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

Daniel Walker
2005-11-15T20:07:31Z

Wasn't this thread related to a real lock up? I thought Luca said that
the stack trace came from his printer.

I thought it might be related to the __delay troubles ..

Daniel

On Tue, 15 Nov 2005, Ingo Molnar wrote:

>
> * 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;
> -
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