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

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Message-ID: <5614AAC0.60002@suse.cz>
Date:	Wed, 7 Oct 2015 07:16:48 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Michal Hocko <mhocko@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	David Rientjes <rientjes@...gle.com>,
	Oleg Nesterov <oleg@...hat.com>,
	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>
Subject: Re: can't oom-kill zap the victim's memory?

On 5.10.2015 16:44, Michal Hocko wrote:
> So I can see basically only few ways out of this deadlock situation.
> Either we face the reality and allow small allocations (withtout
> __GFP_NOFAIL) to fail after all attempts to reclaim memory have failed
> (so after even OOM killer hasn't made any progress).

Note that small allocations already *can* fail if they are done in the context
of a task selected as OOM victim (i.e. TIF_MEMDIE). And yeah I've seen a case
when they failed in a code that "handled" the allocation failure with a
BUG_ON(!page).
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