Index: sys/kern/subr_epoch.c
===================================================================
--- sys/kern/subr_epoch.c
+++ sys/kern/subr_epoch.c
@@ -234,6 +234,17 @@
 	} else
 		SLIST_REMOVE_HEAD(&td->td_epochs, et_tlink);
 }
+
+/* Used by NOEPOCHASSERT() */
+void
+epoch_trace_list(struct thread *td)
+{
+	epoch_tracker_t iet;
+
+	SLIST_FOREACH(iet, &td->td_epochs, et_tlink)
+		printf("Epoch %s entered at %s:%d\n", iet->et_epoch->e_name,
+		    iet->et_file, iet->et_line);
+}
 #endif /* EPOCH_TRACE */
 
 static void
Index: sys/net/if.c
===================================================================
--- sys/net/if.c
+++ sys/net/if.c
@@ -3582,6 +3582,7 @@
 	 * We are certain we have added something, so call down to the
 	 * interface to let them know about it.
 	 */
+	NOEPOCHASSERT();
 	if (ifp->if_ioctl != NULL) {
 		(void) (*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
 	}
Index: sys/sys/epoch.h
===================================================================
--- sys/sys/epoch.h
+++ sys/sys/epoch.h
@@ -83,6 +83,7 @@
 void _epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE);
 void _epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE);
 #ifdef EPOCH_TRACE
+void epoch_trace_list(struct thread *);
 #define	epoch_enter_preempt(epoch, et)	_epoch_enter_preempt(epoch, et, __FILE__, __LINE__)
 #define	epoch_exit_preempt(epoch, et)	_epoch_exit_preempt(epoch, et, __FILE__, __LINE__)
 #else
Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -109,11 +109,27 @@
 		kassert_panic msg;					\
 	}								\
 } while (0)
-#else
+#ifdef EPOCH_TRACE
+#define	NOEPOCHASSERT() do {						\
+	if (__predict_false(curthread->td_epochnest > 0)) {		\
+		epoch_trace_list(curthread);				\
+		kassert_panic("No epoch assertion failed\n");		\
+	}								\
+} while (0)
+#else	/* !EPOCH_TRACE */
+#define	NOEPOCHASSERT() do {						\
+	if (__predict_false(curthread->td_epochnest > 0))		\
+		kassert_panic("No epoch assertion failed");		\
+} while (0)
+#endif
+#else	/* !INVARIANTS */
 #define	KASSERT(exp,msg) do { \
 } while (0)
 
 #define	VNASSERT(exp, vp, msg) do { \
+} while (0)
+
+#define	NOEPOCHASSERT() do { \
 } while (0)
 #endif