linux-stable.git/tools/testing/selftests/mm, branch master

selftests/mm: check stat() return value in khugepaged get_finfo()

2026-08-25T01:43:27+00:00

get_finfo() calls stat() to get metadata about the target directory, but
never checks the return value.  On failure, stat() returns -1 and leaves
path_stat unmodified, so path_stat.st_mode may contain uninitialized stack
data.

The code then checks S_ISDIR(path_stat.st_mode) against this potentially
garbage value.  This can produce a misleading "Not a directory" error when
the real problem is a nonexistent or inaccessible path, or, in the worst
case, the check could pass by chance on garbage data and let the function
continue using an invalid path_stat for the rest of its logic.

Check the return value and fail with a clear error message if stat()
fails, matching the error-handling style already used for statfs() and
read_file() later in the same function.

Link: https://lore.kernel.org/20260819121426.49500-1-anshumantewari123@gmail.com
Signed-off-by: Anshuman 
Reviewed-by: Andrew Morton 
Reviewed-by: SJ Park 
Reviewed-by: Sarthak Sharma 
Acked-by: David Hildenbrand (Arm) 
Cc: Lorenzo Stoakes 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

selftests/mm: fix unchecked ftruncate return value in soft-dirty test

2026-08-25T01:43:27+00:00

test_mprotect() calls ftruncate() to resize the backing file before
mmap()'ing it, but never checks the return value.  If ftruncate() fails,
the file may remain shorter than the requested mapping size.  The
subsequent mmap() with MAP_SHARED can still succeed in this case, but the
very next line writes directly into the mapped memory (*map = 1), which
can trigger SIGBUS if the mapping extends beyond the actual file size.

Check the return value and fail cleanly with ksft_exit_fail_msg() if
ftruncate() fails, matching the error-handling style already used for the
mmap() call immediately below it.

Link: https://lore.kernel.org/20260818133206.39503-1-anshumantewari123@gmail.com
Signed-off-by: Anshuman 
Reviewed-by: Andrew Morton 
Reviewed-by: Sarthak Sharma 
Cc: David Hildenbrand 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

selftests/mm: drop redundant open() in mprotect_tests()

2026-08-25T01:43:26+00:00

Remove duplicate open() for local pagemap_fd in mprotect_tests() that
shadows the global pagemap_fd already opened in main().  The local fd is
never used in the function.

Link: https://lore.kernel.org/20260817080616.52946-1-hongfu.li@linux.dev
Signed-off-by: Hongfu Li 
Reviewed-by: Lorenzo Stoakes (ARM) 
Reviewed-by: Muhammad Usama Anjum 
Reviewed-by: SJ Park 
Acked-by: David Hildenbrand (Arm) 
Reviewed-by: Anshuman Khandual 
Cc: Liam R. Howlett 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests/mm: kmemleak: drop stale min_unref_scans default from comments

2026-08-25T01:43:18+00:00

The test writes min_unref_scans explicitly for every case, so its comments
describing 1 as the default are both unnecessary and, since the default is
now conditional, wrong.  Refer to the threshold values directly.

No functional change.

Link: https://lore.kernel.org/20260731-kmemleak_hardened-v2-3-7b9689ac77cb@debian.org
Signed-off-by: Breno Leitao 
Acked-by: Catalin Marinas 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests: mm: test kmemleak's N-consecutive-scan leak confirmation

2026-08-25T01:43:18+00:00

Add a functional test for the min_unref_scans kmemleak module parameter. 
Using samples/kmemleak's helper module it checks that min_unref_scans=1
reports an orphan on the first scan, min_unref_scans=2 reports nothing on
the first scan but does on the second, and that the parameter reads back
what was written.

It counts only the helper module's own orphans (matched by their
[kmemleak_test] backtrace, with the module kept loaded so the symbols
resolve) so unrelated leaks already present on the system do not perturb
the result.  The test skips when run as non-root, without
CONFIG_DEBUG_KMEMLEAK / CONFIG_SAMPLE_KMEMLEAK, on a kernel without the
parameter, or when the helper yields no detectable orphan.

Link: https://lore.kernel.org/20260713-catalin_pto-v1-4-5b93b1131089@debian.org
Signed-off-by: Breno Leitao 
Reviewed-by: Catalin Marinas 
Cc: David Hildenbrand 
Cc: Geert Uytterhoeven 
Cc: Jonathan Corbet 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests/mm: fix read_file() return value check

2026-08-25T01:43:11+00:00

read_file() returns 0 on open/read failures and never returns negative
values.  Existing < 0 error checks never trigger, so read failures are
silently ignored.  Check for zero return to detect read_file() failures.

Also fix misleading error message in get_finfo().  The error string
incorrectly references read_num when reading uevent files.

Link: https://lore.kernel.org/20260807013555.36525-1-hongfu.li@linux.dev
Fixes: e0c13f9761df ("khugepaged: add self test")
Signed-off-by: Hongfu Li 
Acked-by: David Hildenbrand (Arm) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

selftests/mm: retry migration failures for the full runtime

2026-08-25T01:43:10+00:00

move_pages() is best effort and can temporarily fail when concurrent
faults race with page unmapping.  A busy shared-anon workload can exhaust
the current 100 retries long before the intended 20-second runtime and
produce a false failure.

Use the full runtime as the retry window.  Since the initial page location
is unknown, require it to reach both alternating NUMA targets to confirm
that cross-node migration made progress despite transient contention.

Link: https://lore.kernel.org/20260727095225.372655-6-usama.anjum@arm.com
Signed-off-by: Muhammad Usama Anjum 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: David Hildenbrand 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Miaohe Lin 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Naoya Horiguchi 
Cc: Nico Pache 
Cc: Ryan Roberts 
Cc: Sarthak Sharma 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Usama Arif 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

selftests/mm: skip hard dirty page-cache test on NFS

2026-08-25T01:43:09+00:00

The hard dirty_pagecache variant uses MADV_HWPOISON to exercise recovery
of a dirty file-backed page.  The recovery path records -EIO in the
address_space mapping, which NFS later reports when the test closes the
file.  This makes the test fail after the hwpoison checks have completed.

Skip this variant when the test file is on NFS.  Keep the hard clean-page
and both soft-offline variants enabled because they use folio removal,
invalidation, or migration rather than recording a delayed writeback
error.

The unsupported-filesystem path in clean_pagecache() also returns without
closing the opened test file.  Close the descriptor before skipping there
and in dirty_pagecache().

Link: https://lore.kernel.org/20260727095225.372655-5-usama.anjum@arm.com
Signed-off-by: Muhammad Usama Anjum 
Reviewed-by: Miaohe Lin 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: David Hildenbrand 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Naoya Horiguchi 
Cc: Nico Pache 
Cc: Ryan Roberts 
Cc: Sarthak Sharma 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Usama Arif 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

selftests/mm: skip guard hole-punch test if MADV_REMOVE is unsupported

2026-08-25T01:43:09+00:00

The hole_punch case verifies that guard regions survive MADV_REMOVE and
that the backing range is punched out.  MADV_REMOVE delegates the hole
punch to the backing filesystem, which may reject the operation with
EOPNOTSUPP.

That result means the test cannot establish the state whose guard
semantics it intends to validate.  Treating the missing filesystem
capability as a guard-region failure creates a false regression.

Unmap the range and skip only when MADV_REMOVE fails with EOPNOTSUPP. 
Preserve the assertion for all other errors so failures on supported
configurations remain visible.

Link: https://lore.kernel.org/20260727095225.372655-3-usama.anjum@arm.com
Signed-off-by: Muhammad Usama Anjum 
Tested-by: Sarthak Sharma 
Acked-by: Usama Arif 
Acked-by: David Hildenbrand (Arm) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Miaohe Lin 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Naoya Horiguchi 
Cc: Nico Pache 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

selftests/mm: skip COW tmpfile cases when fallocate() is unsupported

2026-08-25T01:43:09+00:00

Patch series "selftests/mm: Handle unsupported and transient test
conditions", v3.

Several MM selftests report failures when the test environment lacks
an underlying prerequisite, such as fallocate() support, MADV_REMOVE,
local page-cache semantics, or swap.

This series converts those unsupported cases to SKIP while preserving
failures for unexpected errors. It also allows migration tests to retry
transient move_pages() failures.


This patch (of 4):

The tmpfile-backed COW cases allocate a one-page file with fallocate()
before exercising private and shared mappings.  When the filesystem
backing tmpfile() does not implement fallocate(), setup fails with
EOPNOTSUPP and no COW behavior is exercised.

This occurs when the temporary directory resides on a filesystem with
limited allocation support, such as NFSv3.  Reporting a failure adds noise
because the test prerequisite is absent rather than the COW implementation
being broken.

Report EOPNOTSUPP as a skip.  Continue treating every other fallocate()
error as a failure so unexpected setup regressions remain visible.

Link: https://lore.kernel.org/20260727095225.372655-1-usama.anjum@arm.com
Link: https://lore.kernel.org/20260727095225.372655-2-usama.anjum@arm.com
Fixes: f8664f3c4a08 ("selftests/vm: cow: basic COW tests for non-anonymous pages")
Signed-off-by: Muhammad Usama Anjum 
Tested-by: Sarthak Sharma 
Acked-by: Usama Arif 
Acked-by: David Hildenbrand (Arm) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Miaohe Lin 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Naoya Horiguchi 
Cc: Nico Pache 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton