst.de
Fixes: bb90d4bc7b6a ("mm/highmem: Lift memcpy_[to|from]_page to core")
Fixes: 28961998f858 ("iov_iter: lift memzero_page() to highmem.h")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arm64: mte: handle tags zeroing at page allocation time

Currently, on an anonymous page fault, the kernel allocates a zeroed
page and maps it in user space. If the mapping is tagged (PROT_MTE),
set_pte_at() additionally clears the tags. It is, however, more
efficient to clear the tags at the same time as zeroing the data on
allocation. To avoid clearing the tags on any page (which may not be
mapped as tagged), only do this if the vma flags contain VM_MTE. This
requires introducing a new GFP flag that is used to determine whether
to clear the tags.

The DC GZVA instruction with a 0 top byte (and 0 tag) requires
top-byte-ignore. Set the TCR_EL1.{TBI1,TBID1} bits irrespective of
whether KASAN_HW is enabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Id46dc94e30fe11474f7e54f5d65e7658dbdddb26
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>

mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()

In an upcoming change we would like to add a flag to
GFP_HIGHUSER_MOVABLE so that it would no longer be an OR
of GFP_HIGHUSER and __GFP_MOVABLE. This poses a problem for
alloc_zeroed_user_highpage_movable() which passes __GFP_MOVABLE
into an arch-specific __alloc_zeroed_user_highpage() hook which ORs
in GFP_HIGHUSER.

Since __alloc_zeroed_user_highpage() is only ever called from
alloc_zeroed_user_highpage_movable(), we can remove one level
of indirection here. Remove __alloc_zeroed_user_highpage(),
make alloc_zeroed_user_highpage_movable() the hook, and use
GFP_HIGHUSER_MOVABLE in the hook implementations so that they will
pick up the new flag that we are going to add.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ic6361c657b2cdcd896adbe0cf7cb5a7fbb1ed7bf
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210602235230.3928842-2-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>

iov_iter: lift memzero_page() to highmem.h

Patch series "btrfs: Convert kmap/memset/kunmap to memzero_user()".

Lifting memzero_user(), convert it to kmap_local_page() and then use it
in btrfs.

This patch (of 3):

memzero_page() can replace the kmap/memset/kunmap pattern in other
places in the code. While zero_user() has the same interface it is not
the same call and its use should be limited and some of those calls may
be better converted from zero_user() to memzero_page().[1] But that is
not addressed in this series.

Lift memzero_page() to highmem.

[1] https://lore.kernel.org/lkml/CAHk-=wijdojzo56FzYqE5TOYw2Vws7ik3LEMGj9SPQaJJ+Z73Q@mail.gmail.com/

Link: https://lkml.kernel.org/r/20210309212137.2610186-1-ira.weiny@intel.com
Link: https://lkml.kernel.org/r/20210309212137.2610186-2-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/highmem: Add VM_BUG_ON() to mem*_page() calls

Add VM_BUG_ON bounds checks to ensure the newly lifted and created page
memory operations do not result in corrupted data in neighbor pages.[1][2]

[1] https://lore.kernel.org/lkml/20201210053502.GS1563847@iweiny-DESK2.sc.intel.com/
[2] https://lore.kernel.org/lkml/20210209110931.00f00e47d9a0529fcee2ff01@linux-foundation.org/

Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>

mm/highmem: Introduce memcpy_page(), memmove_page(), and memset_page()

3 more common kmap patterns are kmap/memcpy/kunmap, kmap/memmove/kunmap.
and kmap/memset/kunmap.

Add helper functions for those patterns which use kmap_local_page().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>

mm/highmem: Convert memcpy_[to|from]_page() to kmap_local_page()

kmap_local_page() is more efficient and is well suited for these calls.
Convert the kmap() to kmap_local_page()

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>

mm/highmem: Lift memcpy_[to|from]_page to core

Working through a conversion to a call kmap_local_page() instead of
kmap() revealed many places where the pattern kmap/memcpy/kunmap
occurred.

Eric Biggers, Matthew Wilcox, Christoph Hellwig, Dan Williams, and Al
Viro all suggested putting this code into helper functions. Al Viro
further pointed out that these functions already existed in the iov_iter
code.[1]

Various locations for the lifted functions were considered.

Headers like mm.h or string.h seem ok but don't really portray the
functionality well. pagemap.h made some sense but is for page cache
functionality.[2]

Another alternative would be to create a new header for the promoted
memcpy functions, but it masks the fact that these are designed to copy
to/from pages using the kernel direct mappings and complicates matters
with a new header.

Placing these functions in 'highmem.h' is suboptimal especially with the
changes being proposed in the functionality of kmap. From a caller
perspective including/using 'highmem.h' implies that the functions
defined in that header are only required when highmem is in use which is
increasingly not the case with modern processors. However, highmem.h is
where all the current functions like this reside (zero_user(),
clear_highpage(), clear_user_highpage(), copy_user_highpage(), and
copy_highpage()). So it makes the most sense even though it is
distasteful for some.[3]

Lift memcpy_to_page() and memcpy_from_page() to pagemap.h.

[1] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/
https://lore.kernel.org/lkml/20201013112544.GA5249@infradead.org/

[2] https://lore.kernel.org/lkml/20201208122316.GH7338@casper.infradead.org/

[3] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/#t
https://lore.kernel.org/lkml/20201208163814.GN1563847@iweiny-DESK2.sc.intel.com/

Cc: Boris Pismenny <borisp@mellanox.com>
Cc: Or Gerlitz <gerlitz.or@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>

mm: support THPs in zero_user_segments

We can only kmap() one subpage of a THP at a time, so loop over all
relevant subpages, skipping ones which don't need to be zeroed. This is
too large to inline when THPs are enabled and we actually need highmem, so
put it in highmem.c.

[willy@infradead.org: start1 was allowed to be less than start2]

Link: https://lkml.kernel.org/r/20201124041507.28996-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/highmem: Provide kmap_local*

Now that the kmap atomic index is stored in task struct provide a
preemptible variant. On context switch the maps of an outgoing task are
removed and the map of the incoming task are restored. That's obviously
slow, but highmem is slow anyway.

The kmap_local.*() functions can be invoked from both preemptible and
atomic context. kmap local sections disable migration to keep the resulting
virtual mapping address correct, but disable neither pagefaults nor
preemption.

A wholesale conversion of kmap_atomic to be fully preemptible is not
possible because some of the usage sites might rely on the preemption
disable for serialization or on the implicit pagefault disable. Needs to be
done on a case by case basis.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20201118204007.468533059@linutronix.de

highmem: High implementation details and document API

Move the gory details of kmap & al into a private header and only document
the interfaces which are usable by drivers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095858.827582066@linutronix.de

mm/highmem: Remove the old kmap_atomic cruft

All users gone.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20201103095858.516281567@linutronix.de

highmem: Get rid of kmap_types.h

The header is not longer used and on alpha, ia64, openrisc, parisc and um
it was completely unused anyway as these architectures have no highmem
support.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20201103095858.422094352@linutronix.de

x86/mm/highmem: Use generic kmap atomic implementation

Convert X86 to the generic kmap atomic implementation and make the
iomap_atomic() naming convention consistent while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201103095857.375127260@linutronix.de

highmem: Provide generic variant of kmap_atomic*

The kmap_atomic* interfaces in all architectures are pretty much the same
except for post map operations (flush) and pre- and post unmap operations.

Provide a generic variant for that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095857.175939340@linutronix.de

highmem: Remove unused functions

Nothing uses totalhigh_pages_dec() and totalhigh_pages_set().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095856.732891880@linutronix.de

include/linux/highmem.h: fix duplicated words in a comment

Change the doubled word "is" in a comment to "it is".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/ad605959-0083-4794-8d31-6b073300dd6f@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kmap: consolidate kmap_prot definitions

Most architectures define kmap_prot to be PAGE_KERNEL.

Let sparc and xtensa define there own and define PAGE_KERNEL as the
default if not overridden.

[akpm@linux-foundation.org: coding style fixes]
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-16-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parisc/kmap: remove duplicate kmap code

parisc reimplements the kmap calls except to flush its dcache. This is
arguably an abuse of kmap but regardless it is messy and confusing.

Remove the duplicate code and have parisc define ARCH_HAS_FLUSH_ON_KUNMAP
for a kunmap_flush_on_unmap() architecture specific call to flush the
cache.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-14-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/kmap: define kmap_atomic_prot() for all arch's

To support kmap_atomic_prot(), all architectures need to support
protections passed to their kmap_atomic_high() function. Pass protections
into kmap_atomic_high() and change the name to kmap_atomic_high_prot() to
match.

Then define kmap_atomic_prot() as a core function which calls
kmap_atomic_high_prot() when needed.

Finally, redefine kmap_atomic() as a wrapper of kmap_atomic_prot() with
the default kmap_prot exported by the architectures.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-11-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/kunmap_atomic: consolidate duplicate code

Every single architecture (including !CONFIG_HIGHMEM) calls...

pagefault_enable();
preempt_enable();

... before returning from __kunmap_atomic(). Lift this code into the
kunmap_atomic() macro.

While we are at it rename __kunmap_atomic() to kunmap_atomic_high() to
be consistent.

[ira.weiny@intel.com: don't enable pagefault/preempt twice]
Link: http://lkml.kernel.org/r/20200518184843.3029640-1-ira.weiny@intel.com
[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Link: http://lkml.kernel.org/r/20200507150004.1423069-8-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/kmap_atomic: consolidate duplicate code

Every arch has the same code to ensure atomic operations and a check for
!HIGHMEM page.

Remove the duplicate code by defining a core kmap_atomic() which only
calls the arch specific kmap_atomic_high() when the page is high memory.

[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-7-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/kunmap: remove duplicate kunmap implementations

All architectures do exactly the same thing for kunmap(); remove all the
duplicate definitions and lift the call to the core.

This also has the benefit of changing kmap_unmap() on a number of
architectures to be an inline call rather than an actual function.

[akpm@linux-foundation.org: fix CONFIG_HIGHMEM=n build on various architectures]
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-5-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/kmap: remove redundant arch specific kmaps

The kmap code for all the architectures is almost 100% identical.

Lift the common code to the core. Use ARCH_HAS_KMAP_FLUSH_TLB to indicate
if an arch defines kmap_flush_tlb() and call if if needed.

This also has the benefit of changing kmap() on a number of architectures
to be an inline call rather than an actual function.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-4-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: convert totalram_pages and totalhigh_pages variables to atomic

totalram_pages and totalhigh_pages are made static inline function.

Main motivation was that managed_page_count_lock handling was complicating
things. It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: Allow arch code to override copy_highpage()

Some architectures can support metadata for memory pages and when a
page is copied, its metadata must also be copied. Sparc processors
from M7 onwards support metadata for memory pages. This metadata
provides tag based protection for access to memory pages. To maintain
this protection, the tag data must be copied to the new page when a
page is migrated across NUMA nodes. This patch allows arch specific
code to override default copy_highpage() and copy metadata along
with page data upon migration.

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Khalid Aziz <khalid@gonehiking.org>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kmap_atomic_to_page() has no users, remove it

Removal started in commit 5bbeed12bdc3 ("sparc32: drop unused
kmap_atomic_to_page"). Let's do it across the whole tree.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched/preempt, mm/kmap: Explicitly disable/enable preemption in kmap_atomic_*

The existing code relies on pagefault_disable() implicitly disabling
preemption, so that no schedule will happen between kmap_atomic() and
kunmap_atomic().

Let's make this explicit, to prepare for pagefault_disable() not
touching preemption anymore.

Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-5-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR

__kmap_atomic_idx is per_cpu variable. Each CPU can use KM_TYPE_NR
entries from FIXMAP i.e. from 0 to KM_TYPE_NR - 1. Allowing
__kmap_atomic_idx to over- shoot to KM_TYPE_NR can mess up with next
CPU's 0th entry which is a bug. Hence BUG_ON if __kmap_atomic_idx >=
KM_TYPE_NR.

Fix the off-by-on in this test.

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove unused memclear_highpage_flush()

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>

mm: add support for direct_IO to highmem pages

The patch "mm: add support for a filesystem to activate swap files and use
direct_IO for writing swap pages" added support for using direct_IO to
write swap pages but it is insufficient for highmem pages.

To support highmem pages, this patch kmaps() the page before calling the
direct_IO() handler. As direct_IO deals with virtual addresses an
additional helper is necessary for get_kernel_pages() to lookup the struct
page for a kmap virtual address.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

highmem: remove the deprecated form of kmap_atomic

Signed-off-by: Cong Wang <amwang@redhat.com>

highmem: kill all __kmap_atomic()
[swarren@nvidia.com: highmem: Fix ARM build break due to __kmap_atomic rename]

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Cong Wang <amwang@redhat.com>

include/linux/highmem.h: remove the second argument of k[un]map_atomic()

Signed-off-by: Cong Wang <amwang@redhat.com>

highmem: mark k[un]map_atomic() with two arguments as deprecated

For backward compatibility, we still keep the deprecated form,
and will warn the users if they still use the deprecated one, like this:

drivers/block/drbd/drbd_bitmap.c: In function ‘bm_page_io_async’:
drivers/block/drbd/drbd_bitmap.c:973:3: warning: ‘kmap_atomic_deprecated’ is deprecated (declared at /home/wangcong/linux-2.6/include/linux/highmem.h:124)
drivers/block/drbd/drbd_bitmap.c:977:3: warning: ‘kunmap_atomic_deprecated’ is deprecated (declared at /home/wangcong/linux-2.6/include/linux/highmem.h:144)

Thanks to Nick Bowler for the cpp trick!

Cc: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Nick Bowler <nbowler@elliptictech.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Cong Wang <amwang@redhat.com>

BUG: headers with BUG/BUG_ON etc. need linux/bug.h

If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including <linux/bug.h> and not just
expecting it to be implicitly present.

We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

highmem: Use this_cpu_xx_return() operations

Use this_cpu operations to optimize access primitives for highmem.

The main effect is the avoidance of address calculations through the
use of a segment prefix.

V3->V4
- kmap_atomic_idx: Do not return a value.
- Use __this_cpu_dec without HIGHMEM_DEBUG

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

include/linux/highmem.h needs hardirq.h

Commit 3e4d3af501cc ("mm: stack based kmap_atomic()") introduced the
kmap_atomic_idx_push() function which warns on in_irq() with
CONFIG_DEBUG_HIGHMEM enabled. This patch includes linux/hardirq.h for
the in_irq definition.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>

mm: fix race in kunmap_atomic()

Christoph reported a nice splat which illustrated a race in the new stack
based kmap_atomic implementation.

The problem is that we pop our stack slot before we're completely done
resetting its state -- in particular clearing the PTE (sometimes that's
CONFIG_DEBUG_HIGHMEM). If an interrupt happens before we actually clear
the PTE used for the last slot, that interrupt can reuse the slot in a
dirty state, which triggers a BUG in kmap_atomic().

Fix this by introducing kmap_atomic_idx() which reports the current slot
index without actually releasing it and use that to find the PTE and delay
the _pop() until after we're completely done.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm,x86: fix kmap_atomic_push vs ioremap_32.c

It appears i386 uses kmap_atomic infrastructure regardless of
CONFIG_HIGHMEM which results in a compile error when highmem is disabled.

Cure this by providing the needed few bits for both CONFIG_HIGHMEM and
CONFIG_X86_32.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: stack based kmap_atomic()

Keep the current interface but ignore the KM_type and use a stack based
approach.

The advantage is that we get rid of crappy code like:

#define __KM_PTE \
(in_nmi() ? KM_NMI_PTE : \
in_irq() ? KM_IRQ_PTE : \
KM_PTE0)

and in general can stop worrying about what context we're in and what kmap
slots might be appropriate for that.

The downside is that FRV kmap_atomic() gets more expensive.

For now we use a CPP trick suggested by Andrew:

#define kmap_atomic(page, args...) __kmap_atomic(page)

to avoid having to touch all kmap_atomic() users in a single patch.

[ not compiled on:
- mn10300: the arch doesn't actually build with highmem to begin with ]

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c]
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: strictly nested kmap_atomic()

Ensure kmap_atomic() usage is strictly nested

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

gcc-4.6: mm: fix unused but set warnings

No real bugs, just some dead code and some fixups.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kmap_atomic: make kunmap_atomic() harder to misuse

kunmap_atomic() is currently at level -4 on Rusty's "Hard To Misuse"
list[1] ("Follow common convention and you'll get it wrong"), except in
some architectures when CONFIG_DEBUG_HIGHMEM is set[2][3].

kunmap() takes a pointer to a struct page; kunmap_atomic(), however, takes
takes a pointer to within the page itself. This seems to once in a while
trip people up (the convention they are following is the one from
kunmap()).

Make it much harder to misuse, by moving it to level 9 on Rusty's list[4]
("The compiler/linker won't let you get it wrong"). This is done by
refusing to build if the type of its first argument is a pointer to a
struct page.

The real kunmap_atomic() is renamed to kunmap_atomic_notypecheck()
(which is what you would call in case for some strange reason calling it
with a pointer to a struct page is not incorrect in your code).

The previous version of this patch was compile tested on x86-64.

[1] http://ozlabs.org/~rusty/index.cgi/tech/2008-04-01.html
[2] In these cases, it is at level 5, "Do it right or it will always
break at runtime."
[3] At least mips and powerpc look very similar, and sparc also seems to
share a common ancestor with both; there seems to be quite some
degree of copy-and-paste coding here. The include/asm/highmem.h file
for these three archs mention x86 CPUs at its top.
[4] http://ozlabs.org/~rusty/index.cgi/tech/2008-03-30.html
[5] As an aside, could someone tell me why mn10300 uses unsigned long as
the first parameter of kunmap_atomic() instead of void *?

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Russell King <linux@arm.linux.org.uk> (arch/arm)
Cc: Ralf Baechle <ralf@linux-mips.org> (arch/mips)
Cc: David Howells <dhowells@redhat.com> (arch/frv, arch/mn10300)
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> (arch/mn10300)
Cc: Kyle McMartin <kyle@mcmartin.ca> (arch/parisc)
Cc: Helge Deller <deller@gmx.de> (arch/parisc)
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> (arch/parisc)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> (arch/powerpc)
Cc: Paul Mackerras <paulus@samba.org> (arch/powerpc)
Cc: "David S. Miller" <davem@davemloft.net> (arch/sparc)
Cc: Thomas Gleixner <tglx@linutronix.de> (arch/x86)
Cc: Ingo Molnar <mingo@redhat.com> (arch/x86)
Cc: "H. Peter Anvin" <hpa@zytor.com> (arch/x86)
Cc: Arnd Bergmann <arnd@arndb.de> (include/asm-generic)
Cc: Rusty Russell <rusty@rustcorp.com.au> ("Hard To Misuse" list)
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

highmem: remove unneeded #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT for debug_kmap_atomic()

In f4112de6b679d84bd9b9681c7504be7bdfb7c7d5 ("mm: introduce
debug_kmap_atomic") I said that debug_kmap_atomic() needs
CONFIG_TRACE_IRQFLAGS_SUPPORT.

It was wrong. (I thought irqs_disabled() is only available when the
architecture has CONFIG_TRACE_IRQFLAGS_SUPPORT)

Remove the #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT check to enable
kmap_atomic() debugging for the architectures which do not have
CONFIG_TRACE_IRQFLAGS_SUPPORT.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: add coherence API for DMA to vmalloc/vmap areas

On Virtually Indexed architectures (which don't do automatic alias
resolution in their caches), we have to flush via the correct
virtual address to prepare pages for DMA. On some architectures
(like arm) we cannot prevent the CPU from doing data movein along
the alias (and thus giving stale read data), so we not only have to
introduce a flush API to push dirty cache lines out, but also an invalidate
API to kill inconsistent cache lines that may have moved in before
DMA changed the data

Signed-off-by: James Bottomley <James.Bottomley@suse.de>

mm: make totalhigh_pages unsigned long

Makes it consistent with the extern declaration, used when CONFIG_HIGHMEM
is set Removes redundant casts in printout messages

Signed-off-by: Andreas Fenkart <andreas.fenkart@streamunlimited.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: check the argument of kunmap on architectures without highmem

If you're using a non-highmem architecture, passing an argument with the
wrong type to kunmap() doesn't give you a warning because the ifdef
doesn't check the type.

Using a static inline function solves the problem nicely.

Reported-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix highmem PPC build failure

Commit f4112de6b679d84bd9b9681c7504be7bdfb7c7d5 ("mm: introduce
debug_kmap_atomic") broke PPC builds with CONFIG_HIGHMEM=y:

CC init/main.o
In file included from include/linux/highmem.h:25,
from include/linux/pagemap.h:11,
from include/linux/mempolicy.h:63,
from init/main.c:53:
arch/powerpc/include/asm/highmem.h: In function 'kmap_atomic_prot':
arch/powerpc/include/asm/highmem.h:98: error: implicit declaration of function 'debug_kmap_atomic'
In file included from include/linux/pagemap.h:11,
from include/linux/mempolicy.h:63,
from init/main.c:53:
include/linux/highmem.h: At top level:
include/linux/highmem.h:196: warning: conflicting types for 'debug_kmap_atomic'
include/linux/highmem.h:196: error: static declaration of 'debug_kmap_atomic' follows non-static declaration
include/asm/highmem.h:98: error: previous implicit declaration of 'debug_kmap_atomic' was here
make[1]: *** [init/main.o] Error 1
make: *** [init] Error 2

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: introduce debug_kmap_atomic

x86 has debug_kmap_atomic_prot() which is error checking function for
kmap_atomic. It is usefull for the other architectures, although it needs
CONFIG_TRACE_IRQFLAGS_SUPPORT.

This patch exposes it to the other architectures.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Allow architectures to override copy_user_highpage()

With aliasing VIPT cache support, the ARM implementation of
clear_user_page() and copy_user_page() sets up a temporary kernel space
mapping such that we have the same cache colour as the userspace page.
This avoids having to consider any userspace aliases from this operation.

However, when highmem is enabled, kmap_atomic() have to setup mappings.
The copy_user_highpage() and clear_user_highpage() call these functions
before delegating the copies to copy_user_page() and clear_user_page().

The effect of this is that each of the *_user_highpage() functions setup
their own kmap mapping, followed by the *_user_page() functions setting
up another mapping. This is rather wasteful.

Thankfully, copy_user_highpage() can be overriden by architectures by
defining __HAVE_ARCH_COPY_USER_HIGHPAGE. However, replacement of
clear_user_highpage() is more difficult because its inline definition
is not conditional. It seems that you're expected to define
__HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and provide a replacement
__alloc_zeroed_user_highpage() implementation instead.

The allocation itself is fine, so we don't want to override that. What
we really want to do is to override clear_user_highpage() with our own
version which doesn't kmap_atomic() unnecessarily.

Other VIPT architectures (PARISC and SH) would also like to override
this function as well.

Acked-by: Hugh Dickins <hugh@veritas.com>
Acked-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

mm: fix PageUptodate data race

After running SetPageUptodate, preceeding stores to the page contents to
actually bring it uptodate may not be ordered with the store to set the
page uptodate.

Therefore, another CPU which checks PageUptodate is true, then reads the
page contents can get stale data.

Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after
PageUptodate.

Many places that test PageUptodate, do so with the page locked, and this
would be enough to ensure memory ordering in those places if
SetPageUptodate were only called while the page is locked. Unfortunately
that is not always the case for some filesystems, but it could be an idea
for the future.

Also bring the handling of anonymous page uptodateness in line with that of
file backed page management, by marking anon pages as uptodate when they
_are_ uptodate, rather than when our implementation requires that they be
marked as such. Doing allows us to get rid of the smp_wmb's in the page
copying functions, which were especially added for anonymous pages for an
analogous memory ordering problem. Both file and anonymous pages are
handled with the same barriers.

FAQ:
Q. Why not do this in flush_dcache_page?
A. Firstly, flush_dcache_page handles only one side (the smb side) of the
ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away
memory barriers in a completely unrelated function is nasty; at least in the
PageUptodate macros, they are located together with (half) the operations
involved in the ordering. Thirdly, the smp_wmb is only required when first
bringing the page uptodate, wheras flush_dcache_page should be called each time
it is written to through the kernel mapping. It is logically the wrong place to
put it.

Q. Why does this increase my text size / reduce my performance / etc.
A. Because it is adding the necessary instructions to eliminate the data-race.

Q. Can it be improved?
A. Yes, eg. if you were to create a rule that all SetPageUptodate operations
run under the page lock, we could avoid the smp_rmb places where PageUptodate
is queried under the page lock. Requires audit of all filesystems and at least
some would need reworking. That's great you're interested, I'm eagerly awaiting
your patches.

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>

Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user

Simplify page cache zeroing of segments of pages through 3 functions

zero_user_segments(page, start1, end1, start2, end2)

Zeros two segments of the page. It takes the position where to
start and end the zeroing which avoids length calculations and
makes code clearer.

zero_user_segment(page, start, end)

Same for a single segment.

zero_user(page, start, length)

Length variant for the case where we know the length.

We remove the zero_user_page macro. Issues:

1. Its a macro. Inline functions are preferable.

2. The KM_USER0 macro is only defined for HIGHMEM.

Having to treat this special case everywhere makes the
code needlessly complex. The parameter for zeroing is always
KM_USER0 except in one single case that we open code.

Avoiding KM_USER0 makes a lot of code not having to be dealing
with the special casing for HIGHMEM anymore. Dealing with
kmap is only necessary for HIGHMEM configurations. In those
configurations we use KM_USER0 like we do for a series of other
functions defined in highmem.h.

Since KM_USER0 is depends on HIGHMEM the existing zero_user_page
function could not be a macro. zero_user_* functions introduced
here can be be inline because that constant is not used when these
functions are called.

Also extract the flushing of the caches to be outside of the kmap.

[akpm@linux-foundation.org: fix nfs and ntfs build]
[akpm@linux-foundation.org: fix ntfs build some more]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove alloc_zeroed_user_highpage()

alloc_zeroed_user_highpage() has no in-tree users and it is not exported.
As it is not exported, it can simply be removed.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add __GFP_MOVABLE for callers to flag allocations from high memory that may be migrated

It is often known at allocation time whether a page may be migrated or not.
This patch adds a flag called __GFP_MOVABLE and a new mask called
GFP_HIGH_MOVABLE. Allocations using the __GFP_MOVABLE can be either migrated
using the page migration mechanism or reclaimed by syncing with backing
storage and discarding.

An API function very similar to alloc_zeroed_user_highpage() is added for
__GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable(). The
flags used by alloc_zeroed_user_highpage() are not changed because it would
change the semantics of an existing API. After this patch is applied there
are no in-kernel users of alloc_zeroed_user_highpage() so it probably should
be marked deprecated if this patch is merged.

Note that this patch includes a minor cleanup to the use of __GFP_ZERO in
shmem.c to keep all flag modifications to inode->mapping in the
shmem_dir_alloc() helper function. This clean-up suggestion is courtesy of
Hugh Dickens.

Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the
concept. Credit to Hugh Dickens for catching issues with shmem swap vector
and ramfs allocations.

[akpm@linux-foundation.org: build fix]
[hugh@veritas.com: __GFP_ZERO cleanup]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: deprecate memclear_highpage_flush

Now that all the in-tree users are converted over to zero_user_page(),
deprecate the old memclear_highpage_flush() call.

Signed-off-by: Nate Diller <nate.diller@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: convert core functions to zero_user_page

It's very common for file systems to need to zero part or all of a page,
the simplist way is just to use kmap_atomic() and memset(). There's
actually a library function in include/linux/highmem.h that does exactly
that, but it's confusingly named memclear_highpage_flush(), which is
descriptive of *how* it does the work rather than what the *purpose* is.
So this patchset renames the function to zero_user_page(), and calls it
from the various places that currently open code it.

This first patch introduces the new function call, and converts all the
core kernel callsites, both the open-coded ones and the old
memclear_highpage_flush() ones. Following this patch is a series of
conversions for each file system individually, per AKPM, and finally a
patch deprecating the old call. The diffstat below shows the entire
patchset.

[akpm@linux-foundation.org: fix a few things]
Signed-off-by: Nate Diller <nate.diller@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Convert non-highmem kmap_atomic() to static inline function

Convert kmap_atomic() in the non-highmem case from a macro to a static
inline function, for better type-checking and the ability to pass void
pointers instead of struct page pointers.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] i386: PARAVIRT: add kmap_atomic_pte for mapping highpte pages

Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space. These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.

Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.

This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings. Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.

[ Zach - vmi.c will need some attention after this patch. It wasn't
immediately obvious to me what needs to be done. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>

[ARM] pass vma for flush_anon_page()

Since get_user_pages() may be used with processes other than the
current process and calls flush_anon_page(), flush_anon_page() has to
cope in some way with non-current processes.

It may not be appropriate, or even desirable to flush a region of
virtual memory cache in the current process when that is different to
the process that we want the flush to occur for.

Therefore, pass the vma into flush_anon_page() so that the architecture
can work out whether the 'vmaddr' is for the current process or not.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

[PATCH] Pass vma argument to copy_user_highpage().

To allow a more effective copy_user_highpage() on certain architectures,
a vma argument is added to the function and cow_user_page() allowing
the implementation of these functions to check for the VM_EXEC bit.

The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Fix COW D-cache aliasing on fork

Problem:

1. There is a process containing two thread (T1 and T2). The
thread T1 calls fork(). Then dup_mmap() function called on T1 context.

static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
...
flush_cache_mm(current->mm);
... /* A */
(write-protect all Copy-On-Write pages)
... /* B */
flush_tlb_mm(current->mm);
...

2. When preemption happens between A and B (or on SMP kernel), the
thread T2 can run and modify data on COW pages without page fault
(modified data will stay in cache).

3. Some time after fork() completed, the thread T2 may cause a page
fault by write-protect on a COW page.

4. Then data of the COW page will be copied to newly allocated
physical page (copy_cow_page()). It reads data via kernel mapping.
The kernel mapping can have different 'color' with user space
mapping of the thread T2 (dcache aliasing). Therefore
copy_cow_page() will copy stale data. Then the modified data in
cache will be lost.

In order to allow architecture code to deal with this problem allow
architecture code to override copy_user_highpage() by defining
__HAVE_ARCH_COPY_USER_HIGHPAGE in <asm/page.h>.

The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] mm: k{,um}map_atomic() vs in_atomic()

Make kmap_atomic/kunmap_atomic denote a pagefault disabled scope. All non
trivial implementations already do this anyway.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] reduce MAX_NR_ZONES: move HIGHMEM counters into highmem.c/.h

Move totalhigh_pages and nr_free_highpages() into highmem.c/.h

Move the totalhigh_pages definition into highmem.c/.h. Move the
nr_free_highpages function into highmem.c

[yoichi_yuasa@tripeaks.co.jp: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] update to the kernel kmap/kunmap API

Give non-highmem architectures access to the kmap API for the purposes of
overriding (this is what the attached patch does).

The proposal is that we should now require all architectures with coherence
issues to manage data coherence via the kmap/kunmap API. Thus driver
writers never have to write code like

kmap(page)
modify data in page
flush_kernel_dcache_page(page)
kunmap(page)

instead, kmap/kunmap will manage the coherence and driver (and filesystem)
writers don't need to worry about how to flush between kmap and kunmap.

For most architectures, the page only needs to be flushed if it was
actually written to *and* there are user mappings of it, so the best
implementation looks to be: clear the page dirty pte bit in the kernel page
tables on kmap and on kunmap, check page->mappings for user maps, and then
the dirty bit, and only flush if it both has user mappings and is dirty.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Don't include linux/config.h from anywhere else in include/

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

[PATCH] Add flush_kernel_dcache_page() API

We have a problem in a lot of emulated storage in that it takes a page from
get_user_pages() and does something like

kmap_atomic(page)
modify page
kunmap_atomic(page)

However, nothing has flushed the kernel cache view of the page before the
kunmap. We need a lightweight API to do this, so this new API would
specifically be for flushing the kernel cache view of a user page which the
kernel has modified. The driver would need to add
flush_kernel_dcache_page(page) before the final kunmap.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Add API for flushing Anon pages

Currently, get_user_pages() returns fully coherent pages to the kernel for
anything other than anonymous pages. This is a problem for things like
fuse and the SCSI generic ioctl SG_IO which can potentially wish to do DMA
to anonymous pages passed in by users.

The fix is to add a new memory management API: flush_anon_page() which
is used in get_user_pages() to make anonymous pages coherent.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] kdump: Routines for copying dump pages

This patch provides the interfaces necessary to read the dump contents,
treating it as a high memory device.

Signed off by Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@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!