linux-kernel - Re: [PATCH] copy over oom

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: <alpine.DEB.2.00.0907211250530.10356@chino.kir.corp.google.com>
Date:	Tue, 21 Jul 2009 12:54:59 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Paul Menage <menage@...gle.com>
cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, mel@....ul.ie, npiggin@...e.de
Subject: Re: [PATCH] copy over oom_adj value at fork time

On Tue, 21 Jul 2009, Paul Menage wrote:

> No, Rik's patch just fixes the lack of inheritability that David
> introduced originally. It doesn't address the problem that the
> intention of the patches is to disallow separate processes sharing the
> same VM from having different oom_adj scores, which breaks the
> previous ability to vfork() or clone(CLONE_VM) a child and set its
> oom_adj to a non-disabled value prior to execve().
> 

That's exactly the scenario my patches were addressing, actually.  It was 
possible to get an oom killer livelock if a thread was constantly chosen 
when sharing memory with an OOM_DISABLE task.  So your example is a recipe 
for livelock without my patches since the parent is OOM_DISABLE and the 
child is not, yet they share an ->mm so neither can be killed.  If the 
child is repeatedly chosen prior to execve, no memory freeing is possible 
unless another task happens to exceed the badness score of the child.
--
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/