[PATCH v8 0/6] Add support for memmap on memory feature on ppc64

[Aneesh Kumar K.V]

This patch series update memmap on memory feature to fall back to
memmap allocation outside the memory block if the alignment rules are
not met. This makes the feature more useful on architectures like
ppc64 where alignment rules are different with 64K page size.

This patch series is dependent on dax vmemmap optimization series
posted here
https://lore.kernel.org/linux-mm/20230718022934.90447-1-aneesh.kumar@linux.ibm.com/

Changes from v7:
* Drop patch 7 because we are still discussing a runtime update of this
feature is useful.

Changes from v6:
* Update comments in the code
* Update commit message for patch 7

Changes from v5:
* Update commit message
* Move memory alloc/free to the callers in patch 6
* Address review feedback w.r.t patch 4

Changes from v4:
* Use altmap.free instead of altmap.reserve
* Address review feedback

Changes from v3:
* Extend the module parameter memmap_on_memory to force allocation even
  though we can waste hotplug memory.

Changes from v2:
* Rebase to latest linus tree
* Redo the series based on review feedback. Multiple changes to the patchset.

Changes from v1:
* update the memblock to store vmemmap_altmap details. This is required
so that when we remove the memory we can find the altmap details which
is needed on some architectures.
* rebase to latest linus tree


Aneesh Kumar K.V (6):
  mm/memory_hotplug: Simplify ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE kconfig
  mm/memory_hotplug: Allow memmap on memory hotplug request to fallback
  mm/memory_hotplug: Allow architecture to override memmap on memory
    support check
  mm/memory_hotplug: Support memmap_on_memory when memmap is not aligned
    to pageblocks
  powerpc/book3s64/memhotplug: Enable memmap on memory for radix
  mm/memory_hotplug: Embed vmem_altmap details in memory block

 .../admin-guide/mm/memory-hotplug.rst         |  12 ++
 arch/arm64/Kconfig                            |   4 +-
 arch/powerpc/Kconfig                          |   1 +
 arch/powerpc/include/asm/pgtable.h            |  21 ++
 .../platforms/pseries/hotplug-memory.c        |   2 +-
 arch/x86/Kconfig                              |   4 +-
 drivers/acpi/acpi_memhotplug.c                |   3 +-
 drivers/base/memory.c                         |  27 ++-
 include/linux/memory.h                        |   8 +-
 include/linux/memory_hotplug.h                |   3 +-
 mm/Kconfig                                    |   3 +
 mm/memory_hotplug.c                           | 185 ++++++++++++++----
 12 files changed, 209 insertions(+), 64 deletions(-)

-- 
2.41.0