memory-hotplug have such a problem.

when I test the memory online or offline, I find the problem that
memory online always return an error. I peform the operation as follow:

cd /sys/device/system/memory/
echo online > state

it always print "-bash: echo: write error: Operation not permitted".
By my alalysis, I find that the error happen in the memory_notifier(MEM_GOING_ONLINE,&arg) in the function(online_pages()).

The problem occur in the latest kernel versin (linux 4.3.0 -rc4) , but In the lower version (linux 3.10) is correct. I think it may be caused by the confilct.

Thanks
zhongjiang