Why does a VM fail to start in RHEV with libvirt's error "Unable to move tasks from domain cgroup in controller <n> for <vm_name>: No such process" ?

Issue

• A VM fails to start and vdsm.log shows the following error message from libvirt:

Thread-535668::ERROR::2013-05-29 14:13:49,675::vm::680::vm.Vm::(_startUnderlyingVm) vmId=`0855ac56-5f83-4e11-b91c-7651303b4b81`
::The vm start process failed
Traceback (most recent call last):
  File "/usr/share/vdsm/vm.py", line 642, in _startUnderlyingVm
    self._run()
  File "/usr/share/vdsm/libvirtvm.py", line 1474, in _run
    self._connection.createXML(domxml, flags),
  File "/usr/lib64/python2.6/site-packages/vdsm/libvirtconnection.py", line 83, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 2645, in createXML
    if ret is None:raise libvirtError('virDomainCreateXML() failed', conn=self)
libvirtError: Unable to move tasks from domain cgroup to emulator cgroup in controller 1 for <vm_name>: No such process