Poweroff-issue

Hi All,
  I am getting the below error when i am running the power-off command
in linux.Please help me out.Thanking You in adavence


/ # poweroff 
/ # umount: mdev busy - remounted read-only
umount: devtmpfs busy - remounted read-only
umount: can't remount /dev/root read-only
umount: can't remount rootfs read-only
The system is going down NOW!
Sent SIGTERM to all processes
Requesting system poweroffses
 System halted.


Regs,
Madhu