Merge master.kernel.org:/home/rmk/linux-2.6-arm

[deliverable/linux.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 97f609f574b1843556a6a07fc4c6c50180725b31..ae0f2c4e452b8bf4f69bdbc2b96bb16650fc61fc 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -557,6 +557,88 @@ void exit_fs(struct task_struct *tsk)
 
 EXPORT_SYMBOL_GPL(exit_fs);
 
+#ifdef CONFIG_MM_OWNER
+/*
+ * Task p is exiting and it owned mm, lets find a new owner for it
+ */
+static inline int
+mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
+{
+       /*
+        * If there are other users of the mm and the owner (us) is exiting
+        * we need to find a new owner to take on the responsibility.
+        */
+       if (!mm)
+               return 0;
+       if (atomic_read(&mm->mm_users) <= 1)
+               return 0;
+       if (mm->owner != p)
+               return 0;
+       return 1;
+}
+
+void mm_update_next_owner(struct mm_struct *mm)
+{
+       struct task_struct *c, *g, *p = current;
+
+retry:
+       if (!mm_need_new_owner(mm, p))
+               return;
+
+       read_lock(&tasklist_lock);
+       /*
+        * Search in the children
+        */
+       list_for_each_entry(c, &p->children, sibling) {
+               if (c->mm == mm)
+                       goto assign_new_owner;
+       }
+
+       /*
+        * Search in the siblings
+        */
+       list_for_each_entry(c, &p->parent->children, sibling) {
+               if (c->mm == mm)
+                       goto assign_new_owner;
+       }
+
+       /*
+        * Search through everything else. We should not get
+        * here often
+        */
+       do_each_thread(g, c) {
+               if (c->mm == mm)
+                       goto assign_new_owner;
+       } while_each_thread(g, c);
+
+       read_unlock(&tasklist_lock);
+       return;
+
+assign_new_owner:
+       BUG_ON(c == p);
+       get_task_struct(c);
+       /*
+        * The task_lock protects c->mm from changing.
+        * We always want mm->owner->mm == mm
+        */
+       task_lock(c);
+       /*
+        * Delay read_unlock() till we have the task_lock()
+        * to ensure that c does not slip away underneath us
+        */
+       read_unlock(&tasklist_lock);
+       if (c->mm != mm) {
+               task_unlock(c);
+               put_task_struct(c);
+               goto retry;
+       }
+       cgroup_mm_owner_callbacks(mm->owner, c);
+       mm->owner = c;
+       task_unlock(c);
+       put_task_struct(c);
+}
+#endif /* CONFIG_MM_OWNER */
+
 /*
  * Turn us into a lazy TLB process if we
  * aren't already..
@@ -596,6 +678,7 @@ static void exit_mm(struct task_struct * tsk)
        /* We don't want this task to be frozen prematurely */
        clear_freeze_flag(tsk);
        task_unlock(tsk);
+       mm_update_next_owner(mm);
        mmput(mm);
 }
 
@@ -967,7 +1050,7 @@ NORET_TYPE void do_exit(long code)
        proc_exit_connector(tsk);
        exit_notify(tsk, group_dead);
 #ifdef CONFIG_NUMA
-       mpol_free(tsk->mempolicy);
+       mpol_put(tsk->mempolicy);
        tsk->mempolicy = NULL;
 #endif
 #ifdef CONFIG_FUTEX