On 09/21/2016 11:20 AM, Michal Hocko wrote: > I would even question the per page block offlining itself. Why would > anybody want to offline few blocks rather than the whole node? What is > the usecase here?
The original reason was so that you could remove a DIMM or a riser card full of DIMMs, which are certainly a subset of a node. With virtual machines, perhaps you only want to make a small adjustment to the memory that a VM has. Or, perhaps the VM only _has_ one node. Granted, ballooning takes care of a lot of these cases, but memmap[] starts to get annoying at some point if you balloon too much memory away.
