After running the command umount /mnt, the following error message is displayed:umount: /mnt: device is...

The kernel has not finished flushing diskwrites to the mounted device.

A user has a file open in the /mnt directory.

Another file system still contains a symlink to a file inside /mnt.

The files in /mnt have been scanned and added to the locate database.

The kernel thinks that a process is about to open a file in /mnt for reading.