UNMOUNT a windows file system

Hi,
I try to unmount :
smbumount /mnt/directory

But I receive :

Could not umount /mnt/directory: Device or resource busy

Any idea ?
Many thanks.

You have to exit all processes accessing the device. You can find them with:

fuser -c /mnt/directory

Thank you,
but :
# fuser -a /mnt/directory
/mnt/directory: Input/output error

And :

# fuser -k /mnt/directory
/mnt/directory: Input/output error

????

I suppose its fuser -c and not fuser -a

The way I commonly use is to execute lsof and grep the directory in the output. Of course that is only if lsof is installed.