Check this out:
Code:
linux:/home/cloverm # umount /dev/sda1
umount: /auto/camera: device is busy
umount: /auto/camera: device is busy
linux:/home/cloverm # fuser /auto/camera
/auto/camera:
I cannot umount /auto/camera becuse is busy. fuser does not show any program using it.
a.) How can I find out what keeps it busy?
b.) How can I safely umount my camera?

(I ended up rebooting the damn computer : as a quick fix, but I need a better solution.)