Date: Wed, 3 Dec 2014 15:44:39 -0500
From: Dave Jones <davej@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Chris Mason <clm@fb.com>, Mike Galbraith <umgwanakikbuti@gmail.com>,
        Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        =?iso-8859-1?Q?D=E2niel?= Fraga <fragabr@gmail.com>,
        Sasha Levin <sasha.levin@oracle.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: frequent lockups in 3.18rc4
Message-ID: <20141203204439.GA5019@redhat.com>
Mail-Followup-To: Dave Jones <davej@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <john.stultz@linaro.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Chris Mason <clm@fb.com>, Mike Galbraith <umgwanakikbuti@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	=?iso-8859-1?Q?D=E2niel?= Fraga <fragabr@gmail.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20141201230339.GA20487@ret.masoncoding.com>
 <1417529606.3924.26.camel@maggy.simpson.net>
 <CA+55aFw8smHBw9HiCiYL_ohkULLeunWo6qfayM19zhF1hKAxXg@mail.gmail.com>
 <1417540493.21136.3@mail.thefacebook.com>
 <20141203184111.GA32005@redhat.com>
 <CA+55aFzLprvtdLGDXgRr=k3QqO824uQSzbxT-b4vu_4pryMtSA@mail.gmail.com>
 <20141203190045.GB32005@redhat.com>
 <CA+55aFxoBqHtSi3VyoTDrB_v8KA94HyLcn5Sfkma-r9mZ-xzjA@mail.gmail.com>
 <CANcMJZA1NXUMLEveA2k5njFnWc1pCSwSeAOQH7VQCOR-QtiR8g@mail.gmail.com>
 <alpine.DEB.2.11.1412032126130.16275@nanos>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.11.1412032126130.16275@nanos>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org

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.

	Dave

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/