Re: [BUGFIX][PATCH] memcg fix wake up in oom wait queue

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

On Thu, 3 Jun 2010 17:23:53 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> Very sorry that my test wasn't enough and delayed.
> 
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> OOM-waitqueue should be waken up when oom_disable is canceled.
> This is a fix for
>  memcg-oom-kill-disable-and-oom-status.patch
> 
> How to test:
>  Create a cgroup A...
>  1. set memory.limit and memory.memsw.limit to be small value
>  2. echo 1 > /cgroup/A/memory.oom_control, this disables oom-kill.
>  3. run a program which must cause OOM.
> 
> A program executed in 3 will sleep by oom_waiqueue in memcg.
> Then, how to wake it up is problem.
> 
>  1. echo 0 > /cgroup/A/memory.oom_control (enable OOM-killer)
>  2. echo big mem > /cgroup/A/memory.memsw.limit_in_bytes(allow more swap)
> etc..
> 
> Without the patch, a task in slept can not be waken up.
> 

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

> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  mm/memcontrol.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Index: mmotm-2.6.34-May21/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.34-May21.orig/mm/memcontrol.c
> +++ mmotm-2.6.34-May21/mm/memcontrol.c
> @@ -1413,7 +1413,7 @@ static void memcg_wakeup_oom(struct mem_
>  
>  static void memcg_oom_recover(struct mem_cgroup *mem)
>  {
> -	if (mem->oom_kill_disable && atomic_read(&mem->oom_lock))
> +	if (atomic_read(&mem->oom_lock))
>  		memcg_wakeup_oom(mem);
>  }
>  
> @@ -3830,6 +3830,8 @@ static int mem_cgroup_oom_control_write(
>  		return -EINVAL;
>  	}
>  	mem->oom_kill_disable = val;
> +	if (!val)
> +		memcg_oom_recover(mem);
>  	cgroup_unlock();
>  	return 0;
>  }
> 

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