Index: head/sys/dev/netmap/netmap_freebsd.c
===================================================================
--- head/sys/dev/netmap/netmap_freebsd.c
+++ head/sys/dev/netmap/netmap_freebsd.c
@@ -105,6 +105,7 @@
 	snprintf(si->mtxname, sizeof(si->mtxname), "nmkl%s", name);
 	mtx_init(&si->m, si->mtxname, NULL, MTX_DEF);
 	knlist_init_mtx(&si->si.si_note, &si->m);
+	si->kqueue_users = 0;
 
 	return (0);
 }
@@ -1351,7 +1352,9 @@
 nm_os_selwakeup(struct nm_selinfo *si)
 {
 	selwakeuppri(&si->si, PI_NET);
-	taskqueue_enqueue(si->ntfytq, &si->ntfytask);
+	if (si->kqueue_users > 0) {
+		taskqueue_enqueue(si->ntfytq, &si->ntfytask);
+	}
 }
 
 void
@@ -1364,20 +1367,28 @@
 netmap_knrdetach(struct knote *kn)
 {
 	struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
-	struct selinfo *si = &priv->np_si[NR_RX]->si;
+	struct nm_selinfo *si = priv->np_si[NR_RX];
 
-	nm_prinf("remove selinfo %p", si);
-	knlist_remove(&si->si_note, kn, /*islocked=*/0);
+	knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
+	NMG_LOCK();
+	KASSERT(si->kqueue_users > 0, ("kqueue_user underflow on %s",
+	    si->mtxname));
+	si->kqueue_users--;
+	nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
+	NMG_UNLOCK();
 }
 
 static void
 netmap_knwdetach(struct knote *kn)
 {
 	struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
-	struct selinfo *si = &priv->np_si[NR_TX]->si;
+	struct nm_selinfo *si = priv->np_si[NR_TX];
 
-	nm_prinf("remove selinfo %p", si);
-	knlist_remove(&si->si_note, kn, /*islocked=*/0);
+	knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
+	NMG_LOCK();
+	si->kqueue_users--;
+	nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
+	NMG_UNLOCK();
 }
 
 /*
@@ -1465,6 +1476,10 @@
 	kn->kn_fop = (ev == EVFILT_WRITE) ?
 		&netmap_wfiltops : &netmap_rfiltops;
 	kn->kn_hook = priv;
+	NMG_LOCK();
+	si->kqueue_users++;
+	nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
+	NMG_UNLOCK();
 	knlist_add(&si->si.si_note, kn, /*islocked=*/0);
 
 	return 0;
Index: head/sys/dev/netmap/netmap_kern.h
===================================================================
--- head/sys/dev/netmap/netmap_kern.h
+++ head/sys/dev/netmap/netmap_kern.h
@@ -132,11 +132,14 @@
 #define MBUF_QUEUED(m)		1
 
 struct nm_selinfo {
+	/* Support for select(2) and poll(2). */
 	struct selinfo si;
+	/* Support for kqueue(9). See comments in netmap_freebsd.c */
 	struct taskqueue *ntfytq;
 	struct task ntfytask;
 	struct mtx m;
 	char mtxname[32];
+	int kqueue_users;
 };