Memory hotplug failed to offline on bare metal system of multiple nodes

[Baoquan He]

Hi,

A hot removal failure was met on one bare metal system with 8 nodes, and
node1~7 are all hotpluggable and 'movable_node' is set. When try to check
value of  /sys/devices/system/node/node1/memory*/removable, found some of
them are 0, namely un-removable. And a back trace will always be seen. After
bisecting, it points at criminal commit:

  15c30bc09085  ("mm, memory_hotplug: make has_unmovable_pages more robust")

Reverting it fix the failure, and node1~7 can be hot removed and hot
added again. From the log of commit 15c30bc09085, it's to fix a
movable_core setting issue which we allocated node_data firstly in
initmem_init(), then try to mark it as movable in mm_init(). We may need
think about it further to fix it, meanwhile not breaking bare metal
system.

I haven't figured out why the above commit caused those memmory
block in MOVABL zone being not removable. Still checking. Attach the
tested reverting patch in this mail.

Thanks
Baoquan