Re: [PATCH v7 11/13] selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero

[Sayali Patil <sayalip@linux.ibm.com>]

On 21/05/26 12:17, Sayali Patil wrote:
> uffd-stress currently fails when the computed nr_pages_per_cpu
> evaluates to zero:
> 
> nr_pages_per_cpu = bytes / page_size / nr_parallel
> 
> This can occur on systems with large hugepage sizes (e.g. 1GB) and a
> high number of CPUs, where the total allocated memory is sufficient
> overall but not enough to provide at least one page per cpu.
> 
> In such cases, the failure is due to insufficient test resources
> rather than incorrect kernel behaviour. Update the test
> to treat this condition as a test skip instead of reporting an error.
> 
> Fixes: db0f1c138f18 ("selftests/mm: print some details when uffd-stress gets bad params")
> Acked-by: Zi Yan <ziy@nvidia.com>
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>   tools/testing/selftests/mm/uffd-stress.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
> index 43cc79590136..39e13e2078a9 100644
> --- a/tools/testing/selftests/mm/uffd-stress.c
> +++ b/tools/testing/selftests/mm/uffd-stress.c
> @@ -489,9 +489,9 @@ int main(int argc, char **argv)
>   
>   	gopts->nr_pages_per_cpu = bytes / gopts->page_size / gopts->nr_parallel;
>   	if (!gopts->nr_pages_per_cpu) {
> -		_err("pages_per_cpu = 0, cannot test (%lu / %lu / %lu)",
> -			bytes, gopts->page_size, gopts->nr_parallel);
> -		usage();
> +		ksft_print_msg("pages_per_cpu = 0, cannot test (%zu / %lu / %lu)\n",
> +			       bytes, gopts->page_size, gopts->nr_parallel);
> +		return KSFT_SKIP;
>   	}
>   
>   	bounces = atoi(argv[3]);


Hi Andrew,
Can you please apply the below fixlet on top of this patch as suggested 
by Sashiko.

 From aa8f2eea63defd9b9c1342b83838f48e93e1b918 Mon Sep 17 00:00:00 2001
From: Sayali Patil <sayalip@linux.ibm.com>
Date: Thu, 21 May 2026 13:32:51 +0530
Subject: [PATCH] [fixlet] selftests/mm: use ksft_exit_skip() instead of
  KSFT_SKIP in uffd-stress

When nr_pages_per_cpu evaluates to zero, the test is skipped by
printing a message and returning KSFT_SKIP manually.

Replace this with ksft_exit_skip(), which prints the skip message
and exits with the correct skip status in a single helper, making
the code consistent with other selftests.

Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
  tools/testing/selftests/mm/uffd-stress.c | 3 +--
  1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-stress.c 
b/tools/testing/selftests/mm/uffd-stress.c
index 39e13e2078a9..3401dd6028f0 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -489,9 +489,8 @@ int main(int argc, char **argv)

  	gopts->nr_pages_per_cpu = bytes / gopts->page_size / gopts->nr_parallel;
  	if (!gopts->nr_pages_per_cpu) {
-		ksft_print_msg("pages_per_cpu = 0, cannot test (%zu / %lu / %lu)\n",
+		ksft_exit_skip("pages_per_cpu = 0, cannot test (%zu / %lu / %lu)\n",
  			       bytes, gopts->page_size, gopts->nr_parallel);
-		return KSFT_SKIP;
  	}

  	bounces = atoi(argv[3]);
-- 
2.52.0


Thanks,
Sayali