mm/codetag: move tag retrieval back upfront in __free_pages()

Commit 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled()
checks") introduces a possible use-after-free scenario, when page
i

mm/codetag: move tag retrieval back upfront in __free_pages()

Commit 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled()
checks") introduces a possible use-after-free scenario, when page
is non-compound, page[0] could be released by other thread right
after put_page_testzero failed in current thread, pgalloc_tag_sub_pages
afterwards would manipulate an invalid page for accounting remaining
pages:

[timeline] [thread1] [thread2]
| alloc_page non-compound
V
| get_page, rf counter inc
V
| in ___free_pages
| put_page_testzero fails
V
| put_page, page released
V
| in ___free_pages,
| pgalloc_tag_sub_pages
| manipulate an invalid page
V

Restore __free_pages() to its state before, retrieve alloc tag
beforehand.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled() checks")
Signed-off-by: David Wang <[email protected]>
Acked-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Brendan Jackman <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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alloc_tag: uninline code gated by mem_alloc_profiling_key in page allocator

When a sizable code section is protected by a disabled static key, that
code gets into the instruction cache even though i

alloc_tag: uninline code gated by mem_alloc_profiling_key in page allocator

When a sizable code section is protected by a disabled static key, that
code gets into the instruction cache even though it's not executed and
consumes the cache, increasing cache misses. This can be remedied by
moving such code into a separate uninlined function.
On a Pixel6 phone, page allocation profiling overhead measured with
CONFIG_MEM_ALLOC_PROFILING=y and profiling disabled is:

baseline modified
Big core 4.93% 1.53%
Medium core 4.39% 1.41%
Little core 1.02% 0.36%

This improvement comes at the expense of the configuration when profiling
gets enabled, since there is now an additional function call. The overhead
from this additional call on Pixel6 is:

Big core 0.24%
Middle core 0.63%
Little core 1.1%

However this is negligible when compared with the overall overhead of the
memory allocation profiling when it is enabled.
On x86 this patch does not make noticeable difference because the overhead
with mem_alloc_profiling_key disabled is much lower (under 1%) to start
with, so any improvement is less visible and hard to distinguish from the
noise. The overhead from additional call when profiling is enabled is also
within noise levels.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Cc: David Wang <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: Zhenhua Huang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: avoid extra mem_alloc_profiling_enabled() checks

Refactor code to avoid extra mem_alloc_profiling_enabled() checks inside
pgalloc_tag_get() function which is often called after that check was
al

mm: avoid extra mem_alloc_profiling_enabled() checks

Refactor code to avoid extra mem_alloc_profiling_enabled() checks inside
pgalloc_tag_get() function which is often called after that check was
already done.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Cc: David Wang <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: Zhenhua Huang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm/codetag: swap tags when migrate pages

Current solution to adjust codetag references during page migration is
done in 3 steps:

1. sets the codetag reference of the old page as empty (not pointing

mm/codetag: swap tags when migrate pages

Current solution to adjust codetag references during page migration is
done in 3 steps:

1. sets the codetag reference of the old page as empty (not pointing
to any codetag);

2. subtracts counters of the new page to compensate for its own
allocation;

3. sets codetag reference of the new page to point to the codetag of
the old page.

This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because
set_codetag_empty() becomes NOOP. Instead, let's simply swap codetag
references so that the new page is referencing the old codetag and the old
page is referencing the new codetag. This way accounting stays valid and
the logic makes more sense.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()")
Signed-off-by: David Wang <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Acked-by: Suren Baghdasaryan <[email protected]>
Suggested-by: Suren Baghdasaryan <[email protected]>
Acked-by: Yu Zhao <[email protected]>
Cc: Kent Overstreet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm/codetag: uninline and move pgalloc_tag_copy and pgalloc_tag_split

pgalloc_tag_copy() and pgalloc_tag_split() are sizable and outside of any
performance-critical paths, so it should be fine to uni

mm/codetag: uninline and move pgalloc_tag_copy and pgalloc_tag_split

pgalloc_tag_copy() and pgalloc_tag_split() are sizable and outside of any
performance-critical paths, so it should be fine to uninline them. Also
move their declarations into pgalloc_tag.h which seems like a more
appropriate place for them. No functional changes other than uninlining.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Suggested-by: Andrew Morton <[email protected]>
Acked-by: Yu Zhao <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Sourav Panda <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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alloc_tag: support for page allocation tag compression

Implement support for storing page allocation tag references directly in
the page flags instead of page extensions. sysctl.vm.mem_profiling bo

alloc_tag: support for page allocation tag compression

Implement support for storing page allocation tag references directly in
the page flags instead of page extensions. sysctl.vm.mem_profiling boot
parameter it extended to provide a way for a user to request this mode.
Enabling compression eliminates memory overhead caused by page_ext and
results in better performance for page allocations. However this mode
will not work if the number of available page flag bits is insufficient to
address all kernel allocations. Such condition can happen during boot or
when loading a module. If this condition is detected, memory allocation
profiling gets disabled with an appropriate warning. By default
compression mode is disabled.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Daniel Gomez <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kalesh Singh <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport (Microsoft) <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Petr Pavlu <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sami Tolvanen <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Thomas Huth <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xiongwei Song <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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alloc_tag: introduce pgtag_ref_handle to abstract page tag references

To simplify later changes to page tag references, introduce new
pgtag_ref_handle type. This allows easy replacement of page_ext

alloc_tag: introduce pgtag_ref_handle to abstract page tag references

To simplify later changes to page tag references, introduce new
pgtag_ref_handle type. This allows easy replacement of page_ext as a
storage of page allocation tags.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Daniel Gomez <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kalesh Singh <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport (Microsoft) <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Petr Pavlu <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sami Tolvanen <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Thomas Huth <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xiongwei Song <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm/codetag: fix pgalloc_tag_split()

The current assumption is that a large folio can only be split into
order-0 folios. That is not the case for hugeTLB demotion, nor for THP
split: see commit c010

mm/codetag: fix pgalloc_tag_split()

The current assumption is that a large folio can only be split into
order-0 folios. That is not the case for hugeTLB demotion, nor for THP
split: see commit c010d47f107f ("mm: thp: split huge page to any lower
order pages").

When a large folio is split into ones of a lower non-zero order, only the
new head pages should be tagged. Tagging tail pages can cause imbalanced
"calls" counters, since only head pages are untagged by pgalloc_tag_sub()
and the "calls" counts on tail pages are leaked, e.g.,

# echo 2048kB >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote_size
# echo 700 >/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
# time echo 700 >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote
# echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
# grep alloc_gigantic_folio /proc/allocinfo

Before this patch:
0 549427200 mm/hugetlb.c:1549 func:alloc_gigantic_folio

real 0m2.057s
user 0m0.000s
sys 0m2.051s

After this patch:
0 0 mm/hugetlb.c:1549 func:alloc_gigantic_folio

real 0m1.711s
user 0m0.000s
sys 0m1.704s

Not tagging tail pages also improves the splitting time, e.g., by about
15% when demoting 1GB hugeTLB folios to 2MB ones, as shown above.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: be25d1d4e822 ("mm: create new codetag references during page splitting")
Signed-off-by: Yu Zhao <[email protected]>
Acked-by: Suren Baghdasaryan <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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alloc_tag: introduce clear_page_tag_ref() helper function

In several cases we are freeing pages which were not allocated using
common page allocators. For such cases, in order to keep allocation
ac

alloc_tag: introduce clear_page_tag_ref() helper function

In several cases we are freeing pages which were not allocated using
common page allocators. For such cases, in order to keep allocation
accounting correct, we should clear the page tag to indicate that the page
being freed is expected to not have a valid allocation tag. Introduce
clear_page_tag_ref() helper function to be used for this.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: d224eb0287fb ("codetag: debug: mark codetags for reserved pages as empty")
Signed-off-by: Suren Baghdasaryan <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: <[email protected]> [6.10]
Signed-off-by: Andrew Morton <[email protected]>

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alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting

pgalloc_tag_sub() might call page_ext_put() using a page different from
the one used in page_ext_get() call. This does not po

alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting

pgalloc_tag_sub() might call page_ext_put() using a page different from
the one used in page_ext_get() call. This does not pose an issue since
page_ext_put() ignores this parameter as long as it's non-NULL but
technically this is wrong. Fix it by storing the original page used in
page_ext_get() and passing it to page_ext_put().

Link: https://lkml.kernel.org/r/[email protected]
Fixes: be25d1d4e822 ("mm: create new codetag references during page splitting")
Signed-off-by: Suren Baghdasaryan <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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lib: reuse page_ext_data() to obtain codetag_ref

codetag_ref_from_page_ext() reimplements the same calculation as
page_ext_data(). Reuse existing function instead.

Link: https://lkml.kernel.org/r/

lib: reuse page_ext_data() to obtain codetag_ref

codetag_ref_from_page_ext() reimplements the same calculation as
page_ext_data(). Reuse existing function instead.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging")
Signed-off-by: Suren Baghdasaryan <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Sourav Panda <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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lib/alloc_tag: fix RCU imbalance in pgalloc_tag_get()

put_page_tag_ref() should be called only when get_page_tag_ref() returns a
valid reference because only in that case get_page_tag_ref() enters R

lib/alloc_tag: fix RCU imbalance in pgalloc_tag_get()

put_page_tag_ref() should be called only when get_page_tag_ref() returns a
valid reference because only in that case get_page_tag_ref() enters RCU
read section while put_page_tag_ref() will call rcu_read_unlock() even if
the provided reference is NULL. Fix pgalloc_tag_get() which does not
follow this rule causing RCU imbalance. Add a warning in
put_page_tag_ref() to catch any future mistakes.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: cc92eba1c88b ("mm: fix non-compound multi-order memory accounting in __free_pages")
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Acked-by: Vlastimil Babka <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: make page_ext_get() take a const argument

In order to constify other functions, we need page_ext_get() to be const.
This is no problem as lookup_page_ext() already takes a const argument.

Link

mm: make page_ext_get() take a const argument

In order to constify other functions, we need page_ext_get() to be const.
This is no problem as lookup_page_ext() already takes a const argument.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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codetag: debug: mark codetags for reserved pages as empty

To avoid debug warnings while freeing reserved pages which were not
allocated with usual allocators, mark their codetags as empty before
fre

codetag: debug: mark codetags for reserved pages as empty

To avoid debug warnings while freeing reserved pages which were not
allocated with usual allocators, mark their codetags as empty before
freeing.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: fix non-compound multi-order memory accounting in __free_pages

When a non-compound multi-order page is freed, it is possible that a
speculative reference keeps the page pinned. In this case we

mm: fix non-compound multi-order memory accounting in __free_pages

When a non-compound multi-order page is freed, it is possible that a
speculative reference keeps the page pinned. In this case we free all
pages except for the first page, which will be freed later by the last
put_page(). However the page passed to put_page() is indistinguishable
from an order-0 page, so it cannot do the accounting, just as it cannot
free the subsequent pages. Do the accounting here, where we free the
pages.

Link: https://lkml.kernel.org/r/[email protected]
Reported-by: Vlastimil Babka <[email protected]>
Signed-off-by: Suren Baghdasaryan <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: create new codetag references during page splitting

When a high-order page is split into smaller ones, each newly split page
should get its codetag. After the split each split page will be
refe

mm: create new codetag references during page splitting

When a high-order page is split into smaller ones, each newly split page
should get its codetag. After the split each split page will be
referencing the original codetag. The codetag's "bytes" counter remains
the same because the amount of allocated memory has not changed, however
the "calls" counter gets increased to keep the counter correct when these
individual pages get freed.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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lib: introduce support for page allocation tagging

Introduce helper functions to easily instrument page allocators by storing
a pointer to the allocation tag associated with the code that allocated

lib: introduce support for page allocation tagging

Introduce helper functions to easily instrument page allocators by storing
a pointer to the allocation tag associated with the code that allocated
the page in a page_ext field.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Co-developed-by: Kent Overstreet <[email protected]>
Signed-off-by: Kent Overstreet <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...