br-XXX (Openstack bridge interface) shows a lot of RX drops

Issue

A huge number of drops are observed on the br-int interface:

[root@controller-1 ~]# ifconfig br-int
br-int: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether 00:00:00:00:00:aa  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 2167426  overruns 0  frame 0          <<<<<<<<<<<<<<<<<<<<<<<<
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Drop counters on br-XXX other than br-int increase:

br-ex: flags=1234<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.0.0.1  netmask 255.255.255.0  broadcast 10.0.0.255
        ether 00:00:00:00:00:bb  txqueuelen 1000  (Ethernet)
        RX packets 23453456  bytes 7364537643 (6.8 GiB)
        RX errors 0  dropped 12352467  overruns 0  frame 0          <<<<<<<<<<<<<<<<<<<<<<<<
        TX packets 2352673  bytes 1588366465 (1.3 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0