[PATCH 1/6] mm/numa: extract the code of building node fall back list

[Pingfan Liu <kernelfans@gmail.com>]

In coming patch, memblock allocator also utilizes node fall back list info.
Hence extracting the related code for reusing.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: Borislav Petkov <bp@alien8.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: Vlastimil Babka <vbabka@suse.cz>
CC: Mike Rapoport <rppt@linux.vnet.ibm.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Mel Gorman <mgorman@suse.de>
CC: Joonsoo Kim <iamjoonsoo.kim@lge.com>
CC: Andy Lutomirski <luto@kernel.org>
CC: Andi Kleen <ak@linux.intel.com>
CC: Petr Tesarik <ptesarik@suse.cz>
CC: Michal Hocko <mhocko@suse.com>
CC: Stephen Rothwell <sfr@canb.auug.org.au>
CC: Jonathan Corbet <corbet@lwn.net>
CC: Nicholas Piggin <npiggin@gmail.com>
CC: Daniel Vacek <neelx@redhat.com>
CC: linux-kernel@vger.kernel.org
---
 mm/page_alloc.c | 48 +++++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 35fdde0..a6967a1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5380,6 +5380,32 @@ static void build_thisnode_zonelists(pg_data_t *pgdat)
 	zonerefs->zone_idx = 0;
 }
 
+int build_node_order(int *node_oder_array, int sz,
+	int local_node, nodemask_t *used_mask)
+{
+	int node, nr_nodes = 0;
+	int prev_node = local_node;
+	int load = nr_online_nodes;
+
+
+	while ((node = find_next_best_node(local_node, used_mask)) >= 0
+		&& nr_nodes < sz) {
+		/*
+		 * We don't want to pressure a particular node.
+		 * So adding penalty to the first node in same
+		 * distance group to make it round-robin.
+		 */
+		if (node_distance(local_node, node) !=
+		    node_distance(local_node, prev_node))
+			node_load[node] = load;
+
+		node_oder_array[nr_nodes++] = node;
+		prev_node = node;
+		load--;
+	}
+	return nr_nodes;
+}
+
 /*
  * Build zonelists ordered by zone and nodes within zones.
  * This results in conserving DMA zone[s] until all Normal memory is
@@ -5390,32 +5416,16 @@ static void build_thisnode_zonelists(pg_data_t *pgdat)
 static void build_zonelists(pg_data_t *pgdat)
 {
 	static int node_order[MAX_NUMNODES];
-	int node, load, nr_nodes = 0;
+	int local_node, nr_nodes = 0;
 	nodemask_t used_mask;
-	int local_node, prev_node;
 
 	/* NUMA-aware ordering of nodes */
 	local_node = pgdat->node_id;
-	load = nr_online_nodes;
-	prev_node = local_node;
 	nodes_clear(used_mask);
 
 	memset(node_order, 0, sizeof(node_order));
-	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
-		/*
-		 * We don't want to pressure a particular node.
-		 * So adding penalty to the first node in same
-		 * distance group to make it round-robin.
-		 */
-		if (node_distance(local_node, node) !=
-		    node_distance(local_node, prev_node))
-			node_load[node] = load;
-
-		node_order[nr_nodes++] = node;
-		prev_node = node;
-		load--;
-	}
-
+	nr_nodes = build_node_order(node_order, MAX_NUMNODES,
+		local_node, &used_mask);
 	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
 	build_thisnode_zonelists(pgdat);
 }
-- 
2.7.4