cryptsetup luksClose cannot close the device despite not being in use
Binary package hint: cryptsetup
I have a simple LUKS-encrypted volume, used for taking backups with a simple script:
+ cryptsetup luksOpen /dev/disk/
Key slot 1 unlocked.
+ mount -t ext4 /dev/mapper/
+ umount /media/crypt
+ cryptsetup luksClose iomegacrypt
Device iomegacrypt is busy.
Nothing else uses the device apart from this backup script which is automated and happens shortly after I login. Prior to upgrading to Lucid there was no problem. The output of `lsof` does not show anything using the device.