I'm seeing something similar for the Ironic host manager here:

http://logs.openstack.org/20/407220/2/check/gate-tempest-dsvm-ironic-ipa-wholedisk-agent_ipmitool-tinyipa-multinode-ubuntu-xenial-nv/0779f94/logs/screen-n-sch.txt.gz#_2017-01-04_19_05_16_398

2017-01-04 19:05:16.398 20709 DEBUG oslo_concurrency.lockutils [req-6ce318a2-53e5-4b80-84a5-f896ab48d627 tempest-BaremetalMultitenancy-1820943769 tempest-BaremetalMultitenancy-1820943769] Lock "(u'ubuntu-xenial-2-node-rax-ord-6478210', u'21da4933-a128-45f6-a765-7e6bc071e0f3')" released by "nova.scheduler.host_manager._locked_update" :: held 0.002s inner /usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py:282
2017-01-04 19:05:16.398 20709 DEBUG oslo_concurrency.lockutils [req-6ce318a2-53e5-4b80-84a5-f896ab48d627 tempest-BaremetalMultitenancy-1820943769 tempest-BaremetalMultitenancy-1820943769] Lock "(u'ubuntu-xenial-2-node-rax-ord-6478210-359401', u'00d62acd-6f3b-4cb8-9668-12517c84b3b9')" acquired by "nova.scheduler.host_manager._locked_update" :: waited 0.000s inner /usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py:270
2017-01-04 19:05:16.398 20709 DEBUG nova.scheduler.host_manager [req-6ce318a2-53e5-4b80-84a5-f896ab48d627 tempest-BaremetalMultitenancy-1820943769 tempest-BaremetalMultitenancy-1820943769] Update host state from compute node: ComputeNode(cpu_allocation_ratio=16.0,cpu_info='',created_at=2017-01-04T19:02:54Z,current_workload=None,deleted=False,deleted_at=None,disk_allocation_ratio=1.0,disk_available_least=10,free_disk_gb=None,free_ram_mb=None,host='ubuntu-xenial-2-node-rax-ord-6478210-359401',host_ip=10.210.37.31,hypervisor_hostname='00d62acd-6f3b-4cb8-9668-12517c84b3b9',hypervisor_type='ironic',hypervisor_version=1,id=8,local_gb=10,local_gb_used=0,memory_mb=384,memory_mb_used=0,metrics=None,numa_topology=None,pci_device_pools=PciDevicePoolList,ram_allocation_ratio=1.0,running_vms=None,service_id=None,stats={cpu_arch='x86_64'},supported_hv_specs=[HVSpec],updated_at=2017-01-04T19:04:51Z,uuid=521cf775-5a16-4111-bf26-c30fb6725716,vcpus=1,vcpus_used=0) _locked_update /opt/stack/new/nova/nova/scheduler/host_manager.py:168
2017-01-04 19:05:16.400 20709 DEBUG oslo_concurrency.lockutils [req-6ce318a2-53e5-4b80-84a5-f896ab48d627 tempest-BaremetalMultitenancy-1820943769 tempest-BaremetalMultitenancy-1820943769] Lock "(u'ubuntu-xenial-2-node-rax-ord-6478210-359401', u'00d62acd-6f3b-4cb8-9668-12517c84b3b9')" released by "nova.scheduler.host_manager._locked_update" :: held 0.002s inner /usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py:282
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server [req-6ce318a2-53e5-4b80-84a5-f896ab48d627 tempest-BaremetalMultitenancy-1820943769 tempest-BaremetalMultitenancy-1820943769] Exception during message handling
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server Traceback (most recent call last):
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/server.py", line 155, in _process_incoming
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     res = self.dispatcher.dispatch(message)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 222, in dispatch
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     return self._do_dispatch(endpoint, method, ctxt, args)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 192, in _do_dispatch
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     result = func(ctxt, **new_args)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/server.py", line 218, in inner
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     return func(*args, **kwargs)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/manager.py", line 84, in select_destinations
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     dests = self.driver.select_destinations(ctxt, spec_obj)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/filter_scheduler.py", line 51, in select_destinations
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     selected_hosts = self._schedule(context, spec_obj)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/filter_scheduler.py", line 96, in _schedule
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     hosts = self._get_all_host_states(elevated)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/filter_scheduler.py", line 134, in _get_all_host_states
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     return self.host_manager.get_all_host_states(context)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/host_manager.py", line 610, in get_all_host_states
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     self._get_instance_info(context, compute))
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/host_manager.py", line 180, in update
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     return _locked_update(self, compute, service, aggregates, inst_dict)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py", line 271, in inner
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     return f(*args, **kwargs)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/host_manager.py", line 169, in _locked_update
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     self._update_from_compute_node(compute)
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server   File "/opt/stack/new/nova/nova/scheduler/ironic_host_manager.py", line 46, in _update_from_compute_node
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server     self.free_disk_mb = compute.free_disk_gb * 1024
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server TypeError: unsupported operand type(s) for *: 'NoneType' and 'int'
2017-01-04 19:05:16.400 20709 ERROR oslo_messaging.rpc.server 

We might be hitting a race where the compute node record is created by the resource tracker before it's resources are updated.