Pl. http://www.cyberciti.biz/tips/how-do-i-forcefully-unmount-a-disk-partit…
Nálam általában a lazy umount beválik. Elengedi a beragadt mount pontot és nem hal tőle meg a rendszer.
# umount -l /mnt
Where,
-l : Also known as Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore.