On Fri, Mar 31, 2023 at 08:37:15PM +0900, Kyungsan Kim wrote: > >> We resolved the issue using ZONE_EXMEM by allowing seletively choice of the two usecases. > > > >This sounds dangerously confused. Do you want the EXMEM to be removable > >or not? If you do, then allocations from it have to be movable. If > >you don't, why go to all this trouble? > > I'm sorry to make you confused. We will try more to clearly explain our thought. > We think the CXL DRAM device should be removable along with HW pluggable nature. > For MM point of view, we think a page of CXL DRAM can be both movable and unmovable. > An user or kernel context should be able to determine it. Thus, we think dedication on the ZONE_NORMAL or the ZONE_MOVABLE is not enough. No, this is not the right approach. If CXL is to be hot-pluggable, then all CXL allocations must be movable. If even one allocation on a device is not movable, then the device cannot be removed. ZONE_EXMEM feels like a solution in search of a problem.
