Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756367AbcLASRg (ORCPT ); Thu, 1 Dec 2016 13:17:36 -0500 Received: from mail.setcomm.ru ([81.211.32.179]:42812 "EHLO mail.setcomm.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754355AbcLASRf (ORCPT ); Thu, 1 Dec 2016 13:17:35 -0500 X-Greylist: delayed 450 seconds by postgrey-1.27 at vger.kernel.org; Thu, 01 Dec 2016 13:17:35 EST Reply-To: bb@kernelpanic.ru Subject: Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node` References: <20161125212000.GI31360@linux.vnet.ibm.com> <20161128095825.GI14788@dhcp22.suse.cz> <20161128105425.GY31360@linux.vnet.ibm.com> <3a4242cb-0198-0a3b-97ae-536fb5ff83ec@kernelpanic.ru> <20161128143435.GC3924@linux.vnet.ibm.com> <20161128150509.GG3924@linux.vnet.ibm.com> <66fd50e1-a922-846a-f427-7654795bd4b5@kernelpanic.ru> <20161130174802.GM18432@dhcp22.suse.cz> <20161130182552.GN18432@dhcp22.suse.cz> To: Michal Hocko Cc: paulmck@linux.vnet.ibm.com, Paul Menzel , Donald Buczek , linux-mm@kvack.org, linux-kernel@vger.kernel.org From: Boris Zhmurov X-Enigmail-Draft-Status: N1110 Message-ID: Date: Thu, 1 Dec 2016 21:10:01 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161130182552.GN18432@dhcp22.suse.cz> Content-Type: multipart/mixed; boundary="------------541DA7624281D19B58B355C0" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1732 Lines: 51 This is a multi-part message in MIME format. --------------541DA7624281D19B58B355C0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Michal Hocko 30/11/16 21:25: >>> Do I get it right that s@cond_resched_rcu_qs@cond_resched@ didn't help? >> >> I didn't try that. I've tried 4 patches from Paul's linux-rcu tree. >> I can try another portion of patches, no problem :) > > Replacing cond_resched_rcu_qs in shrink_node_memcg by cond_resched would > be really helpful to tell whether we are missing a real scheduling point > or whether something more serious is going on here. Well, I can confirm, that replacing cond_resched_rcu_qs in shrink_node_memcg by cond_resched also makes dmesg clean from RCU CPU stall warnings. I've attached patch (just modification of Paul's patch), that fixes RCU stall messages in situations, when all memory is used by couchbase/memcached + fs cache and linux starts to use swap. -- Boris Zhmurov System/Network Administrator mailto: bb@kernelpanic.ru "wget http://kernelpanic.ru/bb_public_key.pgp -O - | gpg --import" --------------541DA7624281D19B58B355C0 Content-Type: text/x-patch; name="linux-4.8-mm-prevent-shrink_node_memcg-RCU-CPU-stall-warnings.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename*0="linux-4.8-mm-prevent-shrink_node_memcg-RCU-CPU-stall-warning"; filename*1="s.patch" --- a/mm/vmscan.c.orig 2016-11-30 21:52:58.314895320 +0300 +++ b/mm/vmscan.c 2016-11-30 21:53:29.502895320 +0300 @@ -2352,6 +2352,7 @@ nr_reclaimed += shrink_list(lru, nr_to_scan, lruvec, sc); } + cond_resched(); } if (nr_reclaimed < nr_to_reclaim || scan_adjusted) --------------541DA7624281D19B58B355C0--