diff --git a/include/linux/swap.h b/include/linux/swap.h
index f9e576a2c18897a6ae41b3a91cdec1456e93d976..622025ac1461e1d58b8961a1c72df66ecf60efb6 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -235,7 +235,6 @@ 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 */
@@ -276,6 +275,16 @@ 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 8688ae65ef58ac639b0b2202039fa22577309350..6e06821623f690ea7c5adf7a4948f814f137e4fc 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2812,8 +2812,9 @@ 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);