linux-kernel - Re: [PATCH 0/3] introduce memory.oom.group

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Message-ID: <20180802080041.GB10808@dhcp22.suse.cz>
Date:   Thu, 2 Aug 2018 10:00:41 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Roman Gushchin <guro@...com>, linux-mm@...ck.org,
        Johannes Weiner <hannes@...xchg.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Tejun Heo <tj@...nel.org>, kernel-team@...com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] introduce memory.oom.group

On Wed 01-08-18 14:51:25, David Rientjes wrote:
> On Tue, 31 Jul 2018, Roman Gushchin wrote:
> 
> > > What's the plan with the cgroup aware oom killer?  It has been sitting in 
> > > the -mm tree for ages with no clear path to being merged.
> > 
> > It's because your nack, isn't it?
> > Everybody else seem to be fine with it.
> > 
> 
> If they are fine with it, I'm not sure they have tested it :)  Killing 
> entire cgroups needlessly for mempolicy oom kills that will not free 
> memory on target nodes is the first regression they may notice.

I do not remember you would be mentioning this previously. Anyway the
older implementation has considered the nodemask in memcg_oom_badness.
You are right that a cpuset allocation could needlessly select a memcg
with small or no memory from the target nodemask which is something I
could have noticed during the review. If only I didn't have to spend all
my energy to go through repetitive arguments of yours. Anyway this would
be quite trivial to resolve in the same function by checking
node_isset(node, current->mems_allowed).

Thanks for your productive feedback again.

Skipping the rest which is yet again repeating same arguments and it
doesn't add anything new to the table.
-- 
Michal Hocko
SUSE Labs