On Fri, Apr 13, 2018 at 03:16:26PM +0200, David Hildenbrand wrote: > online_pages()/offline_pages() theoretically allows us to work on > sub-section sizes. This is especially relevant in the context of > virtualization. It e.g. allows us to add/remove memory to Linux in a VM in > 4MB chunks. > > While the whole section is marked as online/offline, we have to know > the state of each page. E.g. to not read memory that is not online > during kexec() or to properly mark a section as offline as soon as all > contained pages are offline.
Can you not use PG_reserved for this purpose? > + * PG_offline indicates that a page is offline and the backing storage > + * might already have been removed (virtualization). Don't touch! * PG_reserved is set for special pages, which can never be swapped out. Some * of them might not even exist... They seem pretty congruent to me.