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Date: Fri, 11 May 2012 19:30:42 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20120511162848.GA10344@redhat.com>
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Subject: Re: [Qemu-devel] PCI: Hot-removing a virtio-blk causes guest panic
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To: Amos Kong <akong@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>, qemu-devel@nongnu.org, Anthony Liguori <aliguori@us.ibm.com>

On Fri, May 11, 2012 at 12:37:49PM +0800, Amos Kong wrote:
> good: 3.3.0 guest kernel & qemu-kvm-rhel6
> guest panic:  3.3.0 guest kernel & qemu-upstream (contains fix [1])
> 
> I didn't change anything of guest kernel,
> It seems a bug of qemu-upstream.
> 
> [1] http://marc.info/?l=qemu-devel&m=133670266801022&w=2
>     [PATCH] qom: fix refcounting in object_property_del_child()
> 
> 
> >>> Start VM with one block device:
> qemu-upstream --enable-kvm  -name 'vm1' -nodefaults -drive
> file='nolvm.qcow2',index=0,if=virtio,cache=none,snapshot=on -net none -m
> 2000 -smp 2 -vnc :0  -kernel vmlinuz-3.3.0 -append 'ro root=/dev/vda1
> console=tty0 console=ttyS0,115200'   -drive
> file=images/u0,if=none,id=drive-virtio0-0-0,format=qcow2,cache=none
> -device virtio-blk-pci,drive=drive-virtio0-0-0,id=virti0-0-0 -monitor
> unix:/tmp/m,nowait,server
> 
> >>> hot-remove the virtio disk
> (qemu)# echo "device_del virti0-0-0" | nc -U /tmp/m
> 
> >>> guest panic:


Find a working version and bisect?