diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8e2c11e692baf9bba6380d63888cfbf5a206cf0b..77221c16733a7254bc62c7ab858a0f1f493a7703 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -232,7 +232,6 @@ struct swap_info_struct {
 	unsigned long	flags;		/* SWP_USED etc: see above */
 	signed short	prio;		/* swap priority of this type */
 	struct plist_node list;		/* entry in swap_active_head */
-	struct plist_node avail_lists[MAX_NUMNODES];/* entry in swap_avail_heads */
 	signed char	type;		/* strange name for an index */
 	unsigned int	max;		/* extent of the swap_map */
 	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
@@ -273,6 +272,16 @@ struct swap_info_struct {
 					 */
 	struct work_struct discard_work; /* discard worker */
 	struct swap_cluster_list discard_clusters; /* discard clusters list */
+	struct plist_node avail_lists[0]; /*
+					   * entries in swap_avail_heads, one
+					   * entry per node.
+					   * Must be last as the number of the
+					   * array is nr_node_ids, which is not
+					   * a fixed value so have to allocate
+					   * dynamically.
+					   * And it has to be an array so that
+					   * plist_for_each_* can work.
+					   */
 };
 
 #ifdef CONFIG_64BIT
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 67aaf7ae22ffbd2f6782a3391c3cc5790046c144..340ef317768681cfca69b3b70e9da4fbb82e9aac 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2820,8 +2820,9 @@ static struct swap_info_struct *alloc_swap_info(void)
 	struct swap_info_struct *p;
 	unsigned int type;
 	int i;
+	int size = sizeof(*p) + nr_node_ids * sizeof(struct plist_node);
 
-	p = kvzalloc(sizeof(*p), GFP_KERNEL);
+	p = kvzalloc(size, GFP_KERNEL);
 	if (!p)
 		return ERR_PTR(-ENOMEM);