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?