Comment 22 for bug 1129571

John: you might also like to try with this patchset applied:
http://lists.nongnu.org/archive/html/qemu-devel/2013-02/msg04207.html
as that fixes one category of races. There are still other races that can cause segfaults and other problems (as the cover letter describes) but it's possible this particular case will be fixed by it.