linux-kernel - Re: Oops from calibrate_delay_is_known on qemu machine with Linux v4.5-1523-g271ecc5253e2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160317183038.GG1681@redhat.com>
Date:	Thu, 17 Mar 2016 18:30:38 +0000
From:	"Richard W.M. Jones" <rjones@...hat.com>
To:	Josh Boyer <jwboyer@...oraproject.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, x86 <x86@...nel.org>,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: Oops from calibrate_delay_is_known on qemu machine with Linux
 v4.5-1523-g271ecc5253e2

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
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/