Umount Target is Busy
sudo lsof /dev/sda1
kill -9 [pid]
sudo umount /media/gaoliang/*umount -f /path/to/deviceumount -l /path/to/dev sudo lsof /dev/sda1
kill -9 [pid]
sudo umount /media/gaoliang/*umount -f /path/to/deviceumount -l /path/to/dev