From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: AW: VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel
Date: Fri, 21 Dec 2012 16:05:39 +0100 (CET)
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Cc: "Koehrer Mathias (ETAS/ESS2)" <mathias.koehrer@etas.com>,
	Jan Kiszka <jan.kiszka@web.de>,
	"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
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On Fri, 21 Dec 2012, Steven Rostedt wrote:
> On Fri, 2012-12-21 at 08:23 +0000, Koehrer Mathias (ETAS/ESS2) wrote:
> >  *** DEADLOCK ***
> 
> So this is an obvious bug in virtualbox. No need to send us a config.
> This bug has nothing to do with RT. It's just that RT can expose bugs in
> mainline (or anything added to mainline) much easier.
> 
> Funny thing is, this deadlock isn't even possible in RT, so there's
> probably many more bugs in the virtualbox driver.

It's worse on RT, because that's a smp function call interrupt. Which
just cannot work on RT with the lock not being a raw lock.
 
Thanks,

	tglx