You should boot into a rescue session using a Linux CD, or you can drop to a lower runlevel using init
. It is not a good idea to unmount your $HOME while logged in.
You might also be able to do this if you log in as root
(actually log in, not su
or sudo
). That way the /home
partition is not needed and you will be able to unmount it. You will still have to make sure no one is accessing it (see next paragraph) and unmount it manually.
Finally, a useful tool is lsof /dev/sda3
which will list the processes currently accessing that partition. To kill all processes listed by lsof
(careful, this may crash your system, depending on the process, but if this happens you should be OK after a reboot), do this:
kill `lsof /dev/sda3 | awk ''`