panic at sock_zerocopy_put when I ssh into a VM

Willem:

I updated my host server this morning to top of net-next -- commit
53b948356554. I am not doing anything fancy or intentionally using the
zerocopy code. I launch a VM with vhost and attempt to login via ssh.
Doing that triggers a panic in the host at sock_zerocopy_put. The
attached is a snapshot of the console -- best I can get for the stack trace.

David