Merge branches 'akpm' and 'akpm-hotfixes' (patches from Andrew)

[linux-2.6-microblaze.git] / mm / mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8d14240..1592b08 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1876,17 +1876,26 @@ unsigned int mempolicy_slab_node(void)
  */
 static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
 {
-       unsigned nnodes = nodes_weight(pol->nodes);
-       unsigned target;
+       nodemask_t nodemask = pol->nodes;
+       unsigned int target, nnodes;
        int i;
        int nid;
+       /*
+        * The barrier will stabilize the nodemask in a register or on
+        * the stack so that it will stop changing under the code.
+        *
+        * Between first_node() and next_node(), pol->nodes could be changed
+        * by other threads. So we put pol->nodes in a local stack.
+        */
+       barrier();
 
+       nnodes = nodes_weight(nodemask);
        if (!nnodes)
                return numa_node_id();
        target = (unsigned int)n % nnodes;
-       nid = first_node(pol->nodes);
+       nid = first_node(nodemask);
        for (i = 0; i < target; i++)
-               nid = next_node(nid, pol->nodes);
+               nid = next_node(nid, nodemask);
        return nid;
 }