From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751377AbdAMIkU (ORCPT ); Fri, 13 Jan 2017 03:40:20 -0500 Received: from mx2.suse.de ([195.135.220.15]:59438 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751228AbdAMIkS (ORCPT ); Fri, 13 Jan 2017 03:40:18 -0500 Date: Fri, 13 Jan 2017 09:40:14 +0100 From: Michal Hocko To: David Rientjes Cc: Andrew Morton , Johannes Weiner , Vladimir Davydov , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch v2] mm, memcg: do not retry precharge charges Message-ID: <20170113084014.GB25212@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 12-01-17 14:46:34, David Rientjes wrote: > When memory.move_charge_at_immigrate is enabled and precharges are > depleted during move, mem_cgroup_move_charge_pte_range() will attempt to > increase the size of the precharge. > > This can be allowed to do reclaim, but should not call the oom killer to > oom kill a process. It's better to fail the attach rather than oom kill > a process attached to the memcg hierarchy. This is not the case though since 3812c8c8f395 ("mm: memcg: do not trap chargers with full callstack on OOM") - 3.12. Only the page fault path is allowed to trigger the oom killer. > Prevent precharges from ever looping by setting __GFP_NORETRY. This was > probably the intention of the GFP_KERNEL & ~__GFP_NORETRY, which is > pointless as written. > > Fixes: 0029e19ebf84 ("mm: memcontrol: remove explicit OOM parameter in charge path") > Signed-off-by: David Rientjes Without the note about the oom killer you can add Acked-by: Michal Hocko Thanks! > --- > mm/memcontrol.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4353,9 +4353,12 @@ static int mem_cgroup_do_precharge(unsigned long count) > return ret; > } > > - /* Try charges one by one with reclaim */ > + /* > + * Try charges one by one with reclaim, but do not retry. This avoids > + * calling the oom killer when the precharge should just fail. > + */ > while (count--) { > - ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_NORETRY, 1); > + ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1); > if (ret) > return ret; > mc.precharge++; -- Michal Hocko SUSE Labs