lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20130730145602.GI15847@dhcp22.suse.cz>
Date:	Tue, 30 Jul 2013 16:56:02 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	azurIt <azurit@...ox.sk>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, x86@...nel.org,
	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 6/6] mm: memcg: do not trap chargers with full callstack
 on OOM

On Tue 30-07-13 10:32:28, Johannes Weiner wrote:
> On Tue, Jul 30, 2013 at 04:09:13PM +0200, Michal Hocko wrote:
> > On Fri 26-07-13 17:28:09, Johannes Weiner wrote:
[...]
> > >  	} else {
> > >  		schedule();
> > > +		mem_cgroup_unmark_under_oom(memcg);
> > >  		finish_wait(&memcg_oom_waitq, &owait.wait);
> > >  	}
> > > -	spin_lock(&memcg_oom_lock);
> > > -	if (locked)
> > > -		mem_cgroup_oom_unlock(memcg);
> > > -	memcg_wakeup_oom(memcg);
> > > -	spin_unlock(&memcg_oom_lock);
> > >  
> > > -	mem_cgroup_unmark_under_oom(memcg);
> > > +	if (locked) {
> > > +		mem_cgroup_oom_unlock(memcg);
> > > +		/*
> > > +		 * There is no guarantee that a OOM-lock contender
> > > +		 * sees the wakeups triggered by the OOM kill
> > > +		 * uncharges.  Wake any sleepers explicitely.
> > > +		 */
> > > +		memcg_oom_recover(memcg);
> > 
> > This will be a noop because memcg is no longer under_oom (you wanted
> > memcg_wakeup_oom here I guess). Moreover, even the killed wouldn't wake
> > up anybody for the same reason.
> 
> Anybody entering this path will increase the under_oom counter.  The
> killer decreases it again, but everybody who is sleeping because they
> failed the trylock still hasn't unmarked the hierarchy (they call
> schedule() before unmark_under_oom()).  So we issue wakeups when there
> is somebody waiting for the lock.

True, sorry for the noise. Feel free to add

Acked-by: Michal Hocko <mhocko@...e.cz>
-- 
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ