linux-kernel - Re: frequent lockups in 3.18rc4

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Message-ID: <alpine.DEB.2.11.1412032156210.16275@nanos>
Date:	Wed, 3 Dec 2014 21:59:20 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Dave Jones <davej@...hat.com>
cc:	John Stultz <john.stultz@...aro.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Chris Mason <clm@...com>,
	Mike Galbraith <umgwanakikbuti@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Dâniel Fraga <fragabr@...il.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: frequent lockups in 3.18rc4

On Wed, 3 Dec 2014, Dave Jones wrote:
> On Wed, Dec 03, 2014 at 09:37:10PM +0100, Thomas Gleixner wrote:
>  
>  > Right, that resulted in a delta > 0. I have no idea how we could
>  > create a negative delta via wrapping the HPET around, i.e. HPET being
>  > 96 seconds ahead of TSC.
>  > 
>  > This looks more like a genuine TSC wreckage. So we have these possible
>  > causes:
>  > 
>  >    1) SMI
>  > 
>  >    2) Power states
>  > 
>  >    3) Writing to the wrong MSR
>  > 
>  > So I assume that 1/2 are a non issue. They should surface in normal
>  > non fuzzed operation as well.
>  > 
>  > Dave, does that TSC unstable thing always happen AFTER you started
>  > fuzzing? If yes, what is the fuzzer doing this time?
> 
> I've seen it even after doing just a kernel build sometimes, It's
> happened so regularly I've just assumed "the tsc is crap on this box".
> 
> On occasion I even see it shortly after boot, while idle.

Can you please provide the cpuinfo flags of that box?

Thanks,

	tglx
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