[PATCH] selftests/mm: cleanup -Wformat issues in hugetlb-mmap

[PATCH] selftests/mm: cleanup -Wformat issues in hugetlb-mmap

[Carlos Llamas]

Commit ae571cd6015c ("selftests/mm: hugetlb-mmap: add setup of HugeTLB
pages") and commit 9c5a65f374f8 ("selftests/mm: merge map_hugetlb into
hugepage-mmap") added logs of 'hugepage_size' which has a size_t type.
However, the incorrect format specifier '%lu' was used which triggers
-Wformat warnings when building for 32-bit:

  hugetlb-mmap.c:125:55: warning: format specifies type 'unsigned long'
  but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
    125 | ksft_print_msg("Default size hugepages (%lu kB)\n", hugepage_size >> 10);
        |                                         ~~~         ^~~~~~~~~~~~~~~~~~~
        |                                         %zu

  hugetlb-mmap.c:134:47: warning: format specifies type 'unsigned long'
  but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
    134 | ksft_exit_skip("Not enough %lu Kb pages\n", hugepage_size >> 10);
        |                            ~~~              ^~~~~~~~~~~~~~~~~~~
        |                            %zu

Fix this by switching to the expected '%zu' format specifier.

Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---

Note that I intentionally skipped the 'Fixes:' tag as I've been
previously suggested _not_ to use it for kselftest patches. However, I
can certainly add one if someone prefers it that way. Thanks!

 tools/testing/selftests/mm/hugetlb-mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/hugetlb-mmap.c b/tools/testing/selftests/mm/hugetlb-mmap.c
index 0f2aad1b7dbd..2edbc992e6bc 100644
--- a/tools/testing/selftests/mm/hugetlb-mmap.c
+++ b/tools/testing/selftests/mm/hugetlb-mmap.c
@@ -122,7 +122,7 @@ int main(int argc, char **argv)
 		hugepage_size = default_huge_page_size();
 		if (!hugepage_size)
 			ksft_exit_skip("Could not detect default hugetlb page size.");
-		ksft_print_msg("Default size hugepages (%lu kB)\n", hugepage_size >> 10);
+		ksft_print_msg("Default size hugepages (%zu kB)\n", hugepage_size >> 10);
 	}
 
 	/* munmap will fail if the length is not page aligned */
@@ -131,7 +131,7 @@ int main(int argc, char **argv)
 
 	hugetlb_set_nr_pages(hugepage_size, nr);
 	if (hugetlb_free_pages(hugepage_size) < nr)
-		ksft_exit_skip("Not enough %lu Kb pages\n", hugepage_size >> 10);
+		ksft_exit_skip("Not enough %zu Kb pages\n", hugepage_size >> 10);
 
 	ksft_set_plan(2);
 	ksft_print_msg("Mapping %lu Mbytes\n", (unsigned long)length >> 20);
-- 
2.56.0.rc1.315.gc6ed9934b7-goog

Re: [PATCH] selftests/mm: cleanup -Wformat issues in hugetlb-mmap

[Andrew Morton]

On Sun, 27 Sep 2026 16:24:18 +0000 Carlos Llamas <cmllamas@google.com> wrote:

> Commit ae571cd6015c ("selftests/mm: hugetlb-mmap: add setup of HugeTLB
> pages") and commit 9c5a65f374f8 ("selftests/mm: merge map_hugetlb into
> hugepage-mmap") added logs of 'hugepage_size' which has a size_t type.
> However, the incorrect format specifier '%lu' was used which triggers
> -Wformat warnings when building for 32-bit:
> 
>   hugetlb-mmap.c:125:55: warning: format specifies type 'unsigned long'
>   but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
>     125 | ksft_print_msg("Default size hugepages (%lu kB)\n", hugepage_size >> 10);
>         |                                         ~~~         ^~~~~~~~~~~~~~~~~~~
>         |                                         %zu
> 
>   hugetlb-mmap.c:134:47: warning: format specifies type 'unsigned long'
>   but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
>     134 | ksft_exit_skip("Not enough %lu Kb pages\n", hugepage_size >> 10);
>         |                            ~~~              ^~~~~~~~~~~~~~~~~~~
>         |                            %zu
> 
> Fix this by switching to the expected '%zu' format specifier.

Thanks.

> 
> Note that I intentionally skipped the 'Fixes:' tag as I've been
> previously suggested _not_ to use it for kselftest patches. However, I
> can certainly add one if someone prefers it that way. Thanks!

I added cc:stable.  It's not good and it's worse with -Werror.  mm
selftests don't presently use -Werror, but quite a few other parts of
selftests do this.

Re: [PATCH] selftests/mm: cleanup -Wformat issues in hugetlb-mmap

[Sarthak Sharma]

On 9/27/26 9:54 PM, Carlos Llamas wrote:
> Commit ae571cd6015c ("selftests/mm: hugetlb-mmap: add setup of HugeTLB
> pages") and commit 9c5a65f374f8 ("selftests/mm: merge map_hugetlb into
> hugepage-mmap") added logs of 'hugepage_size' which has a size_t type.
> However, the incorrect format specifier '%lu' was used which triggers
> -Wformat warnings when building for 32-bit:
> 
>   hugetlb-mmap.c:125:55: warning: format specifies type 'unsigned long'
>   but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
>     125 | ksft_print_msg("Default size hugepages (%lu kB)\n", hugepage_size >> 10);
>         |                                         ~~~         ^~~~~~~~~~~~~~~~~~~
>         |                                         %zu
> 
>   hugetlb-mmap.c:134:47: warning: format specifies type 'unsigned long'
>   but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
>     134 | ksft_exit_skip("Not enough %lu Kb pages\n", hugepage_size >> 10);
>         |                            ~~~              ^~~~~~~~~~~~~~~~~~~
>         |                            %zu
> 
> Fix this by switching to the expected '%zu' format specifier.
> 
> Cc: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
LGTM, so:

Reviewed-by: Sarthak Sharma <sarthak.sharma@arm.com>