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Date:   Mon, 23 Apr 2018 16:00:52 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Diego Viola <diego.viola@gmail.com>
Cc:     linux-kernel@vger.kernel.org, tglx@linutronix.de,
        len.brown@intel.com, rui.zhang@intel.com,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: Experiencing freezes with kernel 4.16.3 on a desktop with E5500
 CPU (bisect included)
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On Mon, Apr 23, 2018 at 02:38:47PM +0200, Peter Zijlstra wrote:
> @@ -834,8 +857,12 @@ static int clocksource_unbind(struct clocksource *cs)
>  		if (curr_clocksource == cs)
>  			return -EBUSY;
>  	}
> +
> +	clocksource_watchdog_lock(&flags);
>  	clocksource_dequeue_watchdog(cs);
>  	list_del_init(&cs->list);
> +	clocksource_watchdog_lock(&flags);

It works a lot better when this is _unlock();

> +
>  	return 0;
>  }
>  

With that, and intel_idle.c modified to always issue the "halts in
idle" thing, my IVB comes up in hpet mode. Let me dig up a Core2 era
machine and see if that works too.