From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751942AbcGORCW (ORCPT ); Fri, 15 Jul 2016 13:02:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53377 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751607AbcGORCT (ORCPT ); Fri, 15 Jul 2016 13:02:19 -0400 Date: Fri, 15 Jul 2016 13:02:17 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Michal Hocko cc: Ondrej Kozina , Jerome Marchand , Stanislav Kozina , linux-mm@kvack.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com Subject: Re: System freezes after OOM In-Reply-To: <20160715122210.GG11811@dhcp22.suse.cz> Message-ID: References: <20160712064905.GA14586@dhcp22.suse.cz> <20160713111006.GF28723@dhcp22.suse.cz> <20160714125129.GA12289@dhcp22.suse.cz> <20160714145937.GB12289@dhcp22.suse.cz> <20160715083510.GD11811@dhcp22.suse.cz> <20160715122210.GG11811@dhcp22.suse.cz> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 15 Jul 2016 17:02:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 15 Jul 2016, Michal Hocko wrote: > On Fri 15-07-16 08:11:22, Mikulas Patocka wrote: > > > > The stacktraces showed that the kcryptd process was throttled when it > > tried to do mempool allocation. Mempool adds the __GFP_NORETRY flag to the > > allocation, but unfortunatelly, this flag doesn't prevent the allocator > > from throttling. > > Yes and in fact it shouldn't prevent any throttling. The flag merely > says that the allocation should give up rather than retry > reclaim/compaction again and again. > > > I say that the process doing mempool allocation shouldn't ever be > > throttled. Maybe add __GFP_NOTHROTTLE? > > A specific gfp flag would be an option but we are slowly running out of > bit space there and I am not yet convinced PF_LESS_THROTTLE is > unsuitable. PF_LESS_THROTTLE will make it throttle less, but it doesn't eliminate throttling entirely. So, maybe add PF_NO_THROTTLE? But PF_* flags are also almost exhausted. > I might be missing something but exactly this is what happens in > wait_iff_congested no? If the bdi doesn't see the congestion it wakes up > the reclaim context even before the timeout. Or are we talking past each > other? OK, I see that there is wait queue in congestion_wait. I didn't notice it before. Mikulas > -- > Michal Hocko > SUSE Labs >