Comment 2 for bug 1434779

On Sat, Mar 21, 2015 at 07:44:37AM -0000, youyunyehe wrote:
> We are using “Windows Server 2008” with qemu-kvm-2.0.1 (linux kernel:3.10.0) as a host of a VM.

Please give the exact qemu-kvm package version and Linux distro name.
The code in qemu.git/master is slightly different so maybe the issue no
longer happens, but it would be worth looking at the exact source code
your qemu-kvm is built from.

I have CCed Jeff Cody, who maintains drive-mirror.

> Using drive_mirror to do live-migration on the same host for different disks
> Local disk: /sf/data/local/
> Shared disk(iscsi): /sf/other/local/ --- the disk is busy, the IO rate is about 30MB/s
> qemu-system-x86_64 -k en-us -m 2048 -smp 2 -vnc :3100 -usbdevice tablet -boot c -enable-kvm -drive file=/sf/data/local/vm-disk-1.qcow2,if=none,id=drive-ide0,cache=none,aio=native -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0,id=ide0,bootindex=100
>
> Step 1:
> Start migration: Drive_mirror -f drive-ide0 /sf/other/local/test.qcow2
>
> Step 2:
> When detect the migration has completed, then send cmd: block_job_complete -f drive-ide0
>
> Step 3:
> send cmd: info status
> What surprised me is that the qemu monitor reports can’t be connected.
>
> Then find bellows:
> The qemu process hangs on the mirror_run->bdrv_drain_all->aio_poll->qemu_poll_ns->ppoll (),
> None events were received and poll forever. I don’t know why the aio can’t be responsed. This case is hardly to
> be generated but it really happens sometimes . I’m looking forward to getting help from you .
> The stack capture snapshot: