mm: page_alloc: use div64_ul() instead of do_div()

Fixes Coccinelle/coccicheck warning reported by do_div.cocci.

Compared to do_div(), div64_ul() does not implicitly cast the divisor and
does not unnecessarily calculate the remainder.

Link: https://lkml.kernel.org/r/20240228224911.1164-2-thorsten.blum@toblux.com
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add alloc_contig_migrate_range allocation statistics

alloc_contig_migrate_range has every information to be able to understand
big contiguous allocation latency. For example, how many pages are
migrated, how many times they were needed to unmap from page tables.

This patch adds the trace event to collect the allocation statistics. In
the field, it was quite useful to understand CMA allocation latency.

[akpm@linux-foundation.org: a/trace_mm_alloc_config_migrate_range_info_enabled/trace_mm_alloc_contig_migrate_range_info_enabled]
Link: https://lkml.kernel.org/r/20240228051127.2859472-1-richardycc@google.com
Signed-off-by: Richard Chang <richardycc@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org.
Cc: Martin Liu <liumartin@google.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove free_unref_page_list()

All callers now use free_unref_folios() so we can delete this function.

Link: https://lkml.kernel.org/r/20240227174254.710559-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: handle large folios in free_unref_folios()

Call folio_undo_large_rmappable() if needed. free_unref_page_prepare()
destroys the ability to call folio_order(), so stash the order in
folio->private for the benefit of the second loop.

Link: https://lkml.kernel.org/r/20240227174254.710559-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add free_unref_folios()

Iterate over a folio_batch rather than a linked list. This is easier for
the CPU to prefetch and has a batch count naturally built in so we don't
need to track it. Again, this lowers the maximum lock hold time from
32 folios to 15, but I do not expect this to have a significant effect.

Link: https://lkml.kernel.org/r/20240227174254.710559-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert free_unref_page_list() to use folios

Most of its callees are not yet ready to accept a folio, but we know all
of the pages passed in are actually folios because they're linked through
->lru.

Link: https://lkml.kernel.org/r/20240227174254.710559-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_owner: add support for splitting to any order in split page_owner

It adds a new_order parameter to set new page order in page owner. It
prepares for upcoming changes to support split huge page to any lower
order.

Link: https://lkml.kernel.org/r/20240226205534.1603748-7-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michal Koutny <mkoutny@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memcg: make memcg huge page split support any order split

It sets memcg information for the pages after the split. A new parameter
new_order is added to tell the order of subpages in the new page, always 0
for now. It prepares for upcoming changes to support split huge page to
any lower order.

Link: https://lkml.kernel.org/r/20240226205534.1603748-6-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michal Koutny <mkoutny@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_owner: use order instead of nr in split_page_owner()

We do not have non power of two pages, using nr is error prone if nr is
not power-of-two. Use page order instead.

Link: https://lkml.kernel.org/r/20240226205534.1603748-5-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michal Koutny <mkoutny@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcg: use order instead of nr in split_page_memcg()

We do not have non power of two pages, using nr is error prone if nr is
not power-of-two. Use page order instead.

Link: https://lkml.kernel.org/r/20240226205534.1603748-4-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michal Koutny <mkoutny@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make check_new_page() return bool

Make check_new_page() return bool like check_new_pages()

Link: https://lkml.kernel.org/r/20240222091932.54799-1-gehao@kylinos.cn
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make bad_range() return bool

bad_range() can return bool, so let us change it.

Link: https://lkml.kernel.org/r/20240221073227.276234-1-gehao@kylinos.cn
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/compaction: add support for >0 order folio memory compaction.

Before last commit, memory compaction only migrates order-0 folios and
skips >0 order folios. Last commit splits all >0 order folios during
compaction. This commit migrates >0 order folios during compaction by
keeping isolated free pages at their original size without splitting them
into order-0 pages and using them directly during migration process.

What is different from the prior implementation:
1. All isolated free pages are kept in a NR_PAGE_ORDERS array of page
lists, where each page list stores free pages in the same order.
2. All free pages are not post_alloc_hook() processed nor buddy pages,
although their orders are stored in first page's private like buddy
pages.
3. During migration, in new page allocation time (i.e., in
compaction_alloc()), free pages are then processed by post_alloc_hook().
When migration fails and a new page is returned (i.e., in
compaction_free()), free pages are restored by reversing the
post_alloc_hook() operations using newly added
free_pages_prepare_fpi_none().

Step 3 is done for a latter optimization that splitting and/or merging
free pages during compaction becomes easier.

Note: without splitting free pages, compaction can end prematurely due to
migration will return -ENOMEM even if there is free pages. This happens
when no order-0 free page exist and compaction_alloc() return NULL.

Link: https://lkml.kernel.org/r/20240220183220.1451315-4-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unused fpi_flags in free_pages_prepare()

Patch series "Enable >0 order folio memory compaction", v7.

This patchset enables >0 order folio memory compaction, which is one of
the prerequisitions for large folio support[1].

I am aware of that split free pages is necessary for folio migration in
compaction, since if >0 order free pages are never split and no order-0
free page is scanned, compaction will end prematurely due to migration
returns -ENOMEM. Free page split becomes a must instead of an
optimization.

lkp ncompare results (on a 8-CPU (Intel Xeon E5-2650 v4 @2.20GHz) 16G VM)
for default LRU (-no-mglru) and CONFIG_LRU_GEN are shown at the bottom,
copied from V3[4]. In sum, most of vm-scalability applications do not see
performance change, and the others see ~4% to ~26% performance boost under
default LRU and ~2% to ~6% performance boost under CONFIG_LRU_GEN.

Overview
===

To support >0 order folio compaction, the patchset changes how free pages
used for migration are kept during compaction. Free pages used to be
split into order-0 pages that are post allocation processed (i.e.,
PageBuddy flag cleared, page order stored in page->private is zeroed, and
page reference is set to 1). Now all free pages are kept in a
NR_PAGE_ORDER array of page lists based on their order without post
allocation process. When migrate_pages() asks for a new page, one of the
free pages, based on the requested page order, is then processed and given
out. And THP <2MB would need this feature.


[1] https://lore.kernel.org/linux-mm/f8d47176-03a8-99bf-a813-b5942830fd73@arm.com/
[2] https://lore.kernel.org/linux-mm/20231113170157.280181-1-zi.yan@sent.com/
[3] https://lore.kernel.org/linux-mm/20240123034636.1095672-1-zi.yan@sent.com/
[4] https://lore.kernel.org/linux-mm/20240202161554.565023-1-zi.yan@sent.com/
[5] https://lore.kernel.org/linux-mm/20240212163510.859822-1-zi.yan@sent.com/
[6] https://lore.kernel.org/linux-mm/20240214220420.1229173-1-zi.yan@sent.com/
[7] https://lore.kernel.org/linux-mm/20240216170432.1268753-1-zi.yan@sent.com/


This patch (of 4):

Commit 0a54864f8dfb ("kasan: remove PG_skip_kasan_poison flag") removes
the use of fpi_flags in should_skip_kasan_poison() and fpi_flags is only
passed to should_skip_kasan_poison() in free_pages_prepare(). Remove the
unused parameter.

Link: https://lkml.kernel.org/r/20240220183220.1451315-1-zi.yan@sent.com
Link: https://lkml.kernel.org/r/20240220183220.1451315-2-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm and cache_info: remove unnecessary CPU cache info update

For each CPU hotplug event, we will update per-CPU data slice size and
corresponding PCP configuration for every online CPU to make the
implementation simple. But, Kyle reported that this takes tens seconds
during boot on a machine with 34 zones and 3840 CPUs.

So, in this patch, for each CPU hotplug event, we only update per-CPU data
slice size and corresponding PCP configuration for the CPUs that share
caches with the hotplugged CPU. With the patch, the system boot time
reduces 67 seconds on the machine.

Link: https://lkml.kernel.org/r/20240126081944.414520-1-ying.huang@intel.com
Fixes: 362d37a106dd ("mm, pcp: reduce lock contention for draining high-order pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Originally-by: Kyle Meyer <kyle.meyer@hpe.com>
Reported-and-tested-by: Kyle Meyer <kyle.meyer@hpe.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

net: introduce page_frag_cache_drain()

When draining a page_frag_cache, most user are doing
the similar steps, so introduce an API to avoid code
duplication.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

page_frag: unify gfp bits for order 3 page allocation

Currently there seems to be three page frag implementations
which all try to allocate order 3 page, if that fails, it
then fail back to allocate order 0 page, and each of them
all allow order 3 page allocation to fail under certain
condition by using specific gfp bits.

The gfp bits for order 3 page allocation are different
between different implementation, __GFP_NOMEMALLOC is
or'd to forbid access to emergency reserves memory for
__page_frag_cache_refill(), but it is not or'd in other
implementions, __GFP_DIRECT_RECLAIM is masked off to avoid
direct reclaim in vhost_net_page_frag_refill(), but it is
not masked off in __page_frag_cache_refill().

This patch unifies the gfp bits used between different
implementions by or'ing __GFP_NOMEMALLOC and masking off
__GFP_DIRECT_RECLAIM for order 3 page allocation to avoid
possible pressure for mm.

Leave the gfp unifying for page frag implementation in sock.c
for now as suggested by Paolo Abeni.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
CC: Alexander Duyck <alexander.duyck@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

mm/page_alloc: modify page_frag_alloc_align() to accept align as an argument

napi_alloc_frag_align() and netdev_alloc_frag_align() accept
align as an argument, and they are thin wrappers around the
__napi_alloc_frag_align() and __netdev_alloc_frag_align() APIs
doing the alignment checking and align mask conversion, in order
to call page_frag_alloc_align() directly. The intention here is
to keep the alignment checking and the alignmask conversion in
in-line wrapper to avoid those kind of operations during execution
time since it can usually be handled during compile time.

We are going to use page_frag_alloc_align() in vhost_net.c, it
need the same kind of alignment checking and alignmask conversion,
so split up page_frag_alloc_align into an inline wrapper doing the
above operation, and add __page_frag_alloc_align() which is passed
with the align mask the original function expected as suggested by
Alexander.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
CC: Alexander Duyck <alexander.duyck@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations

Sven reports an infinite loop in __alloc_pages_slowpath() for costly order
__GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination
can happen in a suspend/resume context where a GFP_KERNEL allocation can
have __GFP_IO masked out via gfp_allowed_mask.

Quoting Sven:

1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER)
with __GFP_RETRY_MAYFAIL set.

2. page alloc's __alloc_pages_slowpath tries to get a page from the
freelist. This fails because there is nothing free of that costly
order.

3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim,
which bails out because a zone is ready to be compacted; it pretends
to have made a single page of progress.

4. page alloc tries to compact, but this always bails out early because
__GFP_IO is not set (it's not passed by the snd allocator, and even
if it were, we are suspending so the __GFP_IO flag would be cleared
anyway).

5. page alloc believes reclaim progress was made (because of the
pretense in item 3) and so it checks whether it should retry
compaction. The compaction retry logic thinks it should try again,
because:
a) reclaim is needed because of the early bail-out in item 4
b) a zonelist is suitable for compaction

6. goto 2. indefinite stall.

(end quote)

The immediate root cause is confusing the COMPACT_SKIPPED returned from
__alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be
indicating a lack of order-0 pages, and in step 5 evaluating that in
should_compact_retry() as a reason to retry, before incrementing and
limiting the number of retries. There are however other places that
wrongly assume that compaction can happen while we lack __GFP_IO.

To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO
evaluation and switch the open-coded test in try_to_compact_pages() to use
it.

Also use the new helper in:
- compaction_ready(), which will make reclaim not bail out in step 3, so
there's at least one attempt to actually reclaim, even if chances are
small for a costly order
- in_reclaim_compaction() which will make should_continue_reclaim()
return false and we don't over-reclaim unnecessarily
- in __alloc_pages_slowpath() to set a local variable can_compact,
which is then used to avoid retrying reclaim/compaction for costly
allocations (step 5) if we can't compact and also to skip the early
compaction attempt that we do in some cases

Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz
Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Sven van Ashbrook <svenva@chromium.org>
Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%2Bg@mail.gmail.com/
Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Curtis Malainey <cujomalainey@chromium.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_pool: catch page_pool memory leaks

Pages belonging to a page_pool (PP) instance must be freed through the
PP APIs in-order to correctly release any DMA mappings and release
refcnt on the DMA device when freeing PP instance. When PP release a
page (page_pool_release_page) the page->pp_magic value is cleared.

This patch detect a leaked PP page in free_page_is_bad() via
unexpected state of page->pp_magic value being PP_SIGNATURE.

We choose to report and treat it as a bad page. It would be possible
to release the page via returning it to the PP instance as the
page->pp pointer is likely still valid.

Notice this code is only activated when either compiled with
CONFIG_DEBUG_VM or boot cmdline debug_pagealloc=on, and
CONFIG_PAGE_POOL.

Reduced example output of leak with PP_SIGNATURE = dead000000000040:

BUG: Bad page state in process swapper/4 pfn:141fa6
page:000000006dbf8062 refcount:0 mapcount:0 mapping:0000000000000000 index:0x141fa6000 pfn:0x141fa6
flags: 0x2fffff80000000(node=0|zone=2|lastcpupid=0x1fffff)
page_type: 0xffffffff()
raw: 002fffff80000000 dead000000000040 ffff88814888a000 0000000000000000
raw: 0000000141fa6000 0000000000000001 00000000ffffffff 0000000000000000
page dumped because: page_pool leak
[...]
Call Trace:
<IRQ>
dump_stack_lvl+0x32/0x50
bad_page+0x70/0xf0
free_unref_page_prepare+0x263/0x430
free_unref_page+0x34/0x130
mlx5e_free_rx_mpwqe+0x190/0x1c0 [mlx5_core]
mlx5e_post_rx_mpwqes+0x1ac/0x280 [mlx5_core]
mlx5e_napi_poll+0x12b/0x710 [mlx5_core]
? skb_free_head+0x4f/0x90
__napi_poll+0x2b/0x1c0
net_rx_action+0x27b/0x360

The advantage is the Call Trace directly points to the function
leaking the PP page, which in this case is an on purpose bug
introduced into the mlx5 driver to test this code change.

Currently PP will periodically in page_pool_release_retry()
printk warning "stalled pool shutdown" which cannot be directly
corrolated to leaking and might as well be a false positive
due to SKBs being stuck on a socket for an extended period.
After this patch we should be able to remove this printk.

Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER

commit 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") has
changed the definition of MAX_ORDER to be inclusive. This has caused
issues with code that was not yet upstream and depended on the previous
definition.

To draw attention to the altered meaning of the define, rename MAX_ORDER
to MAX_PAGE_ORDER.

Link: https://lkml.kernel.org/r/20231228144704.14033-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, treewide: introduce NR_PAGE_ORDERS

NR_PAGE_ORDERS defines the number of page orders supported by the page
allocator, ranging from 0 to MAX_ORDER, MAX_ORDER + 1 in total.

NR_PAGE_ORDERS assists in defining arrays of page orders and allows for
more natural iteration over them.

[kirill.shutemov@linux.intel.com: fixup for kerneldoc warning]
Link: https://lkml.kernel.org/r/20240101111512.7empzyifq7kxtzk3@box
Link: https://lkml.kernel.org/r/20231228144704.14033-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, kasan: use KASAN_TAG_KERNEL instead of 0xff

Use the KASAN_TAG_KERNEL marco instead of open-coding 0xff in the mm code.
This macro is provided by include/linux/kasan-tags.h, which does not
include any other headers, so it's safe to include it into mm.h without
causing circular include dependencies.

Link: https://lkml.kernel.org/r/71db9087b0aebb6c4dccbc609cc0cd50621533c7.1703188911.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: page_alloc: simplify __free_pages_ok()

There is redundant code in __free_pages_ok(). Use free_one_page()
simplify it.

Link: https://lkml.kernel.org/r/20231216030503.2126130-1-yajun.deng@linux.dev
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: unreserve highatomic page blocks before oom

__alloc_pages_direct_reclaim() is called from slowpath allocation where
high atomic reserves can be unreserved after there is a progress in
reclaim and yet no suitable page is found. Later should_reclaim_retry()
gets called from slow path allocation to decide if the reclaim needs to be
retried before OOM kill path is taken.

should_reclaim_retry() checks the available(reclaimable + free pages)
memory against the min wmark levels of a zone and returns:

a) true, if it is above the min wmark so that slow path allocation will
do the reclaim retries.

b) false, thus slowpath allocation takes oom kill path.

should_reclaim_retry() can also unreserves the high atomic reserves **but
only after all the reclaim retries are exhausted.**

In a case where there are almost none reclaimable memory and free pages
contains mostly the high atomic reserves but allocation context can't use
these high atomic reserves, makes the available memory below min wmark
levels hence false is returned from should_reclaim_retry() leading the
allocation request to take OOM kill path. This can turn into a early oom
kill if high atomic reserves are holding lot of free memory and
unreserving of them is not attempted.

(early)OOM is encountered on a VM with the below state:
[ 295.998653] Normal free:7728kB boost:0kB min:804kB low:1004kB
high:1204kB reserved_highatomic:8192KB active_anon:4kB inactive_anon:0kB
active_file:24kB inactive_file:24kB unevictable:1220kB writepending:0kB
present:70732kB managed:49224kB mlocked:0kB bounce:0kB free_pcp:688kB
local_pcp:492kB free_cma:0kB
[ 295.998656] lowmem_reserve[]: 0 32
[ 295.998659] Normal: 508*4kB (UMEH) 241*8kB (UMEH) 143*16kB (UMEH)
33*32kB (UH) 7*64kB (UH) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB
0*4096kB = 7752kB

Per above log, the free memory of ~7MB exist in the high atomic reserves
is not freed up before falling back to oom kill path.

Fix it by trying to unreserve the high atomic reserves in
should_reclaim_retry() before __alloc_pages_direct_reclaim() can fallback
to oom kill path.

Link: https://lkml.kernel.org/r/1700823445-27531-1-git-send-email-quic_charante@quicinc.com
Fixes: 0aaa29a56e4f ("mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand")
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Reported-by: Chris Goldsworthy <quic_cgoldswo@quicinc.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Chris Goldsworthy <quic_cgoldswo@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: enforce minimum zone size to do high atomic reserves

Highatomic reserves are set to roughly 1% of zone for maximum and a
pageblock size for minimum. Encountered a system with the below
configuration:
Normal free:7728kB boost:0kB min:804kB low:1004kB high:1204kB
reserved_highatomic:8192KB managed:49224kB

On such systems, even a single pageblock makes highatomic reserves are set
to ~8% of the zone memory. This high value can easily exert pressure on
the zone.

Per discussion with Michal and Mel, it is not much useful to reserve the
memory for highatomic allocations on such small systems[1]. Since the
minimum size for high atomic reserves is always going to be a pageblock
size and if 1% of zone managed pages is going to be below pageblock size,
don't reserve memory for high atomic allocations. Thanks Michal for this
suggestion[2].

Since no memory is being reserved for high atomic allocations and if
respective allocation failures are seen, this patch can be reverted.

[1] https://lore.kernel.org/linux-mm/20231117161956.d3yjdxhhm4rhl7h2@techsingularity.net/
[2] https://lore.kernel.org/linux-mm/ZVYRJMUitykepLRy@tiehlicka/

Link: https://lkml.kernel.org/r/c3a2a48e2cfe08176a80eaf01c110deb9e918055.1700821416.git.quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: correct high atomic reserve calculations

Patch series "mm: page_alloc: fixes for high atomic reserve
caluculations", v3.

The state of the system where the issue exposed shown in oom kill logs:

[ 295.998653] Normal free:7728kB boost:0kB min:804kB low:1004kB high:1204kB reserved_highatomic:8192KB active_anon:4kB inactive_anon:0kB active_file:24kB inactive_file:24kB unevictable:1220kB writepending:0kB present:70732kB managed:49224kB mlocked:0kB bounce:0kB free_pcp:688kBlocal_pcp:492kB free_cma:0kB
[ 295.998656] lowmem_reserve[]: 0 32
[ 295.998659] Normal: 508*4kB (UMEH) 241*8kB (UMEH) 143*16kB (UMEH)
33*32kB (UH) 7*64kB (UH) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 7752kB

From the above, it is seen that ~16MB of memory reserved for high atomic
reserves against the expectation of 1% reserves which is fixed in the 1st
patch.

Don't reserve the high atomic page blocks if 1% of zone memory size is
below a pageblock size.


This patch (of 2):

reserve_highatomic_pageblock() aims to reserve the 1% of the managed pages
of a zone, which is used for the high order atomic allocations.

It uses the below calculation to reserve:
static void reserve_highatomic_pageblock(struct page *page, ....) {

.......
max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;

if (zone->nr_reserved_highatomic >= max_managed)
goto out;

zone->nr_reserved_highatomic += pageblock_nr_pages;
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);

out:
....
}

Since we are always appending the 1% of zone managed pages count to
pageblock_nr_pages, the minimum it is turning into 2 pageblocks as the
nr_reserved_highatomic is incremented/decremented in pageblock sizes.

Encountered a system(actually a VM running on the Linux kernel) with the
below zone configuration:
Normal free:7728kB boost:0kB min:804kB low:1004kB high:1204kB
reserved_highatomic:8192KB managed:49224kB

The existing calculations making it to reserve the 8MB(with pageblock size
of 4MB) i.e. 16% of the zone managed memory. Reserving such high amount
of memory can easily exert memory pressure in the system thus may lead
into unnecessary reclaims till unreserving of high atomic reserves.

Since high atomic reserves are managed in pageblock size granules, as
MIGRATE_HIGHATOMIC is set for such pageblock, fix the calculations for
high atomic reserves as, minimum is pageblock size , maximum is
approximately 1% of the zone managed pages.

Link: https://lkml.kernel.org/r/cover.1700821416.git.quic_charante@quicinc.com
Link: https://lkml.kernel.org/r/1660034138397b82a0a8b6ae51cbe96bd583d89e.1700821416.git.quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: dedupe some memcg uncharging logic

The duplication makes it seem like some work is required before uncharging
in the !PageHWPoison case. But it isn't, so we can simplify the code a
little.

Note the PageMemcgKmem check is redundant, but I've left it in as it
avoids an unnecessary function call.

Link: https://lkml.kernel.org/r/20231108164920.3401565-1-jackmanb@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add page_rmappable_folio() wrapper

folio_prep_large_rmappable() is being used repeatedly along with a
conversion from page to folio, a check non-NULL, a check order > 1: wrap
it all up into struct folio *page_rmappable_folio(struct page *).

Link: https://lkml.kernel.org/r/8d92c6cf-eebe-748-e29c-c8ab224c741@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun heo <tj@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: check the order of compound page even when the order is zero

For compound pages, the head sets the PG_head flag and the tail sets the
compound_head to indicate the head page. If a user allocates a compound
page and frees it with a different order, the compound page information
will not be properly initialized. To detect this problem,
compound_order(page) and the order argument are compared, but this is not
checked when the order argument is zero. That error should be checked
regardless of the order.

Link: https://lkml.kernel.org/r/20231023083217.1866451-1-hyesoo.yu@samsung.com
Signed-off-by: Hyesoo Yu <hyesoo.yu@samsung.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: skip memoryless nodes entirely

Patch series "handle memoryless nodes more appropriately", v3.

Currently, in the process of initialization or offline memory, memoryless
nodes will still be built into the fallback list of itself or other nodes.

This is not what we expected, so this patch series removes memoryless
nodes from the fallback list entirely.


This patch (of 2):

In find_next_best_node(), we skipped the memoryless nodes when building
the zonelists of other normal nodes (N_NORMAL), but did not skip the
memoryless node itself when building the zonelist. This will cause it to
be traversed at runtime.

For example, say we have node0 and node1, node0 is memoryless
node, then the fallback order of node0 and node1 as follows:

[ 0.153005] Fallback order for Node 0: 0 1
[ 0.153564] Fallback order for Node 1: 1

After this patch, we skip memoryless node0 entirely, then
the fallback order of node0 and node1 as follows:

[ 0.155236] Fallback order for Node 0: 1
[ 0.155806] Fallback order for Node 1: 1

So it becomes completely invisible, which will reduce runtime
overhead.

And in this way, we will not try to allocate pages from memoryless node0,
then the panic mentioned in [1] will also be fixed. Even though this
problem has been solved by dropping the NODE_MIN_SIZE constrain in x86
[2], it would be better to fix it in core MM as well.

[1]. https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/
[2]. https://lore.kernel.org/all/20231017062215.171670-1-rppt@kernel.org/

[zhengqi.arch@bytedance.com: update comment, per Ingo]
Link: https://lkml.kernel.org/r/7300fc00a057eefeb9a68c8ad28171c3f0ce66ce.1697799303.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/cover.1697799303.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/cover.1697711415.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/157013e978468241de4a4c05d5337a44638ecb0e.1697711415.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, pcp: reduce detecting time of consecutive high order page freeing

In current PCP auto-tuning design, if the number of pages allocated is
much more than that of pages freed on a CPU, the PCP high may become the
maximal value even if the allocating/freeing depth is small, for example,
in the sender of network workloads. If a CPU was used as sender
originally, then it is used as receiver after context switching, we need
to fill the whole PCP with maximal high before triggering PCP draining for
consecutive high order freeing. This will hurt the performance of some
network workloads.

To solve the issue, in this patch, we will track the consecutive page
freeing with a counter in stead of relying on PCP draining. So, we can
detect consecutive page freeing much earlier.

On a 2-socket Intel server with 128 logical CPU, we tested
SCTP_STREAM_MANY test case of netperf test suite with 64-pair processes.
With the patch, the network bandwidth improves 5.0%. This restores the
performance drop caused by PCP auto-tuning.

Link: https://lkml.kernel.org/r/20231016053002.756205-10-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, pcp: decrease PCP high if free pages < high watermark

One target of PCP is to minimize pages in PCP if the system free pages is
too few. To reach that target, when page reclaiming is active for the
zone (ZONE_RECLAIM_ACTIVE), we will stop increasing PCP high in allocating
path, decrease PCP high and free some pages in freeing path. But this may
be too late because the background page reclaiming may introduce latency
for some workloads. So, in this patch, during page allocation we will
detect whether the number of free pages of the zone is below high
watermark. If so, we will stop increasing PCP high in allocating path,
decrease PCP high and free some pages in freeing path. With this, we can
reduce the possibility of the premature background page reclaiming caused
by too large PCP.

The high watermark checking is done in allocating path to reduce the
overhead in hotter freeing path.

Link: https://lkml.kernel.org/r/20231016053002.756205-9-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: tune PCP high automatically

The target to tune PCP high automatically is as follows,

- Minimize allocation/freeing from/to shared zone

- Minimize idle pages in PCP

- Minimize pages in PCP if the system free pages is too few

To reach these target, a tuning algorithm as follows is designed,

- When we refill PCP via allocating from the zone, increase PCP high.
Because if we had larger PCP, we could avoid to allocate from the
zone.

- In periodic vmstat updating kworker (via refresh_cpu_vm_stats()),
decrease PCP high to try to free possible idle PCP pages.

- When page reclaiming is active for the zone, stop increasing PCP
high in allocating path, decrease PCP high and free some pages in
freeing path.

So, the PCP high can be tuned to the page allocating/freeing depth of
workloads eventually.

One issue of the algorithm is that if the number of pages allocated is
much more than that of pages freed on a CPU, the PCP high may become the
maximal value even if the allocating/freeing depth is small. But this
isn't a severe issue, because there are no idle pages in this case.

One alternative choice is to increase PCP high when we drain PCP via
trying to free pages to the zone, but don't increase PCP high during PCP
refilling. This can avoid the issue above. But if the number of pages
allocated is much less than that of pages freed on a CPU, there will be
many idle pages in PCP and it is hard to free these idle pages.

1/8 (>> 3) of PCP high will be decreased periodically. The value 1/8 is
kind of arbitrary. Just to make sure that the idle PCP pages will be
freed eventually.

On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild instances
in parallel (each with `make -j 28`) in 8 cgroup. This simulates the
kbuild server that is used by 0-Day kbuild service. With the patch, the
build time decreases 3.5%. The cycles% of the spinlock contention (mostly
for zone lock) decreases from 11.0% to 0.5%. The number of PCP draining
for high order pages freeing (free_high) decreases 65.6%. The number of
pages allocated from zone (instead of from PCP) decreases 83.9%.

Link: https://lkml.kernel.org/r/20231016053002.756205-8-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Suggested-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add framework for PCP high auto-tuning

The page allocation performance requirements of different workloads are
usually different. So, we need to tune PCP (per-CPU pageset) high to
optimize the workload page allocation performance. Now, we have a system
wide sysctl knob (percpu_pagelist_high_fraction) to tune PCP high by hand.
But, it's hard to find out the best value by hand. And one global
configuration may not work best for the different workloads that run on
the same system. One solution to these issues is to tune PCP high of each
CPU automatically.

This patch adds the framework for PCP high auto-tuning. With it,
pcp->high of each CPU will be changed automatically by tuning algorithm at
runtime. The minimal high (pcp->high_min) is the original PCP high value
calculated based on the low watermark pages. While the maximal high
(pcp->high_max) is the PCP high value when percpu_pagelist_high_fraction
sysctl knob is set to MIN_PERCPU_PAGELIST_HIGH_FRACTION. That is, the
maximal pcp->high that can be set via sysctl knob by hand.

It's possible that PCP high auto-tuning doesn't work well for some
workloads. So, when PCP high is tuned by hand via the sysctl knob, the
auto-tuning will be disabled. The PCP high set by hand will be used
instead.

This patch only adds the framework, so pcp->high will be set to
pcp->high_min (original default) always. We will add actual auto-tuning
algorithm in the following patches in the series.

Link: https://lkml.kernel.org/r/20231016053002.756205-7-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, page_alloc: scale the number of pages that are batch allocated

When a task is allocating a large number of order-0 pages, it may acquire
the zone->lock multiple times allocating pages in batches. This may
unnecessarily contend on the zone lock when allocating very large number
of pages. This patch adapts the size of the batch based on the recent
pattern to scale the batch size for subsequent allocations.

On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild instances
in parallel (each with `make -j 28`) in 8 cgroup. This simulates the
kbuild server that is used by 0-Day kbuild service. With the patch, the
cycles% of the spinlock contention (mostly for zone lock) decreases from
12.6% to 11.0% (with PCP size == 367).

Link: https://lkml.kernel.org/r/20231016053002.756205-6-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: restrict the pcp batch scale factor to avoid too long latency

In page allocator, PCP (Per-CPU Pageset) is refilled and drained in
batches to increase page allocation throughput, reduce page
allocation/freeing latency per page, and reduce zone lock contention. But
too large batch size will cause too long maximal allocation/freeing
latency, which may punish arbitrary users. So the default batch size is
chosen carefully (in zone_batchsize(), the value is 63 for zone > 1GB) to
avoid that.

In commit 3b12e7e97938 ("mm/page_alloc: scale the number of pages that are
batch freed"), the batch size will be scaled for large number of page
freeing to improve page freeing performance and reduce zone lock
contention. Similar optimization can be used for large number of pages
allocation too.

To find out a suitable max batch scale factor (that is, max effective
batch size), some tests and measurement on some machines were done as
follows.

A set of debug patches are implemented as follows,

- Set PCP high to be 2 * batch to reduce the effect of PCP high

- Disable free batch size scaling to get the raw performance.

- The code with zone lock held is extracted from rmqueue_bulk() and
free_pcppages_bulk() to 2 separate functions to make it easy to
measure the function run time with ftrace function_graph tracer.

- The batch size is hard coded to be 63 (default), 127, 255, 511,
1023, 2047, 4095.

Then will-it-scale/page_fault1 is used to generate the page
allocation/freeing workload. The page allocation/freeing throughput
(page/s) is measured via will-it-scale. The page allocation/freeing
average latency (alloc/free latency avg, in us) and allocation/freeing
latency at 99 percentile (alloc/free latency 99%, in us) are measured with
ftrace function_graph tracer.

The test results are as follows,

Sapphire Rapids Server
======================
Batch throughput free latency free latency alloc latency alloc latency
page/s avg / us 99% / us avg / us 99% / us
----- ---------- ------------ ------------ ------------- -------------
63 513633.4 2.33 3.57 2.67 6.83
127 517616.7 4.35 6.65 4.22 13.03
255 520822.8 8.29 13.32 7.52 25.24
511 524122.0 15.79 23.42 14.02 49.35
1023 525980.5 30.25 44.19 25.36 94.88
2047 526793.6 59.39 84.50 45.22 140.81

Ice Lake Server
===============
Batch throughput free latency free latency alloc latency alloc latency
page/s avg / us 99% / us avg / us 99% / us
----- ---------- ------------ ------------ ------------- -------------
63 620210.3 2.21 3.68 2.02 4.35
127 627003.0 4.09 6.86 3.51 8.28
255 630777.5 7.70 13.50 6.17 15.97
511 633651.5 14.85 22.62 11.66 31.08
1023 637071.1 28.55 42.02 20.81 54.36
2047 638089.7 56.54 84.06 39.28 91.68

Cascade Lake Server
===================
Batch throughput free latency free latency alloc latency alloc latency
page/s avg / us 99% / us avg / us 99% / us
----- ---------- ------------ ------------ ------------- -------------
63 404706.7 3.29 5.03 3.53 4.75
127 422475.2 6.12 9.09 6.36 8.76
255 411522.2 11.68 16.97 10.90 16.39
511 428124.1 22.54 31.28 19.86 32.25
1023 414718.4 43.39 62.52 40.00 66.33
2047 429848.7 86.64 120.34 71.14 106.08

Commet Lake Desktop
===================
Batch throughput free latency free latency alloc latency alloc latency
page/s avg / us 99% / us avg / us 99% / us
----- ---------- ------------ ------------ ------------- -------------

63 795183.13 2.18 3.55 2.03 3.05
127 803067.85 3.91 6.56 3.85 5.52
255 812771.10 7.35 10.80 7.14 10.20
511 817723.48 14.17 27.54 13.43 30.31
1023 818870.19 27.72 40.10 27.89 46.28

Coffee Lake Desktop
===================
Batch throughput free latency free latency alloc latency alloc latency
page/s avg / us 99% / us avg / us 99% / us
----- ---------- ------------ ------------ ------------- -------------
63 510542.8 3.13 4.40 2.48 3.43
127 514288.6 5.97 7.89 4.65 6.04
255 516889.7 11.86 15.58 8.96 12.55
511 519802.4 23.10 28.81 16.95 26.19
1023 520802.7 45.30 52.51 33.19 45.95
2047 519997.1 90.63 104.00 65.26 81.74

From the above data, to restrict the allocation/freeing latency to be less
than 100 us in most times, the max batch scale factor needs to be less
than or equal to 5.

Although it is reasonable to use 5 as max batch scale factor for the
systems tested, there are also slower systems. Where smaller value should
be used to constrain the page allocation/freeing latency.

So, in this patch, a new kconfig option (PCP_BATCH_SCALE_MAX) is added to
set the max batch scale factor. Whose default value is 5, and users can
reduce it when necessary.

Link: https://lkml.kernel.org/r/20231016053002.756205-5-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, pcp: reduce lock contention for draining high-order pages

In commit f26b3fa04611 ("mm/page_alloc: limit number of high-order pages
on PCP during bulk free"), the PCP (Per-CPU Pageset) will be drained when
PCP is mostly used for high-order pages freeing to improve the cache-hot
pages reusing between page allocating and freeing CPUs.

On system with small per-CPU data cache slice, pages shouldn't be cached
before draining to guarantee cache-hot. But on a system with large
per-CPU data cache slice, some pages can be cached before draining to
reduce zone lock contention.

So, in this patch, instead of draining without any caching, "pcp->batch"
pages will be cached in PCP before draining if the size of the per-CPU
data cache slice is more than "3 * batch".

In theory, if the size of per-CPU data cache slice is more than "2 *
batch", we can reuse cache-hot pages between CPUs. But considering the
other usage of cache (code, other data accessing, etc.), "3 * batch" is
used.

Note: "3 * batch" is chosen to make sure the optimization works on recent
x86_64 server CPUs. If you want to increase it, please check whether it
breaks the optimization.

On a 2-socket Intel server with 128 logical CPU, with the patch, the
network bandwidth of the UNIX (AF_UNIX) test case of lmbench test suite
with 16-pair processes increase 70.5%. The cycles% of the spinlock
contention (mostly for zone lock) decreases from 46.1% to 21.3%. The
number of PCP draining for high order pages freeing (free_high) decreases
89.9%. The cache miss rate keeps 0.2%.

Link: https://lkml.kernel.org/r/20231016053002.756205-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, pcp: avoid to drain PCP when process exit

Patch series "mm: PCP high auto-tuning", v3.

The page allocation performance requirements of different workloads are
often different. So, we need to tune the PCP (Per-CPU Pageset) high on
each CPU automatically to optimize the page allocation performance.

The list of patches in series is as follows,

[1/9] mm, pcp: avoid to drain PCP when process exit
[2/9] cacheinfo: calculate per-CPU data cache size
[3/9] mm, pcp: reduce lock contention for draining high-order pages
[4/9] mm: restrict the pcp batch scale factor to avoid too long latency
[5/9] mm, page_alloc: scale the number of pages that are batch allocated
[6/9] mm: add framework for PCP high auto-tuning
[7/9] mm: tune PCP high automatically
[8/9] mm, pcp: decrease PCP high if free pages < high watermark
[9/9] mm, pcp: reduce detecting time of consecutive high order page freeing

Patch [1/9], [2/9], [3/9] optimize the PCP draining for consecutive
high-order pages freeing.

Patch [4/9], [5/9] optimize batch freeing and allocating.

Patch [6/9], [7/9], [8/9] implement and optimize a PCP high
auto-tuning method.

Patch [9/9] optimize the PCP draining for consecutive high order page
freeing based on PCP high auto-tuning.

The test results for patches with performance impact are as follows,

kbuild
======

On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild instances
in parallel (each with `make -j 28`) in 8 cgroup. This simulates the
kbuild server that is used by 0-Day kbuild service.

build time lock contend% free_high alloc_zone
---------- ---------- --------- ----------
base 100.0 14.0 100.0 100.0
patch1 99.5 12.8 19.5 95.6
patch3 99.4 12.6 7.1 95.6
patch5 98.6 11.0 8.1 97.1
patch7 95.1 0.5 2.8 15.6
patch9 95.0 1.0 8.8 20.0

The PCP draining optimization (patch [1/9], [3/9]) and PCP batch
allocation optimization (patch [5/9]) reduces zone lock contention a
little. The PCP high auto-tuning (patch [7/9], [9/9]) reduces build time
visibly. Where the tuning target: the number of pages allocated from zone
reduces greatly. So, the zone contention cycles% reduces greatly.

With PCP tuning patches (patch [7/9], [9/9]), the average used memory
during test increases up to 18.4% because more pages are cached in PCP.
But at the end of the test, the number of the used memory decreases to the
same level as that of the base patch. That is, the pages cached in PCP
will be released to zone after not being used actively.

netperf SCTP_STREAM_MANY
========================

On a 2-socket Intel server with 128 logical CPU, we tested
SCTP_STREAM_MANY test case of netperf test suite with 64-pair processes.

score lock contend% free_high alloc_zone cache miss rate%
----- ---------- --------- ---------- ----------------
base 100.0 2.1 100.0 100.0 1.3
patch1 99.4 2.1 99.4 99.4 1.3
patch3 106.4 1.3 13.3 106.3 1.3
patch5 106.0 1.2 13.2 105.9 1.3
patch7 103.4 1.9 6.7 90.3 7.6
patch9 108.6 1.3 13.7 108.6 1.3

The PCP draining optimization (patch [1/9]+[3/9]) improves performance.
The PCP high auto-tuning (patch [7/9]) reduces performance a little
because PCP draining cannot be triggered in time sometimes. So, the cache
miss rate% increases. The further PCP draining optimization (patch [9/9])
based on PCP tuning restore the performance.

lmbench3 UNIX (AF_UNIX)
=======================

On a 2-socket Intel server with 128 logical CPU, we tested UNIX
(AF_UNIX socket) test case of lmbench3 test suite with 16-pair
processes.

score lock contend% free_high alloc_zone cache miss rate%
----- ---------- --------- ---------- ----------------
base 100.0 51.4 100.0 100.0 0.2
patch1 116.8 46.1 69.5 104.3 0.2
patch3 199.1 21.3 7.0 104.9 0.2
patch5 200.0 20.8 7.1 106.9 0.3
patch7 191.6 19.9 6.8 103.8 2.8
patch9 193.4 21.7 7.0 104.7 2.1

The PCP draining optimization (patch [1/9], [3/9]) improves performance
much. The PCP tuning (patch [7/9]) reduces performance a little because
PCP draining cannot be triggered in time sometimes. The further PCP
draining optimization (patch [9/9]) based on PCP tuning restores the
performance partly.

The patchset adds several fields in struct per_cpu_pages. The struct
layout before/after the patchset is as follows,

base
====

struct per_cpu_pages {
spinlock_t lock; /* 0 4 */
int count; /* 4 4 */
int high; /* 8 4 */
int batch; /* 12 4 */
short int free_factor; /* 16 2 */
short int expire; /* 18 2 */

/* XXX 4 bytes hole, try to pack */

struct list_head lists[13]; /* 24 208 */

/* size: 256, cachelines: 4, members: 7 */
/* sum members: 228, holes: 1, sum holes: 4 */
/* padding: 24 */
} __attribute__((__aligned__(64)));

patched
=======

struct per_cpu_pages {
spinlock_t lock; /* 0 4 */
int count; /* 4 4 */
int high; /* 8 4 */
int high_min; /* 12 4 */
int high_max; /* 16 4 */
int batch; /* 20 4 */
u8 flags; /* 24 1 */
u8 alloc_factor; /* 25 1 */
u8 expire; /* 26 1 */

/* XXX 1 byte hole, try to pack */

short int free_count; /* 28 2 */

/* XXX 2 bytes hole, try to pack */

struct list_head lists[13]; /* 32 208 */

/* size: 256, cachelines: 4, members: 11 */
/* sum members: 237, holes: 2, sum holes: 3 */
/* padding: 16 */
} __attribute__((__aligned__(64)));

The size of the struct doesn't changed with the patchset.


This patch (of 9):

In commit f26b3fa04611 ("mm/page_alloc: limit number of high-order pages
on PCP during bulk free"), the PCP (Per-CPU Pageset) will be drained when
PCP is mostly used for high-order pages freeing to improve the cache-hot
pages reusing between page allocation and freeing CPUs.

But, the PCP draining mechanism may be triggered unexpectedly when process
exits. With some customized trace point, it was found that PCP draining
(free_high == true) was triggered with the order-1 page freeing with the
following call stack,

=> free_unref_page_commit
=> free_unref_page
=> __mmdrop
=> exit_mm
=> do_exit
=> do_group_exit
=> __x64_sys_exit_group
=> do_syscall_64

Checking the source code, this is the page table PGD freeing
(mm_free_pgd()). It's a order-1 page freeing if
CONFIG_PAGE_TABLE_ISOLATION=y. Which is a common configuration for
security.

Just before that, page freeing with the following call stack was found,

=> free_unref_page_commit
=> free_unref_page_list
=> release_pages
=> tlb_batch_pages_flush
=> tlb_finish_mmu
=> exit_mmap
=> __mmput
=> exit_mm
=> do_exit
=> do_group_exit
=> __x64_sys_exit_group
=> do_syscall_64

So, when a process exits,

- a large number of user pages of the process will be freed without
page allocation, it's highly possible that pcp->free_factor becomes >
0. In fact, this is expected behavior to improve process exit
performance.

- after freeing all user pages, the PGD will be freed, which is a
order-1 page freeing, PCP will be drained.

All in all, when a process exits, it's high possible that the PCP will be
drained. This is an unexpected behavior.

To avoid this, in the patch, the PCP draining will only be triggered for 2
consecutive high-order page freeing.

On a 2-socket Intel server with 224 logical CPU, we run 8 kbuild instances
in parallel (each with `make -j 28`) in 8 cgroup. This simulates the
kbuild server that is used by 0-Day kbuild service. With the patch, the
cycles% of the spinlock contention (mostly for zone lock) decreases from
14.0% to 12.8% (with PCP size == 367). The number of PCP draining for
high order pages freeing (free_high) decreases 80.5%.

This helps network workload too for reduced zone lock contention. On a
2-socket Intel server with 128 logical CPU, with the patch, the network
bandwidth of the UNIX (AF_UNIX) test case of lmbench test suite with
16-pair processes increase 16.8%. The cycles% of the spinlock contention
(mostly for zone lock) decreases from 51.4% to 46.1%. The number of PCP
draining for high order pages freeing (free_high) decreases 30.5%. The
cache miss rate keeps 0.2%.

Link: https://lkml.kernel.org/r/20231016053002.756205-1-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20231016053002.756205-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unnecessary next_page in break_down_buddy_pages

The next_page is only used to forward page in case target is in second
half range. Move forward page directly to remove unnecessary next_page.

Link: https://lkml.kernel.org/r/20230927103514.98281-3-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unnecessary check in break_down_buddy_pages

Patch series "Two minor cleanups to break_down_buddy_pages", v2.

Two minor cleanups to break_down_buddy_pages.


This patch (of 2):

1. We always have target in range started with next_page and full free
range started with current_buddy.

2. The last split range size is 1 << low and low should be >= 0, then
size >= 1. So page + size != page is always true (because size > 0).
As summary, current_page will not equal to target page.

Link: https://lkml.kernel.org/r/20230927103514.98281-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230927103514.98281-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: correct start page when guard page debug is enabled

When guard page debug is enabled and set_page_guard returns success, we
miss to forward page to point to start of next split range and we will do
split unexpectedly in page range without target page. Move start page
update before set_page_guard to fix this.

As we split to wrong target page, then splited pages are not able to merge
back to original order when target page is put back and splited pages
except target page is not usable. To be specific:

Consider target page is the third page in buddy page with order 2.
| buddy-2 | Page | Target | Page |

After break down to target page, we will only set first page to Guard
because of bug.
| Guard | Page | Target | Page |

When we try put_page_back_buddy with target page, the buddy page of target
if neither guard nor buddy, Then it's not able to construct original page
with order 2
| Guard | Page | buddy-0 | Page |

All pages except target page is not in free list and is not usable.

Link: https://lkml.kernel.org/r/20230927094401.68205-1-shikemeng@huaweicloud.com
Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: fix CMA and HIGHATOMIC landing on the wrong buddy list

Commit 4b23a68f9536 ("mm/page_alloc: protect PCP lists with a spinlock")
bypasses the pcplist on lock contention and returns the page directly to
the buddy list of the page's migratetype.

For pages that don't have their own pcplist, such as CMA and HIGHATOMIC,
the migratetype is temporarily updated such that the page can hitch a ride
on the MOVABLE pcplist. Their true type is later reassessed when flushing
in free_pcppages_bulk(). However, when lock contention is detected after
the type was already overridden, the bypass will then put the page on the
wrong buddy list.

Once on the MOVABLE buddy list, the page becomes eligible for fallbacks
and even stealing. In the case of HIGHATOMIC, otherwise ineligible
allocations can dip into the highatomic reserves. In the case of CMA, the
page can be lost from the CMA region permanently.

Use a separate pcpmigratetype variable for the pcplist override. Use the
original migratetype when going directly to the buddy. This fixes the bug
and should make the intentions more obvious in the code.

Originally sent here to address the HIGHATOMIC case:
https://lore.kernel.org/lkml/20230821183733.106619-4-hannes@cmpxchg.org/

Changelog updated in response to the CMA-specific bug report.

[mgorman@techsingularity.net: updated changelog]
Link: https://lkml.kernel.org/r/20230911181108.GA104295@cmpxchg.org
Fixes: 4b23a68f9536 ("mm/page_alloc: protect PCP lists with a spinlock")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Joe Liu <joe.liu@mediatek.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: remove stale CMA guard code

In the past, movable allocations could be disallowed from CMA through
PF_MEMALLOC_PIN. As CMA pages are funneled through the MOVABLE pcplist,
this required filtering that cornercase during allocations, such that
pinnable allocations wouldn't accidentally get a CMA page.

However, since 8e3560d963d2 ("mm: honor PF_MEMALLOC_PIN for all movable
pages"), PF_MEMALLOC_PIN automatically excludes __GFP_MOVABLE. Once
again, MOVABLE implies CMA is allowed.

Remove the stale filtering code. Also remove a stale comment that was
introduced as part of the filtering code, because the filtering let
order-0 pages fall through to the buddy allocator. See 1d91df85f399
("mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore}
APIs") for context. The comment's been obsolete since the introduction of
the explicit ALLOC_HIGHATOMIC flag in eb2e2b425c69 ("mm/page_alloc:
explicitly record high-order atomic allocations in alloc_flags").

Link: https://lkml.kernel.org/r/20230824153821.243148-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add large_rmappable page flag

Stored in the first tail page's flags, this flag replaces the destructor.
That removes the last of the destructors, so remove all references to
folio_dtor and compound_dtor.

Link: https://lkml.kernel.org/r/20230816151201.3655946-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove HUGETLB_PAGE_DTOR

We can use a bit in page[1].flags to indicate that this folio belongs to
hugetlb instead of using a value in page[1].dtors. That lets
folio_test_hugetlb() become an inline function like it should be. We can
also get rid of NULL_COMPOUND_DTOR.

Link: https://lkml.kernel.org/r/20230816151201.3655946-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove free_compound_page() and the compound_page_dtors array

The only remaining destructor is free_compound_page(). Inline it into
destroy_large_folio() and remove the array it used to live in.

Link: https://lkml.kernel.org/r/20230816151201.3655946-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert prep_transhuge_page() to folio_prep_large_rmappable()

Match folio_undo_large_rmappable(), and move the casting from page to
folio into the callers (which they were largely doing anyway).

Link: https://lkml.kernel.org/r/20230816151201.3655946-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert free_transhuge_folio() to folio_undo_large_rmappable()

Indirect calls are expensive, thanks to Spectre. Test for
TRANSHUGE_PAGE_DTOR and destroy the folio appropriately. Move the
free_compound_page() call into destroy_large_folio() to simplify later
patches.

Link: https://lkml.kernel.org/r/20230816151201.3655946-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert free_huge_page() to free_huge_folio()

Pass a folio instead of the head page to save a few instructions. Update
the documentation, at least in English.

Link: https://lkml.kernel.org/r/20230816151201.3655946-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: call free_huge_page() directly

Indirect calls are expensive, thanks to Spectre. Call free_huge_page()
directly if the folio belongs to hugetlb.

Link: https://lkml.kernel.org/r/20230816151201.3655946-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use get_pfnblock_migratetype to avoid extra page_to_pfn

We have get_pageblock_migratetype and get_pfnblock_migratetype to get
migratetype of page. get_pfnblock_migratetype accepts both page and pfn
from caller while get_pageblock_migratetype only accept page and get pfn
with page_to_pfn from page.

In case we already record pfn of page, we can simply call
get_pfnblock_migratetype to avoid a page_to_pfn.

Link: https://lkml.kernel.org/r/20230811115945.3423894-3-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unnecessary inner __get_pfnblock_flags_mask

Patch series "Two minor cleanups for get pageblock migratetype".

This series contains two minor cleanups for get pageblock migratetype.
More details can be found in respective patches.


This patch (of 2):

get_pfnblock_flags_mask() just calls inline inner
__get_pfnblock_flags_mask without any extra work. Just opencode
__get_pfnblock_flags_mask in get_pfnblock_flags_mask and replace call to
__get_pfnblock_flags_mask with call to get_pfnblock_flags_mask to remove
unnecessary __get_pfnblock_flags_mask.

Link: https://lkml.kernel.org/r/20230811115945.3423894-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230811115945.3423894-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: remove unused parameter from reserve_highatomic_pageblock()

Just remove the redundant parameter alloc_order from
reserve_highatomic_pageblock(). No functional modification involved.

Link: https://lkml.kernel.org/r/20230809073323.1065286-1-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unnecessary parameter batch of nr_pcp_free

We get batch from pcp and just pass it to nr_pcp_free immediately. Get
batch from pcp inside nr_pcp_free to remove unnecessary parameter batch.

Link: https://lkml.kernel.org/r/20230809100754.3094517-3-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove track of active PCP lists range in bulk free

Patch series "Two minor cleanups for pcp list in page_alloc".

There are two minor cleanups for pcp list in page_alloc. More details
can be found in respective patches.


This patch (of 2):

After commit fd56eef258a17 ("mm/page_alloc: simplify how many pages are
selected per pcp list during bulk free"), we will drain all pages in
selected pcp list. And we ensured passed count is < pcp->count. Then,
the search will finish before wrap-around and track of active PCP lists
range intended for wrap-around case is no longer needed.

Link: https://lkml.kernel.org/r/20230809100754.3094517-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230809100754.3094517-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove unneeded variable base

Since commit 5d0a661d808f ("mm/page_alloc: use only one PCP list for
THP-sized allocations"), local variable base is just as same as order. So
remove it. No functional change intended.

Link: https://lkml.kernel.org/r/20230803114934.693989-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: avoid unneeded alike_pages calculation

When free_pages is 0, alike_pages is not used. So alike_pages calculation
can be avoided by checking free_pages early to save cpu cycles. Also fix
typo 'comparable'. It should be 'compatible' here.

Link: https://lkml.kernel.org/r/20230801123723.2225543-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: avoid false page outside zone error info

If pfn is outside zone boundaries in the first round, ret will be set to
1. But if pfn is changed to inside the zone boundaries in zone span
seqretry path, ret is still set to 1 leading to false page outside zone
error info.

This is from code inspection. The race window should be really small thus
hard to trigger in real world.

[akpm@linux-foundation.org: code simplification, per Matthew]
Link: https://lkml.kernel.org/r/20230704111823.940331-1-linmiaohe@huawei.com
Fixes: bdc8cb984576 ("[PATCH] memory hotplug locking: zone span seqlock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use write_seqlock_irqsave() instead write_seqlock() + local_irq_save().

__build_all_zonelists() acquires zonelist_update_seq by first disabling
interrupts via local_irq_save() and then acquiring the seqlock with
write_seqlock(). This is troublesome and leads to problems on PREEMPT_RT.
The problem is that the inner spinlock_t becomes a sleeping lock on
PREEMPT_RT and must not be acquired with disabled interrupts.

The API provides write_seqlock_irqsave() which does the right thing in one
step. printk_deferred_enter() has to be invoked in non-migrate-able
context to ensure that deferred printing is enabled and disabled on the
same CPU. This is the case after zonelist_update_seq has been acquired.

There was discussion on the first submission that the order should be:
local_irq_disable();
printk_deferred_enter();
write_seqlock();

to avoid pitfalls like having an unaccounted printk() coming from
write_seqlock_irqsave() before printk_deferred_enter() is invoked. The
only origin of such a printk() can be a lockdep splat because the lockdep
annotation happens after the sequence count is incremented. This is
exceptional and subject to change.

It was also pointed that PREEMPT_RT can be affected by the printk problem
since its write_seqlock_irqsave() does not really disable interrupts.
This isn't the case because PREEMPT_RT's printk implementation differs
from the mainline implementation in two important aspects:

- Printing happens in a dedicated threads and not at during the
invocation of printk().
- In emergency cases where synchronous printing is used, a different
driver is used which does not use tty_port::lock.

Acquire zonelist_update_seq with write_seqlock_irqsave() and then defer
printk output.

Link: https://lkml.kernel.org/r/20230623201517.yw286Knb@linutronix.de
Fixes: 1007843a91909 ("mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix min_free_kbytes calculation regarding ZONE_MOVABLE

The current calculation of min_free_kbytes only uses ZONE_DMA and
ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN] will
also divide part of min_free_kbytes.This will cause the min watermark of
ZONE_NORMAL to be too small in the presence of ZONE_MOVEABLE.

__GFP_HIGH and PF_MEMALLOC allocations usually don't need movable zone
pages, so just like ZONE_HIGHMEM, cap pages_min to a small value in
__setup_per_zone_wmarks().

On my testing machine with 16GB of memory (transparent hugepage is turned
off by default, and movablecore=12G is configured) The following is a
comparative test data of watermark_min

no patch add patch
ZONE_DMA 1 8
ZONE_DMA32 151 709
ZONE_NORMAL 233 1113
ZONE_MOVABLE 1434 128
min_free_kbytes 7288 7326

Link: https://lkml.kernel.org/r/20230625031656.23941-1-liuq131@chinatelecom.cn
Signed-off-by: liuq <liuq131@chinatelecom.cn>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: use the correct type of list for free pages

Commit bf75f200569d ("mm/page_alloc: add page->buddy_list and
page->pcp_list") introduces page->buddy_list and page->pcp_list as a union
with page->lru, but missed to change get_page_from_free_area() to use
page->buddy_list to clarify the correct type of list for a free page.

Link: https://lkml.kernel.org/r/7e7ab533247d40c0ea0373c18a6a48e5667f9e10.1687333557.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: make compound_page_dtors static

It's only used inside page_alloc.c now. So make it static and remove the
declaration in mm.h.

Link: https://lkml.kernel.org/r/20230617034622.1235913-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: remove unneeded header files

Remove some unneeded header files. No functional change intended.

Link: https://lkml.kernel.org/r/20230603112558.213694-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: don't wake kswapd from rmqueue() unless __GFP_KSWAPD_RECLAIM is specified

Commit 73444bc4d8f9 ("mm, page_alloc: do not wake kswapd with zone lock
held") moved wakeup_kswapd() from steal_suitable_fallback() to rmqueue()
using ZONE_BOOSTED_WATERMARK flag.

Only allocation contexts that include ALLOC_KSWAPD (which corresponds to
__GFP_KSWAPD_RECLAIM) should wake kswapd, for callers are supposed to
remove __GFP_KSWAPD_RECLAIM if trying to hold pgdat->kswapd_wait has a
risk of deadlock. But since zone->flags is a shared variable, a thread
doing !__GFP_KSWAPD_RECLAIM allocation request might observe this flag
being set immediately after another thread doing __GFP_KSWAPD_RECLAIM
allocation request set this flag, causing possibility of deadlock.

Link: https://lkml.kernel.org/r/c3c3dacf-dd3b-77c9-f96a-d0982b4b2a4f@I-love.SAKURA.ne.jp
Fixes: 73444bc4d8f9 ("mm, page_alloc: do not wake kswapd with zone lock held")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: compaction: simplify should_compact_retry()

The different branches for retry are unnecessarily complicated. There are
really only three outcomes: progress (retry n times), skipped (retry if
reclaim can help), failed (retry with higher priority).

Rearrange the branches and the retry counter to make it simpler.

[hannes@cmpxchg.org: restore behavior when hitting max_retries]
Link: https://lkml.kernel.org/r/20230602144705.GB161817@cmpxchg.org
Link: https://lkml.kernel.org/r/20230519123959.77335-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: compaction: remove compaction result helpers

Patch series "mm: compaction: cleanups & simplifications".

These compaction cleanups are split out from the huge page allocator
series[1], as requested by reviewer feedback.

[1] https://lore.kernel.org/linux-mm/20230418191313.268131-1-hannes@cmpxchg.org/


This patch (of 5):

The compaction result helpers encode quirks that are specific to the
allocator's retry logic. E.g. COMPACT_SUCCESS and COMPACT_COMPLETE
actually represent failures that should be retried upon, and so on. I
frequently found myself pulling up the helper implementation in order to
understand and work on the retry logic. They're not quite clean
abstractions; rather they split the retry logic into two locations.

Remove the helpers and inline the checks. Then comment on the result
interpretations directly where the decision making happens.

Link: https://lkml.kernel.org/r/20230519123959.77335-1-hannes@cmpxchg.org
Link: https://lkml.kernel.org/r/20230519123959.77335-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: set sysctl_lowmem_reserve_ratio storage-class-specifier to static

smatch reports
mm/page_alloc.c:247:5: warning: symbol
'sysctl_lowmem_reserve_ratio' was not declared. Should it be static?

This variable is only used in its defining file, so it should be static

Link: https://lkml.kernel.org/r/20230518141119.927074-1-trix@redhat.com
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move is_check_pages_enabled() into page_alloc.c

The is_check_pages_enabled() only used in page_alloc.c, move it into
page_alloc.c, also use it in free_tail_page_prepare().

Link: https://lkml.kernel.org/r/20230516063821.121844-14-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move sysctls into it own fils

This moves all page alloc related sysctls to its own file, as part of the
kernel/sysctl.c spring cleaning, also move some functions declarations
from mm.h into internal.h.

Link: https://lkml.kernel.org/r/20230516063821.121844-13-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move pm_* function into power

pm_restrict_gfp_mask()/pm_restore_gfp_mask() only used in power, let's
move them out of page_alloc.c.

Adding a general gfp_has_io_fs() function which return true if gfp with
both __GFP_IO and __GFP_FS flags, then use it inside of
pm_suspended_storage(), also the pm_suspended_storage() is moved into
suspend.h.

Link: https://lkml.kernel.org/r/20230516063821.121844-11-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move mark_free_page() into snapshot.c

The mark_free_page() is only used in kernel/power/snapshot.c, move it out
to reduce a bit of page_alloc.c

Link: https://lkml.kernel.org/r/20230516063821.121844-10-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: split out DEBUG_PAGEALLOC

Move DEBUG_PAGEALLOC related functions into a single file to reduce a bit
of page_alloc.c.

Link: https://lkml.kernel.org/r/20230516063821.121844-9-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: split out FAIL_PAGE_ALLOC

... to a single file to reduce a bit of page_alloc.c.

Link: https://lkml.kernel.org/r/20230516063821.121844-8-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: remove alloc_contig_dump_pages() stub

DEFINE_DYNAMIC_DEBUG_METADATA and DYNAMIC_DEBUG_BRANCH already has stub
definitions without dynamic debug feature, remove unnecessary
alloc_contig_dump_pages() stub.

Link: https://lkml.kernel.org/r/20230516063821.121844-7-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: squash page_is_consistent()

Squash the page_is_consistent() into bad_range() as there is only one
caller.

Link: https://lkml.kernel.org/r/20230516063821.121844-6-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: collect mem statistic into show_mem.c

Let's move show_mem.c from lib to mm, as it belongs memory subsystem, also
split some memory statistic related functions from page_alloc.c to
show_mem.c, and we cleanup some unneeded include.

There is no functional change.

Link: https://lkml.kernel.org/r/20230516063821.121844-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move set_zone_contiguous() into mm_init.c

set_zone_contiguous() is only used in mm init/hotplug, and
clear_zone_contiguous() only used in hotplug, move them from page_alloc.c
to the more appropriate file.

Link: https://lkml.kernel.org/r/20230516063821.121844-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move init_on_alloc/free() into mm_init.c

Since commit f2fc4b44ec2b ("mm: move init_mem_debugging_and_hardening() to
mm/mm_init.c"), the init_on_alloc() and init_on_free() define is better to
move there too.

Link: https://lkml.kernel.org/r/20230516063821.121844-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: move mirrored_kernelcore into mm_init.c

Patch series "mm: page_alloc: misc cleanup and refactor", v2.

This aims to reduce more space in page_alloc.c, also do some cleanup, no
functional changes intended.


This patch (of 13):

Since commit 9420f89db2dd ("mm: move most of core MM initialization to
mm/mm_init.c"), mirrored_kernelcore should be moved into mm_init.c, as
most related codes are already there.

Link: https://lkml.kernel.org/r/20230516063821.121844-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20230516063821.121844-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: drop the unnecessary pfn_valid() for start pfn

__pageblock_pfn_to_page() currently performs both pfn_valid check and
pfn_to_online_page(). The former one is redundant because the latter is a
stronger check. Drop pfn_valid().

Link: https://lkml.kernel.org/r/c3868b58c6714c09a43440d7d02c7b4eed6e03f6.1682342634.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: Add support for unaccepted memory

UEFI Specification version 2.9 introduces the concept of memory
acceptance. Some Virtual Machine platforms, such as Intel TDX or AMD
SEV-SNP, require memory to be accepted before it can be used by the
guest. Accepting happens via a protocol specific to the Virtual Machine
platform.

There are several ways the kernel can deal with unaccepted memory:

1. Accept all the memory during boot. It is easy to implement and it
doesn't have runtime cost once the system is booted. The downside is
very long boot time.

Accept can be parallelized to multiple CPUs to keep it manageable
(i.e. via DEFERRED_STRUCT_PAGE_INIT), but it tends to saturate
memory bandwidth and does not scale beyond the point.

2. Accept a block of memory on the first use. It requires more
infrastructure and changes in page allocator to make it work, but
it provides good boot time.

On-demand memory accept means latency spikes every time kernel steps
onto a new memory block. The spikes will go away once workload data
set size gets stabilized or all memory gets accepted.

3. Accept all memory in background. Introduce a thread (or multiple)
that gets memory accepted proactively. It will minimize time the
system experience latency spikes on memory allocation while keeping
low boot time.

This approach cannot function on its own. It is an extension of #2:
background memory acceptance requires functional scheduler, but the
page allocator may need to tap into unaccepted memory before that.

The downside of the approach is that these threads also steal CPU
cycles and memory bandwidth from the user's workload and may hurt
user experience.

Implement #1 and #2 for now. #2 is the default. Some workloads may want
to use #1 with accept_memory=eager in kernel command line. #3 can be
implemented later based on user's demands.

Support of unaccepted memory requires a few changes in core-mm code:

- memblock accepts memory on allocation. It serves early boot memory
allocations and doesn't limit them to pre-accepted pool of memory.

- page allocator accepts memory on the first allocation of the page.
When kernel runs out of accepted memory, it accepts memory until the
high watermark is reached. It helps to minimize fragmentation.

EFI code will provide two helpers if the platform supports unaccepted
memory:

- accept_memory() makes a range of physical addresses accepted.

- range_contains_unaccepted_memory() checks anything within the range
of physical addresses requires acceptance.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mike Rapoport <rppt@linux.ibm.com> # memblock
Link: https://lore.kernel.org/r/20230606142637.5171-2-kirill.shutemov@linux.intel.com

mm/page_alloc: add some comments to explain the possible hole in __pageblock_pfn_to_page()

Now the __pageblock_pfn_to_page() is used by set_zone_contiguous(), which
checks whether the given zone contains holes, and uses
pfn_to_online_page() to validate if the start pfn is online and valid, as
well as using pfn_valid() to validate the end pfn.

However, the __pageblock_pfn_to_page() function may return non-NULL even
if the end pfn of a pageblock is in a memory hole in some situations. For
example, if the pageblock order is MAX_ORDER, which will fall into 2
sub-sections, and the end pfn of the pageblock may be hole even though the
start pfn is online and valid.

See below memory layout as an example and suppose the pageblock order is
MAX_ORDER.

[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff]
[ 0.000000] DMA32 empty
[ 0.000000] Normal [mem 0x0000000100000000-0x0000001fa7ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000040000000-0x0000001fa3c7ffff]
[ 0.000000] node 0: [mem 0x0000001fa3c80000-0x0000001fa3ffffff]
[ 0.000000] node 0: [mem 0x0000001fa4000000-0x0000001fa402ffff]
[ 0.000000] node 0: [mem 0x0000001fa4030000-0x0000001fa40effff]
[ 0.000000] node 0: [mem 0x0000001fa40f0000-0x0000001fa73cffff]
[ 0.000000] node 0: [mem 0x0000001fa73d0000-0x0000001fa745ffff]
[ 0.000000] node 0: [mem 0x0000001fa7460000-0x0000001fa746ffff]
[ 0.000000] node 0: [mem 0x0000001fa7470000-0x0000001fa758ffff]
[ 0.000000] node 0: [mem 0x0000001fa7590000-0x0000001fa7dfffff]

Focus on the last memory range, and there is a hole for the range [mem
0x0000001fa7590000-0x0000001fa7dfffff]. That means the last pageblock
will contain the range from 0x1fa7c00000 to 0x1fa7ffffff, since the
pageblock must be 4M aligned. And in this pageblock, these pfns will fall
into 2 sub-section (the sub-section size is 2M aligned).

So, the 1st sub-section (indicates pfn range: 0x1fa7c00000 - 0x1fa7dfffff
) in this pageblock is valid by calling subsection_map_init() in
free_area_init(), but the 2nd sub-section (indicates pfn range:
0x1fa7e00000 - 0x1fa7ffffff ) in this pageblock is not valid.

This did not break anything until now, but the zone continuous is fragile
in this possible scenario. So as previous discussion[1], it is better to
add some comments to explain this possible issue in case there are some
future pfn walkers that rely on this.

[1] https://lore.kernel.org/all/87r0sdsmr6.fsf@yhuang6-desk2.ccr.corp.intel.com/

Link: https://lkml.kernel.org/r/5c26368865e79c743a453dea48d30670b19d2e4f.1682425534.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/5c26368865e79c743a453dea48d30670b19d2e4f.1682425534.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cpuset: Clean up cpuset_node_allowed

Commit 002f290627c2 ("cpuset: use static key better and convert to new API")
has used __cpuset_node_allowed() instead of cpuset_node_allowed() to check
whether we can allocate on a memory node. Now this function isn't used by
anyone, so we can do the follow things to clean up it.

1. remove unused codes
2. rename __cpuset_node_allowed() to cpuset_node_allowed()
3. update comments in mm/page_alloc.c

Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

mm, page_alloc: use check_pages_enabled static key to check tail pages

Commit 700d2e9a36b9 ("mm, page_alloc: reduce page alloc/free sanity
checks") has introduced a new static key check_pages_enabled to control
when struct pages are sanity checked during allocation and freeing. Mel
Gorman suggested that free_tail_pages_check() could use this static key as
well, instead of relying on CONFIG_DEBUG_VM. That makes sense, so do
that. Also rename the function to free_tail_page_prepare() because it
works on a single tail page and has a struct page preparation component as
well as the optional checking component.

Also remove some unnecessary unlikely() within static_branch_unlikely()
statements that Mel pointed out for commit 700d2e9a36b9.

Link: https://lkml.kernel.org/r/20230405142840.11068-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Alexander Halbuer <halbuer@sra.uni-hannover.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: move mem_init_print_info() to mm_init.c

mem_init_print_info() is only called from mm_core_init().

Move it close to the caller and make it static.

Link: https://lkml.kernel.org/r/20230321170513.2401534-12-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: move init_mem_debugging_and_hardening() to mm/mm_init.c

init_mem_debugging_and_hardening() is only called from mm_core_init().

Move it close to the caller, make it static and rename it to
mem_debugging_and_hardening_init() for consistency with surrounding
convention.

Link: https://lkml.kernel.org/r/20230321170513.2401534-10-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: rename page_alloc_init() to page_alloc_init_cpuhp()

The page_alloc_init() name is really misleading because all this function
does is sets up CPU hotplug callbacks for the page allocator.

Rename it to page_alloc_init_cpuhp() so that name will reflect what the
function does.

Link: https://lkml.kernel.org/r/20230321170513.2401534-6-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: handle hashdist initialization in mm/mm_init.c

The hashdist variable must be initialized before the first call to
alloc_large_system_hash() and free_area_init() looks like a better place
for it than page_alloc_init().

Move hashdist handling to mm/mm_init.c

Link: https://lkml.kernel.org/r/20230321170513.2401534-5-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: move most of core MM initialization to mm/mm_init.c

The bulk of memory management initialization code is spread all over
mm/page_alloc.c and makes navigating through page allocator functionality
difficult.

Move most of the functions marked __init and __meminit to mm/mm_init.c to
make it better localized and allow some more spare room before
mm/page_alloc.c reaches 10k lines.

No functional changes.

Link: https://lkml.kernel.org/r/20230321170513.2401534-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: add helper for checking if check_pages_enabled

Instead of duplicating long static_branch_enabled(&check_pages_enabled)
wrap it in a helper function is_check_pages_enabled()

Link: https://lkml.kernel.org/r/20230321170513.2401534-3-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: move get_page_from_free_area() to mm/page_alloc.c

The get_page_from_free_area() helper is only used in mm/page_alloc.c so
move it there to reduce noise in include/linux/mmzone.h

Link: https://lkml.kernel.org/r/20230319114214.2133332-1-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, treewide: redefine MAX_ORDER sanely

MAX_ORDER currently defined as number of orders page allocator supports:
user can ask buddy allocator for page order between 0 and MAX_ORDER-1.

This definition is counter-intuitive and lead to number of bugs all over
the kernel.

Change the definition of MAX_ORDER to be inclusive: the range of orders
user can ask from buddy allocator is 0..MAX_ORDER now.

[kirill@shutemov.name: fix min() warning]
Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box
[akpm@linux-foundation.org: fix another min_t warning]
[kirill@shutemov.name: fixups per Zi Yan]
Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name
[akpm@linux-foundation.org: fix underlining in docs]
Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: prefer xxx_page() alloc/free functions for order-0 pages

Update instances of alloc_pages(..., 0), __get_free_pages(..., 0) and
__free_pages(..., 0) to use alloc_page(), __get_free_page() and
__free_page() respectively in core code.

Link: https://lkml.kernel.org/r/50c48ca4789f1da2a65795f2346f5ae3eff7d665.1678710232.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: remove PG_skip_kasan_poison flag

Code inspection reveals that PG_skip_kasan_poison is redundant with
kasantag, because the former is intended to be set iff the latter is the
match-all tag. It can also be observed that it's basically pointless to
poison pages which have kasantag=0, because any pages with this tag would
have been pointed to by pointers with match-all tags, so poisoning the
pages would have little to no effect in terms of bug detection.
Therefore, change the condition in should_skip_kasan_poison() to check
kasantag instead, and remove PG_skip_kasan_poison and associated flags.

Link: https://lkml.kernel.org/r/20230310042914.3805818-3-pcc@google.com
Link: https://linux-review.googlesource.com/id/I57f825f2eaeaf7e8389d6cf4597c8a5821359838
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, page_alloc: reduce page alloc/free sanity checks

Historically, we have performed sanity checks on all struct pages being
allocated or freed, making sure they have no unexpected page flags or
certain field values. This can detect insufficient cleanup and some cases
of use-after-free, although on its own it can't always identify the
culprit. The result is a warning and the "bad page" being leaked.

The checks do need some cpu cycles, so in 4.7 with commits 479f854a207c
("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
and 4db7548ccbd9 ("mm, page_alloc: defer debugging checks of freed pages
until a PCP drain") they were no longer performed in the hot paths when
allocating and freeing from pcplists, but only when pcplists are bypassed,
refilled or drained. For debugging purposes, with CONFIG_DEBUG_VM enabled
the checks were instead still done in the hot paths and not when refilling
or draining pcplists.

With 4462b32c9285 ("mm, page_alloc: more extensive free page checking with
debug_pagealloc"), enabling debug_pagealloc also moved the sanity checks
back to hot pahs. When both debug_pagealloc and CONFIG_DEBUG_VM are
enabled, the checks are done both in hotpaths and pcplist refill/drain.

Even though the non-debug default today might seem to be a sensible
tradeoff between overhead and ability to detect bad pages, on closer look
it's arguably not. As most allocations go through the pcplists, catching
any bad pages when refilling or draining pcplists has only a small chance,
insufficient for debugging or serious hardening purposes. On the other
hand the cost of the checks is concentrated in the already expensive
drain/refill batching operations, and those are done under the often
contended zone lock. That was recently identified as an issue for page
allocation and the zone lock contention reduced by moving the checks
outside of the locked section with a patch "mm: reduce lock contention of
pcp buffer refill", but the cost of the checks is still visible compared
to their removal [1]. In the pcplist draining path free_pcppages_bulk()
the checks are still done under zone->lock.

Thus, remove the checks from pcplist refill and drain paths completely.
Introduce a static key check_pages_enabled to control checks during page
allocation a freeing (whether pcplist is used or bypassed). The static
key is enabled if either is true:

- kernel is built with CONFIG_DEBUG_VM=y (debugging)
- debug_pagealloc or page poisoning is boot-time enabled (debugging)
- init_on_alloc or init_on_free is boot-time enabled (hardening)

The resulting user visible changes:
- no checks when draining/refilling pcplists - less overhead, with
likely no practical reduction of ability to catch bad pages
- no checks when bypassing pcplists in default config (no
debugging/hardening) - less overhead etc. as above
- on typical hardened kernels [2], checks are now performed on each page
allocation/free (previously only when bypassing/draining/refilling
pcplists) - the init_on_alloc/init_on_free enabled should be sufficient
indication for preferring more costly alloc/free operations for
hardening purposes and we shouldn't need to introduce another toggle
- code (various wrappers) removal and simplification

[1] https://lore.kernel.org/all/68ba44d8-6899-c018-dcb3-36f3a96e6bea@sra.uni-hannover.de/
[2] https://lore.kernel.org/all/63ebc499.a70a0220.9ac51.29ea@mx.google.com/

[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: make check_pages_enabled static]
Link: https://lkml.kernel.org/r/20230216095131.17336-1-vbabka@suse.cz
Reported-by: Alexander Halbuer <halbuer@sra.uni-hannover.de>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: reduce lock contention of pcp buffer refill

rmqueue_bulk() batches the allocation of multiple elements to refill the
per-CPU buffers into a single hold of the zone lock. Each element is
allocated and checked using check_pcp_refill(). The check touches every
related struct page which is especially expensive for higher order
allocations (huge pages).

This patch reduces the time holding the lock by moving the check out of
the critical section similar to rmqueue_buddy() which allocates a single
element.

Measurements of parallel allocation-heavy workloads show a reduction of
the average huge page allocation latency of 50 percent for two cores and
nearly 90 percent for 24 cores.

Link: https://lkml.kernel.org/r/20230201162549.68384-1-halbuer@sra.uni-hannover.de
Signed-off-by: Alexander Halbuer <halbuer@sra.uni-hannover.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: skip regions with hugetlbfs pages when allocating 1G pages

A bug was reported by Yuanxi Liu where allocating 1G pages at runtime is
taking an excessive amount of time for large amounts of memory. Further
testing allocating huge pages that the cost is linear i.e. if allocating
1G pages in batches of 10 then the time to allocate nr_hugepages from
10->20->30->etc increases linearly even though 10 pages are allocated at
each step. Profiles indicated that much of the time is spent checking the
validity within already existing huge pages and then attempting a
migration that fails after isolating the range, draining pages and a whole
lot of other useless work.

Commit eb14d4eefdc4 ("mm,page_alloc: drop unnecessary checks from
pfn_range_valid_contig") removed two checks, one which ignored huge pages
for contiguous allocations as huge pages can sometimes migrate. While
there may be value on migrating a 2M page to satisfy a 1G allocation, it's
potentially expensive if the 1G allocation fails and it's pointless to try
moving a 1G page for a new 1G allocation or scan the tail pages for valid
PFNs.

Reintroduce the PageHuge check and assume any contiguous region with
hugetlbfs pages is unsuitable for a new 1G allocation.

The hpagealloc test allocates huge pages in batches and reports the
average latency per page over time. This test happens just after boot
when fragmentation is not an issue. Units are in milliseconds.

hpagealloc
6.3.0-rc6 6.3.0-rc6 6.3.0-rc6
vanilla hugeallocrevert-v1r1 hugeallocsimple-v1r2
Min Latency 26.42 ( 0.00%) 5.07 ( 80.82%) 18.94 ( 28.30%)
1st-qrtle Latency 356.61 ( 0.00%) 5.34 ( 98.50%) 19.85 ( 94.43%)
2nd-qrtle Latency 697.26 ( 0.00%) 5.47 ( 99.22%) 20.44 ( 97.07%)
3rd-qrtle Latency 972.94 ( 0.00%) 5.50 ( 99.43%) 20.81 ( 97.86%)
Max-1 Latency 26.42 ( 0.00%) 5.07 ( 80.82%) 18.94 ( 28.30%)
Max-5 Latency 82.14 ( 0.00%) 5.11 ( 93.78%) 19.31 ( 76.49%)
Max-10 Latency 150.54 ( 0.00%) 5.20 ( 96.55%) 19.43 ( 87.09%)
Max-90 Latency 1164.45 ( 0.00%) 5.53 ( 99.52%) 20.97 ( 98.20%)
Max-95 Latency 1223.06 ( 0.00%) 5.55 ( 99.55%) 21.06 ( 98.28%)
Max-99 Latency 1278.67 ( 0.00%) 5.57 ( 99.56%) 22.56 ( 98.24%)
Max Latency 1310.90 ( 0.00%) 8.06 ( 99.39%) 26.62 ( 97.97%)
Amean Latency 678.36 ( 0.00%) 5.44 * 99.20%* 20.44 * 96.99%*

6.3.0-rc6 6.3.0-rc6 6.3.0-rc6
vanilla revert-v1 hugeallocfix-v2
Duration User 0.28 0.27 0.30
Duration System 808.66 17.77 35.99
Duration Elapsed 830.87 18.08 36.33

The vanilla kernel is poor, taking up to 1.3 second to allocate a huge
page and almost 10 minutes in total to run the test. Reverting the
problematic commit reduces it to 8ms at worst and the patch takes 26ms.
This patch fixes the main issue with skipping huge pages but leaves the
page_count() out because a page with an elevated count potentially can
migrate.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=217022
Link: https://lkml.kernel.org/r/20230414141429.pwgieuwluxwez3rj@techsingularity.net
Fixes: eb14d4eefdc4 ("mm,page_alloc: drop unnecessary checks from pfn_range_valid_contig")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Yuanxi Liu <y.liu@naruida.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock

syzbot is reporting circular locking dependency which involves
zonelist_update_seq seqlock [1], for this lock is checked by memory
allocation requests which do not need to be retried.

One deadlock scenario is kmalloc(GFP_ATOMIC) from an interrupt handler.

CPU0
----
__build_all_zonelists() {
write_seqlock(&zonelist_update_seq); // makes zonelist_update_seq.seqcount odd
// e.g. timer interrupt handler runs at this moment
some_timer_func() {
kmalloc(GFP_ATOMIC) {
__alloc_pages_slowpath() {
read_seqbegin(&zonelist_update_seq) {
// spins forever because zonelist_update_seq.seqcount is odd
}
}
}
}
// e.g. timer interrupt handler finishes
write_sequnlock(&zonelist_update_seq); // makes zonelist_update_seq.seqcount even
}

This deadlock scenario can be easily eliminated by not calling
read_seqbegin(&zonelist_update_seq) from !__GFP_DIRECT_RECLAIM allocation
requests, for retry is applicable to only __GFP_DIRECT_RECLAIM allocation
requests. But Michal Hocko does not know whether we should go with this
approach.

Another deadlock scenario which syzbot is reporting is a race between
kmalloc(GFP_ATOMIC) from tty_insert_flip_string_and_push_buffer() with
port->lock held and printk() from __build_all_zonelists() with
zonelist_update_seq held.

CPU0 CPU1
---- ----
pty_write() {
tty_insert_flip_string_and_push_buffer() {
__build_all_zonelists() {
write_seqlock(&zonelist_update_seq);
build_zonelists() {
printk() {
vprintk() {
vprintk_default() {
vprintk_emit() {
console_unlock() {
console_flush_all() {
console_emit_next_record() {
con->write() = serial8250_console_write() {
spin_lock_irqsave(&port->lock, flags);
tty_insert_flip_string() {
tty_insert_flip_string_fixed_flag() {
__tty_buffer_request_room() {
tty_buffer_alloc() {
kmalloc(GFP_ATOMIC | __GFP_NOWARN) {
__alloc_pages_slowpath() {
zonelist_iter_begin() {
read_seqbegin(&zonelist_update_seq); // spins forever because zonelist_update_seq.seqcount is odd
spin_lock_irqsave(&port->lock, flags); // spins forever because port->lock is held
}
}
}
}
}
}
}
}
spin_unlock_irqrestore(&port->lock, flags);
// message is printed to console
spin_unlock_irqrestore(&port->lock, flags);
}
}
}
}
}
}
}
}
}
write_sequnlock(&zonelist_update_seq);
}
}
}

This deadlock scenario can be eliminated by

preventing interrupt context from calling kmalloc(GFP_ATOMIC)

and

preventing printk() from calling console_flush_all()

while zonelist_update_seq.seqcount is odd.

Since Petr Mladek thinks that __build_all_zonelists() can become a
candidate for deferring printk() [2], let's address this problem by

disabling local interrupts in order to avoid kmalloc(GFP_ATOMIC)

and

disabling synchronous printk() in order to avoid console_flush_all()

.

As a side effect of minimizing duration of zonelist_update_seq.seqcount
being odd by disabling synchronous printk(), latency at
read_seqbegin(&zonelist_update_seq) for both !__GFP_DIRECT_RECLAIM and
__GFP_DIRECT_RECLAIM allocation requests will be reduced. Although, from
lockdep perspective, not calling read_seqbegin(&zonelist_update_seq) (i.e.
do not record unnecessary locking dependency) from interrupt context is
still preferable, even if we don't allow calling kmalloc(GFP_ATOMIC)
inside
write_seqlock(&zonelist_update_seq)/write_sequnlock(&zonelist_update_seq)
section...

Link: https://lkml.kernel.org/r/8796b95c-3da3-5885-fddd-6ef55f30e4d3@I-love.SAKURA.ne.jp
Fixes: 3d36424b3b58 ("mm/page_alloc: fix race condition between build_all_zonelists and page allocation")
Link: https://lkml.kernel.org/r/ZCrs+1cDqPWTDFNM@alley [2]
Reported-by: syzbot <syzbot+223c7461c58c58a4cb10@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?extid=223c7461c58c58a4cb10 [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Patrick Daly <quic_pdaly@quicinc.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Revert "kasan: drop skip_kasan_poison variable in free_pages_prepare"

This reverts commit 487a32ec24be819e747af8c2ab0d5c515508086a.

should_skip_kasan_poison() reads the PG_skip_kasan_poison flag from
page->flags. However, this line of code in free_pages_prepare():

page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;

clears most of page->flags, including PG_skip_kasan_poison, before calling
should_skip_kasan_poison(), which meant that it would never return true as
a result of the page flag being set. Therefore, fix the code to call
should_skip_kasan_poison() before clearing the flags, as we were doing
before the reverted patch.

This fixes a measurable performance regression introduced in the reverted
commit, where munmap() takes longer than intended if HW tags KASAN is
supported and enabled at runtime. Without this patch, we see a
single-digit percentage performance regression in a particular
mmap()-heavy benchmark when enabling HW tags KASAN, and with the patch,
there is no statistically significant performance impact when enabling HW
tags KASAN.

Link: https://lkml.kernel.org/r/20230310042914.3805818-2-pcc@google.com
Fixes: 487a32ec24be ("kasan: drop skip_kasan_poison variable in free_pages_prepare")
Link: https://linux-review.googlesource.com/id/Ic4f13affeebd20548758438bb9ed9ca40e312b79
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com> [arm64]
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org> [6.1]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memcontrol: rename memcg_kmem_enabled()

Currently there are two kmem-related helper functions with a confusing
semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled().

The problem is that an obvious expectation
memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(),
can be false.

mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it returns
true only if CONFIG_MEMCG_KMEM is not set or the kmem accounting is
disabled using a boot time kernel option "cgroup.memory=nokmem". It never
changes the value dynamically.

memcg_kmem_enabled() is different: it always returns false until the first
non-root memory cgroup will get online (assuming the kernel memory
accounting is enabled). It's goal is to improve the performance on
systems without the cgroupfs mounted/memory controller enabled or on the
systems with only the root memory cgroup.

To make things more obvious and avoid potential bugs, let's rename
memcg_kmem_enabled() to memcg_kmem_online().

Link: https://lkml.kernel.org/r/20230213192922.1146370-1-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: call panic() when memoryless node allocation fails

In free_area_init(), we will continue to run after allocation of
memoryless node pgdat fails. However, in the subsequent process (such as
when initializing zonelist), the case that NODE_DATA(nid) is NULL is not
handled, which will cause panic. Instead of this, it's better to call
panic() directly when the memory allocation fails during system boot.

Link: https://lkml.kernel.org/r/20230212111027.95520-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: reduce fallbacks to (MIGRATE_PCPTYPES - 1)

The commit 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
pageblocks with others") has removed MIGRATE_CMA and MIGRATE_ISOLATE from
fallbacks list. so there is no need to add an element at the end of every
type.

Reduce fallbacks to (MIGRATE_PCPTYPES - 1).

Link: https://lkml.kernel.org/r/20230203100132.1627787-1-yajun.deng@linux.dev
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: reset page tags properly with sampling

The implementation of page_alloc poisoning sampling assumed that
tag_clear_highpage resets page tags for __GFP_ZEROTAGS allocations.
However, this is no longer the case since commit 70c248aca9e7 ("mm: kasan:
Skip unpoisoning of user pages").

This leads to kernel crashes when MTE-enabled userspace mappings are used
with Hardware Tag-Based KASAN enabled.

Reset page tags for __GFP_ZEROTAGS allocations in post_alloc_hook().

Also clarify and fix related comments.

[andreyknvl@google.com: update comment]
Link: https://lkml.kernel.org/r/5dbd866714b4839069e2d8469ac45b60953db290.1674592780.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/24ea20c1b19c2b4b56cf9f5b354915f8dbccfc77.1674592496.git.andreyknvl@google.com
Fixes: 44383cef54c0 ("kasan: allow sampling page_alloc allocations for HW_TAGS")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Peter Collingbourne <pcc@google.com>
Tested-by: Peter Collingbourne <pcc@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/page_alloc: use deferred_pages_enabled() wherever applicable

Instead of directly accessing static deferred_pages, replace such
instances with the helper deferred_pages_enabled(). No functional change
is intended.

Link: https://lkml.kernel.org/r/20230105082506.241529-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_ext: init page_ext early if there are no deferred struct pages

page_ext must be initialized after all struct pages are initialized.
Therefore, page_ext is initialized after page_alloc_init_late(), and can
optionally be initialized earlier via early_page_ext kernel parameter
which as a side effect also disables deferred struct pages.

Allow to automatically init page_ext early when there are no deferred
struct pages in order to be able to use page_ext during kernel boot and
track for example page allocations early.

[pasha.tatashin@soleen.com: fix build with CONFIG_PAGE_EXTENSION=n]
Link: https://lkml.kernel.org/r/20230118155251.2522985-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20230117204617.1553748-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: discard __GFP_ATOMIC

__GFP_ATOMIC serves little purpose. Its main effect is to set
ALLOC_HARDER which adds a few little boosts to increase the chance of an
allocation succeeding, one of which is to lower the water-mark at which it
will succeed.

It is *always* paired with __GFP_HIGH which sets ALLOC_HIGH which also
adjusts this watermark. It is probable that other users of __GFP_HIGH
should benefit from the other little bonuses that __GFP_ATOMIC gets.

__GFP_ATOMIC also gives a warning if used with __GFP_DIRECT_RECLAIM.
There is little point to this. We already get a might_sleep() warning if
__GFP_DIRECT_RECLAIM is set.

__GFP_ATOMIC allows the "watermark_boost" to be side-stepped. It is
probable that testing ALLOC_HARDER is a better fit here.

__GFP_ATOMIC is used by tegra-smmu.c to check if the allocation might
sleep. This should test __GFP_DIRECT_RECLAIM instead.

This patch:
- removes __GFP_ATOMIC
- allows __GFP_HIGH allocations to ignore watermark boosting as well
as GFP_ATOMIC requests.
- makes other adjustments as suggested by the above.

The net result is not change to GFP_ATOMIC allocations. Other
allocations that use __GFP_HIGH will benefit from a few different extra
privileges. This affects:
xen, dm, md, ntfs3
the vermillion frame buffer
hibernation
ksm
swap
all of which likely produce more benefit than cost if these selected
allocation are more likely to succeed quickly.

[mgorman: Minor adjustments to rework on top of a series]
Link: https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@noble.neil.brown.name
Link: https://lkml.kernel.org/r/20230113111217.14134-7-mgorman@techsingularity.net
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: explicitly define how __GFP_HIGH non-blocking allocations accesses reserves

GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a vague
description. In preparation for the removal of GFP_ATOMIC redefine
__GFP_ATOMIC to simply mean non-blocking and renaming ALLOC_HARDER to
ALLOC_NON_BLOCK accordingly. __GFP_HIGH is required for access to
reserves but non-blocking is granted more access. For example, GFP_NOWAIT
is non-blocking but has no special access to reserves. A __GFP_NOFAIL
blocking allocation is granted access similar to __GFP_HIGH if the only
alternative is an OOM kill.

Link: https://lkml.kernel.org/r/20230113111217.14134-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: explicitly define what alloc flags deplete min reserves

As there are more ALLOC_ flags that affect reserves, define what flags
affect reserves and clarify the effect of each flag.

Link: https://lkml.kernel.org/r/20230113111217.14134-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: explicitly record high-order atomic allocations in alloc_flags

A high-order ALLOC_HARDER allocation is assumed to be atomic. While that
is accurate, it changes later in the series. In preparation, explicitly
record high-order atomic allocations in gfp_to_alloc_flags().

Link: https://lkml.kernel.org/r/20230113111217.14134-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: treat RT tasks similar to __GFP_HIGH

RT tasks are allowed to dip below the min reserve but ALLOC_HARDER is
typically combined with ALLOC_MIN_RESERVE so RT tasks are a little
unusual. While there is some justification for allowing RT tasks access
to memory reserves, there is a strong chance that a RT task that is also
under memory pressure is at risk of missing deadlines anyway. Relax how
much reserves an RT task can access by treating it the same as __GFP_HIGH
allocations.

Note that in a future kernel release that the RT special casing will be
removed. Hard realtime tasks should be locking down resources in advance
and ensuring enough memory is available. Even a soft-realtime task like
audio or video live decoding which cannot jitter should be allocating both
memory and any disk space required up-front before the recording starts
instead of relying on reserves. At best, reserve access will only delay
the problem by a very short interval.

Link: https://lkml.kernel.org/r/20230113111217.14134-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: rename ALLOC_HIGH to ALLOC_MIN_RESERVE

Patch series "Discard __GFP_ATOMIC", v3.

Neil's patch has been residing in mm-unstable as commit 2fafb4fe8f7a ("mm:
discard __GFP_ATOMIC") for a long time and recently brought up again.
Most recently, I was worried that __GFP_HIGH allocations could use
high-order atomic reserves which is unintentional but there was no
response so lets revisit -- this series reworks how min reserves are used,
protects highorder reserves and then finishes with Neil's patch with very
minor modifications so it fits on top.

There was a review discussion on renaming __GFP_DIRECT_RECLAIM to
__GFP_ALLOW_BLOCKING but I didn't think it was that big an issue and is
orthogonal to the removal of __GFP_ATOMIC.

There were some concerns about how the gfp flags affect the min reserves
but it never reached a solid conclusion so I made my own attempt.

The series tries to iron out some of the details on how reserves are used.
ALLOC_HIGH becomes ALLOC_MIN_RESERVE and ALLOC_HARDER becomes
ALLOC_NON_BLOCK and documents how the reserves are affected. For example,
ALLOC_NON_BLOCK (no direct reclaim) on its own allows 25% of the min
reserve. ALLOC_MIN_RESERVE (__GFP_HIGH) allows 50% and both combined
allows deeper access again. ALLOC_OOM allows access to 75%.

High-order atomic allocations are explicitly handled with the caveat that
no __GFP_ATOMIC flag means that any high-order allocation that specifies
GFP_HIGH and cannot enter direct reclaim will be treated as if it was
GFP_ATOMIC.


This patch (of 6):

__GFP_HIGH aliases to ALLOC_HIGH but the name does not really hint what it
means. As ALLOC_HIGH is internal to the allocator, rename it to
ALLOC_MIN_RESERVE to document that the min reserves can be depleted.

Link: https://lkml.kernel.org/r/20230113111217.14134-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20230113111217.14134-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: mlock: update the interface to use folios

Update the mlock interface to accept folios rather than pages, bringing
the interface in line with the internal implementation.

munlock_vma_page() still requires a page_folio() conversion, however this
is consistent with the existent mlock_vma_page() implementation and a
product of rmap still dealing in pages rather than folios.

Link: https://lkml.kernel.org/r/cba12777c5544305014bc0cbec56bb4cc71477d8.1673526881.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert destroy_large_folio() to use folio_dtor

Replace a use of compound_dtor.

Link: https://lkml.kernel.org/r/20230111142915.1001531-21-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

page_alloc: use folio fields directly

Rmove the uses of compound_mapcount_ptr(), head_compound_mapcount() and
subpages_mapcount_ptr()

Link: https://lkml.kernel.org/r/20230111142915.1001531-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove folio_pincount_ptr() and head_compound_pincount()

We can use folio->_pincount directly, since all users are guarded by tests
of compound/large.

Link: https://lkml.kernel.org/r/20230111142915.1001531-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: invert logic for early page initialisation checks

Rename early_page_uninitialised() to early_page_initialised() and invert
its logic to make the code more readable.

Link: https://lkml.kernel.org/r/20230104191805.2535864-1-rppt@kernel.org
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: multi-gen LRU: per-node lru_gen_folio lists

For each node, memcgs are divided into two generations: the old and
the young. For each generation, memcgs are randomly sharded into
multiple bins to improve scalability. For each bin, an RCU hlist_nulls
is virtually divided into three segments: the head, the tail and the
default.

An onlining memcg is added to the tail of a random bin in the old
generation. The eviction starts at the head of a random bin in the old
generation. The per-node memcg generation counter, whose reminder (mod
2) indexes the old generation, is incremented when all its bins become
empty.

There are four operations:
1. MEMCG_LRU_HEAD, which moves an memcg to the head of a random bin in
its current generation (old or young) and updates its "seg" to
"head";
2. MEMCG_LRU_TAIL, which moves an memcg to the tail of a random bin in
its current generation (old or young) and updates its "seg" to
"tail";
3. MEMCG_LRU_OLD, which moves an memcg to the head of a random bin in
the old generation, updates its "gen" to "old" and resets its "seg"
to "default";
4. MEMCG_LRU_YOUNG, which moves an memcg to the tail of a random bin
in the young generation, updates its "gen" to "young" and resets
its "seg" to "default".

The events that trigger the above operations are:
1. Exceeding the soft limit, which triggers MEMCG_LRU_HEAD;
2. The first attempt to reclaim an memcg below low, which triggers
MEMCG_LRU_TAIL;
3. The first attempt to reclaim an memcg below reclaimable size
threshold, which triggers MEMCG_LRU_TAIL;
4. The second attempt to reclaim an memcg below reclaimable size
threshold, which triggers MEMCG_LRU_YOUNG;
5. Attempting to reclaim an memcg below min, which triggers
MEMCG_LRU_YOUNG;
6. Finishing the aging on the eviction path, which triggers
MEMCG_LRU_YOUNG;
7. Offlining an memcg, which triggers MEMCG_LRU_OLD.

Note that memcg LRU only applies to global reclaim, and the
round-robin incrementing of their max_seq counters ensures the
eventual fairness to all eligible memcgs. For memcg reclaim, it still
relies on mem_cgroup_iter().

Link: https://lkml.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Larabel <Michael@MichaelLarabel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: allow sampling page_alloc allocations for HW_TAGS

As Hardware Tag-Based KASAN is intended to be used in production, its
performance impact is crucial. As page_alloc allocations tend to be big,
tagging and checking all such allocations can introduce a significant
slowdown.

Add two new boot parameters that allow to alleviate that slowdown:

- kasan.page_alloc.sample, which makes Hardware Tag-Based KASAN tag only
every Nth page_alloc allocation with the order configured by the second
added parameter (default: tag every such allocation).

- kasan.page_alloc.sample.order, which makes sampling enabled by the first
parameter only affect page_alloc allocations with the order equal or
greater than the specified value (default: 3, see below).

The exact performance improvement caused by using the new parameters
depends on their values and the applied workload.

The chosen default value for kasan.page_alloc.sample.order is 3, which
matches both PAGE_ALLOC_COSTLY_ORDER and SKB_FRAG_PAGE_ORDER. This is
done for two reasons:

1. PAGE_ALLOC_COSTLY_ORDER is "the order at which allocations are deemed
costly to service", which corresponds to the idea that only large and
thus costly allocations are supposed to sampled.

2. One of the workloads targeted by this patch is a benchmark that sends
a large amount of data over a local loopback connection. Most multi-page
data allocations in the networking subsystem have the order of
SKB_FRAG_PAGE_ORDER (or PAGE_ALLOC_COSTLY_ORDER).

When running a local loopback test on a testing MTE-enabled device in sync
mode, enabling Hardware Tag-Based KASAN introduces a ~50% slowdown.
Applying this patch and setting kasan.page_alloc.sampling to a value
higher than 1 allows to lower the slowdown. The performance improvement
saturates around the sampling interval value of 10 with the default
sampling page order of 3. This lowers the slowdown to ~20%. The slowdown
in real scenarios involving the network will likely be better.

Enabling page_alloc sampling has a downside: KASAN misses bad accesses to
a page_alloc allocation that has not been tagged. This lowers the value
of KASAN as a security mitigation.

However, based on measuring the number of page_alloc allocations of
different orders during boot in a test build, sampling with the default
kasan.page_alloc.sample.order value affects only ~7% of allocations. The
rest ~93% of allocations are still checked deterministically.

Link: https://lkml.kernel.org/r/129da0614123bb85ed4dd61ae30842b2dd7c903f.1671471846.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Brand <markbrand@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Fix page corruption caused by racy check in __free_pages

When we upgraded our kernel, we started seeing some page corruption like
the following consistently:

BUG: Bad page state in process ganesha.nfsd pfn:1304ca
page:0000000022261c55 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x1304ca
flags: 0x17ffffc0000000()
raw: 0017ffffc0000000 ffff8a513ffd4c98 ffffeee24b35ec08 0000000000000000
raw: 0000000000000000 0000000000000001 00000000ffffff7f 0000000000000000
page dumped because: nonzero mapcount
CPU: 0 PID: 15567 Comm: ganesha.nfsd Kdump: loaded Tainted: P B O 5.10.158-1.nutanix.20221209.el7.x86_64 #1
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
Call Trace:
dump_stack+0x74/0x96
bad_page.cold+0x63/0x94
check_new_page_bad+0x6d/0x80
rmqueue+0x46e/0x970
get_page_from_freelist+0xcb/0x3f0
? _cond_resched+0x19/0x40
__alloc_pages_nodemask+0x164/0x300
alloc_pages_current+0x87/0xf0
skb_page_frag_refill+0x84/0x110
...

Sometimes, it would also show up as corruption in the free list pointer
and cause crashes.

After bisecting the issue, we found the issue started from commit
e320d3012d25 ("mm/page_alloc.c: fix freeing non-compound pages"):

if (put_page_testzero(page))
free_the_page(page, order);
else if (!PageHead(page))
while (order-- > 0)
free_the_page(page + (1 << order), order);

So the problem is the check PageHead is racy because at this point we
already dropped our reference to the page. So even if we came in with
compound page, the page can already be freed and PageHead can return
false and we will end up freeing all the tail pages causing double free.

Fixes: e320d3012d25 ("mm/page_alloc.c: fix freeing non-compound pages")
Link: https://lore.kernel.org/lkml/BYAPR02MB448855960A9656EEA81141FC94D99@BYAPR02MB4488.namprd02.prod.outlook.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Chunwei Chen <david.chen@nutanix.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc: update comments in __free_pages_ok()

Add a comment to explain why we call get_pfnblock_migratetype() twice in
__free_pages_ok().

Link: https://lkml.kernel.org/r/20221201135045.31663-1-wonder_rock@126.com
Signed-off-by: Deyan Wang <wonder_rock@126.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: simplify locking during free_unref_page_list

While freeing a large list, the zone lock will be released and reacquired
to avoid long hold times since commit c24ad77d962c ("mm/page_alloc.c:
avoid excessive IRQ disabled times in free_unref_page_list()"). As
suggested by Vlastimil Babka, the lockrelease/reacquire logic can be
simplified by reusing the logic that acquires a different lock when
changing zones.

Link: https://lkml.kernel.org/r/20221122131229.5263-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: leave IRQs enabled for per-cpu page allocations

The pcp_spin_lock_irqsave protecting the PCP lists is IRQ-safe as a task
allocating from the PCP must not re-enter the allocator from IRQ context.
In each instance where IRQ-reentrancy is possible, the lock is acquired
using pcp_spin_trylock_irqsave() even though IRQs are disabled and
re-entrancy is impossible.

Demote the lock to pcp_spin_lock avoids an IRQ disable/enable in the
common case at the cost of some IRQ allocations taking a slower path. If
the PCP lists need to be refilled, the zone lock still needs to disable
IRQs but that will only happen on PCP refill and drain. If an IRQ is
raised when a PCP allocation is in progress, the trylock will fail and
fallback to using the buddy lists directly. Note that this may not be a
universal win if an interrupt-intensive workload also allocates heavily
from interrupt context and contends heavily on the zone->lock as a result.

[mgorman@techsingularity.net: migratetype might be wrong if a PCP was locked]
Link: https://lkml.kernel.org/r/20221122131229.5263-2-mgorman@techsingularity.net
[yuzhao@google.com: reported lockdep issue on IO completion from softirq]
[hughd@google.com: fix list corruption, lock improvements, micro-optimsations]
Link: https://lkml.kernel.org/r/20221118101714.19590-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: always remove pages from temporary list

Patch series "Leave IRQs enabled for per-cpu page allocations", v3.


This patch (of 2):

free_unref_page_list() has neglected to remove pages properly from the
list of pages to free since forever. It works by coincidence because
list_add happened to do the right thing adding the pages to just the PCP
lists. However, a later patch added pages to either the PCP list or the
zone list but only properly deleted the page from the list in one path
leading to list corruption and a subsequent failure. As a preparation
patch, always delete the pages from one list properly before adding to
another. On its own, this fixes nothing although it adds a fractional
amount of overhead but is critical to the next patch.

Link: https://lkml.kernel.org/r/20221118101714.19590-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20221118101714.19590-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm,thp,rmap: subpages_mapcount COMPOUND_MAPPED if PMD-mapped

Can the lock_compound_mapcount() bit_spin_lock apparatus be removed now?
Yes. Not by atomic64_t or cmpxchg games, those get difficult on 32-bit;
but if we slightly abuse subpages_mapcount by additionally demanding that
one bit be set there when the compound page is PMD-mapped, then a cascade
of two atomic ops is able to maintain the stats without bit_spin_lock.

This is harder to reason about than when bit_spin_locked, but I believe
safe; and no drift in stats detected when testing. When there are racing
removes and adds, of course the sequence of operations is less well-
defined; but each operation on subpages_mapcount is atomically good. What
might be disastrous, is if subpages_mapcount could ever fleetingly appear
negative: but the pte lock (or pmd lock) these rmap functions are called
under, ensures that a last remove cannot race ahead of a first add.

Continue to make an exception for hugetlb (PageHuge) pages, though that
exception can be easily removed by a further commit if necessary: leave
subpages_mapcount 0, don't bother with COMPOUND_MAPPED in its case, just
carry on checking compound_mapcount too in folio_mapped(), page_mapped().

Evidence is that this way goes slightly faster than the previous
implementation in all cases (pmds after ptes now taking around 103ms); and
relieves us of worrying about contention on the bit_spin_lock.

Link: https://lkml.kernel.org/r/3978f3ca-5473-55a7-4e14-efea5968d892@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Carpenter <error27@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm,thp,rmap: simplify compound page mapcount handling

Compound page (folio) mapcount calculations have been different for anon
and file (or shmem) THPs, and involved the obscure PageDoubleMap flag.
And each huge mapping and unmapping of a file (or shmem) THP involved
atomically incrementing and decrementing the mapcount of every subpage of
that huge page, dirtying many struct page cachelines.

Add subpages_mapcount field to the struct folio and first tail page, so
that the total of subpage mapcounts is available in one place near the
head: then page_mapcount() and total_mapcount() and page_mapped(), and
their folio equivalents, are so quick that anon and file and hugetlb don't
need to be optimized differently. Delete the unloved PageDoubleMap.

page_add and page_remove rmap functions must now maintain the
subpages_mapcount as well as the subpage _mapcount, when dealing with pte
mappings of huge pages; and correct maintenance of NR_ANON_MAPPED and
NR_FILE_MAPPED statistics still needs reading through the subpages, using
nr_subpages_unmapped() - but only when first or last pmd mapping finds
subpages_mapcount raised (double-map case, not the common case).

But are those counts (used to decide when to split an anon THP, and in
vmscan's pagecache_reclaimable heuristic) correctly maintained? Not
quite: since page_remove_rmap() (and also split_huge_pmd()) is often
called without page lock, there can be races when a subpage pte mapcount
0<->1 while compound pmd mapcount 0<->1 is scanning - races which the
previous implementation had prevented. The statistics might become
inaccurate, and even drift down until they underflow through 0. That is
not good enough, but is better dealt with in a followup patch.

Update a few comments on first and second tail page overlaid fields.
hugepage_add_new_anon_rmap() has to "increment" compound_mapcount, but
subpages_mapcount and compound_pincount are already correctly at 0, so
delete its reinitialization of compound_pincount.

A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took
18 seconds on small pages, and used to take 1 second on huge pages, but
now takes 119 milliseconds on huge pages. Mapping by pmds a second time
used to take 860ms and now takes 92ms; mapping by pmds after mapping by
ptes (when the scan is needed) used to take 870ms and now takes 495ms.
But there might be some benchmarks which would show a slowdown, because
tail struct pages now fall out of cache until final freeing checks them.

Link: https://lkml.kernel.org/r/47ad693-717-79c8-e1ba-46c3a6602e48@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

When we specify __GFP_NOWARN, we only expect that no warnings will be
issued for current caller. But in the __should_failslab() and
__should_fail_alloc_page(), the local GFP flags alter the global
{failslab|fail_page_alloc}.attr, which is persistent and shared by all
tasks. This is not what we expected, let's fix it.

[akpm@linux-foundation.org: unexport should_fail_ex()]
Link: https://lkml.kernel.org/r/20221118100011.2634-1-zhengqi.arch@bytedance.com
Fixes: 3f913fc5f974 ("mm: fix missing handler for __GFP_NOWARN")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: prep_compound_tail() clear page->private

Although page allocation always clears page->private in the first page or
head page of an allocation, it has never made a point of clearing
page->private in the tails (though 0 is often what is already there).

But now commit 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t
during THP split") issues a warning when page_tail->private is found to be
non-0 (unless it's swapcache).

Change that warning to dump page_tail (which also dumps head), instead of
just the head: so far we have seen dead000000000122, dead000000000003,
dead000000000001 or 0000000000000002 in the raw output for tail private.

We could just delete the warning, but today's consensus appears to want
page->private to be 0, unless there's a good reason for it to be set: so
now clear it in prep_compound_tail() (more general than just for THP; but
not for high order allocation, which makes no pass down the tails).

Link: https://lkml.kernel.org/r/1c4233bb-4e4d-5969-fbd4-96604268a285@google.com
Fixes: 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t during THP split")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: reduce potential fragmentation in make_alloc_exact()

Try to avoid using the left over split page on the next request for a page
by calling __free_pages_ok() with FPI_TO_TAIL. This increases the
potential of defragmenting memory when it's used for a short period of
time.

Link: https://lkml.kernel.org/r/20220531185626.yvlmymbxyoe5vags@revolver
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix incorrect PGFREE and PGALLOC for high-order page

PGFREE and PGALLOC represent the number of freed and allocated pages. So
the page order must be considered.

Link: https://lkml.kernel.org/r/20221006101540.40686-1-laoar.shao@gmail.com
Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: free device private pages have zero refcount

Since 27674ef6c73f ("mm: remove the extra ZONE_DEVICE struct page
refcount") device private pages have no longer had an extra reference
count when the page is in use. However before handing them back to the
owning device driver we add an extra reference count such that free pages
have a reference count of one.

This makes it difficult to tell if a page is free or not because both free
and in use pages will have a non-zero refcount. Instead we should return
pages to the drivers page allocator with a zero reference count. Kernel
code can then safely use kernel functions such as get_page_unless_zero().

Link: https://lkml.kernel.org/r/cf70cf6f8c0bdb8aaebdbfb0d790aea4c683c3c6.1664366292.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: update comments for rmqueue()

Since commit 44042b449872 ("mm/page_alloc: allow high-order pages to be
stored on the per-cpu lists"), the per-cpu page allocators (PCP) is not
only for order-0 pages. Update the comments.

Link: https://lkml.kernel.org/r/20220918025640.208586-1-ran.xiaokai@zte.com.cn
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix obsolete comment in deferred_pfn_valid()

There are no architectures that can have holes in the memory map within a
pageblock since commit 859a85ddf90e ("mm: remove pfn_valid_within() and
CONFIG_HOLES_IN_ZONE"). Update the corresponding comment.

Link: https://lkml.kernel.org/r/20220916072257.9639-17-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use costly_order in WARN_ON_ONCE_GFP()

There's no need to check whether order > PAGE_ALLOC_COSTLY_ORDER again.
Minor readability improvement.

Link: https://lkml.kernel.org/r/20220916072257.9639-15-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: init local variable buddy_pfn

The local variable buddy_pfn could be passed to buddy_merge_likely()
without initialization if the passed in order is MAX_ORDER - 1. This
looks buggy but buddy_pfn won't be used in this case as there's a order >=
MAX_ORDER - 2 check. Init buddy_pfn to 0 anyway to avoid possible future
misuse.

Link: https://lkml.kernel.org/r/20220916072257.9639-14-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use helper macro SZ_1{K,M}

Use helper macro SZ_1K and SZ_1M to do the size conversion. Minor
readability improvement.

Link: https://lkml.kernel.org/r/20220916072257.9639-13-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make boot_nodestats static

It's only used in mm/page_alloc.c now. Make it static.

Link: https://lkml.kernel.org/r/20220916072257.9639-12-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use local variable zone_idx directly

Use local variable zone_idx directly since it holds the exact value of
zone_idx(). No functional change intended.

Link: https://lkml.kernel.org/r/20220916072257.9639-10-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: add missing is_migrate_isolate() check in set_page_guard()

In MIGRATE_ISOLATE case, zone freepage state shouldn't be modified as
caller will take care of it. Add missing is_migrate_isolate() here to
avoid possible unbalanced freepage state. This would happen if someone
isolates the block, and then we face an MCE failure/soft-offline on a page
within that block. __mod_zone_freepage_state() will be triggered via
below call trace which already had been triggered back when block was
isolated:

take_page_off_buddy
break_down_buddy_pages
set_page_guard

Link: https://lkml.kernel.org/r/20220916072257.9639-9-linmiaohe@huawei.com
Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix freeing static percpu memory

The size of struct per_cpu_zonestat can be 0 on !SMP && !NUMA. In that
case, zone->per_cpu_zonestats will always equal to boot_zonestats. But in
zone_pcp_reset(), zone->per_cpu_zonestats is freed via free_percpu()
directly without checking against boot_zonestats first. boot_zonestats
will be released by free_percpu() unexpectedly.

Link: https://lkml.kernel.org/r/20220916072257.9639-7-linmiaohe@huawei.com
Fixes: 28f836b6777b ("mm/page_alloc: split per cpu page lists and zone stats")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: add __init annotations to init_mem_debugging_and_hardening()

It's only called by mm_init(). Add __init annotations to it.

Link: https://lkml.kernel.org/r/20220916072257.9639-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove obsolete comment in zone_statistics()

Since commit 43c95bcc51e4 ("mm/page_alloc: reduce duration that IRQs are
disabled for VM counters"), zone_statistics() is not called with
interrupts disabled. Update the corresponding comment.

Link: https://lkml.kernel.org/r/20220916072257.9639-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove obsolete macro NR_PCP_ORDER_MASK and NR_PCP_ORDER_WIDTH

Since commit 8b10b465d0e1 ("mm/page_alloc: free pages in a single pass
during bulk free"), they're not used anymore. Remove them.

Link: https://lkml.kernel.org/r/20220916072257.9639-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make zone_pcp_update() static

Since commit b92ca18e8ca5 ("mm/page_alloc: disassociate the pcp->high from
pcp->batch"), zone_pcp_update() is only used in mm/page_alloc.c. Move
zone_pcp_update() up to avoid forward declaration and then make it static.
No functional change intended.

Link: https://lkml.kernel.org/r/20220916072257.9639-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: ensure kswapd doesn't accidentally go to sleep

Patch series "A few cleanup patches for mm", v2.

This series contains a few cleanup patches to remove the obsolete comments
and functions, use helper macro to improve readability and so on. More
details can be found in the respective changelogs.


This patch (of 16):

If ALLOC_KSWAPD is set, wake_all_kswapds() will be called to ensure kswapd
doesn't accidentally go to sleep. But when reserve_flags is set,
alloc_flags will be overwritten and ALLOC_KSWAPD is thus lost. Preserve
the ALLOC_KSWAPD flag in alloc_flags to ensure kswapd won't go to sleep
accidentally.

Link: https://lkml.kernel.org/r/20220916072257.9639-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220916072257.9639-2-linmiaohe@huawei.com
Fixes: 0a79cdad5eb2 ("mm: use alloc_flags to record if kswapd can wake")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

security: kmsan: fix interoperability with auto-initialization

Heap and stack initialization is great, but not when we are trying uses of
uninitialized memory. When the kernel is built with KMSAN, having kernel
memory initialization enabled may introduce false negatives.

We disable CONFIG_INIT_STACK_ALL_PATTERN and CONFIG_INIT_STACK_ALL_ZERO
under CONFIG_KMSAN, making it impossible to auto-initialize stack
variables in KMSAN builds. We also disable
CONFIG_INIT_ON_ALLOC_DEFAULT_ON and CONFIG_INIT_ON_FREE_DEFAULT_ON to
prevent accidental use of heap auto-initialization.

We however still let the users enable heap auto-initialization at
boot-time (by setting init_on_alloc=1 or init_on_free=1), in which case a
warning is printed.

Link: https://lkml.kernel.org/r/20220915150417.722975-31-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>

init: kmsan: call KMSAN initialization routines

kmsan_init_shadow() scans the mappings created at boot time and creates
metadata pages for those mappings.

When the memblock allocator returns pages to pagealloc, we reserve 2/3 of
those pages and use them as metadata for the remaining 1/3. Once KMSAN
starts, every page allocated by pagealloc has its associated shadow and
origin pages.

kmsan_initialize() initializes the bookkeeping for init_task and enables
KMSAN.

Link: https://lkml.kernel.org/r/20220915150417.722975-18-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>

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>

mm/page_alloc.c: document bulkfree_pcp_prepare() return value

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: ke.wang <ke.wang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Zhaoyang Huang <huangzhaoyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc.c: rename check_free_page() to free_page_is_bad()

The name "check_free_page()" provides no information regarding its return
value when the page is indeed found to be bad.

Renaming it to "free_page_is_bad()" makes it clear that a `true' return
value means the page was bad.

And make it return a bool, not an int.

[akpm@linux-foundation.org: don't use bool as int]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: ke.wang <ke.wang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Zhaoyang Huang <huangzhaoyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add pageblock_aligned() macro

Add pageblock_aligned() and use it to simplify code.

Link: https://lkml.kernel.org/r/20220907060844.126891-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: reuse pageblock_start/end_pfn() macro

Move pageblock_start_pfn/pageblock_end_pfn() into pageblock-flags.h, then
they could be used somewhere else, not only in compaction, also use
ALIGN_DOWN() instead of round_down() to be pair with ALIGN(), which should
be same for pageblock usage.

Link: https://lkml.kernel.org/r/20220907060844.126891-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: reduce noise in show_mem for lowmem allocations

While discussing early DMA pool pre-allocation failure with Christoph [1]
I have realized that the allocation failure warning is rather noisy for
constrained allocations like GFP_DMA{32}. Those zones are usually not
populated on all nodes very often as their memory ranges are constrained.

This is an attempt to reduce the ballast that doesn't provide any relevant
information for those allocation failures investigation. Please note that
I have only compile tested it (in my default config setup) and I am
throwing it mostly to see what people think about it.

[1] http://lkml.kernel.org/r/20220817060647.1032426-1-hch@lst.de

[mhocko@suse.com: update]
Link: https://lkml.kernel.org/r/Yw29bmJTIkKogTiW@dhcp22.suse.cz
[mhocko@suse.com: fix build]
[akpm@linux-foundation.org: fix it for mapletree]
[akpm@linux-foundation.org: update it for Michal's update]
[mhocko@suse.com: fix arch/powerpc/xmon/xmon.c]
Link: https://lkml.kernel.org/r/Ywh3C4dKB9B93jIy@dhcp22.suse.cz
[akpm@linux-foundation.org: fix arch/sparc/kernel/setup_32.c]
Link: https://lkml.kernel.org/r/YwScVmVofIZkopkF@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove BUG_ON() in __isolate_free_page()

Drop unneed comment and blank, adjust the variable, and the most important
is to delete BUG_ON(). The page passed is always buddy page into
__isolate_free_page() from compaction, page_isolation and page_reporting,
and the caller also check the return, BUG_ON() is a too drastic measure,
remove it.

Link: https://lkml.kernel.org/r/20220901015043.189276-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc.c: delete a redundant parameter of rmqueue_pcplist

The gfp_flags parameter is not used in rmqueue_pcplist, so directly delete
this parameter.

Link: https://lkml.kernel.org/r/20220831013404.3360714-1-zuoze1@huawei.com
Signed-off-by: zezuo <zuoze1@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix null-ptr-deref in kswapd_is_running()

kswapd_run/stop() will set pgdat->kswapd to NULL, which could race with
kswapd_is_running() in kcompactd(),

kswapd_run/stop() kcompactd()
kswapd_is_running()
pgdat->kswapd // error or nomal ptr
verify pgdat->kswapd
// load non-NULL
pgdat->kswapd
pgdat->kswapd = NULL
task_is_running(pgdat->kswapd)
// Null pointer derefence

KASAN reports the null-ptr-deref shown below,

vmscan: Failed to start kswapd on node 0
...
BUG: KASAN: null-ptr-deref in kcompactd+0x440/0x504
Read of size 8 at addr 0000000000000024 by task kcompactd0/37

CPU: 0 PID: 37 Comm: kcompactd0 Kdump: loaded Tainted: G OE 5.10.60 #1
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
Call trace:
dump_backtrace+0x0/0x394
show_stack+0x34/0x4c
dump_stack+0x158/0x1e4
__kasan_report+0x138/0x140
kasan_report+0x44/0xdc
__asan_load8+0x94/0xd0
kcompactd+0x440/0x504
kthread+0x1a4/0x1f0
ret_from_fork+0x10/0x18

At present kswapd/kcompactd_run() and kswapd/kcompactd_stop() are protected
by mem_hotplug_begin/done(), but without kcompactd(). There is no need to
involve memory hotplug lock in kcompactd(), so let's add a new mutex to
protect pgdat->kswapd accesses.

Also, because the kcompactd task will check the state of kswapd task, it's
better to call kcompactd_stop() before kswapd_stop() to reduce lock
conflicts.

[akpm@linux-foundation.org: add comments]
Link: https://lkml.kernel.org/r/20220827111959.186838-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

page_ext: introduce boot parameter 'early_page_ext'

In commit 2f1ee0913ce5 ("Revert "mm: use early_pfn_to_nid in
page_ext_init""), we call page_ext_init() after page_alloc_init_late() to
avoid some panic problem. It seems that we cannot track early page
allocations in current kernel even if page structure has been initialized
early.

This patch introduces a new boot parameter 'early_page_ext' to resolve
this problem. If we pass it to the kernel, page_ext_init() will be moved
up and the feature 'deferred initialization of struct pages' will be
disabled to initialize the page allocator early and prevent the panic
problem above. It can help us to catch early page allocations. This is
useful especially when we find that the free memory value is not the same
right after different kernel booting.

[akpm@linux-foundation.org: fix section issue by removing __meminitdata]
Link: https://lkml.kernel.org/r/20220825102714.669-1-lizhe.67@bytedance.com
Signed-off-by: Li Zhe <lizhe.67@bytedance.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: kill find_min_pfn_with_active_regions()

find_min_pfn_with_active_regions() is only called from free_area_init().
Open-code the PHYS_PFN(memblock_start_of_DRAM()) into free_area_init(),
and kill find_min_pfn_with_active_regions().

Link: https://lkml.kernel.org/r/20220815111017.39341-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: only search higher order when fallback

It seems unnecessary to search pages with order < alloc_order in
fallback allocation.

This can currently happen with ALLOC_NOFRAGMENT and alloc_order >
pageblock_order, so add a test to prevent it.

[vbabka@suse.cz: changelog addition]
Link: https://lkml.kernel.org/r/20220803025121.47018-1-wuyun.abel@bytedance.com
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

page_alloc: remove inactive initialization

The allocation address of the table pointer variable is first performed in
the function, no initialization assignment is required, and no invalid
pointer will appear.

Link: https://lkml.kernel.org/r/20220803064118.3664-1-kunyu@nfschina.com
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses.

We keep track of several kernel memory stats (total kernel memory, page
tables, stack, vmalloc, etc) on multiple levels (global, per-node,
per-memcg, etc). These stats give insights to users to how much memory
is used by the kernel and for what purposes.

Currently, memory used by KVM mmu is not accounted in any of those
kernel memory stats. This patch series accounts the memory pages
used by KVM for page tables in those stats in a new
NR_SECONDARY_PAGETABLE stat. This stat can be later extended to account
for other types of secondary pages tables (e.g. iommu page tables).

KVM has a decent number of large allocations that aren't for page
tables, but for most of them, the number/size of those allocations
scales linearly with either the number of vCPUs or the amount of memory
assigned to the VM. KVM's secondary page table allocations do not scale
linearly, especially when nested virtualization is in use.

From a KVM perspective, NR_SECONDARY_PAGETABLE will scale with KVM's
per-VM pages_{4k,2m,1g} stats unless the guest is doing something
bizarre (e.g. accessing only 4kb chunks of 2mb pages so that KVM is
forced to allocate a large number of page tables even though the guest
isn't accessing that much memory). However, someone would need to either
understand how KVM works to make that connection, or know (or be told) to
go look at KVM's stats if they're running VMs to better decipher the stats.

Furthermore, having NR_PAGETABLE side-by-side with NR_SECONDARY_PAGETABLE
is informative. For example, when backing a VM with THP vs. HugeTLB,
NR_SECONDARY_PAGETABLE is roughly the same, but NR_PAGETABLE is an order
of magnitude higher with THP. So having this stat will at the very least
prove to be useful for understanding tradeoffs between VM backing types,
and likely even steer folks towards potential optimizations.

The original discussion with more details about the rationale:
https://lore.kernel.org/all/87ilqoi77b.wl-maz@kernel.org

This stat will be used by subsequent patches to count KVM mmu
memory usage.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220823004639.2387269-2-yosryahmed@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

mm: prevent page_frag_alloc() from corrupting the memory

A number of drivers call page_frag_alloc() with a fragment's size >
PAGE_SIZE.

In low memory conditions, __page_frag_cache_refill() may fail the order
3 cache allocation and fall back to order 0; In this case, the cache
will be smaller than the fragment, causing memory corruptions.

Prevent this from happening by checking if the newly allocated cache is
large enough for the fragment; if not, the allocation will fail and
page_frag_alloc() will return NULL.

Link: https://lkml.kernel.org/r/20220715125013.247085-1-mlombard@redhat.com
Fixes: b63ae8ca096d ("mm/net: Rename and move page fragment handling from net/ to mm/")
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Cc: Chen Lin <chen45464546@163.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix race condition between build_all_zonelists and page allocation

Patrick Daly reported the following problem;

NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - before offline operation
[0] - ZONE_MOVABLE
[1] - ZONE_NORMAL
[2] - NULL

For a GFP_KERNEL allocation, alloc_pages_slowpath() will save the
offset of ZONE_NORMAL in ac->preferred_zoneref. If a concurrent
memory_offline operation removes the last page from ZONE_MOVABLE,
build_all_zonelists() & build_zonerefs_node() will update
node_zonelists as shown below. Only populated zones are added.

NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - after offline operation
[0] - ZONE_NORMAL
[1] - NULL
[2] - NULL

The race is simple -- page allocation could be in progress when a memory
hot-remove operation triggers a zonelist rebuild that removes zones. The
allocation request will still have a valid ac->preferred_zoneref that is
now pointing to NULL and triggers an OOM kill.

This problem probably always existed but may be slightly easier to trigger
due to 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones
with pages managed by the buddy allocator") which distinguishes between
zones that are completely unpopulated versus zones that have valid pages
not managed by the buddy allocator (e.g. reserved, memblock, ballooning
etc). Memory hotplug had multiple stages with timing considerations
around managed/present page updates, the zonelist rebuild and the zone
span updates. As David Hildenbrand puts it

memory offlining adjusts managed+present pages of the zone
essentially in one go. If after the adjustments, the zone is no
longer populated (present==0), we rebuild the zone lists.

Once that's done, we try shrinking the zone (start+spanned
pages) -- which results in zone_start_pfn == 0 if there are no
more pages. That happens *after* rebuilding the zonelists via
remove_pfn_range_from_zone().

The only requirement to fix the race is that a page allocation request
identifies when a zonelist rebuild has happened since the allocation
request started and no page has yet been allocated. Use a seqlock_t to
track zonelist updates with a lockless read-side of the zonelist and
protecting the rebuild and update of the counter with a spinlock.

[akpm@linux-foundation.org: make zonelist_update_seq static]
Link: https://lkml.kernel.org/r/20220824110900.vh674ltxmzb3proq@techsingularity.net
Fixes: 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Patrick Daly <quic_pdaly@quicinc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org> [4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: correct the wrong cpuset file path in comment

cpuset.c was moved to kernel/cgroup/ in below commit
201af4c0fab0 ("cgroup: move cgroup files under kernel/cgroup/")
Correct the wrong path in comment.

Link: https://lkml.kernel.org/r/20220718120336.5145-1-mark-pk.tsai@mediatek.com
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use try_cmpxchg in set_pfnblock_flags_mask

Use try_cmpxchg instead of cmpxchg in set_pfnblock_flags_mask. x86
CMPXCHG instruction returns success in ZF flag, so this change saves a
compare after cmpxchg (and related move instruction in front of cmpxchg).
The main loop improves from:

1c5d: 48 89 c2 mov %rax,%rdx
1c60: 48 89 c1 mov %rax,%rcx
1c63: 48 21 fa and %rdi,%rdx
1c66: 4c 09 c2 or %r8,%rdx
1c69: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi)
1c6e: 48 39 c1 cmp %rax,%rcx
1c71: 75 ea jne 1c5d <...>

to:

1c60: 48 89 ca mov %rcx,%rdx
1c63: 48 21 c2 and %rax,%rdx
1c66: 4c 09 c2 or %r8,%rdx
1c69: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi)
1c6e: 75 f0 jne 1c60 <...>

Link: https://lkml.kernel.org/r/20220708140736.8737-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, hugetlb: skip irrelevant nodes in show_free_areas()

show_free_areas() allows to filter out node specific data which is
irrelevant to the allocation request. But hugetlb_show_meminfo() still
shows hugetlb on all nodes, which is redundant and unnecessary.

Use show_mem_node_skip() to skip irrelevant nodes. And replace
hugetlb_show_meminfo() with hugetlb_show_meminfo_node(nid).

before-and-after sample output of OOM:

before:
```
[ 214.362453] Node 1 active_anon:148kB inactive_anon:4050920kB active_file:112kB inactive_file:100kB
[ 214.375429] Node 1 Normal free:45100kB boost:0kB min:45576kB low:56968kB high:68360kB reserved_hig
[ 214.388334] lowmem_reserve[]: 0 0 0 0 0
[ 214.390251] Node 1 Normal: 423*4kB (UE) 320*8kB (UME) 187*16kB (UE) 117*32kB (UE) 57*64kB (UME) 20
[ 214.397626] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[ 214.401518] Node 1 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
```

after:
```
[ 145.069705] Node 1 active_anon:128kB inactive_anon:4049412kB active_file:56kB inactive_file:84kB u
[ 145.110319] Node 1 Normal free:45424kB boost:0kB min:45576kB low:56968kB high:68360kB reserved_hig
[ 145.152315] lowmem_reserve[]: 0 0 0 0 0
[ 145.155244] Node 1 Normal: 470*4kB (UME) 373*8kB (UME) 247*16kB (UME) 168*32kB (UE) 86*64kB (UME)
[ 145.164119] Node 1 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
```

Link: https://lkml.kernel.org/r/20220706034655.1834-1-ligang.bdlg@bytedance.com
Signed-off-by: Gang Li <ligang.bdlg@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: replace local_lock with normal spinlock

struct per_cpu_pages is no longer strictly local as PCP lists can be
drained remotely using a lock for protection. While the use of local_lock
works, it goes against the intent of local_lock which is for "pure CPU
local concurrency control mechanisms and not suited for inter-CPU
concurrency control" (Documentation/locking/locktypes.rst)

local_lock protects against migration between when the percpu pointer is
accessed and the pcp->lock acquired. The lock acquisition is a preemption
point so in the worst case, a task could migrate to another NUMA node and
accidentally allocate remote memory. The main requirement is to pin the
task to a CPU that is suitable for PREEMPT_RT and !PREEMPT_RT.

Replace local_lock with helpers that pin a task to a CPU, lookup the
per-cpu structure and acquire the embedded lock. It's similar to
local_lock without breaking the intent behind the API. It is not a
complete API as only the parts needed for PCP-alloc are implemented but in
theory, the generic helpers could be promoted to a general API if there
was demand for an embedded lock within a per-cpu struct with a guarantee
that the per-cpu structure locked matches the running CPU and cannot use
get_cpu_var due to RT concerns. PCP requires these semantics to avoid
accidentally allocating remote memory.

[mgorman@techsingularity.net: use pcp_spin_trylock_irqsave instead of pcpu_spin_trylock_irqsave]
Link: https://lkml.kernel.org/r/20220627084645.GA27531@techsingularity.net
Link: https://lkml.kernel.org/r/20220624125423.6126-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remotely drain per-cpu lists

Some setups, notably NOHZ_FULL CPUs, are too busy to handle the per-cpu
drain work queued by __drain_all_pages(). So introduce a new mechanism to
remotely drain the per-cpu lists. It is made possible by remotely locking
'struct per_cpu_pages' new per-cpu spinlocks. A benefit of this new
scheme is that drain operations are now migration safe.

There was no observed performance degradation vs. the previous scheme.
Both netperf and hackbench were run in parallel to triggering the
__drain_all_pages(NULL, true) code path around ~100 times per second. The
new scheme performs a bit better (~5%), although the important point here
is there are no performance regressions vs. the previous mechanism.
Per-cpu lists draining happens only in slow paths.

Minchan Kim tested an earlier version and reported;

My workload is not NOHZ CPUs but run apps under heavy memory
pressure so they goes to direct reclaim and be stuck on
drain_all_pages until work on workqueue run.

unit: nanosecond
max(dur) avg(dur) count(dur)
166713013 487511.77786438033 1283

From traces, system encountered the drain_all_pages 1283 times and
worst case was 166ms and avg was 487us.

The other problem was alloc_contig_range in CMA. The PCP draining
takes several hundred millisecond sometimes though there is no
memory pressure or a few of pages to be migrated out but CPU were
fully booked.

Your patch perfectly removed those wasted time.

Link: https://lkml.kernel.org/r/20220624125423.6126-7-mgorman@techsingularity.net
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Yu Zhao <yuzhao@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: protect PCP lists with a spinlock

Currently the PCP lists are protected by using local_lock_irqsave to
prevent migration and IRQ reentrancy but this is inconvenient. Remote
draining of the lists is impossible and a workqueue is required and every
task allocation/free must disable then enable interrupts which is
expensive.

As preparation for dealing with both of those problems, protect the
lists with a spinlock. The IRQ-unsafe version of the lock is used
because IRQs are already disabled by local_lock_irqsave. spin_trylock
is used in combination with local_lock_irqsave() but later will be
replaced with a spin_trylock_irqsave when the local_lock is removed.

The per_cpu_pages still fits within the same number of cache lines after
this patch relative to before the series.

struct per_cpu_pages {
spinlock_t lock; /* 0 4 */
int count; /* 4 4 */
int high; /* 8 4 */
int batch; /* 12 4 */
short int free_factor; /* 16 2 */
short int expire; /* 18 2 */

/* XXX 4 bytes hole, try to pack */

struct list_head lists[13]; /* 24 208 */

/* size: 256, cachelines: 4, members: 7 */
/* sum members: 228, holes: 1, sum holes: 4 */
/* padding: 24 */
} __attribute__((__aligned__(64)));

There is overhead in the fast path due to acquiring the spinlock even
though the spinlock is per-cpu and uncontended in the common case. Page
Fault Test (PFT) running on a 1-socket reported the following results on a
1 socket machine.

5.19.0-rc3 5.19.0-rc3
vanilla mm-pcpspinirq-v5r16
Hmean faults/sec-1 869275.7381 ( 0.00%) 874597.5167 * 0.61%*
Hmean faults/sec-3 2370266.6681 ( 0.00%) 2379802.0362 * 0.40%*
Hmean faults/sec-5 2701099.7019 ( 0.00%) 2664889.7003 * -1.34%*
Hmean faults/sec-7 3517170.9157 ( 0.00%) 3491122.8242 * -0.74%*
Hmean faults/sec-8 3965729.6187 ( 0.00%) 3939727.0243 * -0.66%*

There is a small hit in the number of faults per second but given that the
results are more stable, it's borderline noise.

[akpm@linux-foundation.org: add missing local_unlock_irqrestore() on contention path]
Link: https://lkml.kernel.org/r/20220624125423.6126-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: remove mistaken page == NULL check in rmqueue

If a page allocation fails, the ZONE_BOOSTER_WATERMARK should be tested,
cleared and kswapd woken whether the allocation attempt was via the PCP or
directly via the buddy list.

Remove the page == NULL so the ZONE_BOOSTED_WATERMARK bit is checked
unconditionally. As it is unlikely that ZONE_BOOSTED_WATERMARK is set,
mark the branch accordingly.

Link: https://lkml.kernel.org/r/20220624125423.6126-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: split out buddy removal code from rmqueue into separate helper

This is a preparation page to allow the buddy removal code to be reused in
a later patch.

No functional change.

Link: https://lkml.kernel.org/r/20220624125423.6126-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use only one PCP list for THP-sized allocations

The per_cpu_pages is cache-aligned on a standard x86-64 distribution
configuration but a later patch will add a new field which would push the
structure into the next cache line. Use only one list to store THP-sized
pages on the per-cpu list. This assumes that the vast majority of
THP-sized allocations are GFP_MOVABLE but even if it was another type, it
would not contribute to serious fragmentation that potentially causes a
later THP allocation failure. Align per_cpu_pages on the cacheline
boundary to ensure there is no false cache sharing.

After this patch, the structure sizing is;

struct per_cpu_pages {
int count; /* 0 4 */
int high; /* 4 4 */
int batch; /* 8 4 */
short int free_factor; /* 12 2 */
short int expire; /* 14 2 */
struct list_head lists[13]; /* 16 208 */

/* size: 256, cachelines: 4, members: 6 */
/* padding: 32 */
} __attribute__((__aligned__(64)));

Link: https://lkml.kernel.org/r/20220624125423.6126-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: add page->buddy_list and page->pcp_list

Patch series "Drain remote per-cpu directly", v5.

Some setups, notably NOHZ_FULL CPUs, may be running realtime or
latency-sensitive applications that cannot tolerate interference due to
per-cpu drain work queued by __drain_all_pages(). Introduce a new
mechanism to remotely drain the per-cpu lists. It is made possible by
remotely locking 'struct per_cpu_pages' new per-cpu spinlocks. This has
two advantages, the time to drain is more predictable and other unrelated
tasks are not interrupted.

This series has the same intent as Nicolas' series "mm/page_alloc: Remote
per-cpu lists drain support" -- avoid interference of a high priority task
due to a workqueue item draining per-cpu page lists. While many workloads
can tolerate a brief interruption, it may cause a real-time task running
on a NOHZ_FULL CPU to miss a deadline and at minimum, the draining is
non-deterministic.

Currently an IRQ-safe local_lock protects the page allocator per-cpu
lists. The local_lock on its own prevents migration and the IRQ disabling
protects from corruption due to an interrupt arriving while a page
allocation is in progress.

This series adjusts the locking. A spinlock is added to struct
per_cpu_pages to protect the list contents while local_lock_irq is
ultimately replaced by just the spinlock in the final patch. This allows
a remote CPU to safely. Follow-on work should allow the spin_lock_irqsave
to be converted to spin_lock to avoid IRQs being disabled/enabled in most
cases. The follow-on patch will be one kernel release later as it is
relatively high risk and it'll make bisections more clear if there are any
problems.

Patch 1 is a cosmetic patch to clarify when page->lru is storing buddy pages
and when it is storing per-cpu pages.

Patch 2 shrinks per_cpu_pages to make room for a spin lock. Strictly speaking
this is not necessary but it avoids per_cpu_pages consuming another
cache line.

Patch 3 is a preparation patch to avoid code duplication.

Patch 4 is a minor correction.

Patch 5 uses a spin_lock to protect the per_cpu_pages contents while still
relying on local_lock to prevent migration, stabilise the pcp
lookup and prevent IRQ reentrancy.

Patch 6 remote drains per-cpu pages directly instead of using a workqueue.

Patch 7 uses a normal spinlock instead of local_lock for remote draining


This patch (of 7):

The page allocator uses page->lru for storing pages on either buddy or PCP
lists. Create page->buddy_list and page->pcp_list as a union with
page->lru. This is simply to clarify what type of list a page is on in
the page allocator.

No functional change intended.

[minchan@kernel.org: fix page lru fields in macros]
Link: https://lkml.kernel.org/r/20220624125423.6126-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make the annotations of available memory more accurate

Not all systems use swap, so estimating available memory would help to
prevent swapping or OOM of system that not use swap.

And we need to reserve some page cache to prevent swapping or thrashing.
If somebody is accessing the pages in pagecache, and if too much would be
freed, most accesses might mean reading data from disk, i.e. thrashing.

Link: https://lkml.kernel.org/r/20220623020833.972979-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert destroy_compound_page() to destroy_large_folio()

All callers now have a folio, so push the folio->page conversion
down to this function.

[akpm@linux-foundation.org: uninline destroy_large_folio() to fix build issue]
Link: https://lkml.kernel.org/r/20220617175020.717127-20-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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: rename kernel_init_free_pages to kernel_init_pages

Rename kernel_init_free_pages() to kernel_init_pages(). This function is
not only used for free pages but also for pages that were just allocated.

Link: https://lkml.kernel.org/r/1ecaffc0a9c1404d4d7cf52efe0b2dc8a0c681d8.1654798516.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.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/page_alloc: use might_alloc()

... instead of open coding it. Completely equivalent code, just a notch
more meaningful when reading.

Link: https://lkml.kernel.org/r/20220605152539.3196045-1-daniel.vetter@ffwll.ch
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

memblock: Disable mirror feature if kernelcore is not specified

If system have some mirrored memory and mirrored feature is not specified
in boot parameter, the basic mirrored feature will be enabled and this will
lead to the following situations:

- memblock memory allocation prefers mirrored region. This may have some
unexpected influence on numa affinity.

- contiguous memory will be split into several parts if parts of them
is mirrored memory via memblock_mark_mirror().

To fix this, variable mirrored_kernelcore will be checked in
memblock_mark_mirror(). Mark mirrored memory with flag MEMBLOCK_MIRROR iff
kernelcore=mirror is added in the kernel parameters.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220614092156.1972846-6-mawupeng1@huawei.com
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

mm: kasan: Skip page unpoisoning only if __GFP_SKIP_KASAN_UNPOISON

Currently post_alloc_hook() skips the kasan unpoisoning if the tags will
be zeroed (__GFP_ZEROTAGS) or __GFP_SKIP_KASAN_UNPOISON is passed. Since
__GFP_ZEROTAGS is now accompanied by __GFP_SKIP_KASAN_UNPOISON, remove
the extra check.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-4-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

mm: kasan: Skip unpoisoning of user pages

Commit c275c5c6d50a ("kasan: disable freed user page poisoning with HW
tags") added __GFP_SKIP_KASAN_POISON to GFP_HIGHUSER_MOVABLE. A similar
argument can be made about unpoisoning, so also add
__GFP_SKIP_KASAN_UNPOISON to user pages. To ensure the user page is
still accessible via page_address() without a kasan fault, reset the
page->flags tag.

With the above changes, there is no need for the arm64
tag_clear_highpage() to reset the page->flags tag.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-3-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

page_alloc: fix invalid watermark check on a negative value

There was a report that a task is waiting at the
throttle_direct_reclaim. The pgscan_direct_throttle in vmstat was
increasing.

This is a bug where zone_watermark_fast returns true even when the free
is very low. The commit f27ce0e14088 ("page_alloc: consider highatomic
reserve in watermark fast") changed the watermark fast to consider
highatomic reserve. But it did not handle a negative value case which
can be happened when reserved_highatomic pageblock is bigger than the
actual free.

If watermark is considered as ok for the negative value, allocating
contexts for order-0 will consume all free pages without direct reclaim,
and finally free page may become depleted except highatomic free.

Then allocating contexts may fall into throttle_direct_reclaim. This
symptom may easily happen in a system where wmark min is low and other
reclaimers like kswapd does not make free pages quickly.

Handle the negative case by using MIN.

Link: https://lkml.kernel.org/r/20220725095212.25388-1-jaewon31.kim@samsung.com
Fixes: f27ce0e14088 ("page_alloc: consider highatomic reserve in watermark fast")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: GyeongHwan Hong <gh21.hong@samsung.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kerenl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix is_pinnable_page against a cma page

Pages in the CMA area could have MIGRATE_ISOLATE as well as MIGRATE_CMA so
the current is_pinnable_page() could miss CMA pages which have
MIGRATE_ISOLATE. It ends up pinning CMA pages as longterm for the
pin_user_pages() API so CMA allocations keep failing until the pin is
released.

CPU 0 CPU 1 - Task B

cma_alloc
alloc_contig_range
pin_user_pages_fast(FOLL_LONGTERM)
change pageblock as MIGRATE_ISOLATE
internal_get_user_pages_fast
lockless_pages_from_mm
gup_pte_range
try_grab_folio
is_pinnable_page
return true;
So, pinned the page successfully.
page migration failure with pinned page
..
.. After 30 sec
unpin_user_page(page)

CMA allocation succeeded after 30 sec.

The CMA allocation path protects the migration type change race using
zone->lock but what GUP path need to know is just whether the page is on
CMA area or not rather than exact migration type. Thus, we don't need
zone->lock but just checks migration type in either of (MIGRATE_ISOLATE
and MIGRATE_CMA).

Adding the MIGRATE_ISOLATE check in is_pinnable_page could cause rejecting
of pinning pages on MIGRATE_ISOLATE pageblocks even though it's neither
CMA nor movable zone if the page is temporarily unmovable. However, such
a migration failure by unexpected temporal refcount holding is general
issue, not only come from MIGRATE_ISOLATE and the MIGRATE_ISOLATE is also
transient state like other temporal elevated refcount problem.

Link: https://lkml.kernel.org/r/20220524171525.976723-1-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: split free page with properly free memory accounting and without race

In isolate_single_pageblock(), free pages are checked without holding zone
lock, but they can go away in split_free_page() when zone lock is held.
Check the free page and its order again in split_free_page() when zone lock
is held. Recheck the page if the free page is gone under zone lock.

In addition, in split_free_page(), the free page was deleted from the page
list without changing free page accounting. Add the missing free page
accounting code.

Fix the type of order parameter in split_free_page().

Link: https://lore.kernel.org/lkml/20220525103621.987185e2ca0079f7b97b856d@linux-foundation.org/
Link: https://lkml.kernel.org/r/20220526231531.2404977-2-zi.yan@sent.com
Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Doug Berger <opendmb@gmail.com>
Link: https://lore.kernel.org/linux-mm/c3932a6f-77fe-29f7-0c29-fe6b1c67ab7b@gmail.com/
Cc: David Hildenbrand <david@redhat.com>
Cc: Qian Cai <quic_qiancai@quicinc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michael Walle <michael@walle.cc>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: always attempt to allocate at least one page during bulk allocation

Peter Pavlisko reported the following problem on kernel bugzilla 216007.

When I try to extract an uncompressed tar archive (2.6 milion
files, 760.3 GiB in size) on newly created (empty) XFS file system,
after first low tens of gigabytes extracted the process hangs in
iowait indefinitely. One CPU core is 100% occupied with iowait,
the other CPU core is idle (on 2-core Intel Celeron G1610T).

It was bisected to c9fa563072e1 ("xfs: use alloc_pages_bulk_array() for
buffers") but XFS is only the messenger. The problem is that nothing is
waking kswapd to reclaim some pages at a time the PCP lists cannot be
refilled until some reclaim happens. The bulk allocator checks that there
are some pages in the array and the original intent was that a bulk
allocator did not necessarily need all the requested pages and it was best
to return as quickly as possible.

This was fine for the first user of the API but both NFS and XFS require
the requested number of pages be available before making progress. Both
could be adjusted to call the page allocator directly if a bulk allocation
fails but it puts a burden on users of the API. Adjust the semantics to
attempt at least one allocation via __alloc_pages() before returning so
kswapd is woken if necessary.

It was reported via bugzilla that the patch addressed the problem and that
the tar extraction completed successfully. This may also address bug
215975 but has yet to be confirmed.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216007
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215975
Link: https://lkml.kernel.org/r/20220526091210.GC3441@techsingularity.net
Fixes: 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: <stable@vger.kernel.org> [5.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix a potential infinite loop in start_isolate_page_range()

In isolate_single_pageblock() called by start_isolate_page_range(), there
are some pageblock isolation issues causing a potential infinite loop when
isolating a page range. This is reported by Qian Cai.

1. the pageblock was isolated by just changing pageblock migratetype
without checking unmovable pages. Calling set_migratetype_isolate() to
isolate pageblock properly.
2. an off-by-one error caused migrating pages unnecessarily, since the page
is not crossing pageblock boundary.
3. migrating a compound page across pageblock boundary then splitting the
free page later has a small race window that the free page might be
allocated again, so that the code will try again, causing an potential
infinite loop. Temporarily set the to-be-migrated page's pageblock to
MIGRATE_ISOLATE to prevent that and bail out early if no free page is
found after page migration.

An additional fix to split_free_page() aims to avoid crashing in
__free_one_page(). When the free page is split at the specified
split_pfn_offset, free_page_order should check both the first bit of
free_page_pfn and the last bit of split_pfn_offset and use the smaller
one. For example, if free_page_pfn=0x10000, split_pfn_offset=0xc000,
free_page_order should first be 0x8000 then 0x4000, instead of 0x4000 then
0x8000, which the original algorithm did.

[akpm@linux-foundation.org: suppress min() warning]
Link: https://lkml.kernel.org/r/20220524194756.1698351-1-zi.yan@sent.com
Fixes: b2c9e2fbba3253 ("mm: make alloc_contig_range work at pageblock granularity")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix missing handler for __GFP_NOWARN

We expect no warnings to be issued when we specify __GFP_NOWARN, but
currently in paths like alloc_pages() and kmalloc(), there are still some
warnings printed, fix it.

But for some warnings that report usage problems, we don't deal with them.
If such warnings are printed, then we should fix the usage problems.
Such as the following case:

WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));

[zhengqi.arch@bytedance.com: v2]
Link: https://lkml.kernel.org/r/20220511061951.1114-1-zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/20220510113809.80626-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix tracepoint mm_page_alloc_zone_locked()

Currently, trace point mm_page_alloc_zone_locked() doesn't show correct
information.

First, when alloc_flag has ALLOC_HARDER/ALLOC_CMA, page can be allocated
from MIGRATE_HIGHATOMIC/MIGRATE_CMA. Nevertheless, tracepoint use
requested migration type not MIGRATE_HIGHATOMIC and MIGRATE_CMA.

Second, after commit 44042b4498728 ("mm/page_alloc: allow high-order pages
to be stored on the per-cpu lists") percpu-list can store high order
pages. But trace point determine whether it is a refiil of percpu-list by
comparing requested order and 0.

To handle these problems, make mm_page_alloc_zone_locked() only be called
by __rmqueue_smallest with correct migration type. With a new argument
called percpu_refill, it can show roughly whether it is a refill of
percpu-list.

Link: https://lkml.kernel.org/r/20220512025307.57924-1-vvghjk1234@gmail.com
Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Baik Song An <bsahn@etri.re.kr>
Cc: Hong Yeon Kim <kimhy@etri.re.kr>
Cc: Taeung Song <taeung@reallinux.co.kr>
Cc: <linuxgeek@linuxgeek.io>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c: simplify num_poisoned_pages_dec

Don't decrease the number of poisoned pages in page_alloc.c, let the
memory-failure.c do inc/dec poisoned pages only.

Also simplify unpoison_memory(), only decrease the number of
poisoned pages when:
- TestClearPageHWPoison() succeed
- put_page_back_buddy succeed

After decreasing, print necessary log.

Finally, remove clear_page_hwpoison() and unpoison_taken_off_page().

Link: https://lkml.kernel.org/r/20220509105641.491313-3-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: cma: use pageblock_order as the single alignment

Now alloc_contig_range() works at pageblock granularity. Change CMA
allocation, which uses alloc_contig_range(), to use pageblock_nr_pages
alignment.

Link: https://lkml.kernel.org/r/20220425143118.2850746-6-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_isolation: enable arbitrary range page isolation.

Now start_isolate_page_range() is ready to handle arbitrary range
isolation, so move the alignment check/adjustment into the function body.
Do the same for its counterpart undo_isolate_page_range().
alloc_contig_range(), its caller, can pass an arbitrary range instead of a
MAX_ORDER_NR_PAGES aligned one.

Link: https://lkml.kernel.org/r/20220425143118.2850746-5-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: make alloc_contig_range work at pageblock granularity

alloc_contig_range() worked at MAX_ORDER_NR_PAGES granularity to avoid
merging pageblocks with different migratetypes. It might unnecessarily
convert extra pageblocks at the beginning and at the end of the range.
Change alloc_contig_range() to work at pageblock granularity.

Special handling is needed for free pages and in-use pages across the
boundaries of the range specified by alloc_contig_range(). Because these=

Partially isolated pages causes free page accounting issues. The free
pages will be split and freed into separate migratetype lists; the in-use=

Pages will be migrated then the freed pages will be handled in the
aforementioned way.

[ziy@nvidia.com: fix deadlock/crash]
Link: https://lkml.kernel.org/r/23A7297E-6C84-4138-A9FE-3598234004E6@nvidia.com
Link: https://lkml.kernel.org/r/20220425143118.2850746-4-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>