Re: [PATCH v2 4/4] selftests: mm: add mTHP collapse test cases

["Zi Yan" <ziy@nvidia.com>]

On Sat Aug 1, 2026 at 2:26 AM EDT, Baolin Wang wrote:
> Added a new command 'mthp_khugepaged' for mTHP collapse, along with the '-c'
> parameter to specify the collapse order. Additionally, added mTHP collapse
> test cases for 'collapse_full', 'collapse_empty', and 'collapse_single_mthp'
> for anonymous folios. All khugepaged test cases passed.
>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>  tools/testing/selftests/mm/khugepaged.c   | 130 ++++++++++++++++++----
>  tools/testing/selftests/mm/run_vmtests.sh |   2 +
>  2 files changed, 113 insertions(+), 19 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
> index f69be6be0ecd..64d6da6aa90d 100644
> --- a/tools/testing/selftests/mm/khugepaged.c
> +++ b/tools/testing/selftests/mm/khugepaged.c
> @@ -26,9 +26,11 @@
>  
>  #define BASE_ADDR ((void *)(1UL << 30))
>  static unsigned long hpage_pmd_size;
> +static int hpage_pmd_order;
>  static unsigned long page_size;
>  static int hpage_pmd_nr;
>  static int anon_order;
> +static int collapse_order;

<snip>

>  
> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
> index 687d115e3bd8..d09f9f6a384e 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -410,6 +410,8 @@ CATEGORY="thp" run_test ./khugepaged all:shmem
>  
>  CATEGORY="thp" run_test ./khugepaged -s 4 all:shmem
>  
> +CATEGORY="thp" run_test ./khugepaged -c 4 mthp_khugepaged:anon

Why only testing collapse_order == 4? It is more useful to test all
possible mTHP orders. -c can accept common separated order and a range.


Why only testing mthp_khugepaged:anon? IIRC, file and shmem are not
supported, so khugepaged should reject them, right?


> +
>  # Try to create XFS if not provided
>  if [ -z "${SPLIT_HUGE_PAGE_TEST_XFS_PATH}" ]; then
>      if test_selected "thp"; then




-- 
Best Regards,
Yan, Zi