From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757099Ab3K0BBx (ORCPT ); Tue, 26 Nov 2013 20:01:53 -0500 Received: from mail-yh0-f51.google.com ([209.85.213.51]:53179 "EHLO mail-yh0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754668Ab3K0BBr (ORCPT ); Tue, 26 Nov 2013 20:01:47 -0500 Date: Tue, 26 Nov 2013 17:01:43 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Johannes Weiner cc: Andrew Morton , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch] mm: memcg: do not declare OOM from __GFP_NOFAIL allocations In-Reply-To: <1385140676-5677-1-git-send-email-hannes@cmpxchg.org> Message-ID: References: <1385140676-5677-1-git-send-email-hannes@cmpxchg.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 Nov 2013, Johannes Weiner wrote: > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 13b9d0f..cc4f9cb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2677,6 +2677,9 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, > if (unlikely(task_in_memcg_oom(current))) > goto bypass; > > + if (gfp_mask & __GFP_NOFAIL) > + oom = false; > + > /* > * We always charge the cgroup the mm_struct belongs to. > * The mm_struct's mem_cgroup changes on task migration if the Sorry, I don't understand this. What happens in the following scenario: - memory.usage_in_bytes == memory.limit_in_bytes, - memcg reclaim fails to reclaim memory, and - all processes (perhaps only one) attached to the memcg are doing one of the over dozen __GFP_NOFAIL allocations in the kernel? How do we make forward progress if you cannot oom kill something?