1 files changed, 16 insertions, 0 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e7fb9d25c54e..8b57173c1dd5 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -93,6 +93,7 @@
 
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
+#include <linux/random.h>
 
 #include "internal.h"
 
@@ -1645,6 +1646,21 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
                 return interleave_nodes(pol);
 }
 
+/*
+ * Return the bit number of a random bit set in the nodemask.
+ * (returns -1 if nodemask is empty)
+ */
+int node_random(const nodemask_t *maskp)
+{
+        int w, bit = -1;
+
+        w = nodes_weight(*maskp);
+        if (w)
+                bit = bitmap_ord_to_pos(maskp->bits,
+                        get_random_int() % w, MAX_NUMNODES);
+        return bit;
+}
+
 #ifdef CONFIG_HUGETLBFS
 /*
  * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)