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    SubjectRe: [PATCH RFC v3 8/9] mm/memory_hotplug: Introduce offline_and_remove_memory()
    On Thu 19-09-19 16:22:27, David Hildenbrand wrote:
    > virtio-mem wants to offline and remove a memory block once it unplugged
    > all subblocks (e.g., using alloc_contig_range()). Let's provide
    > an interface to do that from a driver. virtio-mem already supports to
    > offline partially unplugged memory blocks. Offlining a fully unplugged
    > memory block will not require to migrate any pages. All unplugged
    > subblocks are PageOffline() and have a reference count of 0 - so
    > offlining code will simply skip them.
    >
    > All we need an interface to trigger the "offlining" and the removing in a
    > single operation - to make sure the memory block cannot get onlined by
    > user space again before it gets removed.
    >
    > To keep things simple, allow to only work on a single memory block.

    Without a user it is not really clear why do we need this interface.
    I am also not really sure why do you want/need to control beyond the
    offlining stage. Care to explain some more?
    --
    Michal Hocko
    SUSE Labs

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