Index: sys/kern/subr_witness.c
===================================================================
--- sys/kern/subr_witness.c
+++ sys/kern/subr_witness.c
@@ -358,6 +358,8 @@
 static void	witness_list_lock(struct lock_instance *instance,
 		    int (*prnt)(const char *fmt, ...));
 static int	witness_output(const char *fmt, ...) __printflike(1, 2);
+static int	witness_output_drain(void *arg __unused, const char *data,
+		    int len);
 static int	witness_voutput(const char *fmt, va_list ap) __printflike(1, 0);
 static void	witness_setflag(struct lock_object *lock, int flag, int set);
 
@@ -1281,6 +1283,9 @@
 
 	for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
 		for (i = lle->ll_count - 1; i >= 0; i--, j++) {
+			struct witness_lock_order_data *data;
+			struct stack pstack;
+			bool pstackv;
 
 			MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN);
 			lock1 = &lle->ll_children[i];
@@ -1367,6 +1372,17 @@
 			 */
 			if (blessed(w, w1))
 				goto out;
+
+			if (witness_trace) {
+				pstackv = false;
+				data = witness_lock_order_get(w, w1);
+				if (data != NULL) {
+					stack_copy(&data->wlod_stack,
+					    &pstack);
+					pstackv = true;
+				}
+				data = NULL;
+			}
 			mtx_unlock_spin(&w_mtx);
 
 #ifdef WITNESS_NO_VNODE
@@ -1434,6 +1450,24 @@
 				    lock->lo_name, w->w_name,
 				    fixup_filename(file), line);
 			}
+			if (witness_trace && pstackv) {
+				char buf[32];
+				struct sbuf sb;
+
+				sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
+				sbuf_set_drain(&sb, witness_output_drain,
+				    NULL);
+
+				witness_output(
+			"Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
+				    w->w_name, w->w_class->lc_name,
+				    w1->w_name, w1->w_class->lc_name);
+				stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT,
+				    STACK_SBUF_FMT_LONG);
+
+				sbuf_finish(&sb);
+				sbuf_delete(&sb);
+			}
 			witness_debugger(1, __func__);
 			return;
 		}