diff --git a/include/linux/swap.h b/include/linux/swap.h
index ac43d87b89b092a748eae5c04f29929c676f4a0f..9f0ca325e30de235a98879aa320cb8417af31356 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -167,21 +167,21 @@ struct swap_info_struct {
 	signed short	prio;		/* swap priority of this type */
 	signed char	type;		/* strange name for an index */
 	signed char	next;		/* next type on the swap list */
-	struct file *swap_file;
-	struct block_device *bdev;
-	struct swap_extent first_swap_extent;
-	struct swap_extent *curr_swap_extent;
-	unsigned char *swap_map;
-	unsigned int lowest_bit;
-	unsigned int highest_bit;
+	unsigned int	max;		/* extent of the swap_map */
+	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
+	unsigned int lowest_bit;	/* index of first free in swap_map */
+	unsigned int highest_bit;	/* index of last free in swap_map */
+	unsigned int pages;		/* total of usable pages of swap */
+	unsigned int inuse_pages;	/* number of those currently in use */
+	unsigned int cluster_next;	/* likely index for next allocation */
+	unsigned int cluster_nr;	/* countdown to next cluster search */
 	unsigned int lowest_alloc;	/* while preparing discard cluster */
 	unsigned int highest_alloc;	/* while preparing discard cluster */
-	unsigned int cluster_next;
-	unsigned int cluster_nr;
-	unsigned int pages;
-	unsigned int max;
-	unsigned int inuse_pages;
-	unsigned int old_block_size;
+	struct swap_extent *curr_swap_extent;
+	struct swap_extent first_swap_extent;
+	struct block_device *bdev;	/* swap device or bdev of swap file */
+	struct file *swap_file;		/* seldom referenced */
+	unsigned int old_block_size;	/* seldom referenced */
 };
 
 struct swap_list_t {