On 18.09.20 04:07, Wei Yang wrote: > On Wed, Sep 16, 2020 at 08:34:09PM +0200, David Hildenbrand wrote: >> __putback_isolated_page() already documents that pages will be placed to >> the tail of the freelist - this is, however, not the case for >> "order >= MAX_ORDER - 2" (see buddy_merge_likely()) - which should be >> the case for all existing users. >> >> This change affects two users: >> - free page reporting >> - page isolation, when undoing the isolation. >> >> This behavior is desireable for pages that haven't really been touched >> lately, so exactly the two users that don't actually read/write page >> content, but rather move untouched pages. >> >> The new behavior is especially desirable for memory onlining, where we >> allow allocation of newly onlined pages via undo_isolate_page_range() >> in online_pages(). Right now, we always place them to the head of the > > The code looks good, while I don't fully understand the log here. > > undo_isolate_page_range() is used in __offline_pages and alloc_contig_range. I > don't connect them with online_pages(). Do I miss something? Yeah, please look at -mm / -next instead. See https://lkml.kernel.org/r/20200819175957.28465-11-david@xxxxxxxxxx -- Thanks, David / dhildenb
