FYI, we noticed the below changes on

https://github.com/0day-ci/linux David-Ahern/net-ipv6-Make-address-flushing-on-ifdown-optional/20160214-062626
commit 21bb45b419243ee4d9d74f1d1f97164fbfc481c3 ("net: ipv6: Make address flushing on ifdown optional")


[  136.160531] unregister_netdevice: waiting for br-lan to become free. Usage count = 1


Thanks,
Ying Huang