Subject: Re: kvm: repeatable kernel crash with Athlon II cpu
To: Stas Sergeev <stsp@list.ru>, kvm@vger.kernel.org
References: <56FA9DB1.4060704@list.ru>
Cc: Stas Sergeev <stsp@users.sourceforge.net>,
        Linux kernel <linux-kernel@vger.kernel.org>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <56FAA135.1080600@redhat.com>
Date: Tue, 29 Mar 2016 17:37:25 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.6.0
MIME-Version: 1.0
In-Reply-To: <56FA9DB1.4060704@list.ru>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 866
Lines: 27


On 29/03/2016 17:22, Stas Sergeev wrote:
> I've been running dosemu and found out that it hangs
> or reboots one of my PCs. This happens with any fedora-23
> kernels and hand-compiled kernels. The latest I tried, were:
> 4.4.6-300.fc23.x86_64
> 4.5.0-rc6

Can you check if 4.3 works?

> I tried to put the debug printfs into dosemu, and it seems
> the crash happens on KVM_RUN ioctl, but of course the one
> can't say for sure when an instant reboot happens. Yet if
> I disable the KVM use, or try on a different CPU, there is
> no crash too, so I am pretty sure it is the KVM bug.

Yes, that's likely.

> Hope someone can find such an old CPU an reproduce the problem.
> Please let me know what info should I provide or what debugging
> to do to help getting that fixed.

Do you have experience bisecting the kernel?  If so perhaps you can try
doing that.

Paolo