Commit b86c5fc4 authored Oct 15, 2020 by David Hildenbrand Committed by Linus Torvalds Oct 16, 2020

mm/memory_hotplug: update comment regarding zone shuffling



As we no longer shuffle via generic_online_page() and when undoing
isolation, we can simplify the comment.

We now effectively shuffle only once (properly) when onlining new memory.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Link: https://lkml.kernel.org/r/20201005121534.15649-6-david@redhat.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7fef431b

mm/memory_hotplug.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -858,13 +858,10 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
		undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);

		/*
		* When exposing larger, physically contiguous memory areas to the
		* buddy, shuffling in the buddy (when freeing onlined pages, putting
		* them either to the head or the tail of the freelist) is only helpful
		* for maintaining the shuffle, but not for creating the initial
		* shuffle. Shuffle the whole zone to make sure the just onlined pages
		* are properly distributed across the whole freelist. Make sure to
		* shuffle once pageblocks are no longer isolated.
		* Freshly onlined pages aren't shuffled (e.g., all pages are placed to
		* the tail of the freelist when undoing isolation). Shuffle the whole
		* zone to make sure the just onlined pages are properly distributed
		* across the whole freelist - to create an initial shuffle.
		*/
		shuffle_zone(zone);

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