Index: sys/x86/x86/intr_machdep.c
===================================================================
--- sys/x86/x86/intr_machdep.c
+++ sys/x86/x86/intr_machdep.c
@@ -202,14 +202,19 @@
 	isrc = intr_handler_source(cookie);
 	error = intr_event_remove_handler(cookie);
 	if (error == 0) {
-		mtx_lock(&intr_table_lock);
+		int mtx_owned;
+
+		mtx_owned = mtx_owned(&intr_table_lock);
+		if (!mtx_owned)
+			mtx_lock(&intr_table_lock);
 		isrc->is_handlers--;
 		if (isrc->is_handlers == 0) {
 			isrc->is_pic->pic_disable_source(isrc, PIC_NO_EOI);
 			isrc->is_pic->pic_disable_intr(isrc);
 		}
 		intrcnt_updatename(isrc);
-		mtx_unlock(&intr_table_lock);
+		if (!mtx_owned)
+			mtx_unlock(&intr_table_lock);
 	}
 	return (error);
 }