linux-kernel - Re: [PATCH v1 17/36] mm/pagewalk: drop nth_page() usage within folio in folio_walk

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Message-ID: <8842cba4-61bc-48e2-b4aa-df9619409621@lucifer.local>
Date: Thu, 28 Aug 2025 17:21:30 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brendan Jackman <jackmanb@...gle.com>,
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Subject: Re: [PATCH v1 17/36] mm/pagewalk: drop nth_page() usage within folio
 in folio_walk_start()

On Thu, Aug 28, 2025 at 12:01:21AM +0200, David Hildenbrand wrote:
> It's no longer required to use nth_page() within a folio, so let's just
> drop the nth_page() in folio_walk_start().
>
> Signed-off-by: David Hildenbrand <david@...hat.com>

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  mm/pagewalk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index c6753d370ff4e..9e4225e5fcf5c 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -1004,7 +1004,7 @@ struct folio *folio_walk_start(struct folio_walk *fw,
>  found:
>  	if (expose_page)
>  		/* Note: Offset from the mapped page, not the folio start. */
> -		fw->page = nth_page(page, (addr & (entry_size - 1)) >> PAGE_SHIFT);
> +		fw->page = page + ((addr & (entry_size - 1)) >> PAGE_SHIFT);

Be nice to clean this horrid one liner up a bit also but that's out of
scope here :)

>  	else
>  		fw->page = NULL;
>  	fw->ptl = ptl;
> --
> 2.50.1
>