Merge branch 'linus' into tracing-v28-for-linus-v3

[linux-2.6-block.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 7b71f87f1207bf6b5aab8fa8daa1ee27c24a4f7a..138887881a11f6eda22d9bc2b2f6db19c9d24427 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -644,24 +644,23 @@ retry:
 assign_new_owner:
        BUG_ON(c == p);
        get_task_struct(c);
+       read_unlock(&tasklist_lock);
+       down_write(&mm->mmap_sem);
        /*
         * 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);
+               up_write(&mm->mmap_sem);
                put_task_struct(c);
                goto retry;
        }
        cgroup_mm_owner_callbacks(mm->owner, c);
        mm->owner = c;
        task_unlock(c);
+       up_write(&mm->mmap_sem);
        put_task_struct(c);
 }
 #endif /* CONFIG_MM_OWNER */