There are at least six consumers of hotplug_memory_notifier that what they
really are interested in is whether any numa node changed its state, e.g: going
from having memory to not having memory and vice versa.
Implement a specific notifier for numa nodes when their state gets changed,
which will later be used by those consumers that are only interested
in numa node state changes.
Add documentation as well.
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Reviewed-by: Harry Yoo <harry.yoo@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
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