Re: Experiencing freezes with kernel 4.16.3 on a desktop with E5500 CPU (bisect included)

[Peter Zijlstra]

On Mon, Apr 23, 2018 at 02:38:47PM +0200, Peter Zijlstra wrote:

> @@ -142,6 +152,13 @@ static void __clocksource_unstable(struct clocksource *cs)
>  	cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
>  	cs->flags |= CLOCK_SOURCE_UNSTABLE;
>  
> +	if (list_empty(&cs->list)) {
> +		cs->rating = 0;
> +		return;
> +	}
> +
> +	__clocksource_change_rating(cs, 0);
> +
>  	if (cs->mark_unstable)
>  		cs->mark_unstable(cs);
>  

Thomas, we could not find the de-rate stuff, but the above can be
simplified; what happens is:

	cs->flags |= UNSTABLE;
	schedule_work(&watchdog_work)
	  kthread_run(clocksource_watchdog_kthread)
	    __clocksource_watchdog_kthread()
	      if (cs->flags & UNSTABLE)
	        __clocksource_change_rating()
	   clocksource_select()