mm: use two zonelist that are filtered by GFP mask

Currently a node has two sets of zonelists, one for each zone type in the
system and a second set for GFP_THISNODE allocations.  Based on the zones
allowed by a gfp mask, one of these zonelists is selected.  All of these
zonelists consume memory and occupy cache lines.

This patch replaces the multiple zonelists per-node with two zonelists.  The
first contains all populated zones in the system, ordered by distance, for
fallback allocations when the target/preferred node has no free pages.  The
second contains all populated zones in the node suitable for GFP_THISNODE
allocations.

An iterator macro is introduced called for_each_zone_zonelist() that interates
through each zone allowed by the GFP flags in the selected zonelist.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index beb592f..2c93502 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -175,12 +175,14 @@ static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
 						    gfp_t gfp_mask)
 {
 #ifdef CONFIG_NUMA
+	struct zone *zone;
 	struct zone **z;
+	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
 	nodemask_t nodes = node_states[N_HIGH_MEMORY];
 
-	for (z = zonelist->zones; *z; z++)
-		if (cpuset_zone_allowed_softwall(*z, gfp_mask))
-			node_clear(zone_to_nid(*z), nodes);
+	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
+		if (cpuset_zone_allowed_softwall(zone, gfp_mask))
+			node_clear(zone_to_nid(zone), nodes);
 		else
 			return CONSTRAINT_CPUSET;