Error creating Live CD : Could not create snapshot device using: /sbin/dmsetup create imgcreate-6494-41649 -vv --verifyudev --uuid LIVECD-imgcreate-6494-41649 --table 0 7168000 snapshot /dev/loop0 /dev/loop3 p 8

[Moez Roy]

Running F21 Gnome Shell, and trying to make an F20 live cd.

Checking filesystem /root/Desktop/tmp/imgcreate-Ys7d4E/tmp-O8PCNH/ext3fs.img
e2fsck 1.42.11 (09-Jul-2014)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
_f20v3: 73889/224000 files (0.1% non-contiguous), 591688/896000 blocks

Losetup add /dev/loop0 mapping to
/root/Desktop/tmp/imgcreate-Ys7d4E/tmp-O8PCNH/ext3fs.img
Extending sparse file
/root/Desktop/tmp/imgcreate-Ys7d4E/iso-H7qkD6/LiveOS/osmin to 67108864
Losetup add /dev/loop3 mapping to
/root/Desktop/tmp/imgcreate-Ys7d4E/iso-H7qkD6/LiveOS/osmin
device-mapper: reload ioctl on imgcreate-6494-41649 failed: Device or
resource busy
Command failed
dm version   OF   [16384] (*1)
Udev cookie 0xd4deca0 (semid 0) created
Udev cookie 0xd4deca0 (semid 0) incremented to 1
Udev cookie 0xd4deca0 (semid 0) incremented to 2
Udev cookie 0xd4deca0 (semid 0) assigned to CREATE task(0) with flags
       (0x0)
dm create imgcreate-6494-41649 LIVECD-imgcreate-6494-41649 OF   [16384] (*1)
dm reload imgcreate-6494-41649  OF   [16384] (*1)
<backtrace>
Udev cookie 0xd4deca0 (semid 0) decremented to 1
Udev cookie 0xd4deca0 (semid 0) incremented to 2
Udev cookie 0xd4deca0 (semid 0) assigned to REMOVE task(2) with flags
       (0x0)
dm remove imgcreate-6494-41649  OF   [16384] (*1)
imgcreate-6494-41649: Stacking NODE_DEL [verify_udev]
Udev cookie 0xd4deca0 (semid 0) decremented to 1
Udev cookie 0xd4deca0 (semid 0) waiting for zero
Udev cookie 0xd4deca0 (semid 0) destroyed
imgcreate-6494-41649: Processing NODE_DEL [verify_udev]

Losetup remove /dev/loop3
Losetup remove /dev/loop0
Error creating Live CD : Could not create snapshot device using:
/sbin/dmsetup create imgcreate-6494-41649 -vv --verifyudev --uuid
LIVECD-imgcreate-6494-41649 --table 0 7168000 snapshot /dev/loop0
/dev/loop3 p 8

Any idea why it fails above?