linux-kernel - [PATCH 10/31] mm, vmscan: remove duplicate logic clearing node congestion and dirty state

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Date:	Fri,  1 Jul 2016 21:01:18 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>
Cc:	Rik van Riel <riel@...riel.com>, Vlastimil Babka <vbabka@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 10/31] mm, vmscan: remove duplicate logic clearing node congestion and dirty state

Reclaim may stall if there is too much dirty or congested data on a node.
This was previously based on zone flags and the logic for clearing the
flags is in two places.  As congestion/dirty tracking is now tracked on a
per-node basis, we can remove some duplicate logic.

Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
---
 mm/vmscan.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 34656173a670..911142d25de2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3005,7 +3005,17 @@ static bool zone_balanced(struct zone *zone, int order, int classzone_idx)
 {
 	unsigned long mark = high_wmark_pages(zone);
 
-	return zone_watermark_ok_safe(zone, order, mark, classzone_idx);
+	if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx))
+		return false;
+
+	/*
+	 * If any eligible zone is balanced then the node is not considered
+	 * to be congested or dirty
+	 */
+	clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags);
+	clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags);
+
+	return true;
 }
 
 /*
@@ -3151,13 +3161,6 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 			if (!zone_balanced(zone, order, 0)) {
 				classzone_idx = i;
 				break;
-			} else {
-				/*
-				 * If any eligible zone is balanced then the
-				 * node is not considered congested or dirty.
-				 */
-				clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags);
-				clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags);
 			}
 		}
 
@@ -3216,11 +3219,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 			if (!populated_zone(zone))
 				continue;
 
-			if (zone_balanced(zone, sc.order, classzone_idx)) {
-				clear_bit(PGDAT_CONGESTED, &pgdat->flags);
-				clear_bit(PGDAT_DIRTY, &pgdat->flags);
+			if (zone_balanced(zone, sc.order, classzone_idx))
 				goto out;
-			}
 		}
 
 		/*
-- 
2.6.4