[PATCH v2 5/5] mm/memory_hotplug: update comment regarding zone shuffling

[David Hildenbrand <david@xxxxxxxxxx>]

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.

Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 mm/memory_hotplug.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 03a00cb68bf7..b44d4c7ba73b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -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);
 
-- 
2.26.2