linux-kernel - Re: [PATCH v2 1/2] memcg, oom: remove unnecessary check in mem_cgroup_oom

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Date:   Wed, 19 Apr 2023 09:35:13 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Haifeng Xu <haifeng.xu@...pee.com>
Cc:     hannes@...xchg.org, roman.gushchin@...ux.dev, shakeelb@...gle.com,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] memcg, oom: remove unnecessary check in
 mem_cgroup_oom_synchronize()

On Wed 19-04-23 03:07:38, Haifeng Xu wrote:
> mem_cgroup_oom_synchronize() is only used when the memcg oom handling is
> handed over to the edge of the #PF path. Since commit 29ef680ae7c2 ("memcg,
> oom: move out_of_memory back to the charge path") this is the case only
> when the kernel memcg oom killer is disabled (current->memcg_in_oom is
> only set if memcg->oom_kill_disable). Therefore a check for
> oom_kill_disable in mem_cgroup_oom_synchronize() is not required.
> 
> Signed-off-by: Haifeng Xu <haifeng.xu@...pee.com>
> Suggested-by: Michal Hocko <mhocko@...e.com>

Acked-by: Michal Hocko <mhocko@...e.com>

> ---
> v2: split original into two and improve patch description
> ---
>  mm/memcontrol.c | 13 +++----------
>  1 file changed, 3 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5abffe6f8389..fbf4d2bb1003 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1999,16 +1999,9 @@ bool mem_cgroup_oom_synchronize(bool handle)
>  	if (locked)
>  		mem_cgroup_oom_notify(memcg);
>  
> -	if (locked && !memcg->oom_kill_disable) {
> -		mem_cgroup_unmark_under_oom(memcg);
> -		finish_wait(&memcg_oom_waitq, &owait.wait);
> -		mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
> -					 current->memcg_oom_order);
> -	} else {
> -		schedule();
> -		mem_cgroup_unmark_under_oom(memcg);
> -		finish_wait(&memcg_oom_waitq, &owait.wait);
> -	}
> +	schedule();
> +	mem_cgroup_unmark_under_oom(memcg);
> +	finish_wait(&memcg_oom_waitq, &owait.wait);
>  
>  	if (locked) {
>  		mem_cgroup_oom_unlock(memcg);
> -- 
> 2.25.1

-- 
Michal Hocko
SUSE Labs