kernel/linux.git/tools/testing/selftests/mm, branch v7.2-rc1

Merge tag 'mm-stable-2026-06-23-08-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-06-23T19:03:44+00:00

Pull more MM updates from Andrew Morton: - "khugepaged: add mTHP collapse support" (Nico Pache) Provide khugepaged with the capability to collapse anonymous memory regions to mTHPs - "Remove CONFIG_READ_ONLY_THP_FOR_FS and enable file THP for writable files" (Zi Yan) Remove the READ_ONLY_THP_FOR_FS check in file_thp_enabled(), so that khugepaged and MADV_COLLAPSE can run on filesystems with PMD THP pagecache support even without READ_ONLY_THP_FOR_FS enabled - "make MM selftests more CI friendly" (Mike Rapoport) General fixes and cleanups to the MM selftests. Also move more MM selftests under the kselftest framework, making them more amenable to ongoing CI testing - "selftests/mm: fix failures and robustness improvements" and "selftests/mm: assorted fixes for hmm-tests" (Sayali Patil) Fix several issues in MM selftests which were revealed by powerpc 64k pagesize * tag 'mm-stable-2026-06-23-08-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (118 commits) Revert "mm: limit filemap_fault readahead to VMA boundaries" mm/vmscan: pass NULL to trace vmscan node reclaim mm: use mapping_mapped to simplify the code selftests/mm: fix exclusive_cow test fork() handling selftests/mm: remove hardcoded THP sizing assumptions in hmm tests selftests/mm: allow PUD-level entries in compound testcase of hmm tests mm/gup_test: reject wrapped user ranges mm/page_frag: reject invalid CPUs in page_frag_test mm/damon/core: always put unsuccessfully committed target pids mm: page_isolation: avoid unsafe folio reads while scanning compound pages mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() selftests: mm: fix and speedup "droppable" test mm: merge writeout into pageout MAINTAINERS: add Hao Ge as reviewer for codetag and alloc_tag selftests/mm: clarify alternate unmapping in compaction_test selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported selftests/mm: ensure destination is hugetlb-backed in hugetlb-mremap selftest/mm: register existing mapping with userfaultfd in hugetlb-mremap ...

selftests/mm: fix exclusive_cow test fork() handling

2026-06-21T18:37:38+00:00

The test ignores the return value of fork(), so both the parent and the (newly created) child run the COW verification loops and then call hmm_buffer_free() before returning into the kselftest harness, which _exit()s each side. This duplicated teardown sequence has been observed to manifest as a SIGSEGV in the test child, e.g.: hmm-tests[360141]: segfault (11) at 0 nip 10006964 lr 1000ac3c code 1 in hmm-tests[6964,10000000+30000] Fix this by adopting the same fork()-then-wait pattern already used by the nearby anon_write_child / anon_write_child_shared tests in this file: the child performs the COW verification and then _exit(0)s so it does not run the test teardown, while the parent independently verifies COW, waits for the child, and only then frees the buffer. Link: https://lore.kernel.org/20260611034102.1030738-4-aboorvad@linux.ibm.com Fixes: b659baea75469 ("mm: selftests for exclusive device memory") Signed-off-by: Aboorva Devarajan Cc: Alex Sierra Cc: Alistair Popple Cc: Balbir Singh Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Ralph Campbell Cc: Sayali Patil Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/mm: remove hardcoded THP sizing assumptions in hmm tests

2026-06-21T18:37:37+00:00

migrate_partial_unmap_fault() and migrate_remap_fault() use hardcoded offsets based on a 2MB PMD size. Similarly, benchmark_thp_migration() assumes a fixed 2MB THP size when generating test buffer sizes. Derive offsets and test sizes from the runtime PMD page size returned by read_pmd_pagesize(). If unavailable, fall back to TWOMEG. This allows the tests to adapt correctly on systems where PMD-sized THP differs from 2MB. Also replace the fixed 1MB unmap size with a PMD-relative value derived from the runtime PMD size. On systems with larger PMD sizes, computed test buffer sizes can exceed INT_MAX. Skip such test cases to avoid overflow. Link: https://lore.kernel.org/20260611034102.1030738-3-aboorvad@linux.ibm.com Fixes: 24c2c5b8ffbd ("selftests/mm/hmm-tests: partial unmap, mremap and anon_write tests") Fixes: 271a7b2e3c13 ("selftests/mm/hmm-tests: new throughput tests including THP") Signed-off-by: Sayali Patil Signed-off-by: Aboorva Devarajan Acked-by: Balbir Singh Cc: Alex Sierra Cc: Alistair Popple Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Ralph Campbell Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/mm: allow PUD-level entries in compound testcase of hmm tests

2026-06-21T18:37:37+00:00

Patch series "selftests/mm: assorted fixes for hmm-tests", v3. This series fixes a few issues in hmm-tests that show up when page-size and huge-page configuration differ from the hardcoded assumptions the tests were written for (PMD/THP sizing, default hugepage size, and related cases). It also includes a fix to exclusive_cow: the test ignored the return value of fork(), so both parent and child ran the same teardown path. This patch (of 3): The HMM compound testcase currently assumes only PMD-level mappings and fails on systems where default_hugepagesz=1G is set, because the region is then reported by the device at PUD level. Determine the mapping level (PMD or PUD) the device reports for the first page of the range and require every page to match that level exactly via ASSERT_EQ(). This accepts PUD-level mappings while preserving the expected/observed protection values printed on failure, and rejects a fragmented mapping that mixes PMD- and PUD-level entries within the same range (which a per-page OR check would have let pass). Link: https://lore.kernel.org/20260611034102.1030738-1-aboorvad@linux.ibm.com Link: https://lore.kernel.org/20260611034102.1030738-2-aboorvad@linux.ibm.com Fixes: e478425bec93 ("mm/hmm: add tests for hmm_pfn_to_map_order()") Signed-off-by: Sayali Patil Co-developed-by: Aboorva Devarajan Signed-off-by: Aboorva Devarajan Cc: Alex Sierra Cc: Alistair Popple Cc: Balbir Singh Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Ralph Campbell Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/page_frag: reject invalid CPUs in page_frag_test

2026-06-21T18:37:37+00:00

The page_frag selftest module accepts test_push_cpu and test_pop_cpu as signed module parameters, then validates them by passing them directly to cpu_active(). That validation is itself unsafe for negative or out-of-range CPU numbers. For example, test_push_cpu=-1 is converted to a very large unsigned CPU number before cpu_active() reaches cpumask_test_cpu(), which trips the cpumask range check with CONFIG_DEBUG_PER_CPU_MAPS enabled. Reject CPU values outside [0, nr_cpu_ids) before asking whether the CPU is active. Assisted-by: Codex:gpt-5.5-cyber-preview Link: https://lore.kernel.org/20260605184157.2490353-1-sam.moelius@trailofbits.com Signed-off-by: Samuel Moelius Cc: David Hildenbrand 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 and speedup "droppable" test

2026-06-21T18:37:36+00:00

The droppable test currently relies on creating memory pressure in a child process to trigger dropping the droppable pages. That not only takes a long time on some machines (allocating and filling all that memory), on large machines this will not work as we hardcode the area size to 134217728 bytes. ... further, we rely on timeouts to detect that memory was not dropped, which is really suboptimal. Instead, let's just use MADV_PAGEOUT on a 2 MiB region. MADV_PAGEOUT works with droppable memory even without swap. There is the low chance of MADV_PAGEOUT failing to drop a page because of speculative references. We'll wait 1s and retry 10 times to rule that unlikely case out as best as we can. On a machine without swap: $ ./droppable TAP version 13 1..1 ok 1 madvise(MADV_PAGEOUT) behavior # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0 Link: https://lore.kernel.org/20260611-droppable_test-v1-1-b6a73d99f658@kernel.org Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Signed-off-by: David Hildenbrand (Arm) Reported-by: Aishwarya TCV Tested-by: Sarthak Sharma Tested-by: Lance Yang Reviewed-by: Dev Jain Reviewed-by: SeongJae Park Tested-by: Lorenzo Stoakes Reviewed-by: Lorenzo Stoakes Reviewed-by: Jason A. Donenfeld Cc: Anthony Yznaga Cc: Liam R. Howlett Cc: Mark Brown Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton

selftests/mm: clarify alternate unmapping in compaction_test

2026-06-21T18:37:35+00:00

Add a comment explaining that every other entry in the list is unmapped to intentionally create fragmentation with locked pages before invoking check_compaction(). Link: https://lore.kernel.org/da5e0a8d5152e54152c0d2f456aac2fac35af291.1779296493.git.sayalip@linux.ibm.com Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory") Signed-off-by: Sayali Patil Tested-by: Venkat Rao Bagalkote Cc: David Hildenbrand (Arm) Cc: Dev Jain Cc: Liam Howlett Cc: Miaohe Lin Cc: Michal Hocko Cc: Oscar Salvador Cc: "Ritesh Harjani (IBM)" Cc: Shuah Khan Cc: Zi Yan Signed-off-by: Andrew Morton

selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category

2026-06-21T18:37:34+00:00

run_vmtests.sh contains special handling to ensure the hwpoison_inject module is available for the memory-failure tests. This logic was implemented outside of run_test(), making the setup category-specific but managed globally. Move the hwpoison_inject handling into run_test() and restrict it to the memory-failure category so that: 1. the module is checked and loaded only when memory-failure tests run, 2. the test is skipped if the module or the debugfs interface (/sys/kernel/debug/hwpoison/) is not available. 3. the module is unloaded after the test if it was loaded by the script. This localizes category-specific setup and makes the test flow consistent with other per-category preparations. While updating this logic, fix the module availability check. The script previously used: modprobe -R hwpoison_inject The -R option prints the resolved module name to stdout, causing every run to print: hwpoison_inject in the test output, even when no action is required, introducing unnecessary noise. Replace this with: modprobe -n hwpoison_inject which verifies that the module is loadable without producing output, keeping the selftest logs clean and consistent. Also, ensure that skipped tests do not override a previously recorded failure. A skipped test currently sets exitcode to ksft_skip even if a prior test has failed, which can mask failures in the final exit status. Update the logic to only set exitcode to ksft_skip when no failure has been recorded. Link: https://lore.kernel.org/93441f34f7ef5add47d1a130d03daa79e21b5050.1779296493.git.sayalip@linux.ibm.com Fixes: ff4ef2fbd101 ("selftests/mm: add memory failure anonymous page test") Signed-off-by: Sayali Patil Reviewed-by: Miaohe Lin Tested-by: Venkat Rao Bagalkote Cc: David Hildenbrand (Arm) Cc: Dev Jain Cc: Liam Howlett Cc: Michal Hocko Cc: Oscar Salvador Cc: "Ritesh Harjani (IBM)" Cc: Shuah Khan Cc: Zi Yan Signed-off-by: Andrew Morton

selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero

2026-06-21T18:37:34+00:00

uffd-stress currently fails when the computed nr_pages_per_cpu evaluates to zero: nr_pages_per_cpu = bytes / page_size / nr_parallel This can occur on systems with large hugepage sizes (e.g. 1GB) and a high number of CPUs, where the total allocated memory is sufficient overall but not enough to provide at least one page per cpu. In such cases, the failure is due to insufficient test resources rather than incorrect kernel behaviour. Update the test to treat this condition as a test skip instead of reporting an error. [sayalip@linux.ibm.com: use ksft_exit_skip() instead of KSFT_SKIP] Link: https://lore.kernel.org/88202b56-1dc5-43e2-9d1f-a0823a9531f0@linux.ibm.com Link: https://lore.kernel.org/0707e9a0f1b3dd904c4a069b91db317f9c160faa.1779296493.git.sayalip@linux.ibm.com Fixes: db0f1c138f18 ("selftests/mm: print some details when uffd-stress gets bad params") Signed-off-by: Sayali Patil Acked-by: Zi Yan Acked-by: David Hildenbrand (Arm) Tested-by: Venkat Rao Bagalkote Cc: Dev Jain Cc: Liam Howlett Cc: Miaohe Lin Cc: Michal Hocko Cc: Oscar Salvador Cc: "Ritesh Harjani (IBM)" Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported

2026-06-21T18:37:34+00:00

The uffd-wp-mremap test requires the UFFD_FEATURE_PAGEFAULT_FLAG_WP capability. On systems where userfaultfd write-protect is not supported, uffd_register() fails and the test reports failures. Check for the required feature at startup and skip the test when the UFFD_FEATURE_PAGEFAULT_FLAG_WP capability is not present, preventing false failures on unsupported configurations. Before patch: running ./uffd-wp-mremap ------------------------ [INFO] detected THP size: 256 KiB [INFO] detected THP size: 512 KiB [INFO] detected THP size: 1024 KiB [INFO] detected THP size: 2048 KiB [INFO] detected hugetlb page size: 2048 KiB [INFO] detected hugetlb page size: 1048576 KiB 1..24 [RUN] test_one_folio(size=65536, private=false, swapout=false, hugetlb=false) not ok 1 uffd_register() failed [RUN] test_one_folio(size=65536, private=true, swapout=false, hugetlb=false) not ok 2 uffd_register() failed [RUN] test_one_folio(size=65536, private=false, swapout=true, hugetlb=false) not ok 3 uffd_register() failed [RUN] test_one_folio(size=65536, private=true, swapout=true, hugetlb=false) not ok 4 uffd_register() failed [RUN] test_one_folio(size=262144, private=false, swapout=false, hugetlb=false) not ok 5 uffd_register() failed [RUN] test_one_folio(size=524288, private=false, swapout=false, hugetlb=false) not ok 6 uffd_register() failed . . . Bail out! 24 out of 24 tests failed Totals: pass:0 fail:24 xfail:0 xpass:0 skip:0 error:0 [FAIL] not ok 1 uffd-wp-mremap # exit=1 After patch: running ./uffd-wp-mremap ------------------------ 1..0 # SKIP uffd-wp feature not supported [SKIP] ok 1 uffd-wp-mremap # SKIP Link: https://lore.kernel.org/c3c5af76d71d5f4446f773f4de94882efc33ebe4.1779296493.git.sayalip@linux.ibm.com Signed-off-by: Sayali Patil Tested-by: Venkat Rao Bagalkote Cc: David Hildenbrand (Arm) Cc: Dev Jain Cc: Liam Howlett Cc: Miaohe Lin Cc: Michal Hocko Cc: Oscar Salvador Cc: "Ritesh Harjani (IBM)" Cc: Shuah Khan Cc: Zi Yan Signed-off-by: Andrew Morton