[PATCH v2] Correct Memory Hotplug for Power

[Nathan Fontenot]

Memory hotplug on Power is currently broken, these two patches correct the
issues needed to get memory hotplug working again.

This update marks memory resources that are added at boot time are also
marked as busy. It sounds a bit counter intuitive but the core mm code will
not free memory resources if they are not marked as busy.

This also ensures that bootmem memory is is registered at boot time. A
previous commit (46723bfa540...) that enabled memory hotplug remove with
SPARSE_VMEMMAP enabled broke this on Power.

Additional patches to follow to correct the current memory hotplug
implementation on Power.

Nathan Fontenot

Updates for v2:

- The WARN_ONCE is removed from the added register_page_bootmem_memmap()
routine. I have been able to verify that memory hotplug works with
SPARSE_VMEMMAP enabled and do not think the warning is needed.

---
 arch/powerpc/mm/mem.c           |    9 +++++++++
 linux/arch/powerpc/mm/init_64.c |    4 ++++
 linux/arch/powerpc/mm/mem.c     |    2 +-
 linux/mm/Kconfig                |    2 +-
 4 files changed, 15 insertions(+), 2 deletions(-)