memcg: fix possible panic when CONFIG_MM_OWNER=y

[linux-2.6-omap-h63xx.git] / include / linux / mm_types.h

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index eb7c16cc95596fae106848e0a66b3b04f6f6b68a..02a27ae78539cfe536106f46a8f89b50ea63985e 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -226,8 +226,17 @@ struct mm_struct {
        rwlock_t                ioctx_list_lock;        /* aio lock */
        struct kioctx           *ioctx_list;
 #ifdef CONFIG_MM_OWNER
-       struct task_struct *owner;      /* The thread group leader that */
-                                       /* owns the mm_struct.          */
+       /*
+        * "owner" points to a task that is regarded as the canonical
+        * user/owner of this mm. All of the following must be true in
+        * order for it to be changed:
+        *
+        * current == mm->owner
+        * current->mm != mm
+        * new_owner->mm == mm
+        * new_owner->alloc_lock is held
+        */
+       struct task_struct *owner;
 #endif
 
 #ifdef CONFIG_PROC_FS