[libvirt] FYI, "Unable to create cgroup for ..."

[Jim Meyering]

In case someone else encounters this...

Today none of my VMs would start on F15:

    # virsh create rawhide.xml
    error: Failed to create domain from rawhide.xml
    error: Unable to create cgroup for rawhide: No such file or directory

Luckily, I noticed that Rich Jones had the same problem
a week ago and he found that restarting libvirtd was enough
to solve the problem:

    # service libvirtd restart

That did it for me, too.