Revert "mm: vmscan: fix endless loop in kswapd balancing"

This reverts commit 39d18dc4 which
was commit 60cefed4 upstream.

This was not needed and is not suitable for 3.2.y.
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

mm/vmscan.c

@@ -2492,19 +2492,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 }
 #endif
 
-static bool zone_balanced(struct zone *zone, int order,
-			  unsigned long balance_gap, int classzone_idx)
-{
-	if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
-				    balance_gap, classzone_idx, 0))
-		return false;
-
-	if (COMPACTION_BUILD && order && !compaction_suitable(zone, order))
-		return false;
-
-	return true;
-}
-
 /*
  * pgdat_balanced is used when checking if a node is balanced for high-order
  * allocations. Only zones that meet watermarks and are in a zone allowed
@@ -2564,7 +2551,8 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
 			continue;
 		}
 
-		if (!zone_balanced(zone, order, 0, i))
+		if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
+							i, 0))
 			all_zones_ok = false;
 		else
 			balanced += zone->present_pages;
@@ -2667,7 +2655,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 				shrink_active_list(SWAP_CLUSTER_MAX, zone,
 							&sc, priority, 0);
 
-			if (!zone_balanced(zone, order, 0, 0)) {
+			if (!zone_watermark_ok_safe(zone, order,
+					high_wmark_pages(zone), 0, 0)) {
 				end_zone = i;
 				break;
 			} else {
@@ -2728,8 +2717,9 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 				(zone->present_pages +
 					KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
 				KSWAPD_ZONE_BALANCE_GAP_RATIO);
-			if (!zone_balanced(zone, order,
-					   balance_gap, end_zone)) {
+			if (!zone_watermark_ok_safe(zone, order,
+					high_wmark_pages(zone) + balance_gap,
+					end_zone, 0)) {
 				shrink_zone(priority, zone, &sc);
 
 				reclaim_state->reclaimed_slab = 0;
@@ -2756,7 +2746,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
 				continue;
 			}
 
-			if (!zone_balanced(zone, order, 0, end_zone)) {
+			if (!zone_watermark_ok_safe(zone, order,
+					high_wmark_pages(zone), end_zone, 0)) {
 				all_zones_ok = 0;
 				/*
 				 * We are still under min water mark.  This