On Thu, Feb 25, 2021 at 07:38:44PM +0100, Vlastimil Babka wrote: > On 2/25/21 7:05 PM, Mike Rapoport wrote: > >> > >> What if two zones are adjacent? I.e. if the hole was at a boundary between two > >> zones. > > > > What do you mean by "adjacent zones"? If there is a hole near the zone > > boundary, zone span would be clamped to exclude the hole. > > Yeah, zone span should exclude those pages, but you still somehow handle them? > That's how I read "pages that are not spanned by any node will get links to the > adjacent zone/node." > So is it always a unique zone/node can be determined? > > Let's say we have: > > <memory on node 0> > ---- pageblock boundary ---- > <more memory on node 0> > <a hole> > <memory on node 1> > ---- pageblock boundary ---- > > Now I hope such configurations don't really exist :) But if we simulated them in > QEMU, what would be the linkage in struct pages in that hole? I don't think such configuration is possible in practice but it can be forced with e.g memmap="2M hole at 4G - 1M". The hole in your example the hole will get node1 for node and zone that spans the beginning of node1 for zone. -- Sincerely yours, Mike.
