Description of problem:
After opening and mounting a LUKS volume it's impossible to close it.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. cryptsetup luksOpen <volume> crypt
2. mount /dev/mapper/crypt
3. umount /dev/mapper/crypt
4. cryptsetup luksClose -v /dev/mapper/crypt
Closing of the LUKS volume
Device crypt is busy.
Command failed with code 16: Device crypt is busy.
This has been happening a few kernel versions ago, I can't recall exactly when it started.
A reboot will close the volume without problems.
*** This bug has been marked as a duplicate of bug 809188 ***