Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758160Ab1EZSbb (ORCPT ); Thu, 26 May 2011 14:31:31 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:58494 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757634Ab1EZSba convert rfc822-to-8bit (ORCPT ); Thu, 26 May 2011 14:31:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type:content-transfer-encoding; b=cxbD0AfU/qZ1u91ukVl6kER4rS4iV3H4lsDZQSaHh7cgoIfssAfX0/DU1lGYwqOpVC QQdSPDI/0R7gu6VPhEZjUovbp4tTsVwI6FnTEttTP/N6/O+sKXHE99Tuy5e8KeP8SqwC DlZFu8uOWkmra7g4Ht8yRazoAEZD6aF53ZqXA= MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <20110526173128.GE2386@linux.vnet.ibm.com> References: <20110526173128.GE2386@linux.vnet.ibm.com> Date: Thu, 26 May 2011 20:31:28 +0200 Message-ID: Subject: Re: linux-next: Tree for May 26 (RCU stalls) From: Sedat Dilek To: paulmck@linux.vnet.ibm.com Cc: Stephen Rothwell , linux-next@vger.kernel.org, LKML Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4924 Lines: 125 On Thu, May 26, 2011 at 7:31 PM, Paul E. McKenney wrote: > On Thu, May 26, 2011 at 05:48:32PM +0200, Sedat Dilek wrote: >> On Thu, May 26, 2011 at 8:39 AM, Stephen Rothwell wrote: >> > Hi all, >> > >> > [The kernel.org mirroring is being slow today] >> > >> > Changes since 20110525: >> > >> > Linus' tree gained a build failure for which I applied a patch. >> > >> > The m68knommu tree lost its conflicts. >> > >> > The hwmon-staging lost its conflict. >> > >> > The wireless lost its conflict. >> > >> > The mmc lost its conflict. >> > >> > The dwmw2-iommu tree lost its conflict. >> > >> > The kvm tree still had its build failure so I used the version from >> > next-20110524. >> > >> > The namespace lost its conflicts. >> > >> > ---------------------------------------------------------------------------- >> > >> >> Hi, >> >> I see these call-traces on x86 UP machine: >> >> [ 240.268061] INFO: task rcun0:8 blocked for more than 120 seconds. >> [ 240.268069] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" >> disables this message. >> [ 240.268072] rcun0 D 00000000 0 8 2 0x00000000 >> [ 240.268079] f6473fb8 00000046 013131b6 00000000 c1461ac0 00000000 >> 00000000 c1461ac0 >> [ 240.268089] 00000000 00000000 f645dc70 f645bf60 00000003 f6473f78 >> c102a570 f6473f9c >> [ 240.268097] c1021476 00000000 f645bf6c 00000001 00000000 00000286 >> f6473f9c c129b35a >> [ 240.268106] Call Trace: >> [ 240.268121] [] ? default_wake_function+0xb/0xd >> [ 240.268127] [] ? __wake_up_common+0x33/0x5b >> [ 240.268134] [] ? _raw_spin_unlock_irqrestore+0xe/0x10 >> [ 240.268140] [] ? complete+0x34/0x3e >> [ 240.268147] [] ? cpumask_weight+0xc/0xc >> [ 240.268157] [] kthread+0x53/0x67 >> [ 240.268162] [] ? kthread_worker_fn+0x111/0x111 >> [ 240.268169] [] kernel_thread_helper+0x6/0xd >> >> dmesg and kernel-config are attached. > > Hello, Sedat, > > Does the following patch clear things up? > > Thanx, Paul > > ------------------------------------------------------------------------ > > rcu: Start RCU kthreads in TASK_INTERRUPTIBLE state > > Upon creation, kthreads are in TASK_UNINTERRUPTIBLE state, which can > result in softlockup warnings. Because some of RCU's kthreads can > legitimately be idle indefinitely, start them in TASK_INTERRUPTIBLE > state in order to avoid those warnings. > > Suggested-by: Peter Zijlstra > Signed-off-by: Paul E. McKenney > Signed-off-by: Paul E. McKenney > Tested-by: Yinghai Lu > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index a1a8bb6..40aab8d 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -1647,6 +1647,7 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) > if (IS_ERR(t)) > return PTR_ERR(t); > kthread_bind(t, cpu); > + set_task_state(t, TASK_INTERRUPTIBLE); > per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu; > WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL); > per_cpu(rcu_cpu_kthread_task, cpu) = t; > @@ -1754,6 +1755,7 @@ static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp, > if (IS_ERR(t)) > return PTR_ERR(t); > raw_spin_lock_irqsave(&rnp->lock, flags); > + set_task_state(t, TASK_INTERRUPTIBLE); > rnp->node_kthread_task = t; > raw_spin_unlock_irqrestore(&rnp->lock, flags); > sp.sched_priority = 99; > diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h > index 049f278..a767b7d 100644 > --- a/kernel/rcutree_plugin.h > +++ b/kernel/rcutree_plugin.h > @@ -1295,6 +1295,7 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, > if (IS_ERR(t)) > return PTR_ERR(t); > raw_spin_lock_irqsave(&rnp->lock, flags); > + set_task_state(t, TASK_INTERRUPTIBLE); > rnp->boost_kthread_task = t; > raw_spin_unlock_irqrestore(&rnp->lock, flags); > sp.sched_priority = RCU_KTHREAD_PRIO; > Thanks for the quick reply and patch! On 1st look at dmesg the RCU stalls are gone. I tested against linux-next (next-20110526). Feel free to add: Tested-by: Sedat Dilek - Sedat - -- 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/