Re: race between kvm-kmod-3.0 and kvm-kmod-3.3 // was: race condition in qemu-kvm-1.0.1

[Peter Lieven <pl@dlhnet.de>]

On 07/03/12 15:25, Avi Kivity wrote:
> On 07/03/2012 04:15 PM, Peter Lieven wrote:
>> On 03.07.2012 15:13, Avi Kivity wrote:
>>> On 07/03/2012 04:01 PM, Peter Lieven wrote:
>>>> Further output from my testing.
>>>>
>>>> Working:
>>>> Linux 2.6.38 with included kvm module
>>>> Linux 3.0.0 with included kvm module
>>>>
>>>> Not-Working:
>>>> Linux 3.2.0 with included kvm module
>>>> Linux 2.6.28 with kvm-kmod 3.4
>>>> Linux 3.0.0 with kvm-kmod 3.4
>>>> Linux 3.2.0 with kvm-kmod 3.4
>>>>
>>>> I can trigger the race with any of qemu-kvm 0.12.5, 1.0 or 1.0.1.
>>>> It might be that the code was introduced somewhere between 3.0.0
>>>> and 3.2.0 in the kvm kernel module and that the flaw is not
>>>> in qemu-kvm.
>>>>
>>>> Any hints?
>>>>
>>> A bisect could tell us where the problem is.
>>>
>>> To avoid bisecting all of linux, try
>>>
>>>      git bisect v3.2 v3.0 virt/kvm arch/x86/kvm
>>>
>>>
>> would it also be ok to bisect kvm-kmod?
> Yes, but note that kvm-kmod is spread across two repositories which are
> not often tested out of sync, so you may get build failures.
>
ok, i just started with this with a 3.0 (good) and 3.2 (bad) vanilla 
kernel. i can confirm
the bug and i am no starting to bisect. it will take while with my 
equipment if anyone
has a powerful testbed to run this i would greatly appreciate help.

if anyone wants to reproduce:

a) v3.2 from git.kernel.org
b) qemu-kvm 1.0.1 from sourceforge
c) ubuntu 64-bit 12.04 server cd
d) empty (e.g. all zero) hard disk image

cmdline:
./qemu-system-x86_64 -m 512 -cdrom 
/home/lieven/Downloads/ubuntu-12.04-server-amd64.iso -hda 
/dev/hd1/vmtest -vnc :1 -monitor stdio -boot dc

then choose boot from first harddisk and try to quit the qemu monitor 
with 'quit'. -> hypervisor hangs.

peter