Messages in this thread |  | | Date | Fri, 13 Apr 2018 15:40:47 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH RFC 2/8] mm: introduce PG_offline |
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On Fri 13-04-18 15:16:26, 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.
Well, theoretically possible but this would require a lot of auditing because the hotplug and per section assumption is quite a spread one.
> 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.
But you cannot use a page flag for that, I am afraid. Page flags are extremely scarce resource. I haven't looked at the rest of the series but _if_ we have a bit spare which I am not really sure about then you should prove there are no other ways around this.
> Signed-off-by: David Hildenbrand <david@redhat.com> -- Michal Hocko SUSE Labs
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