sunhme sometimes causes the VM to hang forever
Description of problem:
When using sunhme, sometimes on receiving traffic (and doing disk IO?) it will get slower and slower until it becomes entirely unresponsive, which does not happen on the real hardware I have sitting next to me (Sun Netra T1, running the same OS+kernel, though not the same image)

virtio-net-pci does not, so far, demonstrate the problem, and neither does just sending a lot of traffic out over the sunhme interface, so it appears to require receiving or some more complex interaction.

It doesn't always happen immediately, it sometimes takes a couple of tries with the command, but when it does, it's gone.

Output logged to console below.
Steps to reproduce:
1. Log into VM (rich/omgqemu)
2. sudo apt clean;sudo apt update;
3. If it doesn't lock up the VM, repeat step 2 a few times.
Additional information:
Disk image can be found [here](https://www.dropbox.com/s/0oosyf7xej44v9n/sunhme_repro_disk.tgz?dl=0) (tarred in the hope that it does something reasonable with sparseness)
 
Console output can be found [here](https://www.dropbox.com/s/t1wxx41vzv8p3l6/sunhme%20sadness.txt?dl=0)

Ah yes, [the initrd and vmlinux](https://www.dropbox.com/s/t7i4gs7poqaeanz/oops_boot.tgz?dl=0) would help, wouldn't they, though I imagine the ones in the VM itself would boot...