linux-kernel - Re: [PATCH v2] mm: oom: deduplicate victim selection code for memcg and global oom

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Date:	Tue, 28 Jun 2016 19:16:42 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mm: oom: deduplicate victim selection code for memcg
 and global oom

On Mon, Jun 27, 2016 at 05:14:31PM -0700, David Rientjes wrote:
> On Mon, 27 Jun 2016, 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 don't know how others feel, but this actually turns out harder to read 
> for me with all the extra redirection with minimal savings (a few dozen 
> lines of code).

Well, if you guys find the code difficult to read after this patch,
let's leave it as is. Sorry for the noise.