Re: [BUG] Softlockup detected with linux-2.6.14-rt6

Ingo Molnar
2005-11-15T20:00:06Z

* john cooper <john.cooper@timesys.com> wrote:

> Ingo Molnar wrote:
> >* Luca Falavigna <dktrkranz@gmail.com> wrote:
> >>I found this softlockup bug involving arts daemon using a
> >>linux-2.6.14-rt6 kernel (with "Complete Preemption" and "Detect Soft
> >>Lockups" compiled in).
> >>This bug does not happen everytime: I was able to reproduce it only
> >>three times in a week. [...]
> >
> >
> >does this happen with -rt13 too? I have fixed a softlockup
> >false-positive in it.
>
> Just curious what the cause of the false positive was?

the fix is below - we didnt reset the 'light' counter in the else
branch.

Ingo

Index: linux/kernel/softlockup.c
===================================================================
--- linux.orig/kernel/softlockup.c
+++ linux/kernel/softlockup.c
@@ -90,7 +90,8 @@ void softlockup_tick(void)

wake_up_process(per_cpu(watchdog_task, this_cpu));
per_cpu(timeout, this_cpu) = jiffies + msecs_to_jiffies(1000);
- }
+ } else
+ touch_light_softlockup_watchdog();

if (per_cpu(print_timestamp, this_cpu) == timestamp)
return;