Comment 9 for bug 1730717

Torkoal (our Jenkins node) was idle atm and Ryan reported he had seen the issues there before, so trying there as well.
This is LTS + HWE - Kernel 4.10.0-38-generic, qemu: 1:2.5+dfsg-5ubuntu10

I thought about your case since you seem just to start a lot of them and reboot,
this shouldn't be so much different to:
$ uvt-simplestreams-libvirt --verbose sync --source arch=amd64 label=daily release=artful
$ for i in {1..30}; do uvt-kvm create --log-console-output --password=ubuntu artful-${i}-bug1730717 release=artful arch=amd64 label=daily; done
$ for i in {1..30}; do uvt-kvm wait --insecure artful-${i}-bug1730717; done
$ for i in {1..30}; do uvt-kvm ssh --insecure artful-${i}-bug1730717 "sudo reboot"; done
$ sudo grep "soft lockup" /var/log/libvirt/qemu/artful-*-bug1730717.log

But this works for me :-/

Waiting for your feedback if you can trigger the same issue on a non-busy openstack system (could after all be some openstack magic at work that makes it behave differently).