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From: "Richard W.M. Jones" <rjones@redhat.com>
To: Josh Boyer <jwboyer@fedoraproject.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, x86 <x86@kernel.org>,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>
Subject: Re: Oops from calibrate_delay_is_known on qemu machine with Linux v4.5-1523-g271ecc5253e2
Date: Thu, 17 Mar 2016 18:30:38 +0000	[thread overview]
Message-ID: <20160317183038.GG1681@redhat.com> (raw)
In-Reply-To: <CA+5PVA6muHRN_sQZ=6Xy-ATA76U8g9djFXW09Lj5zWvP=JbObA@mail.gmail.com>

On Thu, Mar 17, 2016 at 01:54:36PM -0400, Josh Boyer wrote:
> Hi Thomas,
> 
> We've had a report [1] of the mainline kernel crashing on a single-cpu
> QEMU machine (not kvm) in Fedora.  It looks as if the emulated machine
> is failing to provide a TSC and the calibrate_delay_is_known function
> is passing NULL to cpumask_any_but for the mask parameter.  At least
> that's all I've been able to discern thus far.
> 
> I was wondering if you had any insight into this issue, given your
> recent commit to change calibrate_delay_is_known to use
> topology_core_cpumask.  The backtrace is below.

Thanks for reporting this upstream Josh.

I've added to the bug a simple test script that reproduces the issue,
not 100% reliably by any means, but some of the time.  See:

  https://bugzilla.redhat.com/show_bug.cgi?id=1318596#c6

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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  reply	other threads:[~2016-03-17 18:30 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-17 17:54 Oops from calibrate_delay_is_known on qemu machine with Linux v4.5-1523-g271ecc5253e2 Josh Boyer
2016-03-17 18:30 ` Richard W.M. Jones [this message]
2016-03-17 21:01 ` Thomas Gleixner
2016-03-17 22:30   ` Richard W.M. Jones

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