Re: Crashes in perf_event_ctx_lock_nested

[Peter Zijlstra]

On Tue, Oct 31, 2017 at 10:32:00PM +0100, Thomas Gleixner wrote:
> That means we can have the following situation:
> 
>     lock(watchdog_mutex);
>     lockup_detector_reconfigure();
>         cpus_read_lock();
> 	stop();
> 	   park()
> 	update();
> 	start();
> 	   unpark()
> 	cpus_read_unlock();		thread runs()
> 	cleanup();						
>     unlock(watchdog_mutex);
> 

Isn't there also a where hardlockup_detector_perf_init() creates an
event to 'probe' stuff, and then hardlockup_detector_perf_enable()
_again_ creates the event?