Re: [BUGFIX][PATCH] memcg: fix oom killing a child process in an other cgroup

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

On Fri, 12 Feb 2010 10:53:18 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> This patch itself is againt mmotm-Feb10 but can be applied to 2.6.32.8
> without problem.
> 
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> Now, oom-killer is memcg aware and it finds the worst process from
> processes under memcg(s) in oom. Then, it kills victim's child at first.
> It may kill a child in other cgroup and may not be any help for recovery.
> And it will break the assumption users have...
> 
> This patch fixes it.
> 
This bug should definitely be fixed. Thank you for finding and fixing it.

	Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

> CC: stable@kernel.org
> CC: Minchan Kim <minchan.kim@gmail.com>
> CC: Balbir Singh <balbir@linux.vnet.ibm.com>
> CC: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> Acked-by: David Rientjes <rientjes@google.com>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> ---
>  mm/oom_kill.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: mmotm-2.6.33-Feb10/mm/oom_kill.c
> ===================================================================
> --- mmotm-2.6.33-Feb10.orig/mm/oom_kill.c
> +++ mmotm-2.6.33-Feb10/mm/oom_kill.c
> @@ -459,6 +459,8 @@ static int oom_kill_process(struct task_
>  	list_for_each_entry(c, &p->children, sibling) {
>  		if (c->mm == p->mm)
>  			continue;
> +		if (mem && !task_in_mem_cgroup(c, mem))
> +			continue;
>  		if (!oom_kill_task(c))
>  			return 0;
>  	}
> 

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