can not umount rbind mounts

Status changed to 'Confirmed' because the bug affects multiple users.

Please check if "umount -l" helps you in this case.

Hi.

Same problem here. Some partitions still appear in `mount` output and `/proc/mounts` but can't be unmounted via either device name or mount point.
Repeatedly trying `umount -l` with device names and mount points finally managed to get the partitions unmounted.

Yet it feels awkward, like a worn out door lock that locks okay but you have to shake for a while to have it unlock.

This is very likely not Ubuntu specific, e.g.
http://unix.stackexchange.com/questions/120827/recursive-umount-after-rbind-mount

This worked for me correctly -- https://unix.stackexchange.com/a/264488/4319 :

mount --rbind /dev /mnt/test
mount --make-rslave /mnt/test
umount -R /mnt/test

It was important to have the two first commands as two separate commands: do not combine --rbind and --make-rslave in one invocation of mount.

Without --make-rslave , the behavior was unwanted (and not successful):

* umount -l would affect the original old mountpoints, too,
* and umount -R would be affected by the busy (open) files under the original old mountpoints. (Very unexpected...)