netlink socket errors happen sometime in iotop

[chensong2000]

get_xxxid_info: Bad file descriptor
or
get_xxxid_info: Socket operation on non-socket

[21cnbao]

we need kernel to enable:
General setup --->
CPU/Task time and stats accounting --->
[] Export task/process statistics through netlink
[] Enable per-task delay accounting
[] Enable extended accounting over taskstats
[] Enable per-task storage I/O accounting