linux-kernel - Re: [PATCH 4/4] mm/slub: don't read slab->cpu_partial

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Date: Tue, 2 Apr 2024 11:42:38 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: xiongwei.song@...driver.com, rientjes@...gle.com, cl@...ux.com,
 penberg@...nel.org, iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
 roman.gushchin@...ux.dev, 42.hyeyoo@...il.com
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, chengming.zhou@...ux.dev
Subject: Re: [PATCH 4/4] mm/slub: don't read slab->cpu_partial_slabs directly

On 3/31/24 4:19 AM, xiongwei.song@...driver.com wrote:
> From: Xiongwei Song <xiongwei.song@...driver.com>
> 
> We can use slub_get_cpu_partial() to read cpu_partial_slabs.

This code is under the #ifdef so it's not necessary to use the wrapper, only
makes it harder to read imho.

> Signed-off-by: Xiongwei Song <xiongwei.song@...driver.com>
> ---
>  mm/slub.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index ec91c7435d4e..47ea06d6feae 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2966,7 +2966,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain)
>  	oldslab = this_cpu_read(s->cpu_slab->partial);
>  
>  	if (oldslab) {
> -		if (drain && oldslab->slabs >= s->cpu_partial_slabs) {
> +		if (drain && oldslab->slabs >= slub_get_cpu_partial(s)) {
>  			/*
>  			 * Partial array is full. Move the existing set to the
>  			 * per node partial list. Postpone the actual unfreezing