powerpc/mm/radix: Split linear mapping on hot-unplug
This patch splits the linear mapping if the hot-unplug range is smaller than the mapping size. The code detects if the mapping needs to be split into a smaller size and if so, uses the stop machine infrastructure to clear the existing mapping and then remap the remaining range using a smaller page size. The code will skip any region of the mapping that overlaps with kernel text and warn about it once. We don't want to remove a mapping where the kernel text and the LMB we intend to remove overlap in the same TLB mapping as it may affect the currently executing code. I've tested these changes under a kvm guest with 2 vcpus, from a split mapping point of view, some of the caveats mentioned above applied to the testing I did. Fixes: 4b5d62ca ("powerpc/mm: add radix__remove_section_mapping()") Signed-off-by: Balbir Singh <bsingharora@gmail.com> [mpe: Tweak change log to match updated behaviour] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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