linux-kernel - Re: [PATCH 2/3] mm/slub: remove full list manipulation for non-debug slab

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Message-ID: <05e23c85-1bae-48a5-b1d1-cb61e0b1efdf@suse.cz>
Date: Tue, 23 Jan 2024 09:45:15 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Chengming Zhou <zhouchengming@...edance.com>,
 Hyeonggon Yoo <42.hyeyoo@...il.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
 Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 David Rientjes <rientjes@...gle.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] mm/slub: remove full list manipulation for non-debug
 slab

On 1/17/24 12:45, Chengming Zhou wrote:
> Since debug slab is processed by free_to_partial_list(), and only debug
> slab which has SLAB_STORE_USER flag would care about the full list, we
> can remove these unrelated full list manipulations from __slab_free().

Well spotted.

> Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  mm/slub.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 20c03555c97b..f0307e8b4cd2 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -4187,7 +4187,6 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>  	 * then add it.
>  	 */
>  	if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
> -		remove_full(s, n, slab);
>  		add_partial(n, slab, DEACTIVATE_TO_TAIL);
>  		stat(s, FREE_ADD_PARTIAL);
>  	}
> @@ -4201,9 +4200,6 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
>  		 */
>  		remove_partial(n, slab);
>  		stat(s, FREE_REMOVE_PARTIAL);
> -	} else {
> -		/* Slab must be on the full list */
> -		remove_full(s, n, slab);
>  	}
>  
>  	spin_unlock_irqrestore(&n->list_lock, flags);
>