[PATCHv2] mm/compaction: reset compaction scanner positions

From: Gioh Kim
Date: Mon Mar 23 2015 - 21:35:36 EST


When the compaction is activated via /proc/sys/vm/compact_memory
it would better scan the whole zone.
And some platform, for instance ARM, has the start_pfn of a zone is zero.
Therefore the first try to compaction via /proc doesn't work.
It needs to force to reset compaction scanner position at first.

Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
---
mm/compaction.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/mm/compaction.c b/mm/compaction.c
index 8c0d945..ccf48ce 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1587,6 +1587,14 @@ static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
INIT_LIST_HEAD(&cc->freepages);
INIT_LIST_HEAD(&cc->migratepages);

+ /*
+ * When called via /proc/sys/vm/compact_memory
+ * this makes sure we compact the whole zone regardless of
+ * cached scanner positions.
+ */
+ if (cc->order == -1)
+ __reset_isolation_suitable(zone);
+
if (cc->order == -1 || !compaction_deferred(zone, cc->order))
compact_zone(zone, cc);

--
1.7.9.5

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