diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c
index 92b7d289a8af..5c9299aaabae 100644
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -214,7 +214,19 @@ EXPORT_SYMBOL_GPL(__rt_mutex_init);
 void __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock,
 					struct task_struct *proxy_owner)
 {
+	static struct lock_class_key pi_futex_key;
+
 	__rt_mutex_base_init(lock);
+	/*
+	 * On PREEMPT_RT the futex hashbucket spinlock becomes 'sleeping'
+	 * and rtmutex based. That causes a lockdep false positive, because
+	 * some of the futex functions invoke spin_unlock(&hb->lock) with
+	 * the wait_lock of the rtmutex associated to the pi_futex held.
+	 * spin_unlock() in turn takes wait_lock of the rtmutex on which
+	 * the spinlock is based, which makes lockdep notice a lock
+	 * recursion. Give the futex/rtmutex wait_lock a separate key.
+	 */
+	lockdep_set_class(&lock->wait_lock, &pi_futex_key);
 	rt_mutex_set_owner(lock, proxy_owner);
 }