arm64/mm: Check the requested PFN range during memory removal

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prevent_memory_remove_notifier() advances pfn while scanning the requested
range for early memory. When the loop completes, pfn is at or beyond
end_pfn. Passing it to can_unmap_without_split() therefore checks a range
after the one being offlined.

Consequently, a valid request can be rejected based on the following
range, while a request that would split a leaf mapping can be accepted if
the shifted range can be unmapped without a split. This was observed with
CXL DAX memory, where the final memory block was incorrectly allowed to
be offlined.

Pass arg->start_pfn into can_unmap_without_split() so it checks the
requested range.

Fixes: 95a58852b0 ("arm64/mm: Reject memory removal that splits a kernel leaf mapping")
Signed-off-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

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Richard Cheng 2026-07-21 18:00:26 +08:00 • committed by Will Deacon

parent b877075d0b

commit 285f90a4d1

1 changed files with 1 additions and 1 deletions

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arch/arm64/mm/mmu.c

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