Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757275AbcLBRDE (ORCPT ); Fri, 2 Dec 2016 12:03:04 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:36104 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751729AbcLBRCx (ORCPT ); Fri, 2 Dec 2016 12:02:53 -0500 Date: Fri, 2 Dec 2016 18:02:49 +0100 From: Michal Hocko To: "Paul E. McKenney" Cc: Boris Zhmurov , Paul Menzel , Donald Buczek , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node` Message-ID: <20161202170248.GT6830@dhcp22.suse.cz> References: <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> <20161202164408.GM3924@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161202164408.GM3924@linux.vnet.ibm.com> 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 Content-Length: 1339 Lines: 36 On Fri 02-12-16 08:44:08, Paul E. McKenney wrote: > On Fri, Dec 02, 2016 at 07:39:24PM +0300, Boris Zhmurov wrote: > > Paul E. McKenney Thu Dec 01 2016 - 14:39:21 EST: > > > > >> 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. > > > > > Nice! Just to double-check, could you please also test your patch > > > above with these two commits from -rcu? > > > > > > d2db185bfee8 ("rcu: Remove short-term CPU kicking") f8f127e738e3 > > > ("rcu: Add long-term CPU kicking") > > > > > > Thanx, Paul > > > > > > Looks like patches d2db185bfee8 and f8f127e738e3 change nothing. > > > > With cond_resched() in shrink_node_memcg and these two patches dmesg is > > clean. No any RCU CPU stall messages. > > Very good! I have these two patches queued for 4.11. FWIW I have posted the cond_resched patch to Andrew [1]. I didn't CC you Paul to save you from emails as this is more MM than anything else related ;) [1] http://lkml.kernel.org/r/20161202095841.16648-1-mhocko@kernel.org -- Michal Hocko SUSE Labs