memory_hotplug: check for walk_memory_resource() failure in online_pages()

memory_hotplug: check for walk_memory_resource() failure in online_pages()

Add a check to online_pages() to test for failure of
walk_memory_resource().  This fixes a condition where a failure
of walk_memory_resource() can lead to online_pages() returning
success without the requested pages being onlined.

Signed-off-by: Geoff Levand <[email protected]>
Cc: Yasunori Goto <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Keith Mannthey <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Paul Jackson <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>