Description of problem:
Migrate VM after Memory hotplug, VM is stuck in migrating state and 
can't shutdown/reboot.
Happened while verify BZ: 1392903

Version-Release number of selected component (if applicable):
oVirt Engine Version: 4.1.0-0.0.master.20161119231317.git06d9054.el7.centos
Host:
OS Version:RHEL - 7.3 - 7.el7
OS Description:Red Hat Enterprise Linux Server 7.3 (Maipo)
Kernel Version:3.10.0 - 514.el7.x86_64
KVM Version:2.3.0 - 31.el7_2.23
LIBVIRT Version:libvirt-2.0.0-10.el7
VDSM Version:vdsm-4.18.999-919.git723413e.el7.centos

Steps to Reproduce:
1. Create and Start VM
2. Hotplug Memory 
3. Migrate VM

Actual results:
VM is stuck in migrating after the second migration

From vdsm log:
2016-11-20 09:12:41,033 ERROR (jsonrpc/5) [virt.vm] (vmId='f8d4c72d-acbb-4c86-8399-c79de41cb2b1') Error fetching vm stats (vm:1288)
Traceback (most recent call last):
  File "/usr/share/vdsm/virt/vm.py", line 1284, in _getRunningVmStats
    vm_sample.interval)
  File "/usr/lib/python2.7/site-packages/vdsm/virt/vmstats.py", line 47, in produce
    balloon(vm, stats, last_sample)
  File "/usr/lib/python2.7/site-packages/vdsm/virt/vmstats.py", line 151, in balloon
    max_mem = int(vm.conf.get('memSize')) * 1024
TypeError: int() argument must be a string or a number, not 'NoneType'
2016-11-20 09:12:41,033 ERROR (jsonrpc/5) [DynamicBridge] TypeError raised by dispatched function (Bridge:204)
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/vdsm/rpc/Bridge.py", line 202, in _dynamicMethod
    result = fn(*methodArgs)
  File "/usr/share/vdsm/API.py", line 1389, in getAllVmStats
    statsList = self._cif.getAllVmStats()
  File "/usr/share/vdsm/clientIF.py", line 442, in getAllVmStats
    return [v.getStats() for v in self.vmContainer.values()]
  File "/usr/share/vdsm/virt/vm.py", line 1217, in getStats
    stats.update(self._getGuestStats())
  File "/usr/share/vdsm/virt/vm.py", line 1399, in _getGuestStats
    int(self.conf['memSize']) * 100)
TypeError: int() argument must be a string or a number, not 'NoneType'
2016-11-20 09:12:41,034 ERROR (jsonrpc/5) [jsonrpc.JsonRpcServer] Internal server error (__init__:552)
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/yajsonrpc/__init__.py", line 547, in _handle_request
    res = method(**params)
  File "/usr/lib/python2.7/site-packages/vdsm/rpc/Bridge.py", line 205, in _dynamicMethod
    raise InvalidCall(fn, methodArgs, e)
InvalidCall: Attempt to call function: <bound method Global.getAllVmStats of <API.Global object at 0x28b2f50>> with arguments: () error: int() argument must be a string or a number, not 'NoneType'


From engine log:
2016-11-20 16:08:16,140 ERROR [org.ovirt.engine.core.vdsbroker.vdsbroker.GetAllVmStatsVDSCommand] (DefaultQuartzScheduler4) [929f2d12-ee89-4c6c-87be-3d3cf1f4ea89] Command 'GetAllVmStatsVDSCommand(HostName = host_mixed_1, VdsIdVDSCommandParametersBase:{runAsync='true', hostId='f6a54c7f-fc6c-415e-8931-f27b5ad82109'})' execution failed: VDSGenericException: VDSErrorException: Failed to GetAllVmStatsVDS, error = Attempt to call function: <bound method Global.getAllVmStats of <API.Global object at 0x3b3be50>> with arguments: () error: int() argument must be a string or a number, not 'NoneType', code = -32603