The patch which went in six months or so back which said "only reclaim slab
if we're scanning lowmem pagecache" was wrong.  I must have been asleep at
the time.

We do need to scan slab in response to highmem page reclaim as well.  Because
all the math is based around the total amount of memory in the machine, and
we know that if we're performing highmem page reclaim then the lower zones
have no free memory.


---

 mm/vmscan.c |   18 +++++++-----------
 1 files changed, 7 insertions(+), 11 deletions(-)

diff -puN mm/vmscan.c~shrink_slab-for-all-zones-2 mm/vmscan.c
--- 25/mm/vmscan.c~shrink_slab-for-all-zones-2	2004-02-28 23:38:02.000000000 -0800
+++ 25-akpm/mm/vmscan.c	2004-02-28 23:38:02.000000000 -0800
@@ -874,12 +874,10 @@ int try_to_free_pages(struct zone **zone
 		get_page_state(&ps);
 		nr_reclaimed += shrink_caches(zones, priority, &total_scanned,
 						gfp_mask, nr_pages, &ps);
-		if (zones[0] - zones[0]->zone_pgdat->node_zones < ZONE_HIGHMEM) {
-			shrink_slab(total_scanned, gfp_mask);
-			if (reclaim_state) {
-				nr_reclaimed += reclaim_state->reclaimed_slab;
-				reclaim_state->reclaimed_slab = 0;
-			}
+		shrink_slab(total_scanned, gfp_mask);
+		if (reclaim_state) {
+			nr_reclaimed += reclaim_state->reclaimed_slab;
+			reclaim_state->reclaimed_slab = 0;
 		}
 		if (nr_reclaimed >= nr_pages) {
 			ret = 1;
@@ -966,11 +964,9 @@ static int balance_pgdat(pg_data_t *pgda
 				max_scan = SWAP_CLUSTER_MAX;
 			reclaimed = shrink_zone(zone, max_scan, GFP_KERNEL,
 					to_reclaim, &total_scanned, ps);
-			if (i < ZONE_HIGHMEM) {
-				reclaim_state->reclaimed_slab = 0;
-				shrink_slab(total_scanned, GFP_KERNEL);
-				reclaimed += reclaim_state->reclaimed_slab;
-			}
+			reclaim_state->reclaimed_slab = 0;
+			shrink_slab(total_scanned, GFP_KERNEL);
+			reclaimed += reclaim_state->reclaimed_slab;
 			to_free -= reclaimed;
 			if (zone->all_unreclaimable)
 				continue;

_