kernel/tools/testing/selftests/mm/cow.c, branch linux-rolling-stable

selftests/mm: fix usage of FORCE_READ() in cow tests

2026-02-26T23:01:09Z

[ Upstream commit bce1dabd310e87fefe0645fec9ba98b84d37e418 ] Commit 5bbc2b785e63 ("selftests/mm: fix FORCE_READ to read input value correctly") modified FORCE_READ() to take a value instead of a pointer. It also changed most of the call sites accordingly, but missed many of them in cow.c. In those cases, we ended up with the pointer itself being read, not the memory it points to. No failure occurred as a result, so it looks like the tests work just fine without faulting in. However, the huge_zeropage tests explicitly check that pages are populated, so those became skipped. Convert all the remaining FORCE_READ() to fault in the mapped page, as was originally intended. This allows the huge_zeropage tests to run again (3 tests in total). Link: https://lkml.kernel.org/r/20260122170224.4056513-5-kevin.brodsky@arm.com Fixes: 5bbc2b785e63 ("selftests/mm: fix FORCE_READ to read input value correctly") Signed-off-by: Kevin Brodsky Acked-by: SeongJae Park Reviewed-by: wang lian Acked-by: David Hildenbrand (Red Hat) Reviewed-by: Dev Jain Cc: Jason Gunthorpe Cc: John Hubbard Cc: Lorenzo Stoakes Cc: Mark Brown Cc: Paolo Abeni Cc: Ryan Roberts Cc: Shuah Khan Cc: Usama Anjum Cc: Yunsheng Lin Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

selftests: complete kselftest include centralization

2025-11-27T22:24:31Z

This follow-up patch completes centralization of kselftest.h and ksefltest_harness.h includes in remaining seltests files, replacing all relative paths with a non-relative paths using shared -I include path in lib.mk Tested with gcc-13.3 and clang-18.1, and cross-compiled successfully on riscv, arm64, x86_64 and powerpc arch. [reddybalavignesh9979@gmail.com: add selftests include path for kselftest.h] Link: https://lkml.kernel.org/r/20251017090201.317521-1-reddybalavignesh9979@gmail.com Link: https://lkml.kernel.org/r/20251016104409.68985-1-reddybalavignesh9979@gmail.com Signed-off-by: Bala-Vignesh-Reddy Suggested-by: Andrew Morton Link: https://lore.kernel.org/lkml/20250820143954.33d95635e504e94df01930d0@linux-foundation.org/ Reviewed-by: Wei Yang Cc: David Hildenbrand Cc: David S. Miller Cc: Eric Dumazet Cc: Günther Noack Cc: Jakub Kacinski Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mickael Salaun Cc: Ming Lei Cc: Paolo Abeni Cc: Shuah Khan Cc: Simon Horman Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftest/mm: extract sz2ord function into vm_util.h

2025-09-13T23:55:06Z

The function already has 2 uses and will have a 3rd one in prctl selftests. The pagesize argument is added into the function, as it's not a global variable anymore. No functional change intended with this patch. Link: https://lkml.kernel.org/r/20250815135549.130506-6-usamaarif642@gmail.com Suggested-by: David Hildenbrand Signed-off-by: Usama Arif Reviewed-by: Lorenzo Stoakes Reviewed-by: Zi Yan Cc: Arnd Bergmann Cc: Baolin Wang Cc: Barry Song Cc: Dev Jain Cc: Jann Horn Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Liam Howlett Cc: Mariano Pache Cc: Michal Hocko Cc: Mike Rapoport Cc: Rik van Riel Cc: Ryan Roberts Cc: SeongJae Park Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Yafang Signed-off-by: Andrew Morton

mm/selftests: fix split_huge_page_test failure on systems with 64KB page size

2025-09-13T23:55:03Z

The split_huge_page_test fails on systems with a 64KB base page size. This is because the order of a 2MB huge page is different: On 64KB systems, the order is 5. On 4KB systems, it's 9. The test currently assumes a maximum huge page order of 9, which is only valid for 4KB base page systems. On systems with 64KB pages, attempting to split huge pages beyond their actual order (5) causes the test to fail. In this patch, we calculate the huge page order based on the system's base page size. With this change, the tests now run successfully on both 64KB and 4KB page size systems. Link: https://lkml.kernel.org/r/20250816040113.760010-5-aboorvad@linux.ibm.com Fixes: fa6c02315f74 ("mm: huge_memory: a new debugfs interface for splitting THP tests") Co-developed-by: Aboorva Devarajan Signed-off-by: Aboorva Devarajan Signed-off-by: Donet Tom Reviewed-by: Dev Jain Reviewed-by: Zi Yan Reviewed-by: Wei Yang Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Mariano Pache Cc: "Ritesh Harjani (IBM)" Cc: Ryan Roberts Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/mm: fix FORCE_READ to read input value correctly

2025-08-28T05:45:42Z

FORCE_READ() converts input value x to its pointer type then reads from address x. This is wrong. If x is a non-pointer, it would be caught it easily. But all FORCE_READ() callers are trying to read from a pointer and FORCE_READ() basically reads a pointer to a pointer instead of the original typed pointer. Almost no access violation was found, except the one from split_huge_page_test. Fix it by implementing a simplified READ_ONCE() instead. Link: https://lkml.kernel.org/r/20250805175140.241656-1-ziy@nvidia.com Fixes: 3f6bfd4789a0 ("selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));"") Signed-off-by: Zi Yan Reviewed-by: Lorenzo Stoakes Acked-by: David Hildenbrand Reviewed-by: wang lian Reviewed-by: Wei Yang Cc: Christian Brauner Cc: Jann Horn Cc: Kairui Song Cc: Liam Howlett Cc: Mark Brown Cc: SeongJae Park Cc: Shuah Khan Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton

selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));"

2025-07-25T02:12:41Z

Patch series "selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup", v2. This series introduces a common FORCE_READ() macro to replace the cryptic asm volatile("" : "+r" (variable)); construct used in several mm selftests. This improves code readability and maintainability by removing duplicated, hard-to-understand code. This patch (of 2): Several mm selftests use the `asm volatile("" : "+r" (variable));` construct to force a read of a variable, preventing the compiler from optimizing away the memory access. This idiom is cryptic and duplicated across multiple test files. Following a suggestion from David[1], this patch refactors this common pattern into a FORCE_READ() macro Link: https://lkml.kernel.org/r/20250717131857.59909-1-lianux.mm@gmail.com Link: https://lkml.kernel.org/r/20250717131857.59909-2-lianux.mm@gmail.com Link: https://lore.kernel.org/lkml/4a3e0759-caa1-4cfa-bc3f-402593f1eee3@redhat.com/ [1] Signed-off-by: wang lian Reviewed-by: Lorenzo Stoakes Acked-by: David Hildenbrand Reviewed-by: Zi Yan Reviewed-by: Wei Yang Cc: Christian Brauner Cc: Jann Horn Cc: Kairui Song Cc: Liam Howlett Cc: Mark Brown Cc: SeongJae Park Cc: Shuah Khan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/mm: pagemap_scan ioctl: add PFN ZERO test cases

2025-07-20T01:59:44Z

Add test cases to test the correctness of PFN ZERO flag of pagemap_scan ioctl. Test with normal pages backed memory and huge pages backed memory. Link: https://lkml.kernel.org/r/20250707073321.106431-1-usama.anjum@collabora.com Signed-off-by: Muhammad Usama Anjum Cc: David Hildenbrand Cc: Muhammad Usama Anjum Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/mm: add messages about test errors to the cow tests

2025-07-10T05:42:04Z

It is not sufficiently clear what the individual tests in the cow test program are checking so add messages for the failure cases. Link: https://lkml.kernel.org/r/20250610-selftest-mm-cow-tweaks-v1-4-43cd7457500f@kernel.org Signed-off-by: Mark Brown Suggested-by: David Hildenbrand Acked-by: David Hildenbrand Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/mm: don't compare return values to in cow

2025-07-10T05:42:04Z

Tweak the coding style for checking for non-zero return values. While we're at it also remove a now redundant oring of the madvise() return code. Link: https://lkml.kernel.org/r/20250610-selftest-mm-cow-tweaks-v1-3-43cd7457500f@kernel.org Signed-off-by: Mark Brown Suggested-by: David Hildenbrand Acked-by: David Hildenbrand Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/mm: convert some cow error reports to ksft_perror()

2025-07-10T05:42:04Z

This prints the errno and a string decode of it. Link: https://lkml.kernel.org/r/20250610-selftest-mm-cow-tweaks-v1-2-43cd7457500f@kernel.org Signed-off-by: Mark Brown Acked-by: David Hildenbrand Cc: Shuah Khan Signed-off-by: Andrew Morton