linux-kernel - Re: [PATCH] mm/slub: make add_full() condition more explicit

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Message-ID: <40c24455-02fd-4b4c-7740-bb7d2af0f5c7@huawei.com>
Date:   Mon, 17 Aug 2020 17:19:54 +0800
From:   Abel Wu <wuyun.wu@...wei.com>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        "David Rientjes" <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        "Andrew Morton" <akpm@...ux-foundation.org>
CC:     <liu.xiang6@....com.cn>,
        "open list:SLAB ALLOCATOR" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/slub: make add_full() condition more explicit

ping :)

On 2020/8/11 10:02, wuyun.wu@...wei.com wrote:
> From: Abel Wu <wuyun.wu@...wei.com>
> 
> The commit below is incomplete, as it didn't handle the add_full() part.
> commit a4d3f8916c65 ("slub: remove useless kmem_cache_debug() before remove_full()")
> 
> This patch checks for SLAB_STORE_USER instead of kmem_cache_debug(),
> since that should be the only context in which we need the list_lock for
> add_full().
> 
> Signed-off-by: Abel Wu <wuyun.wu@...wei.com>
> ---
>  mm/slub.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index f226d66408ee..df93a5a0e9a4 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2182,7 +2182,8 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
>  		}
>  	} else {
>  		m = M_FULL;
> -		if (kmem_cache_debug(s) && !lock) {
> +#ifdef CONFIG_SLUB_DEBUG
> +		if ((s->flags & SLAB_STORE_USER) && !lock) {
>  			lock = 1;
>  			/*
>  			 * This also ensures that the scanning of full
> @@ -2191,6 +2192,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
>  			 */
>  			spin_lock(&n->list_lock);
>  		}
> +#endif
>  	}
>  
>  	if (l != m) {
>