[PATCH v1 5/5] mm/memory_hotplug: update comment regarding zone shuffling

David Hildenbrand
2020-09-28T18:21:58Z

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.

Cc: Andrew Morton <akpm@linux-foundation.org>
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>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
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 9db80ee29caa..c589bd8801bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -859,13 +859,10 @@ 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