[v1] mm: remove nth_page()

[PATCH v1 17/36] mm/pagewalk: drop nth_page() usage within folio in folio_walk_start()

Posted by David Hildenbrand 1 month ago

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@redhat.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);
 	else
 		fw->page = NULL;
 	fw->ptl = ptl;
-- 
2.50.1

Re: [PATCH v1 17/36] mm/pagewalk: drop nth_page() usage within folio in folio_walk_start()

Posted by Liam R. Howlett 1 month ago

* David Hildenbrand <david@redhat.com> [250827 18:07]:
> 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@redhat.com>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.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);
>  	else
>  		fw->page = NULL;
>  	fw->ptl = ptl;
> -- 
> 2.50.1
>

Re: [PATCH v1 17/36] mm/pagewalk: drop nth_page() usage within folio in folio_walk_start()

Posted by Lorenzo Stoakes 1 month ago

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@redhat.com>

LGTM, so:

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