[v1] mm: remove nth_page()

[PATCH v1 14/36] mm/mm/percpu-km: drop nth_page() usage within single allocation

Posted by David Hildenbrand 1 month ago

We're allocating a higher-order page from the buddy. For these pages
(that are guaranteed to not exceed a single memory section) there is no
need to use nth_page().

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 mm/percpu-km.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index fe31aa19db81a..4efa74a495cb6 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -69,7 +69,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
 	}
 
 	for (i = 0; i < nr_pages; i++)
-		pcpu_set_page_chunk(nth_page(pages, i), chunk);
+		pcpu_set_page_chunk(pages + i, chunk);
 
 	chunk->data = pages;
 	chunk->base_addr = page_address(pages);
-- 
2.50.1

Re: [PATCH v1 14/36] mm/mm/percpu-km: drop nth_page() usage within single allocation

Posted by Liam R. Howlett 1 month ago

* David Hildenbrand <david@redhat.com> [250827 18:06]:
> We're allocating a higher-order page from the buddy. For these pages
> (that are guaranteed to not exceed a single memory section) there is no
> need to use nth_page().
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>


> ---
>  mm/percpu-km.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/percpu-km.c b/mm/percpu-km.c
> index fe31aa19db81a..4efa74a495cb6 100644
> --- a/mm/percpu-km.c
> +++ b/mm/percpu-km.c
> @@ -69,7 +69,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
>  	}
>  
>  	for (i = 0; i < nr_pages; i++)
> -		pcpu_set_page_chunk(nth_page(pages, i), chunk);
> +		pcpu_set_page_chunk(pages + i, chunk);
>  
>  	chunk->data = pages;
>  	chunk->base_addr = page_address(pages);
> -- 
> 2.50.1
>

Re: [PATCH v1 14/36] mm/mm/percpu-km: drop nth_page() usage within single allocation

Posted by Lorenzo Stoakes 1 month ago

On Thu, Aug 28, 2025 at 12:01:18AM +0200, David Hildenbrand wrote:
> We're allocating a higher-order page from the buddy. For these pages
> (that are guaranteed to not exceed a single memory section) there is no
> need to use nth_page().
>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Oh hello! Now it all comes together :)

nth_tag():

LGTM, so:

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

> ---
>  mm/percpu-km.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/percpu-km.c b/mm/percpu-km.c
> index fe31aa19db81a..4efa74a495cb6 100644
> --- a/mm/percpu-km.c
> +++ b/mm/percpu-km.c
> @@ -69,7 +69,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
>  	}
>
>  	for (i = 0; i < nr_pages; i++)
> -		pcpu_set_page_chunk(nth_page(pages, i), chunk);
> +		pcpu_set_page_chunk(pages + i, chunk);
>
>  	chunk->data = pages;
>  	chunk->base_addr = page_address(pages);
> --
> 2.50.1
>