Re: [PATCH stable 6.1] mm: Fix is_zero_page() usage in try_grab_page()

[David Hildenbrand]

On 16.04.25 22:24, Alex Williamson wrote:
> The backport of upstream commit c8070b787519 ("mm: Don't pin ZERO_PAGE
> in pin_user_pages()") into v6.1.130 noted below in Fixes does not
> account for commit 0f0892356fa1 ("mm: allow multiple error returns in
> try_grab_page()"), which changed the return value of try_grab_page()
> from bool to int.  Therefore returning 0, success in the upstream
> version, becomes an error here.  Fix the return value.
>
> Fixes: 476c1dfefab8 ("mm: Don't pin ZERO_PAGE in pin_user_pages()")
> Link: https://lore.kernel.org/all/Z_6uhLQjJ7SSzI13@xxxxxxxxxxx
> Reported-by: Salvatore Bonaccorso <carnil@xxxxxxxxxx>
> Reported-by: Milan Broz <gmazyland@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> Cc: Sasha Levin <sashal@xxxxxxxxxx>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
>   mm/gup.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index b1daaa9d89aa..76a2b0943e2d 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -232,7 +232,7 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags)
>   		 * and it is used in a *lot* of places.
>   		 */
>   		if (is_zero_page(page))
> -			return 0;
> +			return true;
>   
>   		/*
>   		 * Similar to try_grab_folio(): be sure to *also*

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb