linux-kernel - Re: can't oom-kill zap the victim's memory?

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.2.10.1509211638580.27715@chino.kir.corp.google.com>
Date:	Mon, 21 Sep 2015 16:42:44 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Oleg Nesterov <oleg@...hat.com>
cc:	Michal Hocko <mhocko@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kyle Walker <kwalker@...hat.com>,
	Christoph Lameter <cl@...ux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Vladimir Davydov <vdavydov@...allels.com>,
	linux-mm <linux-mm@...ck.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Stanislav Kozina <skozina@...hat.com>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Subject: Re: can't oom-kill zap the victim's memory?

On Mon, 21 Sep 2015, Oleg Nesterov wrote:

> Yes we should try to do this in the OOM killer context, and in this case
> (of course) we need trylock. Let me quote my previous email:
> 
> 	And we want to avoid using workqueues when the caller can do this
> 	directly. And in this case we certainly need trylock. But this needs
> 	some refactoring: we do not want to do this under oom_lock, otoh it
> 	makes sense to do this from mark_oom_victim() if current && killed,
> 	and a lot more details.
> 
> and probably this is another reason why do we need MMF_MEMDIE. But again,
> I think the initial change should be simple.
> 

I agree with the direction and I don't think it would be too complex to 
have a dedicated kthread that is kicked when we queue an mm to do 
MADV_DONTNEED behavior, and have that happen only if a trylock in 
oom_kill_process() fails to do it itself for anonymous mappings.  We may 
have different opinions of simplicity.
--
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/