1 files changed, 2 insertions, 3 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 988e232254e9..63d82957baae 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -678,10 +678,9 @@ static void exit_mm(struct task_struct * tsk)
         down_read(&mm->mmap_sem);
         if (mm->core_state) {
                 up_read(&mm->mmap_sem);
-                down_write(&mm->mmap_sem);
-                if (!--mm->core_state->nr_threads)
+
+                if (atomic_dec_and_test(&mm->core_state->nr_threads))
                         complete(&mm->core_state->startup);
-                up_write(&mm->mmap_sem);
 
                 wait_for_completion(&mm->core_done);
                 down_read(&mm->mmap_sem);