Unmounted device is still in use in RHEL 5

Issue

• Filesystem and its storage still in use after being unmounted without error
• Logical volumes fail to deactivate because they are still in use, even though they are unmounted and no processes are listed in lsof or fuser holding them open
• Unable to migrate a filesystem in a cluster even though it doesn't show up as mounted.

• When trying to deactivate an LV, we get an error saying its still in use, but restarting multipathd clears it:

  # lvchange -an productVG/lv1
  LV productvg/lv1 in use: not deactivating
  

• When trying to use dmsetup to remove the umounted device, we get an error saying :

device-mapper: resume ioctl failed: Invalid argument
device-mapper: remove ioctl failed: Device or resource busy
Command failed