From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f198.google.com (mail-wj0-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 0DC0C6B0038 for ; Fri, 2 Dec 2016 04:37:39 -0500 (EST) Received: by mail-wj0-f198.google.com with SMTP id xr1so43798610wjb.7 for ; Fri, 02 Dec 2016 01:37:39 -0800 (PST) Received: from mail-wj0-f193.google.com (mail-wj0-f193.google.com. [209.85.210.193]) by mx.google.com with ESMTPS id bt18si4380652wjb.137.2016.12.02.01.37.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Dec 2016 01:37:37 -0800 (PST) Received: by mail-wj0-f193.google.com with SMTP id kp2so29479696wjc.0 for ; Fri, 02 Dec 2016 01:37:37 -0800 (PST) Date: Fri, 2 Dec 2016 10:37:35 +0100 From: Michal Hocko Subject: Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node` Message-ID: <20161202093734.GE6830@dhcp22.suse.cz> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Boris Zhmurov Cc: paulmck@linux.vnet.ibm.com, Paul Menzel , Donald Buczek , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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. -- Michal Hocko SUSE Labs -- 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