* INFO: task rcu_kthread:6 blocked for more than 120 seconds. @ 2011-01-12 17:43 Russell King 2011-01-12 22:22 ` Paul E. McKenney 0 siblings, 1 reply; 6+ messages in thread From: Russell King @ 2011-01-12 17:43 UTC (permalink / raw) To: Linux Kernel List I'm seeing rcu_kthread get stuck from time to time on ARM Versatile PB (ARM926). Kernel is based upon commit 9e9bc973 (immediately prior to the merge of the OMAP tree.) ~ # ps aux|grep rcu root 6 0.0 0.0 0 0 ? S 02:31 0:01 [rcu_kthread] root 502 9.0 0.3 3740 472 ttyAMA0 S+ 02:59 0:00 grep rcu ~ # ps aux|grep rcu root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] root 504 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu ~ # ps aux|grep rcu root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] root 506 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu ~ # ps aux|grep rcu root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] root 508 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu ~ # cat /proc/6/wchan rcu_kthread ~ # INFO: task rcu_kthread:6 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. rcu_kthread D c02c6684 0 6 2 0x00000000 Backtrace: [<c02c6388>] (schedule+0x0/0x354) from [<c00836a0>] (rcu_kthread+0x78/0xf4) [<c0083628>] (rcu_kthread+0x0/0xf4) from [<c00633ac>] (kthread+0x88/0x90) [<c0063324>] (kthread+0x0/0x90) from [<c004d12c>] (do_exit+0x0/0x5f8) r7:00000013 r6:c004d12c r5:c0063324 r4:c181df28 no locks held by rcu_kthread/6. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: INFO: task rcu_kthread:6 blocked for more than 120 seconds. 2011-01-12 17:43 INFO: task rcu_kthread:6 blocked for more than 120 seconds Russell King @ 2011-01-12 22:22 ` Paul E. McKenney 2011-01-13 15:17 ` Thomas Weber 2011-01-13 20:05 ` Russell King 0 siblings, 2 replies; 6+ messages in thread From: Paul E. McKenney @ 2011-01-12 22:22 UTC (permalink / raw) To: Russell King; +Cc: Linux Kernel List On Wed, Jan 12, 2011 at 05:43:00PM +0000, Russell King wrote: > I'm seeing rcu_kthread get stuck from time to time on ARM Versatile PB > (ARM926). Kernel is based upon commit 9e9bc973 (immediately prior to > the merge of the OMAP tree.) > > ~ # ps aux|grep rcu > root 6 0.0 0.0 0 0 ? S 02:31 0:01 [rcu_kthread] > root 502 9.0 0.3 3740 472 ttyAMA0 S+ 02:59 0:00 grep rcu > ~ # ps aux|grep rcu > root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > root 504 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > ~ # ps aux|grep rcu > root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > root 506 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > ~ # ps aux|grep rcu > root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > root 508 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > ~ # cat /proc/6/wchan > rcu_kthread > ~ # INFO: task rcu_kthread:6 blocked for more than 120 seconds. > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > rcu_kthread D c02c6684 0 6 2 0x00000000 > Backtrace: > [<c02c6388>] (schedule+0x0/0x354) from [<c00836a0>] (rcu_kthread+0x78/0xf4) > [<c0083628>] (rcu_kthread+0x0/0xf4) from [<c00633ac>] (kthread+0x88/0x90) > [<c0063324>] (kthread+0x0/0x90) from [<c004d12c>] (do_exit+0x0/0x5f8) > r7:00000013 r6:c004d12c r5:c0063324 r4:c181df28 > no locks held by rcu_kthread/6. Does the following patch help? Thanx, Paul ------------------------------------------------------------------------ commit 70ce43253a4465211a9c51e33d56a417c759a718 Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Date: Wed Jan 12 14:18:11 2011 -0800 rcu: avoid pointless blocked-task warnings If the RCU callback-processing kthread has nothing to do, it parks in a wait_event(). If RCU remains idle for more than two minutes, the kernel complains about this. This commit changes from wait_event() to wait_event_interruptible() to prevent the kernel from complaining just because RCU is idle. Reported-by: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 0344937..0c343b9 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -189,7 +189,8 @@ static int rcu_kthread(void *arg) unsigned long flags; for (;;) { - wait_event(rcu_kthread_wq, have_rcu_kthread_work != 0); + wait_event_interruptible(rcu_kthread_wq, + have_rcu_kthread_work != 0); morework = rcu_boost(); local_irq_save(flags); work = have_rcu_kthread_work; ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: INFO: task rcu_kthread:6 blocked for more than 120 seconds. 2011-01-12 22:22 ` Paul E. McKenney @ 2011-01-13 15:17 ` Thomas Weber 2011-01-13 15:42 ` Paul E. McKenney 2011-01-13 20:05 ` Russell King 1 sibling, 1 reply; 6+ messages in thread From: Thomas Weber @ 2011-01-13 15:17 UTC (permalink / raw) To: paulmck; +Cc: Russell King, Linux Kernel List Am 12.01.2011 23:22, schrieb Paul E. McKenney: > On Wed, Jan 12, 2011 at 05:43:00PM +0000, Russell King wrote: >> I'm seeing rcu_kthread get stuck from time to time on ARM Versatile PB >> (ARM926). Kernel is based upon commit 9e9bc973 (immediately prior to >> the merge of the OMAP tree.) >> >> ~ # ps aux|grep rcu >> root 6 0.0 0.0 0 0 ? S 02:31 0:01 [rcu_kthread] >> root 502 9.0 0.3 3740 472 ttyAMA0 S+ 02:59 0:00 grep rcu >> ~ # ps aux|grep rcu >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] >> root 504 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu >> ~ # ps aux|grep rcu >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] >> root 506 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu >> ~ # ps aux|grep rcu >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] >> root 508 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu >> ~ # cat /proc/6/wchan >> rcu_kthread >> ~ # INFO: task rcu_kthread:6 blocked for more than 120 seconds. >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. >> rcu_kthread D c02c6684 0 6 2 0x00000000 >> Backtrace: >> [<c02c6388>] (schedule+0x0/0x354) from [<c00836a0>] (rcu_kthread+0x78/0xf4) >> [<c0083628>] (rcu_kthread+0x0/0xf4) from [<c00633ac>] (kthread+0x88/0x90) >> [<c0063324>] (kthread+0x0/0x90) from [<c004d12c>] (do_exit+0x0/0x5f8) >> r7:00000013 r6:c004d12c r5:c0063324 r4:c181df28 >> no locks held by rcu_kthread/6. > > Does the following patch help? > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 70ce43253a4465211a9c51e33d56a417c759a718 > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Date: Wed Jan 12 14:18:11 2011 -0800 > > rcu: avoid pointless blocked-task warnings > > If the RCU callback-processing kthread has nothing to do, it parks in > a wait_event(). If RCU remains idle for more than two minutes, the > kernel complains about this. This commit changes from wait_event() > to wait_event_interruptible() to prevent the kernel from complaining > just because RCU is idle. > > Reported-by: Russell King <rmk@arm.linux.org.uk> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c > index 0344937..0c343b9 100644 > --- a/kernel/rcutiny.c > +++ b/kernel/rcutiny.c > @@ -189,7 +189,8 @@ static int rcu_kthread(void *arg) > unsigned long flags; > > for (;;) { > - wait_event(rcu_kthread_wq, have_rcu_kthread_work != 0); > + wait_event_interruptible(rcu_kthread_wq, > + have_rcu_kthread_work != 0); > morework = rcu_boost(); > local_irq_save(flags); > work = have_rcu_kthread_work; > -- > 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/ Hello Paul, here it helps. Tested on Devkit8000 (omap3, beagleboard clone). Without this patch I had permanent crashes. With this patch board is running. Tested-by: Thomas Weber <weber@corscience.de> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: INFO: task rcu_kthread:6 blocked for more than 120 seconds. 2011-01-13 15:17 ` Thomas Weber @ 2011-01-13 15:42 ` Paul E. McKenney 0 siblings, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2011-01-13 15:42 UTC (permalink / raw) To: Thomas Weber; +Cc: Russell King, Linux Kernel List On Thu, Jan 13, 2011 at 04:17:50PM +0100, Thomas Weber wrote: > Am 12.01.2011 23:22, schrieb Paul E. McKenney: > > On Wed, Jan 12, 2011 at 05:43:00PM +0000, Russell King wrote: > >> I'm seeing rcu_kthread get stuck from time to time on ARM Versatile PB > >> (ARM926). Kernel is based upon commit 9e9bc973 (immediately prior to > >> the merge of the OMAP tree.) > >> > >> ~ # ps aux|grep rcu > >> root 6 0.0 0.0 0 0 ? S 02:31 0:01 [rcu_kthread] > >> root 502 9.0 0.3 3740 472 ttyAMA0 S+ 02:59 0:00 grep rcu > >> ~ # ps aux|grep rcu > >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > >> root 504 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > >> ~ # ps aux|grep rcu > >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > >> root 506 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > >> ~ # ps aux|grep rcu > >> root 6 0.0 0.0 0 0 ? D 02:31 0:01 [rcu_kthread] > >> root 508 0.0 0.3 3740 472 ttyAMA0 S+ 03:00 0:00 grep rcu > >> ~ # cat /proc/6/wchan > >> rcu_kthread > >> ~ # INFO: task rcu_kthread:6 blocked for more than 120 seconds. > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >> rcu_kthread D c02c6684 0 6 2 0x00000000 > >> Backtrace: > >> [<c02c6388>] (schedule+0x0/0x354) from [<c00836a0>] (rcu_kthread+0x78/0xf4) > >> [<c0083628>] (rcu_kthread+0x0/0xf4) from [<c00633ac>] (kthread+0x88/0x90) > >> [<c0063324>] (kthread+0x0/0x90) from [<c004d12c>] (do_exit+0x0/0x5f8) > >> r7:00000013 r6:c004d12c r5:c0063324 r4:c181df28 > >> no locks held by rcu_kthread/6. > > > > Does the following patch help? > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 70ce43253a4465211a9c51e33d56a417c759a718 > > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Date: Wed Jan 12 14:18:11 2011 -0800 > > > > rcu: avoid pointless blocked-task warnings > > > > If the RCU callback-processing kthread has nothing to do, it parks in > > a wait_event(). If RCU remains idle for more than two minutes, the > > kernel complains about this. This commit changes from wait_event() > > to wait_event_interruptible() to prevent the kernel from complaining > > just because RCU is idle. > > > > Reported-by: Russell King <rmk@arm.linux.org.uk> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > > diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c > > index 0344937..0c343b9 100644 > > --- a/kernel/rcutiny.c > > +++ b/kernel/rcutiny.c > > @@ -189,7 +189,8 @@ static int rcu_kthread(void *arg) > > unsigned long flags; > > > > for (;;) { > > - wait_event(rcu_kthread_wq, have_rcu_kthread_work != 0); > > + wait_event_interruptible(rcu_kthread_wq, > > + have_rcu_kthread_work != 0); > > morework = rcu_boost(); > > local_irq_save(flags); > > work = have_rcu_kthread_work; > > -- > > 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/ > > Hello Paul, > here it helps. Tested on Devkit8000 (omap3, beagleboard clone). Without > this patch I had permanent crashes. With this patch board is running. > > Tested-by: Thomas Weber <weber@corscience.de> Thank you, Thomas!!! I have added your Tested-by. Thanx, Paul ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: INFO: task rcu_kthread:6 blocked for more than 120 seconds. 2011-01-12 22:22 ` Paul E. McKenney 2011-01-13 15:17 ` Thomas Weber @ 2011-01-13 20:05 ` Russell King 2011-01-13 20:41 ` Paul E. McKenney 1 sibling, 1 reply; 6+ messages in thread From: Russell King @ 2011-01-13 20:05 UTC (permalink / raw) To: Paul E. McKenney; +Cc: Linux Kernel List On Wed, Jan 12, 2011 at 02:22:19PM -0800, Paul E. McKenney wrote: > Does the following patch help? Yes it does, thanks. Tested-by: Russell King <rmk+kernel@arm.linux.org.uk> > commit 70ce43253a4465211a9c51e33d56a417c759a718 > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Date: Wed Jan 12 14:18:11 2011 -0800 > > rcu: avoid pointless blocked-task warnings > > If the RCU callback-processing kthread has nothing to do, it parks in > a wait_event(). If RCU remains idle for more than two minutes, the > kernel complains about this. This commit changes from wait_event() > to wait_event_interruptible() to prevent the kernel from complaining > just because RCU is idle. > > Reported-by: Russell King <rmk@arm.linux.org.uk> Please add '+kernel' in there, thanks. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: INFO: task rcu_kthread:6 blocked for more than 120 seconds. 2011-01-13 20:05 ` Russell King @ 2011-01-13 20:41 ` Paul E. McKenney 0 siblings, 0 replies; 6+ messages in thread From: Paul E. McKenney @ 2011-01-13 20:41 UTC (permalink / raw) To: Russell King; +Cc: Linux Kernel List On Thu, Jan 13, 2011 at 08:05:26PM +0000, Russell King wrote: > On Wed, Jan 12, 2011 at 02:22:19PM -0800, Paul E. McKenney wrote: > > Does the following patch help? > > Yes it does, thanks. > > Tested-by: Russell King <rmk+kernel@arm.linux.org.uk> > > > commit 70ce43253a4465211a9c51e33d56a417c759a718 > > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Date: Wed Jan 12 14:18:11 2011 -0800 > > > > rcu: avoid pointless blocked-task warnings > > > > If the RCU callback-processing kthread has nothing to do, it parks in > > a wait_event(). If RCU remains idle for more than two minutes, the > > kernel complains about this. This commit changes from wait_event() > > to wait_event_interruptible() to prevent the kernel from complaining > > just because RCU is idle. > > > > Reported-by: Russell King <rmk@arm.linux.org.uk> > > Please add '+kernel' in there, thanks. Done! FWIW, I copied the original from my email agent. Thanx, Paul ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-01-13 20:41 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-01-12 17:43 INFO: task rcu_kthread:6 blocked for more than 120 seconds Russell King 2011-01-12 22:22 ` Paul E. McKenney 2011-01-13 15:17 ` Thomas Weber 2011-01-13 15:42 ` Paul E. McKenney 2011-01-13 20:05 ` Russell King 2011-01-13 20:41 ` Paul E. McKenney
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