Re: [PATCH v2 4/4] mm/memory_hotplug: Remove MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers
From: David Hildenbrand
Date: Thu Oct 09 2025 - 15:03:50 EST
On 09.10.25 15:18, Sumanth Korikkar wrote:
MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers were introduced
to prepare the transition of memory to and from a physically accessible
state. This enhancement was crucial for implementing the "memmap on memory"
feature for s390.
With introduction of dynamic (de)configuration of hotpluggable memory,
memory can be brought to accessible state before add_memory(). Memory
can be brought to inaccessible state before remove_memory(). Hence,
there is no need of MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory
notifiers anymore.
This basically reverts commit
c5f1e2d18909 ("mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers")
Additionally, apply minor adjustments to the function parameters of
move_pfn_range_to_zone() and mhp_supports_memmap_on_memory() to ensure
compatibility with the latest branch.
Signed-off-by: Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>
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Acked-by: David Hildenbrand <david@xxxxxxxxxx>
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Cheers
David / dhildenb