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

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Message-ID: <20160527142626.GQ27686@dhcp22.suse.cz>
Date:	Fri, 27 May 2016 16:26:26 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Vladimir Davydov <vdavydov@...tuozzo.com>
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 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 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.

[1] http://lkml.kernel.org/r/1464266415-15558-1-git-send-email-mhocko@kernel.org

Thanks!

> 
> Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com>
> ---
>  include/linux/memcontrol.h |  15 ++++
>  include/linux/oom.h        |  51 -------------
>  mm/memcontrol.c            | 112 ++++++++++-----------------
>  mm/oom_kill.c              | 183 +++++++++++++++++++++++++++++----------------
>  4 files changed, 176 insertions(+), 185 deletions(-)
-- 
Michal Hocko
SUSE Labs