On 2/26/21 11:59 AM, Mike Rapoport wrote: > 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".
Right. > The hole in your example the hole will get node1 for node and zone that > spans the beginning of node1 for zone. Yeah the comments in v8 make that clear now, thanks!
