mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug
mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug

We don't need to do register_memory_resource() under
lock_memory_hotplug() since it has its own lock and doesn't make any
callbacks.

Also register_memory_resource return NULL on failure so we don't have
anything to cleanup at this point.

The reason for this rfc is I was doing some experiments with hotplugging
of memory on some of our larger systems.  While it seems to work, it can
be quite slow.  With some preliminary digging I found that
lock_memory_hotplug is clearly ripe for breakup.

It could be broken up per nid or something but it also covers the
online_page_callback.  The online_page_callback shouldn't be very hard
to break out.

Also there is the issue of various structures(wmarks come to mind) that
are only updated under the lock_memory_hotplug that would need to be
dealt with.

Cc: Tang Chen <4f61c4810b5ff5aa3e373c07e6d9ef9c55e4952f@cn.fujitsu.com>
Cc: Wen Congyang <59c7438a9275f5dd0b96a91958b493a9d005ad46@cn.fujitsu.com>
Cc: Kamezawa Hiroyuki <634f508bd7c47cf0ee4126243675c3e598920fbc@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <9b26f769475fafc2d25107053b1bdd774d49438a@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <27ffc44a8ec6a212fba98cfc3246c6ce8ab131e0@intel.com>
Cc: Hedi <e4a37f39837f34802ddf825db7fff764be6d206d@sgi.com>
Cc: Mike Travis <e6cc0fb2b8dad4110ef62e9a33e5a8aa4e0f86d7@sgi.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs