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 13:23:04 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Vladimir Davydov <vdavydov@...tuozzo.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...nel.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	David Rientjes <rientjes@...gle.com>, 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 05:17:42PM +0300, 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).
> 
> Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com>

Cool work!

I'll do a full review after the rebase on top of Michal's stuff.