Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932971AbaJYAVG (ORCPT ); Fri, 24 Oct 2014 20:21:06 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36411 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932111AbaJYAVF (ORCPT ); Fri, 24 Oct 2014 20:21:05 -0400 From: Jay Vosburgh To: paulmck@linux.vnet.ibm.com cc: Yanko Kaneti , Josh Boyer , "Eric W. Biederman" , Cong Wang , Kevin Fenzi , netdev , "Linux-Kernel@Vger. Kernel. Org" , mroos@linux.ee, tj@kernel.org Subject: Re: localed stuck in recent 3.18 git in copy_net_ns? In-reply-to: <20141024230524.GA16023@linux.vnet.ibm.com> References: <20141024162943.GA16621@declera.com> <20141024165454.GS4977@linux.vnet.ibm.com> <20141024170931.GA21849@declera.com> <20141024172009.GV4977@linux.vnet.ibm.com> <20141024173526.GA26058@declera.com> <20141024183226.GW4977@linux.vnet.ibm.com> <20141024212557.GA15537@declera.com> <20141024214927.GA4977@linux.vnet.ibm.com> <8915.1414190047@famine> <20141024225931.GC4977@linux.vnet.ibm.com> <20141024230524.GA16023@linux.vnet.ibm.com> Comments: In-reply-to "Paul E. McKenney" message dated "Fri, 24 Oct 2014 16:05:24 -0700." X-Mailer: MH-E 8.5+bzr; nmh 1.5; GNU Emacs 24.4.50 Date: Fri, 24 Oct 2014 17:20:48 -0700 Message-ID: <10136.1414196448@famine> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul E. McKenney wrote: >On Fri, Oct 24, 2014 at 03:59:31PM -0700, Paul E. McKenney wrote: [...] >> Hmmm... It sure looks like we have some callbacks stuck here. I clearly >> need to take a hard look at the sleep/wakeup code. >> >> Thank you for running this!!! > >Could you please try the following patch? If no joy, could you please >add rcu:rcu_nocb_wake to the list of ftrace events? I tried the patch, it did not change the behavior. I enabled the rcu:rcu_barrier and rcu:rcu_nocb_wake tracepoints and ran it again (with this patch and the first patch from earlier today); the trace output is a bit on the large side so I put it and the dmesg log at: http://people.canonical.com/~jvosburgh/nocb-wake-dmesg.txt http://people.canonical.com/~jvosburgh/nocb-wake-trace.txt -J > Thanx, Paul > >------------------------------------------------------------------------ > >rcu: Kick rcuo kthreads after their CPU goes offline > >If a no-CBs CPU were to post an RCU callback with interrupts disabled >after it entered the idle loop for the last time, there might be no >deferred wakeup for the corresponding rcuo kthreads. This commit >therefore adds a set of calls to do_nocb_deferred_wakeup() after the >CPU has gone completely offline. > >Signed-off-by: Paul E. McKenney > >diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c >index 84b41b3c6ebd..f6880052b917 100644 >--- a/kernel/rcu/tree.c >+++ b/kernel/rcu/tree.c >@@ -3493,8 +3493,10 @@ static int rcu_cpu_notify(struct notifier_block *self, > case CPU_DEAD_FROZEN: > case CPU_UP_CANCELED: > case CPU_UP_CANCELED_FROZEN: >- for_each_rcu_flavor(rsp) >+ for_each_rcu_flavor(rsp) { > rcu_cleanup_dead_cpu(cpu, rsp); >+ do_nocb_deferred_wakeup(per_cpu_ptr(rsp->rda, cpu)); >+ } > break; > default: > break; > --- -Jay Vosburgh, jay.vosburgh@canonical.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/