BusyBox v1.19.3 (Debian 1.19.3power5) built-in shell (ash) Enter 'help' for a list of built-in commands. ~ $ sudo gainroot Root shell enabled BusyBox v1.19.3 (Debian 1.19.3power5) built-in shell (ash) Enter 'help' for a list of built-in commands. /home/user # umount /dev/mmcblk0p2 umount: can't umount /home: Device or resource busy /home/user # cant umout. why?