Re: [PATCH 2/2] selftests/mm: add tests for splitting pmd THPs to all lower orders.

On 10 Jan 2025, at 18:50, Zi Yan wrote:

Kernel already supports splitting a folio to any lower order. Test it.

Signed-off-by: Zi Yan ziy@nvidia.com

tools/testing/selftests/mm/split_huge_page_test.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 128004308233..3d3bc40a268b 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -144,7 +144,7 @@ void split_pmd_zero_pages(void) free(one_page); }

-void split_pmd_thp(void) +void split_pmd_thp_to_order(int order) { char *one_page; size_t len = 4 * pmd_pagesize; @@ -164,7 +164,7 @@ void split_pmd_thp(void)

/* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,

• (uint64_t)one_page + len, 0);
  

• (uint64_t)one_page + len, order);
  
  

  for (i = 0; i < len; i++) if (one_page[i] != (char)i)

@@ -174,7 +174,7 @@ void split_pmd_thp(void) if (!check_huge_anon(one_page, 0, pmd_pagesize)) ksft_exit_fail_msg("Still AnonHugePages not split\n");

• ksft_test_result_pass("Split huge pages successful\n");

• ksft_test_result_pass("Split huge pages to order %d successful\n", order); free(one_page);

}

@@ -481,7 +481,7 @@ int main(int argc, char **argv) if (argc > 1) optional_xfs_path = argv[1];

• ksft_set_plan(4+9);

• ksft_set_plan(1+9+2+9);

  pagesize = getpagesize(); pageshift = ffs(pagesize) - 1;

@@ -492,7 +492,10 @@ int main(int argc, char **argv) fd_size = 2 * pmd_pagesize;

split_pmd_zero_pages();

• split_pmd_thp();

• for (i = 0; i < 9; i++)

• split_pmd_thp_to_order(i);
  

• split_pte_mapped_thp(); split_file_backed_thp();

Hi Andrew,

Can you fold the patch below into this one? Anonymous memory does not support order-1 folio, so there is no need to test splitting to order-1. Kernel will WARN_ONCE for split_pmd_thp_to_order(1) test and the whole test will fail at that point.

Thanks.

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 3d3bc40a268b..4b47ab544a0c 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -494,7 +494,8 @@ int main(int argc, char **argv) split_pmd_zero_pages();

for (i = 0; i < 9; i++) - split_pmd_thp_to_order(i); + if (i != 1) + split_pmd_thp_to_order(i);

split_pte_mapped_thp(); split_file_backed_thp();

-- Best Regards, Yan, Zi