Unreclaimable pages: Remove all_unreclaimable

The lru lists will now be empty if all pages are not reclaimable.

There is no purpose anymore for the all_unreclaimable flag.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c	2007-07-31 18:43:50.000000000 -0700
+++ linux-2.6/mm/vmscan.c	2007-07-31 18:49:07.000000000 -0700
@@ -65,8 +65,6 @@ struct scan_control {
 
 	int swappiness;
 
-	int all_unreclaimable;
-
 	int order;
 };
 
@@ -1081,7 +1079,6 @@ static unsigned long shrink_zones(int pr
 	unsigned long nr_reclaimed = 0;
 	int i;
 
-	sc->all_unreclaimable = 1;
 	for (i = 0; zones[i] != NULL; i++) {
 		struct zone *zone = zones[i];
 
@@ -1093,11 +1090,6 @@ static unsigned long shrink_zones(int pr
 
 		note_zone_scanning_priority(zone, priority);
 
-		if (zone->all_unreclaimable && priority != DEF_PRIORITY)
-			continue;	/* Let kswapd poll it */
-
-		sc->all_unreclaimable = 0;
-
 		nr_reclaimed += shrink_zone(priority, zone, sc);
 	}
 	return nr_reclaimed;
@@ -1180,7 +1172,7 @@ unsigned long try_to_free_pages(struct z
 			congestion_wait(WRITE, HZ/10);
 	}
 	/* top priority shrink_caches still had more to do? don't OOM, then */
-	if (!sc.all_unreclaimable)
+	if (priority < 0)
 		ret = 1;
 out:
 	/*
@@ -1274,9 +1266,6 @@ loop_again:
 			if (!populated_zone(zone))
 				continue;
 
-			if (zone->all_unreclaimable && priority != DEF_PRIORITY)
-				continue;
-
 			if (!zone_watermark_ok(zone, order, zone->pages_high,
 					       0, 0)) {
 				end_zone = i;
@@ -1309,9 +1298,6 @@ loop_again:
 			if (!populated_zone(zone))
 				continue;
 
-			if (zone->all_unreclaimable && priority != DEF_PRIORITY)
-				continue;
-
 			if (!zone_watermark_ok(zone, order, zone->pages_high,
 					       end_zone, 0))
 				all_zones_ok = 0;
@@ -1324,12 +1310,6 @@ loop_again:
 						lru_pages);
 			nr_reclaimed += reclaim_state->reclaimed_slab;
 			total_scanned += sc.nr_scanned;
-			if (zone->all_unreclaimable)
-				continue;
-			if (nr_slab == 0 && zone->pages_scanned >=
-				(zone_page_state(zone, NR_ACTIVE)
-				+ zone_page_state(zone, NR_INACTIVE)) * 6)
-					zone->all_unreclaimable = 1;
 			/*
 			 * If we've done a decent amount of scanning and
 			 * the reclaim ratio is low, start doing writepage
@@ -1495,9 +1475,6 @@ static unsigned long shrink_all_zones(un
 		if (!populated_zone(zone))
 			continue;
 
-		if (zone->all_unreclaimable && prio != DEF_PRIORITY)
-			continue;
-
 		/* For pass = 0 we don't shrink the active list */
 		if (pass > 0) {
 			zone->nr_scan_active +=
@@ -1819,7 +1796,6 @@ int zone_reclaim(struct zone *zone, gfp_
 	 * then do not scan.
 	 */
 	if (!(gfp_mask & __GFP_WAIT) ||
-		zone->all_unreclaimable ||
 		atomic_read(&zone->reclaim_in_progress) > 0 ||
 		(current->flags & PF_MEMALLOC))
 			return 0;