Re: [Patch v2] selftests/mm: do check_huge_anon() with a number been passed in

[Donet Tom <donettom@linux.ibm.com>]

On 8/10/25 1:12 AM, Wei Yang wrote:
> Currently it hard codes the number of hugepage to check for
> check_huge_anon(), but it would be more reasonable to do the check based
> on a number passed in.
>
> Pass in the hugepage number and do the check based on it.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Donet Tom <donettom@linux.ibm.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Dev Jain <dev.jain@arm.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: Zi Yan <ziy@nvidia.com>
>
> ---
> v2:
>    * use mm-new
>    * add back nr_hpages which is removed by an early commit
>    * adjust the change log a little
>    * drop RB and resend
> ---
>   tools/testing/selftests/mm/split_huge_page_test.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index 5ab488fab1cd..63ac82f0b9e0 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -105,12 +105,12 @@ static char *allocate_zero_filled_hugepage(size_t len)
>   	return result;
>   }
>   
> -static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, size_t len)
> +static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len)


We are re-adding this argument because nr_hpages should be the same in both
split_pmd_zero_pages and verify_rss_anon_split_huge_page_all_zeroes,
correct? I was just wondering — since the value is currently hardcoded
in both functions, would it be preferable to pass it as an argument,
or keep it hardcoded, What benefit do we gain by re-adding this argument?


>   {
>   	unsigned long rss_anon_before, rss_anon_after;
>   	size_t i;
>   
> -	if (!check_huge_anon(one_page, 4, pmd_pagesize))
> +	if (!check_huge_anon(one_page, nr_hpages, pmd_pagesize))
>   		ksft_exit_fail_msg("No THP is allocated\n");
>   
>   	rss_anon_before = rss_anon();
> @@ -141,7 +141,7 @@ void split_pmd_zero_pages(void)
>   	size_t len = nr_hpages * pmd_pagesize;
>   
>   	one_page = allocate_zero_filled_hugepage(len);
> -	verify_rss_anon_split_huge_page_all_zeroes(one_page, len);
> +	verify_rss_anon_split_huge_page_all_zeroes(one_page, nr_hpages, len);
>   	ksft_test_result_pass("Split zero filled huge pages successful\n");
>   	free(one_page);
>   }