On 23.09.19 14:07, Michal Hocko wrote: > On Mon 23-09-19 13:34:18, David Hildenbrand wrote: >> On 23.09.19 13:15, Michal Hocko wrote: > [...] >>> I am wondering why those pages get onlined when they are, in fact, >>> supposed to be offline. >>> >> >> It's the current way of emulating sub-memory-block hotplug on top of the >> memory bock device API we have. Hyper-V and XEN have been using that for >> a long time. > > Do they really have to use the existing block interface when they in > fact do not operate on the block granularity? Zone device memory already > acts on sub section/block boundaries. > Yes, we need memory blocks, especially for user space to properly online them (as we discussed a while back, to decide on a zone) and for udev events, to e.g., properly reload kexec when memory blocks get added/removed/onlined/offlined. ZONE_DEVICE is special as it doesn't have to worry about onlining/offlining/dumping. Also, it doesn't care about SECTION_IS_ONLINE, but figuring out how to detect which sub sections/blocks have a valid memmap is still something to get fixed and is still getting discussed on MM. -- Thanks, David / dhildenb
