Comment 4 for bug 1511294

Kamil, we haven't seen this issue in Docker 1.4.1 so much, but it was quite prevalent in Docker 0.10, which we used previously. This logic would try to clear any pending mounts for the container:

https://github.com/openstack/fuel-library/blob/master/files/fuel-docker-utils/functions.sh#L253-L255

I'll try to reproduce your issue locally, but there are two short term workarounds you can try:
Option 1: Reboot. It's not so graceful, but it works
Option 2 : service docker stop; grep docker /proc/mounts/ | awk '{print $2}' | sort -r | xargs --no-run-if-empty -n1 umount -l;service docker start; dockerctl start all