linux-kernel - Re: [RFC PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init

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Date:	Tue, 7 Jun 2016 08:26:50 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	linux-mm@...ck.org, rientjes@...gle.com, oleg@...hat.com,
	vdavydov@...allels.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 10/10] mm, oom: hide mm which is shared with kthread
 or global init

On Mon 06-06-16 15:26:50, Michal Hocko wrote:
[...]
> @@ -922,8 +941,17 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
>  	}
>  	rcu_read_unlock();
>  
> -	if (can_oom_reap)
> +	if (can_oom_reap) {
>  		wake_oom_reaper(victim);
> +	} else if (victim != current) {
> +		/*
> +		 * If we want to guarantee a forward progress we cannot keep
> +		 * the oom victim TIF_MEMDIE here. Sleep for a while and then
> +		 * drop the flag to make sure another victim can be selected.
> +		 */
> +		schedule_timeout_killable(HZ);
> +		exit_oom_victim(victim);

thiking about it more, with the other change in the
oom_scan_process_thread we do not need to exit_oom_victim. In fact we
even shouldn't because of the oom_disabled synchronization. I will
respin the patch and drop the exit_oom_victim part.
schedule_timeout_killable will stay...

> +	}
>  
>  	mmdrop(mm);
>  	put_task_struct(victim);
> -- 
> 2.8.1
> 
> -- 
> Michal Hocko
> SUSE Labs

-- 
Michal Hocko
SUSE Labs