Lockup with vhost network

[rm]

After using Qemu in this configuration successfully for quite a while, I changed two things:
- moved the VM from a 8-core 4GHz host to a slower 2-core 1.6 Ghz machine
- upgraded qemu from 2.1 to 2.5

and almost immediately (in a couple hours) got hit with a vhost-related lockup.

QEMU command line is:

qemu-system-x86_64 -enable-kvm -daemonize -monitor unix:./monitor,server,nowait -cpu host -M q35 -balloon virtio -device virtio-scsi-pci,id=scsi -device scsi-hd,drive=hd -drive if=none,id=hd,cache=writeback,aio=native,format=raw,file=xxxx.img,discard=unmap,detect-zeroes=unmap -device virtio-net-pci,netdev=net0,mac=xxxx -netdev tap,vhost=on,id=net0,script=xxxx.sh -usbdevice tablet -smp 2 -m 512 -vnc xxxx:yz

VM was running fine, except no network traffic was passed from/to it. Shutting down the VM, it hung at "Will now halt." The QEMU process was unkillable, so the only choice was to sysrq-b the entire box.

dmesg with sysrq-w attached.

[Thomas Huth (th-huth)]

The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]