[PATCH RFC v1 0/3] powerpc/memtrace: Don't offline memory blocks via offline_pages()

[David Hildenbrand <david@redhat.com>]

This RFC is based on linux-next and
- 2 patches from "PATCH RFC v4 00/13] virtio-mem: paravirtualized memory"
 -> "mm: Allow to offline unmovable PageOffline() pages via
     MEM_GOING_OFFLINE" [1]
 -> "mm/memory_hotplug: Introduce offline_and_remove_memory()" [2]
- "mm/memory_hotplug: Don't free usage map when removing a re-added early
   section" [3]

A branch with all patches (kept updated) is available at:
	https://github.com/davidhildenbrand/linux.git memtrace

Stop using offline_pages() to offline memory blocks. Allocate the memory
blocks using alloc_contig_pages() first and offline+remove the allcoated
memory blocks using a clean MM interface. Offlining of allocated memory is
made possible by using PageOffline() in combination with a memory notifier
(similar to virto-mem).

Note: In the future, we might want to switch to only removing/readding the
page tables of the allocated memory (while still marking it PageOffline()).
However, that might have other implications, and requires work from PPC
people (IOW, I won't fiddle with that :) ).

[1] https://lkml.kernel.org/r/20191212171137.13872-8-david@redhat.com
[2] https://lkml.kernel.org/r/20191212171137.13872-10-david@redhat.com
[3] https://lkml.kernel.org/r/20191217104637.5509-1-david@redhat.com


David Hildenbrand (3):
  powerpc/memtrace: Enforce power of 2 for memory buffer size
  powerpc/memtrace: Factor out readding memory into memtrace_free_node()
  powerpc/memtrace: Don't offline memory blocks via offline_pages()

 arch/powerpc/platforms/powernv/Kconfig    |   1 +
 arch/powerpc/platforms/powernv/memtrace.c | 217 ++++++++++++++--------
 2 files changed, 136 insertions(+), 82 deletions(-)

-- 
2.23.0