lkml.org 
[lkml]   [2008]   [Feb]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: 2.6.25-rc2 rcupreempt WARN after suspend to ram
Date
Am Dienstag, 26. Februar 2008 schrieb Karsten Wiese:
> Am Sonntag, 24. Februar 2008 schrieb Paul E. McKenney:
> > On Sun, Feb 24, 2008 at 04:38:15PM +0100, Karsten Wiese wrote:
> > > Am Samstag, 23. Februar 2008 schrieb Karsten Wiese:
> > > > Am Samstag, 23. Februar 2008 schrieb Paul E. McKenney:
> > > > > On Sat, Feb 23, 2008 at 01:41:02PM +0100, Karsten Wiese wrote:
> > > > > > Hi,
> > > > > >
> > > > > > This appeared in dmesg after
> > > > > > $ echo core > /sys/power/pm_test
> > > > > > followed by 3 cycles of
> > > > > > $ echo mem > /sys/power/state
> > > > > > . .config attached.
> > > > > >
> > > > > > dmesg excerpt (, full ~1MByte available):
> > > > >
> > > > > Does this tree have http://lkml.org/lkml/2008/1/29/208 applied?
> > > >
> > > > Yes. This tree was linus' git head as of yesterday or the day before.
> > >
> > > Updated to git-head of today, same test and .config, different symptoms
> > > like in this thread: http://lkml.org/lkml/2008/2/23/260
> > > Later in this thread, Alan Cox said it looked like irq problems.
> > > Maybe also the rcupreemt related WARN_ON I saw are caused by irq problems.
> >
> > Might be, but am taking a closer look at the interaction between irq,
> > dynticks, and rcupreempt in any case.
>
> [Added Rafael, Thomas and Steven to CC]
>
> The "different symptoms" above are indeed unrelated and solved by reverting
> "commit 559bbe6cbd0d8c68d40076a5f7dc98e3bf5864b2
> power_state: get rid of write-only variable in SATA"
>
> The cpu_hotplug code used by suspend together with hr_timer and nohz looks
> suspicious:
> $ echo 0 > /sys/devices/system/cpu/cpu1/online
> $ echo 1 > /sys/devices/system/cpu/cpu1/online
> (repeat until dmesg|tail shows WARNs; here it took 2 iterations)
> causes symptoms like in 1st message of this thread again.

[Added Andrew]

This fixes it, not sure if its not just papering over, though it seams to be
likely for an offlined CPU to have ticks stopped.

Thanks,
Karsten
---
Don't touch an offlined CPU's ts->tick_stopped in tick_cancel_sched_timer()

Silences WARN_ONs in rcu_enter_nohz() and rcu_exit_nohz(), which appeared
before caused by (repeated) calls to:
$ echo 0 > /sys/devices/system/cpu/cpu1/online
$ echo 1 > /sys/devices/system/cpu/cpu1/online
Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de>
---
kernel/time/tick-sched.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2968298..686da82 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -640,7 +640,7 @@ void tick_cancel_sched_timer(int cpu)

if (ts->sched_timer.base)
hrtimer_cancel(&ts->sched_timer);
- ts->tick_stopped = 0;
+
ts->nohz_mode = NOHZ_MODE_INACTIVE;
}
#endif /* HIGH_RES_TIMERS */
--
1.5.3.3


\
 
 \ /
  Last update: 2008-02-26 22:17    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site