mm/memory_hotplug: online/offline_pages refactorings

While looking into onlining/offlining of subsections, I noticed that online/offlining code can in its current form only deal with whole sections and that onlining/offlining of sections that are already online/offline is problematic. So let's add some additional checks (that also serve as implicit documentation) and do some cleanups.

David Hildenbrand (5):
mm/memory_hotplug: drop intermediate __offline_pages mm/memory_hotplug: enforce section alignment when onlining/offlining mm/memory_hotplug: check if sections are already online/offline mm/memory_hotplug: onlining pages can only fail due to notifiers mm/memory_hotplug: print only with DEBUG_VM in online/offline_pages()

 include/linux/mmzone.h |  2 ++
 mm/memory_hotplug.c    | 43 ++++++++++++++++++++++--------------------
 mm/sparse.c            | 28 +++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 20 deletions(-)

2.17.1