Merge tag 'asoc-fix-v6.17-rc2' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v6.17

A few fixes that came in during the past week, there's some upda

Merge tag 'asoc-fix-v6.17-rc2' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v6.17

A few fixes that came in during the past week, there's some updates for
the CS35L56 which adjust the driver for production silicon and a fix for
buggy resume of the ES9389.

show more ...

Merge drm/drm-fixes into drm-misc-fixes

Update drm-misc-fixes to -rc2.

Signed-off-by: Maxime Ripard <mripard@kernel.org>

Merge drm/drm-fixes into drm-misc-fixes

Updating drm-misc-fixes to the state of v6.17-rc1. Begins a new release
cycle.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge tag 'mm-hotfixes-stable-2025-08-12-20-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
"12 hotfixes. 5 are cc:stable and the remainder address

Merge tag 'mm-hotfixes-stable-2025-08-12-20-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
"12 hotfixes. 5 are cc:stable and the remainder address post-6.16
issues or aren't considered necessary for -stable kernels.

10 of these fixes are for MM"

* tag 'mm-hotfixes-stable-2025-08-12-20-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
proc: proc_maps_open allow proc_mem_open to return NULL
mm/mremap: avoid expensive folio lookup on mremap folio pte batch
userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry
mm: pass page directly instead of using folio_page
selftests/proc: fix string literal warning in proc-maps-race.c
fs/proc/task_mmu: hold PTL in pagemap_hugetlb_range and gather_hugetlb_stats
mm/smaps: fix race between smaps_hugetlb_range and migration
mm: fix the race between collapse and PT_RECLAIM under per-vma lock
mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()
MAINTAINERS: add Masami as a reviewer of hung task detector
mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock
kasan/test: fix protection against compiler elision

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selftests/proc: fix string literal warning in proc-maps-race.c

This change resolves non literal string format warning invoked for
proc-maps-race.c while compiling.

proc-maps-race.c:205:17: warning:

selftests/proc: fix string literal warning in proc-maps-race.c

This change resolves non literal string format warning invoked for
proc-maps-race.c while compiling.

proc-maps-race.c:205:17: warning: format not a string literal and no format arguments [-Wformat-security]
205 | printf(text);
| ^~~~~~
proc-maps-race.c:209:17: warning: format not a string literal and no format arguments [-Wformat-security]
209 | printf(text);
| ^~~~~~
proc-maps-race.c: In function `print_last_lines':
proc-maps-race.c:224:9: warning: format not a string literal and no format arguments [-Wformat-security]
224 | printf(start);
| ^~~~~~

Add string format specifier %s for the printf calls in both
print_first_lines() and print_last_lines() thus resolving the warnings.

The test executes fine after this change thus causing no effect to the
functional behavior of the test.

Link: https://lkml.kernel.org/r/20250804225633.841777-1-hsukrut3@gmail.com
Fixes: aadc099c480f ("selftests/proc: add verbose mode for /proc/pid/maps tearing tests")
Signed-off-by: Sukrut Heroorkar <hsukrut3@gmail.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Cc: David Hunter <david.hunter.linux@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

Merge tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
"As usual, many cleanups. The below blurbiage describes 42 patchs

Merge tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
"As usual, many cleanups. The below blurbiage describes 42 patchsets.
21 of those are partially or fully cleanup work. "cleans up",
"cleanup", "maintainability", "rationalizes", etc.

I never knew the MM code was so dirty.

"mm: ksm: prevent KSM from breaking merging of new VMAs" (Lorenzo Stoakes)
addresses an issue with KSM's PR_SET_MEMORY_MERGE mode: newly
mapped VMAs were not eligible for merging with existing adjacent
VMAs.

"mm/damon: introduce DAMON_STAT for simple and practical access monitoring" (SeongJae Park)
adds a new kernel module which simplifies the setup and usage of
DAMON in production environments.

"stop passing a writeback_control to swap/shmem writeout" (Christoph Hellwig)
is a cleanup to the writeback code which removes a couple of
pointers from struct writeback_control.

"drivers/base/node.c: optimization and cleanups" (Donet Tom)
contains largely uncorrelated cleanups to the NUMA node setup and
management code.

"mm: userfaultfd: assorted fixes and cleanups" (Tal Zussman)
does some maintenance work on the userfaultfd code.

"Readahead tweaks for larger folios" (Ryan Roberts)
implements some tuneups for pagecache readahead when it is reading
into order>0 folios.

"selftests/mm: Tweaks to the cow test" (Mark Brown)
provides some cleanups and consistency improvements to the
selftests code.

"Optimize mremap() for large folios" (Dev Jain)
does that. A 37% reduction in execution time was measured in a
memset+mremap+munmap microbenchmark.

"Remove zero_user()" (Matthew Wilcox)
expunges zero_user() in favor of the more modern memzero_page().

"mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes" (David Hildenbrand)
addresses some warts which David noticed in the huge page code.
These were not known to be causing any issues at this time.

"mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD" (SeongJae Park)
provides some cleanup and consolidation work in DAMON.

"use vm_flags_t consistently" (Lorenzo Stoakes)
uses vm_flags_t in places where we were inappropriately using other
types.

"mm/memfd: Reserve hugetlb folios before allocation" (Vivek Kasireddy)
increases the reliability of large page allocation in the memfd
code.

"mm: Remove pXX_devmap page table bit and pfn_t type" (Alistair Popple)
removes several now-unneeded PFN_* flags.

"mm/damon: decouple sysfs from core" (SeongJae Park)
implememnts some cleanup and maintainability work in the DAMON
sysfs layer.

"madvise cleanup" (Lorenzo Stoakes)
does quite a lot of cleanup/maintenance work in the madvise() code.

"madvise anon_name cleanups" (Vlastimil Babka)
provides additional cleanups on top or Lorenzo's effort.

"Implement numa node notifier" (Oscar Salvador)
creates a standalone notifier for NUMA node memory state changes.
Previously these were lumped under the more general memory
on/offline notifier.

"Make MIGRATE_ISOLATE a standalone bit" (Zi Yan)
cleans up the pageblock isolation code and fixes a potential issue
which doesn't seem to cause any problems in practice.

"selftests/damon: add python and drgn based DAMON sysfs functionality tests" (SeongJae Park)
adds additional drgn- and python-based DAMON selftests which are
more comprehensive than the existing selftest suite.

"Misc rework on hugetlb faulting path" (Oscar Salvador)
fixes a rather obscure deadlock in the hugetlb fault code and
follows that fix with a series of cleanups.

"cma: factor out allocation logic from __cma_declare_contiguous_nid" (Mike Rapoport)
rationalizes and cleans up the highmem-specific code in the CMA
allocator.

"mm/migration: rework movable_ops page migration (part 1)" (David Hildenbrand)
provides cleanups and future-preparedness to the migration code.

"mm/damon: add trace events for auto-tuned monitoring intervals and DAMOS quota" (SeongJae Park)
adds some tracepoints to some DAMON auto-tuning code.

"mm/damon: fix misc bugs in DAMON modules" (SeongJae Park)
does that.

"mm/damon: misc cleanups" (SeongJae Park)
also does what it claims.

"mm: folio_pte_batch() improvements" (David Hildenbrand)
cleans up the large folio PTE batching code.

"mm/damon/vaddr: Allow interleaving in migrate_{hot,cold} actions" (SeongJae Park)
facilitates dynamic alteration of DAMON's inter-node allocation
policy.

"Remove unmap_and_put_page()" (Vishal Moola)
provides a couple of page->folio conversions.

"mm: per-node proactive reclaim" (Davidlohr Bueso)
implements a per-node control of proactive reclaim - beyond the
current memcg-based implementation.

"mm/damon: remove damon_callback" (SeongJae Park)
replaces the damon_callback interface with a more general and
powerful damon_call()+damos_walk() interface.

"mm/mremap: permit mremap() move of multiple VMAs" (Lorenzo Stoakes)
implements a number of mremap cleanups (of course) in preparation
for adding new mremap() functionality: newly permit the remapping
of multiple VMAs when the user is specifying MREMAP_FIXED. It still
excludes some specialized situations where this cannot be performed
reliably.

"drop hugetlb_free_pgd_range()" (Anthony Yznaga)
switches some sparc hugetlb code over to the generic version and
removes the thus-unneeded hugetlb_free_pgd_range().

"mm/damon/sysfs: support periodic and automated stats update" (SeongJae Park)
augments the present userspace-requested update of DAMON sysfs
monitoring files. Automatic update is now provided, along with a
tunable to control the update interval.

"Some randome fixes and cleanups to swapfile" (Kemeng Shi)
does what is claims.

"mm: introduce snapshot_page" (Luiz Capitulino and David Hildenbrand)
provides (and uses) a means by which debug-style functions can grab
a copy of a pageframe and inspect it locklessly without tripping
over the races inherent in operating on the live pageframe
directly.

"use per-vma locks for /proc/pid/maps reads" (Suren Baghdasaryan)
addresses the large contention issues which can be triggered by
reads from that procfs file. Latencies are reduced by more than
half in some situations. The series also introduces several new
selftests for the /proc/pid/maps interface.

"__folio_split() clean up" (Zi Yan)
cleans up __folio_split()!

"Optimize mprotect() for large folios" (Dev Jain)
provides some quite large (>3x) speedups to mprotect() when dealing
with large folios.

"selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup" (wang lian)
does some cleanup work in the selftests code.

"tools/testing: expand mremap testing" (Lorenzo Stoakes)
extends the mremap() selftest in several ways, including adding
more checking of Lorenzo's recently added "permit mremap() move of
multiple VMAs" feature.

"selftests/damon/sysfs.py: test all parameters" (SeongJae Park)
extends the DAMON sysfs interface selftest so that it tests all
possible user-requested parameters. Rather than the present minimal
subset"

* tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (370 commits)
MAINTAINERS: add missing headers to mempory policy & migration section
MAINTAINERS: add missing file to cgroup section
MAINTAINERS: add MM MISC section, add missing files to MISC and CORE
MAINTAINERS: add missing zsmalloc file
MAINTAINERS: add missing files to page alloc section
MAINTAINERS: add missing shrinker files
MAINTAINERS: move memremap.[ch] to hotplug section
MAINTAINERS: add missing mm_slot.h file THP section
MAINTAINERS: add missing interval_tree.c to memory mapping section
MAINTAINERS: add missing percpu-internal.h file to per-cpu section
mm/page_alloc: remove trace_mm_alloc_contig_migrate_range_info()
selftests/damon: introduce _common.sh to host shared function
selftests/damon/sysfs.py: test runtime reduction of DAMON parameters
selftests/damon/sysfs.py: test non-default parameters runtime commit
selftests/damon/sysfs.py: generalize DAMON context commit assertion
selftests/damon/sysfs.py: generalize monitoring attributes commit assertion
selftests/damon/sysfs.py: generalize DAMOS schemes commit assertion
selftests/damon/sysfs.py: test DAMOS filters commitment
selftests/damon/sysfs.py: generalize DAMOS scheme commit assertion
selftests/damon/sysfs.py: test DAMOS destinations commitment
...

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selftests/proc: add verbose mode for /proc/pid/maps tearing tests

Add verbose mode to the /proc/pid/maps tearing tests to print debugging
information. VERBOSE environment variable is used to enable

selftests/proc: add verbose mode for /proc/pid/maps tearing tests

Add verbose mode to the /proc/pid/maps tearing tests to print debugging
information. VERBOSE environment variable is used to enable it.

Usage example: VERBOSE=1 ./proc-maps-race

Link: https://lkml.kernel.org/r/20250719182854.3166724-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

selftests/proc: extend /proc/pid/maps tearing test to include vma remapping

Test that /proc/pid/maps does not report unexpected holes in the address
space when we concurrently remap a part of a vma

selftests/proc: extend /proc/pid/maps tearing test to include vma remapping

Test that /proc/pid/maps does not report unexpected holes in the address
space when we concurrently remap a part of a vma into the middle of
another vma. This remapping results in the destination vma being split
into three parts and the part in the middle being patched back from, all
done concurrently from under the reader. We should always see either
original vma or the split one with no holes.

Link: https://lkml.kernel.org/r/20250719182854.3166724-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

selftests/proc: extend /proc/pid/maps tearing test to include vma resizing

Test that /proc/pid/maps does not report unexpected holes in the address
space when a vma at the edge of the page is being

selftests/proc: extend /proc/pid/maps tearing test to include vma resizing

Test that /proc/pid/maps does not report unexpected holes in the address
space when a vma at the edge of the page is being concurrently remapped.
This remapping results in the vma shrinking and expanding from under the
reader. We should always see either shrunk or expanded (original) version
of the vma.

Link: https://lkml.kernel.org/r/20250719182854.3166724-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

selftests/proc: add /proc/pid/maps tearing from vma split test

Patch series "use per-vma locks for /proc/pid/maps reads", v8.

Reading /proc/pid/maps requires read-locking mmap_lock which prevents a

selftests/proc: add /proc/pid/maps tearing from vma split test

Patch series "use per-vma locks for /proc/pid/maps reads", v8.

Reading /proc/pid/maps requires read-locking mmap_lock which prevents any
other task from concurrently modifying the address space. This guarantees
coherent reporting of virtual address ranges, however it can block
important updates from happening. Oftentimes /proc/pid/maps readers are
low priority monitoring tasks and them blocking high priority tasks
results in priority inversion.

Locking the entire address space is required to present fully coherent
picture of the address space, however even current implementation does not
strictly guarantee that by outputting vmas in page-size chunks and
dropping mmap_lock in between each chunk. Address space modifications are
possible while mmap_lock is dropped and userspace reading the content is
expected to deal with possible concurrent address space modifications.
Considering these relaxed rules, holding mmap_lock is not strictly needed
as long as we can guarantee that a concurrently modified vma is reported
either in its original form or after it was modified.

This patchset switches from holding mmap_lock while reading /proc/pid/maps
to taking per-vma locks as we walk the vma tree. This reduces the
contention with tasks modifying the address space because they would have
to contend for the same vma as opposed to the entire address space.
Previous version of this patchset [1] tried to perform /proc/pid/maps
reading under RCU, however its implementation is quite complex and the
results are worse than the new version because it still relied on
mmap_lock speculation which retries if any part of the address space gets
modified. New implementaion is both simpler and results in less
contention. Note that similar approach would not work for /proc/pid/smaps
reading as it also walks the page table and that's not RCU-safe.

Paul McKenney's designed a test [2] to measure mmap/munmap latencies while
concurrently reading /proc/pid/maps. The test has a pair of processes
scanning /proc/PID/maps, and another process unmapping and remapping 4K
pages from a 128MB range of anonymous memory. At the end of each 10
second run, the latency of each mmap() or munmap() operation is measured,
and for each run the maximum and mean latency is printed. The map/unmap
process is started first, its PID is passed to the scanners, and then the
map/unmap process waits until both scanners are running before starting
its timed test. The scanners keep scanning until the specified
/proc/PID/maps file disappears.

The latest results from Paul:
Stock mm-unstable, all of the runs had maximum latencies in excess of 0.5
milliseconds, and with 80% of the runs' latencies exceeding a full
millisecond, and ranging up beyond 4 full milliseconds. In contrast, 99%
of the runs with this patch series applied had maximum latencies of less
than 0.5 milliseconds, with the single outlier at only 0.608 milliseconds.

From a median-performance (as opposed to maximum-latency) viewpoint, this
patch series also looks good, with stock mm weighing in at 11 microseconds
and patch series at 6 microseconds, better than a 2x improvement.

Before the change:
./run-proc-vs-map.sh --nsamples 100 --rawdata -- --busyduration 2
0.011 0.008 0.521
0.011 0.008 0.552
0.011 0.008 0.590
0.011 0.008 0.660
...
0.011 0.015 2.987
0.011 0.015 3.038
0.011 0.016 3.431
0.011 0.016 4.707

After the change:
./run-proc-vs-map.sh --nsamples 100 --rawdata -- --busyduration 2
0.006 0.005 0.026
0.006 0.005 0.029
0.006 0.005 0.034
0.006 0.005 0.035
...
0.006 0.006 0.421
0.006 0.006 0.423
0.006 0.006 0.439
0.006 0.006 0.608

The patchset also adds a number of tests to check for /proc/pid/maps data
coherency. They are designed to detect any unexpected data tearing while
performing some common address space modifications (vma split, resize and
remap). Even before these changes, reading /proc/pid/maps might have
inconsistent data because the file is read page-by-page with mmap_lock
being dropped between the pages. An example of user-visible inconsistency
can be that the same vma is printed twice: once before it was modified and
then after the modifications. For example if vma was extended, it might
be found and reported twice. What is not expected is to see a gap where
there should have been a vma both before and after modification. This
patchset increases the chances of such tearing, therefore it's even more
important now to test for unexpected inconsistencies.

In [3] Lorenzo identified the following possible vma merging/splitting
scenarios:

Merges with changes to existing vmas:
1 Merge both - mapping a vma over another one and between two vmas which
can be merged after this replacement;
2. Merge left full - mapping a vma at the end of an existing one and
completely over its right neighbor;
3. Merge left partial - mapping a vma at the end of an existing one and
partially over its right neighbor;
4. Merge right full - mapping a vma before the start of an existing one
and completely over its left neighbor;
5. Merge right partial - mapping a vma before the start of an existing one
and partially over its left neighbor;

Merges without changes to existing vmas:
6. Merge both - mapping a vma into a gap between two vmas which can be
merged after the insertion;
7. Merge left - mapping a vma at the end of an existing one;
8. Merge right - mapping a vma before the start end of an existing one;

Splits
9. Split with new vma at the lower address;
10. Split with new vma at the higher address;

If such merges or splits happen concurrently with the /proc/maps reading
we might report a vma twice, once before the modification and once after
it is modified:

Case 1 might report overwritten and previous vma along with the final
merged vma;
Case 2 might report previous and the final merged vma;
Case 3 might cause us to retry once we detect the temporary gap caused by
shrinking of the right neighbor;
Case 4 might report overritten and the final merged vma;
Case 5 might cause us to retry once we detect the temporary gap caused by
shrinking of the left neighbor;
Case 6 might report previous vma and the gap along with the final marged
vma;
Case 7 might report previous and the final merged vma;
Case 8 might report the original gap and the final merged vma covering the
gap;
Case 9 might cause us to retry once we detect the temporary gap caused by
shrinking of the original vma at the vma start;
Case 10 might cause us to retry once we detect the temporary gap caused by
shrinking of the original vma at the vma end;

In all these cases the retry mechanism prevents us from reporting possible
temporary gaps.

[1] https://lore.kernel.org/all/20250418174959.1431962-1-surenb@google.com/
[2] https://github.com/paulmckrcu/proc-mmap_sem-test
[3] https://lore.kernel.org/all/e1863f40-39ab-4e5b-984a-c48765ffde1c@lucifer.local/


The /proc/pid/maps file is generated page by page, with the mmap_lock
released between pages. This can lead to inconsistent reads if the
underlying vmas are concurrently modified. For instance, if a vma split
or merge occurs at a page boundary while /proc/pid/maps is being read, the
same vma might be seen twice: once before and once after the change. This
duplication is considered acceptable for userspace handling. However,
observing a "hole" where a vma should be (e.g., due to a vma being
replaced and the space temporarily being empty) is unacceptable.

Implement a test that:
1. Forks a child process which continuously modifies its address
space, specifically targeting a vma at the boundary between two pages.
2. The parent process repeatedly reads the child's /proc/pid/maps.
3. The parent process checks the last vma of the first page and the
first vma of the second page for consistency, looking for the effects
of vma splits or merges.

The test duration is configurable via DURATION environment variable
expressed in seconds. The default test duration is 5 seconds.

Example Command: DURATION=10 ./proc-maps-race

Link: https://lore.kernel.org/all/20250418174959.1431962-1-surenb@google.com/ [1]
Link: https://github.com/paulmckrcu/proc-mmap_sem-test [2]
Link: https://lore.kernel.org/all/e1863f40-39ab-4e5b-984a-c48765ffde1c@lucifer.local/ [3]
Link: https://lkml.kernel.org/r/20250719182854.3166724-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250719182854.3166724-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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