Re: [RESEND PATCH 3/4] selftests/mm: split_huge_page_test: skip the test when thp is not available

[Zi Yan <ziy@nvidia.com>]

On 12 Mar 2026, at 7:40, Chunyu Hu wrote:

> When thp is not enabled on some kernel config such as realtime kernel, the
> test will report failure. Fix the false positive by skipping the test
> directly when thp is not enabled.
>
> There's a naming conflict on write_file() function, both thp_settings.h and
> split_huge_page_test.c define it. To make use of thp_is_enabled() helper in
> the thp_settings.h, rename this local write_file to safe_write_file to
> avoid the conflict. The reason to use 'safe_' is it does some error check.

Both write_file() do safe checks. Actually the code of both functions looks
almost identical except that the thp_settings one does exit() instead of
ksft_exit_fail_msg().

Can you rename the split_huge_page_test’s write_file() to write_file_local()
and add a comment above the function like
/* add _local to avoid a function conflict with thp_settings.h */?

With that, feel free to add:

Reviewed-by: Zi Yan <ziy@nvidia.com>

Thanks.

>
> Tested with thp disabled kernel:
> Before The fix:
>   # --------------------------------------------------
>   # running ./split_huge_page_test /tmp/xfs_dir_Ywup9p
>   # --------------------------------------------------
>   # TAP version 13
>   # Bail out! Reading PMD pagesize failed
>   # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
>   # [FAIL]
>   not ok 61 split_huge_page_test /tmp/xfs_dir_Ywup9p # exit=1
>
> After the fix:
>   # --------------------------------------------------
>   # running ./split_huge_page_test /tmp/xfs_dir_YHPUPl
>   # --------------------------------------------------
>   # TAP version 13
>   # 1..0 # SKIP Transparent Hugepages not available
>   # [SKIP]
>   ok 6 split_huge_page_test /tmp/xfs_dir_YHPUPl # SKIP
>
> CC: Li Wang <liwang@redhat.com>
> Signed-off-by: Chunyu Hu <chuhu@redhat.com>
> ---
>  tools/testing/selftests/mm/split_huge_page_test.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index e0167111bdd1..615b75ca62cc 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -21,6 +21,7 @@
>  #include <time.h>
>  #include "vm_util.h"
>  #include "kselftest.h"
> +#include "thp_settings.h"
>
>  uint64_t pagesize;
>  unsigned int pageshift;
> @@ -255,7 +256,7 @@ static int check_after_split_folio_orders(char *vaddr_start, size_t len,
>  	return status;
>  }
>
> -static void write_file(const char *path, const char *buf, size_t buflen)
> +static void safe_write_file(const char *path, const char *buf, size_t buflen)
>  {
>  	int fd;
>  	ssize_t numwritten;
> @@ -283,7 +284,7 @@ static void write_debugfs(const char *fmt, ...)
>  	if (ret >= INPUT_MAX)
>  		ksft_exit_fail_msg("%s: Debugfs input is too long\n", __func__);
>
> -	write_file(SPLIT_DEBUGFS, input, ret + 1);
> +	safe_write_file(SPLIT_DEBUGFS, input, ret + 1);
>  }
>
>  static char *allocate_zero_filled_hugepage(size_t len)
> @@ -772,6 +773,10 @@ int main(int argc, char **argv)
>  		ksft_finished();
>  	}
>
> +	if (!thp_is_enabled()) {
> +		ksft_exit_skip("Transparent Hugepages not available\n");
> +	}
> +
>  	if (argc > 1)
>  		optional_xfs_path = argv[1];
>
> -- 
> 2.53.0


Best Regards,
Yan, Zi