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/[email protected]/ 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 v5.10-rc7 and has been tested on arm64. But only build tested on s390. Changes in V1: - Fixed build problems with (MEMORY_HOTPLUG & !MEMORY_HOTREMOVE) - Added missing prototype for arch_get_mappable_range() - Added VM_BUG_ON() check for memhp_range_allowed() in arch_add_memory() per David Changes in RFC V2: https://lore.kernel.org/linux-mm/[email protected]/ Incorporated all review feedbacks from David. - Added additional range check in __segment_load() on s390 which was lost - Changed is_private init in pagemap_range() - Moved the framework into mm/memory_hotplug.c - Made arch_get_addressable_range() a __weak function - Renamed arch_get_addressable_range() as arch_get_mappable_range() - Callback arch_get_mappable_range() only handles range requiring linear mapping - Merged multiple memhp_range_allowed() checks in register_memory_resource() - Replaced WARN() with pr_warn() in memhp_range_allowed() - Replaced error return code ERANGE with E2BIG Changes in RFC V1: https://lore.kernel.org/linux-mm/[email protected]/ Cc: Heiko Carstens <[email protected]> Cc: Vasily Gorbik <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Mark Rutland <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Andrew Morton <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Anshuman Khandual (3): mm/hotplug: Prevalidate the address range being added with platform arm64/mm: Define arch_get_mappable_range() s390/mm: Define arch_get_mappable_range() arch/arm64/mm/mmu.c | 15 +++---- arch/s390/mm/extmem.c | 5 +++ arch/s390/mm/init.c | 10 +++++ arch/s390/mm/vmem.c | 4 -- include/linux/memory_hotplug.h | 3 ++ mm/memory_hotplug.c | 78 +++++++++++++++++++++++++--------- mm/memremap.c | 6 ++- 7 files changed, 88 insertions(+), 33 deletions(-) -- 2.20.1
