From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id 8AD9B6B026B for ; Wed, 30 Nov 2016 11:38:27 -0500 (EST) Received: by mail-io0-f200.google.com with SMTP id r101so23986688ioi.3 for ; Wed, 30 Nov 2016 08:38:27 -0800 (PST) Received: from merlin.infradead.org (merlin.infradead.org. [2001:4978:20e::2]) by mx.google.com with ESMTPS id b124si6247963itc.90.2016.11.30.08.38.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Nov 2016 08:38:26 -0800 (PST) Date: Wed, 30 Nov 2016 17:38:20 +0100 From: Peter Zijlstra Subject: Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node` Message-ID: <20161130163820.GQ3092@twins.programming.kicks-ass.net> References: <68025f6c-6801-ab46-b0fc-a9407353d8ce@molgen.mpg.de> <20161124101525.GB20668@dhcp22.suse.cz> <583AA50A.9010608@molgen.mpg.de> <20161128110449.GK14788@dhcp22.suse.cz> <109d5128-f3a4-4b6e-db17-7a1fcb953500@molgen.mpg.de> <29196f89-c35e-f79d-8e4d-2bf73fe930df@molgen.mpg.de> <20161130110944.GD18432@dhcp22.suse.cz> <20161130115320.GO3924@linux.vnet.ibm.com> <20161130131910.GF18432@dhcp22.suse.cz> <20161130142955.GS3924@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161130142955.GS3924@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Paul E. McKenney" Cc: Michal Hocko , Donald Buczek , Paul Menzel , dvteam@molgen.mpg.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Triplett On Wed, Nov 30, 2016 at 06:29:55AM -0800, Paul E. McKenney wrote: > We can, and you are correct that cond_resched() does not unconditionally > supply RCU quiescent states, and never has. Last time I tried to add > cond_resched_rcu_qs() semantics to cond_resched(), I got told "no", > but perhaps it is time to try again. Well, you got told: "ARRGH my benchmark goes all regress", or something along those lines. Didn't we recently dig out those commits for some reason or other? Finding out what benchmark that was and running it against this patch would make sense. Also, I seem to have missed, why are we going through this again? -- 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