kvm spinning on exit

Hi,

I've had this problem before and worked around it using scripts, but this seems to happen a lot more now that a host has been upgraded to 2.6.31.4 (could just be me noticing more too)

After the guest kernel shuts off, the qemu process ends up spinning, consuming 200% cpu (both cores!) and strace reveals it is truly spinning:

[pid 14382] wait4(3604, <unfinished ...>
[pid 14383] <... ioctl resumed> , 0) = 0
[pid 14382] <... wait4 resumed> 0x7fff2e8ae02c, 0, NULL) = -1 ECHILD (No child processes)
[pid 14383] ioctl(14, 0xae80 <unfinished ...>

This is repeated 100% identical, ad-infinitum.

Host qemu 0.10.50

Cheers
Antoine