linux-kernel - [PATCH v3 3/7] mm/compaction: initialize compact_order_failed to MAX

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Date:	Thu,  3 Dec 2015 16:11:17 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vlastimil Babka <vbabka@...e.cz>, Mel Gorman <mgorman@...e.de>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Minchan Kim <minchan@...nel.org>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v3 3/7] mm/compaction: initialize compact_order_failed to MAX_ORDER

If compact_order_failed is initialized to 0 and order-9
compaction is continually failed, defer counter will be updated
to activate deferring. Although other defer counters will be properly
updated, compact_order_failed will not be updated because failed order
cannot be lower than compact_order_failed, 0. In this case,
low order compaction such as 2, 3 could be deferred due to
this wrongly initialized compact_order_failed value. This patch
removes this possibility by initializing it to MAX_ORDER.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 mm/page_alloc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d0499ff..7002c66 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5273,6 +5273,9 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat)
 		zone_seqlock_init(zone);
 		zone->zone_pgdat = pgdat;
 		zone_pcp_init(zone);
+#ifdef CONFIG_COMPACTION
+		zone->compact_order_failed = MAX_ORDER;
+#endif
 
 		/* For bootup, initialized properly in watermark setup */
 		mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages);
-- 
1.9.1

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