linux-kernel - Re: [PATCH 0/2] mm, oom: do not grant oom victims full memory reserves access

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Message-ID: <20170807142121.GK32434@dhcp22.suse.cz>
Date:   Mon, 7 Aug 2017 16:21:21 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     David Rientjes <rientjes@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] mm, oom: do not grant oom victims full memory
 reserves access

On Thu 27-07-17 11:03:55, Michal Hocko wrote:
> Hi,
> this is a part of a larger series I posted back in Oct last year [1]. I
> have dropped patch 3 because it was incorrect and patch 4 is not
> applicable without it.
> 
> The primary reason to apply patch 1 is to remove a risk of the complete
> memory depletion by oom victims. While this is a theoretical risk right
> now there is a demand for memcg aware oom killer which might kill all
> processes inside a memcg which can be a lot of tasks. That would make
> the risk quite real.
> 
> This issue is addressed by limiting access to memory reserves. We no
> longer use TIF_MEMDIE to grant the access and use tsk_is_oom_victim
> instead. See Patch 1 for more details. Patch 2 is a trivial follow up
> cleanup.
> 
> I would still like to get rid of TIF_MEMDIE completely but I do not have
> time to do it now and it is not a pressing issue.
> 
> [1] http://lkml.kernel.org/r/20161004090009.7974-1-mhocko@kernel.org

Are there any more comments/questions? I will resubmit if not.

-- 
Michal Hocko
SUSE Labs