diff --git a/include/net/sock.h b/include/net/sock.h
index 48e4d5c38f85..8c85791fc196 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1697,6 +1697,7 @@ static inline void sock_orphan(struct sock *sk)
 
 static inline void sock_graft(struct sock *sk, struct socket *parent)
 {
+	WARN_ON(parent->sk);
 	write_lock_bh(&sk->sk_callback_lock);
 	sk->sk_wq = parent->wq;
 	parent->sk = sk;