linux-stable.git/tools/testing/selftests/mm/split_huge_page_test.c, branch linux-rolling-stable

selftests/mm: introduce helper to read every page

2026-01-31T22:22:41+00:00

FORCE_READ(*addr) ensures that the compiler will emit a load from addr. 
Several tests need to trigger such a load for a range of pages, ensuring
that every page is faulted in, if it wasn't already.

Introduce a new helper force_read_pages() that does exactly that and
replace existing loops with a call to it.

The step size (regular/huge page size) is preserved for all loops, except
in split_huge_page_test.  Reading every byte is unnecessary; we now read
every huge page, matching the following call to check_huge_file().

Link: https://lkml.kernel.org/r/20260122170224.4056513-7-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky 
Reviewed-by: Dev Jain 
Reviewed-by: Muhammad Usama Anjum 
Acked-by: David Hildenbrand (Red Hat) 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Cc: Lorenzo Stoakes 
Cc: Mark Brown 
Cc: Paolo Abeni 
Cc: Ryan Roberts 
Cc: SeongJae Park 
Cc: Shuah Khan 
Cc: wang lian 
Cc: Yunsheng Lin 
Signed-off-by: Andrew Morton

selftests: complete kselftest include centralization

2025-11-27T22:24:31+00:00

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

selftests/mm: add -Wunreachable-code and fix warnings

2025-09-21T21:22:34+00:00

Patch series "selftests/mm: Add -Wunreachable-code and fix warnings".

Add -Wunreachable-code to selftests and remove dead code from generated
warnings.


This patch (of 2):

Enable -Wunreachable-code flag to catch dead code and fix them.

1. Remove the dead code and write a comment instead:
hmm-tests.c:2033:3: warning: code will never be executed
[-Wunreachable-code]
                perror("Should not reach this\n");
                ^~~~~~

2. ksft_exit_fail_msg() calls exit(). So cleanup isn't done. Replace it
   with ksft_print_msg().
split_huge_page_test.c:301:3: warning: code will never be executed
[-Wunreachable-code]
                goto cleanup;
                ^~~~~~~~~~~~

3. Remove duplicate inline.
pkey_sighandler_tests.c:44:15: warning: duplicate 'inline' declaration
specifier [-Wduplicate-decl-specifier]
static inline __always_inline

Link: https://lkml.kernel.org/r/20250912123025.1271051-1-usama.anjum@collabora.com
Link: https://lkml.kernel.org/r/20250912123025.1271051-2-usama.anjum@collabora.com
Signed-off-by: Muhammad Usama Anjum 
Reviewed-by: Sidhartha Kumar 
Reviewed-by: Kevin Brodsky 
Acked-by: David Hildenbrand 
Reviewed-by: Zi Yan 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Jason Gunthorpe 
Cc: Lance Yang 
Cc: Leon Romanovsky 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests/mm: split_huge_page_test: cleanups for split_pte_mapped_thp test

2025-09-21T21:22:20+00:00

There is room for improvement, so let's clean up a bit:

(1) Define "4" as a constant.

(2) SKIP if we fail to allocate all THPs (e.g., fragmented) and add
    recovery code for all other failure cases: no need to exit the test.

(3) Rename "len" to thp_area_size, and "one_page" to "thp_area".

(4) Allocate a new area "page_area" into which we will mremap the
    pages; add "page_area_size". Now we can easily merge the two
    mremap instances into a single one.

(5) Iterate THPs instead of bytes when checking for missed THPs after
    mremap.

(6) Rename "pte_mapped2" to "tmp", used to verify mremap(MAP_FIXED)
    result.

(7) Split the corruption test from the failed-split test, so we can just
    iterate bytes vs. thps naturally.

(8) Extend comments and clarify why we are using mremap in the first
    place.

Link: https://lkml.kernel.org/r/20250903070253.34556-3-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Zi Yan 
Reviewed-by: Wei Yang 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Ryan Roberts 
Signed-off-by: Andrew Morton

selftests/mm: split_huge_page_test: fix occasional is_backed_by_folio() wrong results

2025-09-21T21:22:20+00:00

Patch series "selftests/mm: split_huge_page_test: split_pte_mapped_thp
improvements", v2.

One fix for occasional failures I found while testing and a bunch of
cleanups that should make that test easier to digest.


This patch (of 2):

When checking for actual tail or head pages of a folio, we must make sure
that the KPF_COMPOUND_HEAD/KPF_COMPOUND_TAIL flag is paired with KPF_THP.

For example, if we have another large folio after our large folio in
physical memory, our "pfn_flags & (KPF_THP | KPF_COMPOUND_TAIL)" would
trigger even though it's actually a head page of the next folio.

If is_backed_by_folio() returns a wrong result, split_pte_mapped_thp() can
fail with "Some THPs are missing during mremap".

Fix it by checking for head/tail pages of folios properly.  Add
folio_tail_flags/folio_head_flags to improve readability and use these
masks also when just testing for any compound page.

Link: https://lkml.kernel.org/r/20250903070253.34556-1-david@redhat.com
Link: https://lkml.kernel.org/r/20250903070253.34556-2-david@redhat.com
Fixes: 169b456b0162 ("selftests/mm: reimplement is_backed_by_thp() with more precise check")
Signed-off-by: David Hildenbrand 
Reviewed-by: Zi Yan 
Reviewed-by: Wei Yang 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Ryan Roberts 
Signed-off-by: Andrew Morton

selftests/mm: check after-split folio orders in split_huge_page_test

2025-09-13T23:55:12+00:00

Instead of just checking the existence of PMD folios before and after folio
split tests, use check_folio_orders() to check after-split folio orders.

The split ranges in split_thp_in_pagecache_to_order_at() are changed to
[addr, addr + pagesize) for every pmd_pagesize. It prevents folios within
the range being split multiple times due to debugfs split function always
perform splits with a pagesize step for a given range.

The following tests are not changed:
1. split_pte_mapped_thp: the test already uses kpageflags to check;
2. split_file_backed_thp: no vaddr available.

Link: https://lkml.kernel.org/r/20250818184622.1521620-6-ziy@nvidia.com
Signed-off-by: Zi Yan 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: David Hildenbrand 
Cc: Dev Jain 
Cc: Donet Tom 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: wang lian 
Cc: Wei Yang 
Signed-off-by: Andrew Morton

selftests/mm: add check_after_split_folio_orders() helper

2025-09-13T23:55:12+00:00

The helper gathers a folio order statistics of folios within a virtual
address range and checks it against a given order list. It aims to provide
a more precise folio order check instead of just checking the existence of
PMD folios.

The helper will be used the upcoming commit.

Link: https://lkml.kernel.org/r/20250818184622.1521620-5-ziy@nvidia.com
Signed-off-by: Zi Yan 
Tested-by: Baolin Wang 
Cc: Barry Song 
Cc: David Hildenbrand 
Cc: Dev Jain 
Cc: Donet Tom 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: wang lian 
Cc: Wei Yang 
Signed-off-by: Andrew Morton

selftests/mm: reimplement is_backed_by_thp() with more precise check

2025-09-13T23:55:12+00:00

and rename it to is_backed_by_folio().

is_backed_by_folio() checks if the given vaddr is backed a folio with
a given order. It does so by:
1. getting the pfn of the vaddr;
2. checking kpageflags of the pfn;

if order is greater than 0:
3. checking kpageflags of the head pfn;
4. checking kpageflags of all tail pfns.

pmd_order is added to split_huge_page_test.c and replaces max_order.

[ziy@nvidia.com: reduce code duplication, per David]
  Link: https://lkml.kernel.org/r/F54782D6-65A3-4D35-AE03-8ADE636EE258@nvidia.com
Link: https://lkml.kernel.org/r/20250818184622.1521620-4-ziy@nvidia.com
Signed-off-by: Zi Yan 
Reviewed-by: Wei Yang 
Reviewed-by: wang lian 
Acked-by: David Hildenbrand 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Donet Tom 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests/mm: mark all functions static in split_huge_page_test.c

2025-09-13T23:55:11+00:00

All functions are only used within the file.

Link: https://lkml.kernel.org/r/20250818184622.1521620-3-ziy@nvidia.com
Signed-off-by: Zi Yan 
Reviewed-by: Wei Yang 
Reviewed-by: wang lian 
Acked-by: David Hildenbrand 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Donet Tom 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Mariano Pache 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftest/mm: extract sz2ord function into vm_util.h

2025-09-13T23:55:06+00:00

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