linux-kernel - Re: [PATCH v2] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves

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Message-ID: <alpine.DEB.2.10.1512021601040.22865@chino.kir.corp.google.com>
Date:	Wed, 2 Dec 2015 16:01:18 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Michal Hocko <mhocko@...nel.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v2] mm, oom: Give __GFP_NOFAIL allocations access to
 memory reserves

On Wed, 2 Dec 2015, Michal Hocko wrote:

> From: Michal Hocko <mhocko@...e.com>
> 
> __GFP_NOFAIL is a big hammer used to ensure that the allocation
> request can never fail. This is a strong requirement and as such
> it also deserves a special treatment when the system is OOM. The
> primary problem here is that the allocation request might have
> come with some locks held and the oom victim might be blocked
> on the same locks. This is basically an OOM deadlock situation.
> 
> This patch tries to reduce the risk of such a deadlocks by giving
> __GFP_NOFAIL allocations a special treatment and let them dive into
> memory reserves after oom killer invocation. This should help them
> to make a progress and release resources they are holding. The OOM
> victim should compensate for the reserves consumption.
> 
> Suggested-by: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Acked-by: David Rientjes <rientjes@...gle.com>
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