2016-03-29 15:22:35

by Stas Sergeev

[permalink] [raw]
Subject: kvm: repeatable kernel crash with Athlon II cpu

Hello.

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

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.

The CPU on which the problem happens:
AMD Athlon(tm) II X2 245 Processor

The CPUs on which the problem doesn't happen:
AMD FX 8350
Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz

I've set up the test-case here:
https://github.com/stsp/dosemu2/tree/bug

After checking out this branch, you need to get the file
c_drive/c.tar.gz
and unpack it into ~/.dosemu/drives so that ~/.dosemu/drives/c
exists.
After that you need to build and run dosemu.
Make sure to install slang-devel first, so that it can work
on a text-console (kms or non-kms).
Then run dosemu. Dos Navigator should load. Hit Alt-x to exit,
then Enter to confirm. At this point the host machine reboots,
or, if there is a different CPU - dosemu just exits.
The test must be repeated 2-3 times to make sure, but in most
cases it works from the first time.

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.


2016-03-29 15:37:31

by Paolo Bonzini

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu



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

2016-03-29 16:08:53

by Stas Sergeev

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu

29.03.2016 18:37, Paolo Bonzini пишет:
>
>
> 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?
Same crash on kernel-4.2.3-300.fc23.x86_64 - the oldest
available for f23.

>> 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.
But it looks like a genuine bug, not a regression.
Of course I can check some 3.x versions...

2016-03-29 16:27:15

by Paolo Bonzini

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu



On 29/03/2016 18:08, 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?
>
> Same crash on kernel-4.2.3-300.fc23.x86_64 - the oldest
> available for f23.
>
>>> >> 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.
> But it looks like a genuine bug, not a regression.

Yeah, I was hoping it was introduced recently.

> Of course I can check some 3.x versions...

That would help a lot, thanks.

Paolo

2016-03-29 17:10:36

by Stas Sergeev

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu

29.03.2016 19:27, Paolo Bonzini пишет:
> On 29/03/2016 18:08, 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?
>>
>> Same crash on kernel-4.2.3-300.fc23.x86_64 - the oldest
>> available for f23.
>>
>>>>>> 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.
>> But it looks like a genuine bug, not a regression.
>
> Yeah, I was hoping it was introduced recently.
>
>> Of course I can check some 3.x versions...
>
> That would help a lot, thanks.
Same on 3.18, and that's the oldest kernel that can be built
on f23 (gcc5).
So that's a genuine bug after all, not a regression.
So does anyone have the AMD AthlonII X2 245 to try reproducing this?

2016-03-29 17:13:57

by Paolo Bonzini

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu



On 29/03/2016 19:10, Stas Sergeev wrote:
> Same on 3.18, and that's the oldest kernel that can be built
> on f23 (gcc5).

Can you try getting even older kernel directly from Koji? Worst case it
doesn't boot. :)

Paolo

> So that's a genuine bug after all, not a regression.
> So does anyone have the AMD AthlonII X2 245 to try reproducing this?

2016-03-30 13:29:00

by Stas Sergeev

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu

29.03.2016 20:13, Paolo Bonzini пишет:
>
>
> On 29/03/2016 19:10, Stas Sergeev wrote:
>> Same on 3.18, and that's the oldest kernel that can be built
>> on f23 (gcc5).
>
> Can you try getting even older kernel directly from Koji? Worst case it
> doesn't boot. :)
Could you please send me the URLs?
This koji server is too slow to successfully browse it.

2016-03-30 14:10:07

by Paolo Bonzini

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu



On 30/03/2016 15:28, Stas Sergeev wrote:
> 29.03.2016 20:13, Paolo Bonzini пишет:
>>
>>
>> On 29/03/2016 19:10, Stas Sergeev wrote:
>>> Same on 3.18, and that's the oldest kernel that can be built
>>> on f23 (gcc5).
>>
>> Can you try getting even older kernel directly from Koji? Worst case it
>> doesn't boot. :)
> Could you please send me the URLs?
> This koji server is too slow to successfully browse it.
>

Here they are:

kernel-2.6.35.6-45.fc14
http://koji.fedoraproject.org/koji/buildinfo?buildID=201002

kernel-2.6.38.6-26.rc1.fc15
http://koji.fedoraproject.org/koji/buildinfo?buildID=243161

kernel-3.1.0-7.fc16
http://koji.fedoraproject.org/koji/buildinfo?buildID=271832

kernel-3.3.4-5.fc17
http://koji.fedoraproject.org/koji/buildinfo?buildID=317848

kernel-3.6.10-4.fc18
http://koji.fedoraproject.org/koji/buildinfo?buildID=372260

kernel-3.9.5-301.fc19
http://koji.fedoraproject.org/koji/buildinfo?buildID=426020

kernel-3.11.10-301.fc20
http://koji.fedoraproject.org/koji/buildinfo?buildID=483008

kernel-3.17.4-301.fc21
http://koji.fedoraproject.org/koji/buildinfo?buildID=596012

Paolo

2016-03-31 13:24:36

by Stas Sergeev

[permalink] [raw]
Subject: Re: kvm: repeatable kernel crash with Athlon II cpu

29.03.2016 20:13, Paolo Bonzini пишет:
> On 29/03/2016 19:10, Stas Sergeev wrote:
>> Same on 3.18, and that's the oldest kernel that can be built
>> on f23 (gcc5).
>
> Can you try getting even older kernel directly from Koji? Worst case it
> doesn't boot. :)
kernel-3.9.5-301.fc19.x86_64: crash happens
any older: no boot.