Index: sys/kern/kern_mutex.c
===================================================================
--- sys/kern/kern_mutex.c
+++ sys/kern/kern_mutex.c
@@ -172,10 +172,14 @@
 
 static void _mtx_lock_indefinite_check(struct mtx *, struct lock_delay_arg *);
 
-void
+static void
 assert_mtx(const struct lock_object *lock, int what)
 {
 
+	if (what & LA_LOCKED) {
+		what &= ~LA_LOCKED;
+		what |= LA_XLOCKED;
+	}
 	mtx_assert((const struct mtx *)lock, what);
 }