1 files changed, 16 insertions, 13 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 19f87565be17..cf8203a5fa71 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -639,25 +639,14 @@ void cpuset_update_task_memory_state()
         task_unlock(tsk);
 
         if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
-                nodemask_t oldmem = tsk->mems_allowed;
-                int migrate;
-
                 down(&callback_sem);
                 task_lock(tsk);
                 cs = tsk->cpuset;       /* Maybe changed when task not locked */
-                migrate = is_memory_migrate(cs);
                 guarantee_online_mems(cs, &tsk->mems_allowed);
                 tsk->cpuset_mems_generation = cs->mems_generation;
                 task_unlock(tsk);
                 up(&callback_sem);
                 mpol_rebind_task(tsk, &tsk->mems_allowed);
-                if (!nodes_equal(oldmem, tsk->mems_allowed)) {
-                        if (migrate) {
-                                do_migrate_pages(tsk->mm, &oldmem,
-                                        &tsk->mems_allowed,
-                                        MPOL_MF_MOVE_ALL);
-                        }
-                }
         }
 }
 
@@ -815,7 +804,9 @@ static int update_cpumask(struct cpuset *cs, char *buf)
  * Handle user request to change the 'mems' memory placement
  * of a cpuset.  Needs to validate the request, update the
  * cpusets mems_allowed and mems_generation, and for each
- * task in the cpuset, rebind any vma mempolicies.
+ * task in the cpuset, rebind any vma mempolicies and if
+ * the cpuset is marked 'memory_migrate', migrate the tasks
+ * pages to the new memory.
  *
  * Call with manage_sem held.  May take callback_sem during call.
  * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
@@ -826,9 +817,11 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 static int update_nodemask(struct cpuset *cs, char *buf)
 {
         struct cpuset trialcs;
+        nodemask_t oldmem;
         struct task_struct *g, *p;
         struct mm_struct **mmarray;
         int i, n, ntasks;
+        int migrate;
         int fudge;
         int retval;
 
@@ -837,6 +830,11 @@ static int update_nodemask(struct cpuset *cs, char *buf)
         if (retval < 0)
                 goto done;
         nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
+        oldmem = cs->mems_allowed;
+        if (nodes_equal(oldmem, trialcs.mems_allowed)) {
+                retval = 0;             /* Too easy - nothing to do */
+                goto done;
+        }
         if (nodes_empty(trialcs.mems_allowed)) {
                 retval = -ENOSPC;
                 goto done;
@@ -908,12 +906,17 @@ static int update_nodemask(struct cpuset *cs, char *buf)
          * cpuset manage_sem, we know that no other rebind effort will
          * be contending for the global variable cpuset_being_rebound.
          * It's ok if we rebind the same mm twice; mpol_rebind_mm()
-         * is idempotent.
+         * is idempotent.  Also migrate pages in each mm to new nodes.
          */
+        migrate = is_memory_migrate(cs);
         for (i = 0; i < n; i++) {
                 struct mm_struct *mm = mmarray[i];
 
                 mpol_rebind_mm(mm, &cs->mems_allowed);
+                if (migrate) {
+                        do_migrate_pages(mm, &oldmem, &cs->mems_allowed,
+                                                        MPOL_MF_MOVE_ALL);
+                }
                 mmput(mm);
         }