linux-kernel - Re: [patch 1/2] mm, memcg: avoid oom notification when current needs access to memory reserves

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Date:	Mon, 18 Nov 2013 17:19:00 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Michal Hocko <mhocko@...e.cz>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	cgroups@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [patch 1/2] mm, memcg: avoid oom notification when current needs
 access to memory reserves

On Mon, 18 Nov 2013, Michal Hocko wrote:

> > > When current has a pending SIGKILL or is already in the exit path, it
> > > only needs access to memory reserves to fully exit.  In that sense, the
> > > memcg is not actually oom for current, it simply needs to bypass memory
> > > charges to exit and free its memory, which is guarantee itself that
> > > memory will be freed.
> > > 
> > > We only want to notify userspace for actionable oom conditions where
> > > something needs to be done (and all oom handling can already be deferred
> > > to userspace through this method by disabling the memcg oom killer with
> > > memory.oom_control), not simply when a memcg has reached its limit, which
> > > would actually have to happen before memcg reclaim actually frees memory
> > > for charges.
> > 
> > I believe this also fixes the issue reported by Eric
> > (https://lkml.org/lkml/2013/7/28/74). I had a patch for this
> > https://lkml.org/lkml/2013/7/31/94 but the code changed since then and
> > this should be equivalent.
> >  
> > > Reported-by: Johannes Weiner <hannes@...xchg.org>
> > > Signed-off-by: David Rientjes <rientjes@...gle.com>
> 
> Anyway, the patch looks good to me but please mention the above bug in
> the changelog.
> 

The patch is in -mm, so perhaps we can change the changelog if/when Eric 
confirms it fixes his issue.

> Acked-by: Michal Hocko <mhocko@...e.cz>
> 

Thanks!
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