[RESOLVED OSADL QA 3.18.9-rt5 #1]

[Carsten Emde <C.Emde@osadl.org>]

Hi Sebastian,

>>>> an Intel Bay Trail board (Intel(R) Celeron(R) CPU  J1900  @ 1.99GHz) at
>>>> the OSADL QA Farm rack #b/slot #6 (https://www.osadl.org/?id=1894)
>>>> stops
>>>> working every 12 to 36 hours. The only way to get the board back to
>>>> work
>>> [..]
>> Could you try this:
>> --
>> Subject: [PATCH] kernel/irq_work: fix no_hz deadlock
>>
>> Invoking NO_HZ's irq_work callback from timer irq is not working very
>> well if the callback decides to invoke hrtimer_cancel():
>>
>> |hrtimer_try_to_cancel+0x55/0x5f
>> |hrtimer_cancel+0x16/0x28
>> |tick_nohz_restart+0x17/0x72
>> |__tick_nohz_full_check+0x8e/0x93
>> |nohz_full_kick_work_func+0xe/0x10
>> |irq_work_run_list+0x39/0x57
>> |irq_work_tick+0x60/0x67
>> |update_process_times+0x57/0x67
>> |tick_sched_handle+0x4a/0x59
>> |tick_sched_timer+0x3b/0x64
>> |__run_hrtimer+0x7a/0x149
>> |hrtimer_interrupt+0x1cc/0x2c5
>>
>> and here we deadlock while waiting for the lock which we are holding.
>> To fix this I'm doing the same thing that upstream is doing: is the
>> irq_work dedicated IRQ and use it only for what is marked as "hirq"
>> which should only be the FULL_NO_HZ related work.
>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>> [..]
> Thanks a lot! Applied the patch and restarted the box. Given the fact
> that it took up to 36 hours until the board stopped, we unfortunately
> need to see at least one week of crash-free operation, before we may
> consider the bug as fixed.
The board survived nine days without a crash -> RESOLVED.

Thanks,
	Carsten.