mm: filter based on a nodemask as well as a gfp_mask

The MPOL_BIND policy creates a zonelist that is used for allocations
controlled by that mempolicy.  As the per-node zonelist is already being
filtered based on a zone id, this patch adds a version of __alloc_pages() that
takes a nodemask for further filtering.  This eliminates the need for
MPOL_BIND to create a custom zonelist.

A positive benefit of this is that allocations using MPOL_BIND now use the
local node's distance-ordered zonelist instead of a custom node-id-ordered
zonelist.  I.e., pages will be allocated from the closest allowed node with
available memory.

[Lee.Schermerhorn@hp.com: Mempolicy: update stale documentation and comments]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask]
[Lee.Schermerhorn@hp.com: Mempolicy: make dequeue_huge_page_vma() obey MPOL_BIND nodemask rework]
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: 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, 30 insertions, 0 deletions

diff --git a/mm/mmzone.c b/mm/mmzone.c
index eb5838634f18..486ed595ee6f 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -42,3 +42,33 @@ struct zone *next_zone(struct zone *zone)
         return zone;
 }
 
+static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
+{
+#ifdef CONFIG_NUMA
+        return node_isset(zonelist_node_idx(zref), *nodes);
+#else
+        return 1;
+#endif /* CONFIG_NUMA */
+}
+
+/* Returns the next zone at or below highest_zoneidx in a zonelist */
+struct zoneref *next_zones_zonelist(struct zoneref *z,
+                                        enum zone_type highest_zoneidx,
+                                        nodemask_t *nodes,
+                                        struct zone **zone)
+{
+        /*
+         * Find the next suitable zone to use for the allocation.
+         * Only filter based on nodemask if it's set
+         */
+        if (likely(nodes == NULL))
+                while (zonelist_zone_idx(z) > highest_zoneidx)
+                        z++;
+        else
+                while (zonelist_zone_idx(z) > highest_zoneidx ||
+                                (z->zone && !zref_in_nodemask(z, nodes)))
+                        z++;
+
+        *zone = zonelist_zone(z++);
+        return z;
+}