cryptsetup luksClose cannot close the device despite not being in use

[Oliver Hookins]

Binary package hint: cryptsetup

I have a simple LUKS-encrypted volume, used for taking backups with a simple script:

+ cryptsetup luksOpen /dev/disk/by-id/usb-ST925031_5AS_5C75FFFFFFFF-0:0 iomegacrypt -d /root/keyfile
Key slot 1 unlocked.
+ mount -t ext4 /dev/mapper/iomegacrypt /media/crypt
+ /usr/local/sbin/runbackup
+ 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.

[audience (stefan-sch)]

For me it seems it is not the same bug as #529502 because there is only a bug at the gui and not at the commandline "Manually running cryptsetup luksClose udisks-luks-uuid-[...] afterwards works as expected.".
But here it is the commandline-tool that is not working.
I got the same problem with the commandline - everything is unmounted but it says device is busy.

[Launchpad Janitor (janitor)]

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

[Karl Maier (w-wall2001)]

It may be rather be a duplicate of Bug #484429