From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754554AbaJWSz6 (ORCPT ); Thu, 23 Oct 2014 14:55:58 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42860 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754244AbaJWSz5 (ORCPT ); Thu, 23 Oct 2014 14:55:57 -0400 Message-ID: <54494F2F.6020005@oracle.com> Date: Thu, 23 Oct 2014 14:55:43 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Dave Jones , Linux Kernel , htejun@gmail.com Subject: Re: rcu_preempt detected stalls. References: <20141013173504.GA27955@redhat.com> <543DDD5E.9080602@oracle.com> <20141023183917.GX4977@linux.vnet.ibm.com> In-Reply-To: <20141023183917.GX4977@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/23/2014 02:39 PM, Paul E. McKenney wrote: > On Tue, Oct 14, 2014 at 10:35:10PM -0400, Sasha Levin wrote: >> On 10/13/2014 01:35 PM, Dave Jones wrote: >>> oday in "rcu stall while fuzzing" news: >>> >>> INFO: rcu_preempt detected stalls on CPUs/tasks: >>> Tasks blocked on level-0 rcu_node (CPUs 0-3): P766 P646 >>> Tasks blocked on level-0 rcu_node (CPUs 0-3): P766 P646 >>> (detected by 0, t=6502 jiffies, g=75434, c=75433, q=0) >> >> I've complained about RCU stalls couple days ago (in a different context) >> on -next. I guess whatever causing them made it into Linus's tree? >> >> https://lkml.org/lkml/2014/10/11/64 > > And on that one, I must confess that I don't see where the RCU read-side > critical section might be. > > Hmmm... Maybe someone forgot to put an rcu_read_unlock() somewhere. > Can you reproduce this with CONFIG_PROVE_RCU=y? Paul, if that was directed to me - Yes, I see stalls with CONFIG_PROVE_RCU set and nothing else is showing up before/after that. Thanks, Sasha