linux-kernel - Re: [patch 2/2] memcg: do not sleep on OOM waitqueue with full charge context

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Date:	Wed, 12 Jun 2013 22:37:05 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 2/2] memcg: do not sleep on OOM waitqueue with full
 charge context

On Wed 12-06-13 13:12:09, David Rientjes wrote:
> On Wed, 12 Jun 2013, Michal Hocko wrote:
> 
> > > > > > > > Reported-by: Reported-by: azurIt <azurit@...ox.sk>
> > > 
> > > Ok, so the key here is that azurIt was able to reliably reproduce this 
> > > issue and now it has been resurrected after seven months of silence since 
> > > that thread.  I also notice that azurIt isn't cc'd on this thread.  Do we 
> > > know if this is still a problem?
> > 
> > I have backported the patch for his 3.2 and waiting for his feedback.
> > 
> 
> Ok, thanks.  I thought this was only going seven months back when it was 
> reported, I missed that the issue this patch is trying to address goes 
> back a 1 1/2 years to 3.2 and nobody else has reported it.  I think his 
> feedback would be the key, specifically if he can upgrade to a later 
> kernel first.

The patch is a big improvement with a minimum code overhead. Blocking
any task which sits on top of an unpredictable amount of locks is just
broken. So regardless how many users are affected we should merge it and
backport to stable trees. The problem is there since ever. We seem to
be surprisingly lucky to not hit this more often.

I am not quite sure I understand your reservation about the patch to be
honest. Andrew still hasn't merged this one although 1/2 is in.
-- 
Michal Hocko
SUSE Labs
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