Comment 2 for bug 1648094

The issue has been reproduced again on Fuel10 - #1435

logs from compute (http://paste.ubuntu.com/24124288/)

00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent [req-718ad23e-dadd-4e16-ad06-446ad48293ca - - - - -] Error while processing VIF ports
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent Traceback (most recent call last):
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 2038, in rpc_loop
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent port_info, ovs_restarted)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/osprofiler/profiler.py", line 154, in wrapper
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent return f(*args, **kwargs)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 1646, in process_network_ports
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent port_info.get('updated', set()))
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 265, in setup_port_filters
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent self.prepare_devices_filter(new_devices)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 130, in decorated_function
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent *args, **kwargs)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 138, in prepare_devices_filter
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent self._apply_port_filter(device_ids)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 163, in _apply_port_filter
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent self.firewall.prepare_port_filter(device)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/iptables_firewall.py", line 190, in prepare_port_filter
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent self._enable_netfilter_for_bridges()
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/iptables_firewall.py", line 114, in _enable_netfilter_for_bridges
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent run_as_root=True).splitlines()
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/utils.py", line 144, in execute
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent raise ProcessExecutionError(msg, returncode=returncode)
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent ProcessExecutionError: Exit code: 255; Stdin: ; Stdout: ; Stderr: sysctl: cannot stat /proc/sys/net/bridge: No such file or directory
2017-03-06 00:44:00.942 7007 ERROR neutron.plugins.ml2.drivers.openvswitch.agent.ovs_neutron_agent