Comment 3 for bug 1849802

After some digging around, and reading LP:1822884, which may be related or the same bug, I found that there were extra entries in the ml2_port_bindings and ml2_port_binding_levels tables for the port in question:

mysql> select * from ml2_port_bindings where port_id = '5a3c5d23-8727-47d2-af72-a53b495358d2';
+--------------------------------------+---------+----------+-----------+---------+----------------------------------------------------------------------------------------------------+----------+
| port_id | host | vif_type | vnic_type | profile | vif_details | status |
+--------------------------------------+---------+----------+-----------+---------+----------------------------------------------------------------------------------------------------+----------+
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | happiny | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"} | INACTIVE |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | jynx | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"} | INACTIVE |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | shinx | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"} | INACTIVE |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | sliggoo | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"} | ACTIVE |
+--------------------------------------+---------+----------+-----------+---------+----------------------------------------------------------------------------------------------------+----------+
4 rows in set (0.00 sec)

mysql> select * from ml2_port_binding_levels where port_id = '5a3c5d23-8727-47d2-af72-a53b495358d2';

+--------------------------------------+---------+-------+-------------+--------------------------------------+
| port_id | host | level | driver | segment_id |
+--------------------------------------+---------+-------+-------------+--------------------------------------+
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | happiny | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | jynx | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | shinx | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | sliggoo | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
+--------------------------------------+---------+-------+-------------+--------------------------------------+
4 rows in set (0.00 sec)

After removing the INACTIVE rows from the first table, and the entries for every host except the host the instances was running on from the second, I was able to successfully invoke a migration, which failed due to lack of resources on the destination host:

$ openstack server migrate --block-migration 8703d9db-81b0-4e86-a2ef-c4ba5250556c --live shinx --disk-overcommit --wait
No valid host was found. Unable to move instance 8703d9db-81b0-4e86-a2ef-c4ba5250556c to host shinx. There is not enough capacity on the host for the instance. (HTTP 400) (Request-ID: req-70e5caea-8fa9-4314-b2b2-a7ae190179a6)

Attempting the migration again:

jujumanage@corsola:~$ openstack server migrate --block-migration 8703d9db-81b0-4e86-a2ef-c4ba5250556c --live shinx --disk-overcommit --wait
Migration pre-check error: Binding failed for port 5a3c5d23-8727-47d2-af72-a53b495358d2, please check neutron logs for more information. (HTTP 400) (Request-ID: req-eb051a44-a965-4df
4-9b3b-14ac3a30acf8)

And indeed the database is back in a similar state as before:

mysql> select * from ml2_port_bindings where port_id = '5a3c5d23-8727-47d2-af72-a53b495358d2';
+--------------------------------------+---------+----------+-----------+---------+---------------------------------------------------------------------------------------------------
-+----------+
| port_id | host | vif_type | vnic_type | profile | vif_details
 | status |
+--------------------------------------+---------+----------+-----------+---------+---------------------------------------------------------------------------------------------------
-+----------+
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | shinx | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"} | INACTIVE |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | sliggoo | ovs | normal | | {"port_filter": true, "ovs_hybrid_plug": true, "datapath_type": "system", "bridge_name": "br-int"}
 | ACTIVE |
+--------------------------------------+---------+----------+-----------+---------+---------------------------------------------------------------------------------------------------
-+----------+
2 rows in set (0.00 sec)

mysql> select * from ml2_port_binding_levels where port_id = '5a3c5d23-8727-47d2-af72-a53b495358d2';
+--------------------------------------+---------+-------+-------------+--------------------------------------+
| port_id | host | level | driver | segment_id |
+--------------------------------------+---------+-------+-------------+--------------------------------------+
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | shinx | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
| 5a3c5d23-8727-47d2-af72-a53b495358d2 | sliggoo | 0 | openvswitch | afaa634a-dff5-437e-a7a0-8630c21b2a73 |
+--------------------------------------+---------+-------+-------------+--------------------------------------+
2 rows in set (0.00 sec)

mysql>