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

[Andrew Morton <akpm@linux-foundation.org>]

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.