linux-kernel - Re: [PATCH] mm: memcontrol: Fix do not put the css reference

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Message-ID: <20200614172238.GA755479@carbon.DHCP.thefacebook.com>
Date:   Sun, 14 Jun 2020 10:22:38 -0700
From:   Roman Gushchin <guro@...com>
To:     Muchun Song <songmuchun@...edance.com>
CC:     <hannes@...xchg.org>, <mhocko@...nel.org>,
        <vdavydov.dev@...il.com>, <akpm@...ux-foundation.org>,
        <cai@....pw>, <cgroups@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: memcontrol: Fix do not put the css reference

On Sun, Jun 14, 2020 at 08:26:53PM +0800, Muchun Song wrote:
> We should put the css reference when memory allocation failed.
> 
> Fixes: f0a3a24b532d ("mm: memcg/slab: rework non-root kmem_cache lifecycle management")
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> ---
>  mm/memcontrol.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Good catch, thank you!

Acked-by: Roman Gushchin <guro@...com>

> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 0b38b6ad547d..2323d811ee8e 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2772,8 +2772,10 @@ static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
>  		return;
>  
>  	cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN);
> -	if (!cw)
> +	if (!cw) {
> +		css_put(&memcg->css);
>  		return;
> +	}
>  
>  	cw->memcg = memcg;
>  	cw->cachep = cachep;
> -- 
> 2.11.0
>