linux-kernel - Re: [PATCH 3/4] OOM, PM: OOM killed task shouldn't escape PM suspend

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]

Date:	Wed, 5 Nov 2014 11:54:28 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Cong Wang <xiyou.wangcong@...il.com>,
	David Rientjes <rientjes@...gle.com>,
	Oleg Nesterov <oleg@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 3/4] OOM, PM: OOM killed task shouldn't escape PM suspend

On Wed, Nov 05, 2014 at 05:39:56PM +0100, Michal Hocko wrote:
> On Wed 05-11-14 11:29:29, Tejun Heo wrote:
> > Hello, Michal.
> > 
> > On Wed, Nov 05, 2014 at 05:01:15PM +0100, Michal Hocko wrote:
> > > I am not sure I am following. With the latest patch OOM path is no
> > > longer blocked by the PM (aka oom_killer_disable()). Allocations simply
> > > fail if the read_trylock fails.
> > > oom_killer_disable is moved before tasks are frozen and it will wait for
> > > all on-going OOM killers on the write lock. OOM killer is enabled again
> > > on the resume path.
> > 
> > Sure, but why are we exposing new interfaces?  Can't we just make
> > oom_killer_disable() first set the disable flag and wait for the
> > on-going ones to finish (and make the function fail if it gets chosen
> > as an OOM victim)?
> 
> Still not following. How do you want to detect an on-going OOM without
> any interface around out_of_memory?

I thought you were using oom_killer_allowed_start() outside OOM path.
Ugh.... why is everything weirdly structured?  oom_killer_disabled
implies that oom killer may fail, right?  Why is
__alloc_pages_slowpath() checking it directly?  If whether oom killing
failed or not is relevant to its users, make out_of_memory() return an
error code.  There's no reason for the exclusion detail to leak out of
the oom killer proper.  The only interface should be disable/enable
and whether oom killing failed or not.

Thanks.

-- 
tejun
--
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/