[PATCH v4 0/3] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro

[Yeoreum Yun <yeoreum.yun@arm.com>]

HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE.
When this macro is used in some test, test result would be strange in
the system where PAGE_SIZE is more then 4KB.

Here is the example with transhuge-stress test with 16KB PAGE_SIZE:

  transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram
    3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s       2566 succeed, 58507 failed, 2566 different pages
    0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s          0 succeed, 61073 failed,    0 different pages
    3.292 s/loop, 0.054 ms/page,  37106.002 MiB/s       2566 succeed, 58507 failed, 2566 different pages
    0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s          0 succeed, 61073 failed,    0 different pages
    0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s          0 succeed, 61073 failed,    0 different pages
    ...
  ok 1 Completed

To address this, remove the HPAGE_SIZE and HPAGE_SHIFT macro,
introduce pmd_pshift() and rename read_pmd_pagesize() to pmd_psize()
to keep consistency with psize() and pshift().

Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB,
which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB,
and 64 KiB base pages. Since allocate_transhuge() allocates mappings in
PMD-sized units, the test may fail with the previous size of 100 MiB,
which is not a multiple of the PMD size when the base page size is
16 KiB or 64 KiB.

After this patch, output of transhuge-stress:

  transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram
    2.558 s/loop, 0.670 ms/page,  47755.759 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.640 s/loop, 0.692 ms/page,  46268.432 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.635 s/loop, 0.690 ms/page,  46360.298 MiB/s       2585 succeed, 1232 failed, 2585 different pages
    2.782 s/loop, 0.729 ms/page,  43899.795 MiB/s       2616 succeed, 1201 failed, 2616 different pages
    2.692 s/loop, 0.705 ms/page,  45380.876 MiB/s       2627 succeed, 1190 failed, 2627 different pages
    2.612 s/loop, 0.684 ms/page,  46765.812 MiB/s       2628 succeed, 1189 failed, 2628 different pages
    2.683 s/loop, 0.703 ms/page,  45520.990 MiB/s       2630 succeed, 1187 failed, 2630 different pages
    2.727 s/loop, 0.714 ms/page,  44789.321 MiB/s       2631 succeed, 1186 failed, 2631 different pages
    ...
  ok 1 Completed

Additionally, introduce size_to_shift() for future users that need to
obtain shift of a huge-page which is other than pmd_psize().

Patch History
=============
Changes in v4:
  - make size_to_shift() as inline function.
  - initialise __pmd_psize and __pmd_pshift with -1ull.
  - Link to v3: https://lore.kernel.org/r/20260914-fix_hpage_macro-v3-0-c9a305a01d39@arm.com

Change in v3:
 - rename read_pmd_pagesize() to pmd_psize()
 - introduce size_to_shift()
 - Link to v2: https://lore.kernel.org/all/20260907081509.924979-1-yeoreum.yun@arm.com/

Chnage in v2:
 - rename hpage_* to pmd_page_*
 - Link to v1: https://lore.kernel.org/all/20260902175611.1241118-1-yeoreum.yun@arm.com/#t

---
Yeoreum Yun (3):
      kselftest: mm: rename read_pmd_pagesize() to pmd_psize()
      kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro
      kselftest: mm: introduce size_to_shift() helper

 tools/testing/selftests/mm/cow.c                   |  2 +-
 tools/testing/selftests/mm/folio_split_race_test.c |  2 +-
 tools/testing/selftests/mm/guard-regions.c         | 11 +++++-
 tools/testing/selftests/mm/hmm-tests.c             | 22 +++++------
 tools/testing/selftests/mm/khugepaged.c            |  2 +-
 tools/testing/selftests/mm/ksm_tests.c             | 16 +++++---
 tools/testing/selftests/mm/migration.c             |  4 +-
 tools/testing/selftests/mm/mkdirty.c               |  2 +-
 tools/testing/selftests/mm/pagemap_ioctl.c         |  2 +-
 tools/testing/selftests/mm/prctl_thp_disable.c     |  4 +-
 tools/testing/selftests/mm/process_madv.c          |  2 +-
 tools/testing/selftests/mm/run_vmtests.sh          |  4 +-
 tools/testing/selftests/mm/soft-dirty.c            |  2 +-
 tools/testing/selftests/mm/split_huge_page_test.c  |  2 +-
 tools/testing/selftests/mm/transhuge-stress.c      | 25 +++++++-----
 tools/testing/selftests/mm/uffd-common.c           |  6 +--
 tools/testing/selftests/mm/uffd-unit-tests.c       |  8 ++--
 tools/testing/selftests/mm/uffd-wp-mremap.c        |  2 +-
 tools/testing/selftests/mm/vm_util.c               | 46 +++++++++++++++++-----
 tools/testing/selftests/mm/vm_util.h               | 23 +++++++----
 20 files changed, 120 insertions(+), 67 deletions(-)
---
base-commit: 8d61431ed2607386b427752505379536eb634ce8
change-id: 20260909-fix_hpage_macro-da069ae04502

Best regards,
-- 
Sincerely,
Yeoreum Yun