1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 09b180063ee1..50d9af615dc4 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -198,15 +198,22 @@ static void __rwsem_mark_wake(struct rw_semaphore *sem,
                 woken++;
                 tsk = waiter->task;
 
-                wake_q_add(wake_q, tsk);
+                get_task_struct(tsk);
                 list_del(&waiter->list);
                 /*
-                 * Ensure that the last operation is setting the reader
+                 * Ensure calling get_task_struct() before setting the reader
                  * waiter to nil such that rwsem_down_read_failed() cannot
                  * race with do_exit() by always holding a reference count
                  * to the task to wakeup.
                  */
                 smp_store_release(&waiter->task, NULL);
+                /*
+                 * Ensure issuing the wakeup (either by us or someone else)
+                 * after setting the reader waiter to nil.
+                 */
+                wake_q_add(wake_q, tsk);
+                /* wake_q_add() already take the task ref */
+                put_task_struct(tsk);
         }
 
         adjustment = woken * RWSEM_ACTIVE_READ_BIAS - adjustment;