mm: introduce node_zonelist() for accessing the zonelist for a GFP mask

Introduce a node_zonelist() helper function.  It is used to lookup the
appropriate zonelist given a node and a GFP mask.  The patch on its own is a
cleanup but it helps clarify parts of the two-zonelist-per-node patchset.  If
necessary, it can be merged with the next patch in this set without problems.

Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
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>

4 files changed, 6 insertions, 9 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3c3601121509..5d20bf44062f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1183,7 +1183,7 @@ static struct zonelist *zonelist_policy(gfp_t gfp, struct mempolicy *policy)
 		nd = 0;
 		BUG();
 	}
-	return NODE_DATA(nd)->node_zonelists + gfp_zone(gfp);
+	return node_zonelist(nd, gfp);
 }
 
 /* Do dynamic interleaving for a process */
@@ -1299,7 +1299,7 @@ struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
 		if (unlikely(pol != &default_policy &&
 				pol != current->mempolicy))
 			__mpol_free(pol);	/* finished with pol */
-		return NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_flags);
+		return node_zonelist(nid, gfp_flags);
 	}
 
 	zl = zonelist_policy(GFP_HIGHUSER, pol);
@@ -1321,7 +1321,7 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
 	struct zonelist *zl;
 	struct page *page;
 
-	zl = NODE_DATA(nid)->node_zonelists + gfp_zone(gfp);
+	zl = node_zonelist(nid, gfp);
 	page = __alloc_pages(gfp, order, zl);
 	if (page && page_zone(page) == zl->zones[0])
 		inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1bda771a072a..63ff71830ea4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1713,10 +1713,9 @@ EXPORT_SYMBOL(free_pages);
 static unsigned int nr_free_zone_pages(int offset)
 {
 	/* Just pick one node, since fallback list is circular */
-	pg_data_t *pgdat = NODE_DATA(numa_node_id());
 	unsigned int sum = 0;
 
-	struct zonelist *zonelist = pgdat->node_zonelists + offset;
+	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
 	struct zone **zonep = zonelist->zones;
 	struct zone *zone;
 
diff --git a/mm/slab.c b/mm/slab.c
index 03927cb5ec9e..5488c54b1172 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3249,8 +3249,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
 	if (flags & __GFP_THISNODE)
 		return NULL;
 
-	zonelist = &NODE_DATA(slab_node(current->mempolicy))
-			->node_zonelists[gfp_zone(flags)];
+	zonelist = node_zonelist(slab_node(current->mempolicy), flags);
 	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
 retry:
diff --git a/mm/slub.c b/mm/slub.c
index 39592b5ce68a..19ebbfb20689 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1309,8 +1309,7 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
 			get_cycles() % 1024 > s->remote_node_defrag_ratio)
 		return NULL;
 
-	zonelist = &NODE_DATA(
-		slab_node(current->mempolicy))->node_zonelists[gfp_zone(flags)];
+	zonelist = node_zonelist(slab_node(current->mempolicy), flags);
 	for (z = zonelist->zones; *z; z++) {
 		struct kmem_cache_node *n;