Comment 11 for bug 1098378

We're seeing something very similar to this bug in 12.04LTS (kernel 3.2.0-49-generic) running LXC containers on overlayfs mounts. In our case a front-end script we're using to run tests in isolation successfully umounts the overlayfs after the contained test completes, but attempting to rmdir the mountpoint fails. There are no processes left keeping the mount busy, and the umount completes without complaint. Interestingly after a few seconds (5 - 20) the mount is no longer busy, and sometimes everything works without incident. I've looked at the overlayfs source in the kernel and it seems to have the same issue as above; any chance this can patch can be back-ported?