Index: sys/netinet/in_mcast.c
===================================================================
--- sys/netinet/in_mcast.c
+++ sys/netinet/in_mcast.c
@@ -2211,7 +2211,10 @@
                             __func__);
 			goto out_inp_locked;
 		}
-		inm_acquire(imf->imf_inm);
+		/*
+		 * NOTE: Refcount from in_joingroup_locked()
+		 * is protecting membership.
+		 */
 	} else {
 		CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
 		IN_MULTI_LIST_LOCK();