diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 23241c2..b7edf82 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -39,7 +39,15 @@
  * when it is shrunk, before we rcu free the node. See shrink code for
  * details.
  */
-#define RADIX_TREE_INDIRECT_PTR	1
+#define RADIX_TREE_INDIRECT_PTR		1
+/*
+ * A common use of the radix tree is to store pointers to struct pages;
+ * but shmem/tmpfs needs also to store swap entries in the same tree:
+ * those are marked as exceptional entries to distinguish them.
+ * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it.
+ */
+#define RADIX_TREE_EXCEPTIONAL_ENTRY	2
+#define RADIX_TREE_EXCEPTIONAL_SHIFT	2
 
 #define radix_tree_indirect_to_ptr(ptr) \
 	radix_tree_indirect_to_ptr((void __force *)(ptr))
@@ -174,6 +182,28 @@
 }
 
 /**
+ * radix_tree_exceptional_entry	- radix_tree_deref_slot gave exceptional entry?
+ * @arg:	value returned by radix_tree_deref_slot
+ * Returns:	0 if well-aligned pointer, non-0 if exceptional entry.
+ */
+static inline int radix_tree_exceptional_entry(void *arg)
+{
+	/* Not unlikely because radix_tree_exception often tested first */
+	return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY;
+}
+
+/**
+ * radix_tree_exception	- radix_tree_deref_slot returned either exception?
+ * @arg:	value returned by radix_tree_deref_slot
+ * Returns:	0 if well-aligned pointer, non-0 if either kind of exception.
+ */
+static inline int radix_tree_exception(void *arg)
+{
+	return unlikely((unsigned long)arg &
+		(RADIX_TREE_INDIRECT_PTR | RADIX_TREE_EXCEPTIONAL_ENTRY));
+}
+
+/**
  * radix_tree_replace_slot	- replace item in a slot
  * @pslot:	pointer to slot, returned by radix_tree_lookup_slot
  * @item:	new item to store in the slot.
@@ -194,8 +224,8 @@
 unsigned int
 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 			unsigned long first_index, unsigned int max_items);
-unsigned int
-radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
+unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,
+			void ***results, unsigned long *indices,
 			unsigned long first_index, unsigned int max_items);
 unsigned long radix_tree_next_hole(struct radix_tree_root *root,
 				unsigned long index, unsigned long max_scan);