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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/