linux-kernel - Re: [PATCH 2/2] mm: oom: deduplicate victim selection code for memcg and global oom

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Date:	Fri, 27 May 2016 17:45:49 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Michal Hocko <mhocko@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	David Rientjes <rientjes@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mm: oom: deduplicate victim selection code for memcg
 and global oom

On Fri, May 27, 2016 at 04:26:26PM +0200, Michal Hocko wrote:
> On Fri 27-05-16 17:17:42, Vladimir Davydov wrote:
> > When selecting an oom victim, we use the same heuristic for both memory
> > cgroup and global oom. The only difference is the scope of tasks to
> > select the victim from. So we could just export an iterator over all
> > memcg tasks and keep all oom related logic in oom_kill.c, but instead we
> > duplicate pieces of it in memcontrol.c reusing some initially private
> > functions of oom_kill.c in order to not duplicate all of it. That looks
> > ugly and error prone, because any modification of select_bad_process
> > should also be propagated to mem_cgroup_out_of_memory.
> > 
> > Let's rework this as follows: keep all oom heuristic related code
> > private to oom_kill.c and make oom_kill.c use exported memcg functions
> > when it's really necessary (like in case of iterating over memcg tasks).
> 
> I am doing quite large changes in this area and this would cause many
> conflicts. Do you think you can postpone this after my patchset [1] gets
> sorted out please?

I'm fine with it.

> 
> I haven't looked at the patch carefully so I cannot tell much about it
> right now but just wanted to give a heads up for the conflicts.

I'd appreciate if you could take a look at this patch once time permits.

Thanks,
Vladimir