[PATCH v7 0/7] Add support for memmap on memory feature on ppc64

[Michal Hocko]

I cannot really judge the ppc specific part but other patches seem
reasonable. Patch 4 could print a more useful information about the
wastage but this is nothing really earth shattering. I am not sure about
the last patch which makes the on-memory property dynamic. This needs
much more justification and use case description IMHO.

That being said for patches 1 - 4 and 6 feel free to add
Acked-by: Michal Hocko <mhocko at suse.com>

On Tue 01-08-23 10:11:09, Aneesh Kumar K.V wrote:
> 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 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 (7):
>   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
>   mm/memory_hotplug: Enable runtime update of memmap_on_memory parameter
> 
>  .../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                           | 205 ++++++++++++++----
>  12 files changed, 220 insertions(+), 73 deletions(-)
> 
> -- 
> 2.41.0

-- 
Michal Hocko
SUSE Labs