From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 50AF76B025E for ; Fri, 2 Dec 2016 08:52:20 -0500 (EST) Received: by mail-pg0-f71.google.com with SMTP id g186so168732967pgc.2 for ; Fri, 02 Dec 2016 05:52:20 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id q127si5258908pfb.189.2016.12.02.05.52.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Dec 2016 05:52:19 -0800 (PST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uB2DnjSY131328 for ; Fri, 2 Dec 2016 08:52:18 -0500 Received: from e33.co.us.ibm.com (e33.co.us.ibm.com [32.97.110.151]) by mx0a-001b2d01.pphosted.com with ESMTP id 2737vwywm0-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 02 Dec 2016 08:52:17 -0500 Received: from localhost by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 2 Dec 2016 06:52:16 -0700 Date: Fri, 2 Dec 2016 05:52:16 -0800 From: "Paul E. McKenney" Subject: Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node` Reply-To: paulmck@linux.vnet.ibm.com References: <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> <20161202093734.GE6830@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161202093734.GE6830@dhcp22.suse.cz> Message-Id: <20161202135216.GJ3924@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Boris Zhmurov , Paul Menzel , Donald Buczek , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Dec 02, 2016 at 10:37:35AM +0100, Michal Hocko wrote: > On Thu 01-12-16 21:10:01, Boris Zhmurov wrote: > > 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. > > OK, thanks for the confirmation! I will send a patch because it is true > that we do not have any scheduling point if no pages can be isolated > fromm the LRU. This might be what you are seeing. Thank you both! Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org