umount: /usr & home: device is busy

[Kerry <kerrykong pacific net sg>]

Hello

Anybody can help me please ?

Encounter error message when try to fsck /dev/hda3 and /dev/hda4.
It prompt :
/dev/hda3 was not cleanly unmounted, check forced
/dev/hda4 was not cleanly unmounted, check forced

Have tried to umount all file system with command
#umount -a
get below messages :
umount: /usr: device is busy
umount: /home: device is busy

Have also try to mount above to read only, but get below message :
# mount -r /dev/hda4
mount: /dev/hda4 already mounted or /usr busy
mount: according to mtab, /dev/hda4 is already mounted on /usr

# mount -r /dev/hda3
mount: /dev/hda3 already mounted or /home busy
mount: according to mtab, /dev/hda3 is already mounted on /home

This is how my mtab file looks like :
/dev/hda1 / ext2 rw 0 0
none /proc proc rw 0 0
/dev/hda3 /home ext2 rw 0 0
/dev/hda4 /usr ext2 rw 0 0

I am running rh 5.2.

Appreciate your advise
Kerry