Re: [PATCH 1/1] mm,swapops: Fix compile error on set_pmd_migration_entry.

[Barry Song <21cnbao@gmail.com>]

On Thu, Dec 25, 2025 at 10:41 PM Wale Zhang <wale.zhang.ftd@gmail.com> wrote:
>
> ../include/linux/swapops.h: In function ‘set_pmd_migration_entry’:
> ../include/linux/swapops.h:346:1: error: no return statement in function returning non-void [-Werror=return-type]
>   346 | }
>       | ^
> cc1: some warnings being treated as errors
>
> Signed-off-by: Wale Zhang <wale.zhang.ftd@gmail.com>

Sorry. NAK.

This looks odd. We already have a BUILD_BUG(), so no fix is needed.

we should already have:
././include/linux/compiler_types.h:631:45: error: call to
‘__compiletime_assert_907’ declared with attribute error: BUILD_BUG
failed
  631 |         _compiletime_assert(condition, msg,
__compiletime_assert_, __COUNTER__)
      |                                             ^
././include/linux/compiler_types.h:612:25: note: in definition of
macro ‘__compiletime_assert’
  612 |                         prefix ## suffix();
         \
      |                         ^~~~~~

Do you actually see this being built? If so, please help identify why it
gets built.

> ---
>  include/linux/swapops.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/swapops.h b/include/linux/swapops.h
> index 8cfc966eae48..84eb36d97212 100644
> --- a/include/linux/swapops.h
> +++ b/include/linux/swapops.h
> @@ -343,6 +343,7 @@ static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
>                 struct page *page)
>  {
>         BUILD_BUG();
> +       return 0;
>  }
>
>  static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
> --
> 2.43.0
>

Thanks
Barry