On 18.01.21 14:12, Anshuman Khandual wrote:

This series adds a mechanism allowing platforms to weigh in and prevalidate
incoming address range before proceeding further with the memory hotplug.
This helps prevent potential platform errors for the given address range,
down the hotplug call chain, which inevitably fails the hotplug itself.

This mechanism was suggested by David Hildenbrand during another discussion
with respect to a memory hotplug fix on arm64 platform.

https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/ (local)

This mechanism focuses on the addressibility aspect and not [sub] section
alignment aspect. Hence check_hotplug_memory_range() and check_pfn_span()
have been left unchanged. Wondering if all these can still be unified in
an expanded memhp_range_allowed() check, that can be called from multiple
memory hot add and remove paths.

This series applies on v5.11-rc4 and has been tested on arm64. But only
build tested on s390.

Changes in V3

- Updated the commit message in [PATCH 1/3]
- Replaced 1 with 'true' and 0 with 'false' in memhp_range_allowed()
- Updated memhp_range.end as VMEM_MAX_PHYS - 1 and updated vmem_add_mapping() on s390
- Changed memhp_range_allowed() behaviour in __add_pages()
- Updated __add_pages() to return E2BIG when memhp_range_allowed() fails for non-linear mapping based requests

Minor thing, we should make up our mind if we want to call stuff
internally "memhp_" or "mhp". I prefer the latter, because it is shorter.


-- 
Thanks,

David / dhildenb


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