diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 90d99fb02ae4ee5c216341d25ee9d784446fe8e3..53042f118f2365eeedb5be4cbea70a2fde2570fe 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1628,8 +1628,13 @@ void ftrace_retfunc_init_task(struct task_struct *t)
 
 void ftrace_retfunc_exit_task(struct task_struct *t)
 {
-	kfree(t->ret_stack);
+	struct ftrace_ret_stack	*ret_stack = t->ret_stack;
+
 	t->ret_stack = NULL;
+	/* NULL must become visible to IRQs before we free it: */
+	barrier();
+
+	kfree(ret_stack);
 }
 #endif