Re: [PATCH v4 4/7] mm/selftests: Fix split_huge_page_test failure on systems with 64KB page size

[Giant Sand Fans <rampxxxx@gmail.com>]

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On Saturday, 16 August 2025, Wei Yang <richard.weiyang@gmail.com> wrote:
> On Sat, Aug 16, 2025 at 09:31:10AM +0530, Aboorva Devarajan wrote:
>>From: Donet Tom <donettom@linux.ibm.com>
>>
>>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.
>>
>>Fixes: fa6c02315f745 ("mm: huge_memory: a new debugfs interface for
splitting THP tests")
>>Co-developed-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
>>Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
>>Reviewed-by: Dev Jain <dev.jain@arm.com>
>>Reviewed-by: Zi Yan <ziy@nvidia.com>
>>Signed-off-by: Donet Tom <donettom@linux.ibm.com>
>
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
>
> Nit below:
>
>>---
>> tools/testing/selftests/mm/cow.c              |  5 -----
>> .../selftests/mm/split_huge_page_test.c       | 22 ++++++++++++-------
>> tools/testing/selftests/mm/uffd-wp-mremap.c   |  5 -----
>> tools/testing/selftests/mm/vm_util.h          |  5 +++++
>> 4 files changed, 19 insertions(+), 18 deletions(-)
>>
>>diff --git a/tools/testing/selftests/mm/cow.c
b/tools/testing/selftests/mm/cow.c
>>index 90ee5779662f..e742d9313798 100644
>>--- a/tools/testing/selftests/mm/cow.c
>>+++ b/tools/testing/selftests/mm/cow.c
>>@@ -41,11 +41,6 @@ static size_t hugetlbsizes[10];
>> static int gup_fd;
>> static bool has_huge_zeropage;
>>
>>-static int sz2ord(size_t size)
>>-{
>>-      return __builtin_ctzll(size / pagesize);
>>-}
>>-
>> static int detect_thp_sizes(size_t sizes[], int max)
>> {
>>       int count = 0;
>>diff --git a/tools/testing/selftests/mm/split_huge_page_test.c
b/tools/testing/selftests/mm/split_huge_page_test.c
>>index eadbeb820d71..7cbeaebc9d71 100644
>>--- a/tools/testing/selftests/mm/split_huge_page_test.c
>>+++ b/tools/testing/selftests/mm/split_huge_page_test.c
>>@@ -523,6 +523,9 @@ int main(int argc, char **argv)
>>       const char *fs_loc;
>>       bool created_tmp;
>>       int offset;
>>+      unsigned int max_order;
>>+      unsigned int nr_pages;
>>+      unsigned int tests;
>>
>>       ksft_print_header();
>>
>>@@ -534,35 +537,38 @@ int main(int argc, char **argv)
>>       if (argc > 1)
>>               optional_xfs_path = argv[1];
>>
>>-      ksft_set_plan(1+8+1+9+9+8*4+2);
>>-
>>       pagesize = getpagesize();
>>       pageshift = ffs(pagesize) - 1;
>>       pmd_pagesize = read_pmd_pagesize();
>>       if (!pmd_pagesize)
>>               ksft_exit_fail_msg("Reading PMD pagesize failed\n");
>>
>>+      nr_pages = pmd_pagesize / pagesize;
>>+      max_order =  sz2ord(pmd_pagesize);
>                     ^
>                     extra space here
>
>>+      tests = 2 + (max_order - 1) + (2 * max_order) + (max_order - 1) *
4 + 2;

Is it possible to have some defines here instead plain numbers?
Thanks

>>+      ksft_set_plan(tests);
>>+
>>       fd_size = 2 * pmd_pagesize;
>>
>>       split_pmd_zero_pages();
>>
>
> --
> Wei Yang
> Help you, Help me
>
>

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