Hikey 960 hangs while giving 'adb root' command

Hi all,
We have build Android Source tree (commit version bae95f19a8c1c86e59a70b40e2c0827f08c790a9) successfully and flashed in Hikey 960 board. It is booting up properly and ‘adb devices’ is getting detected. But on providing ‘adb root’ command the board gets hang very often.

Your kind assistance will be greatly appreciated.