From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
htejun@gmail.com
Subject: Re: rcu_preempt detected stalls.
Date: Mon, 27 Oct 2014 14:13:29 -0700 [thread overview]
Message-ID: <20141027211329.GJ5718@linux.vnet.ibm.com> (raw)
In-Reply-To: <544A80B3.9070800@oracle.com>
On Fri, Oct 24, 2014 at 12:39:15PM -0400, Sasha Levin wrote:
> On 10/24/2014 12:13 PM, Paul E. McKenney wrote:
> > On Fri, Oct 24, 2014 at 08:28:40AM -0400, Sasha Levin wrote:
> >> > On 10/23/2014 03:58 PM, Paul E. McKenney wrote:
> >>> > > On Thu, Oct 23, 2014 at 02:55:43PM -0400, Sasha Levin wrote:
> >>>>> > >> > 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.
> >>> > > Indeed it was directed to you. ;-)
> >>> > >
> >>> > > Does the following crude diagnostic patch turn up anything?
> >> >
> >> > Nope, seeing stalls but not seeing that pr_err() you added.
> > OK, color me confused. Could you please send me the full dmesg or a
> > pointer to it?
>
> Attached.
Thank you! I would complain about the FAULT_INJECTION messages, but
they don't appear to be happening all that frequently.
The stack dumps do look different here. I suspect that this is a real
issue in the VM code.
Thanx, Paul
next prev parent reply other threads:[~2014-10-27 21:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-13 17:35 rcu_preempt detected stalls Dave Jones
2014-10-15 2:35 ` Sasha Levin
2014-10-23 18:39 ` Paul E. McKenney
2014-10-23 18:55 ` Sasha Levin
2014-10-23 19:58 ` Paul E. McKenney
2014-10-24 12:28 ` Sasha Levin
2014-10-24 16:13 ` Paul E. McKenney
2014-10-24 16:39 ` Sasha Levin
2014-10-27 21:13 ` Paul E. McKenney [this message]
2014-10-27 23:44 ` Paul E. McKenney
2014-11-13 23:07 ` Paul E. McKenney
2014-11-13 23:10 ` Sasha Levin
2014-10-30 23:41 ` Sasha Levin
2014-10-23 18:32 ` Paul E. McKenney
2014-10-23 18:40 ` Dave Jones
2014-10-23 19:28 ` Paul E. McKenney
2014-10-23 19:37 ` Dave Jones
2014-10-23 19:52 ` Paul E. McKenney
2014-10-23 20:28 ` Dave Jones
2014-10-23 20:44 ` Paul E. McKenney
2014-10-23 19:13 ` Oleg Nesterov
2014-10-23 19:38 ` Paul E. McKenney
2014-10-23 19:53 ` Oleg Nesterov
2014-10-23 20:24 ` Paul E. McKenney
2014-10-23 21:13 ` Oleg Nesterov
2014-10-23 21:38 ` Paul E. McKenney
2014-10-25 3:16 ` Dâniel Fraga
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