diff --git a/sys/dev/rtsx/rtsx.c b/sys/dev/rtsx/rtsx.c
--- a/sys/dev/rtsx/rtsx.c
+++ b/sys/dev/rtsx/rtsx.c
@@ -686,40 +686,46 @@
 rtsx_card_task(void *arg, int pending __unused)
 {
 	struct rtsx_softc *sc = arg;
+	device_t child;
+	bool present;
 
-	if (rtsx_is_card_present(sc)) {
-		sc->rtsx_flags |= RTSX_F_CARD_PRESENT;
+	RTSX_LOCK(sc);
+	child = sc->rtsx_mmc_dev;
+	present = rtsx_is_card_present(sc);
+	RTSX_UNLOCK(sc);
+
+	if (present && child == NULL) {
 		/* Card is present, attach if necessary. */
-		if (sc->rtsx_mmc_dev == NULL) {
-			if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
-				device_printf(sc->rtsx_dev, "Card inserted\n");
+		if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
+			device_printf(sc->rtsx_dev, "Card inserted\n");
 
-			sc->rtsx_read_count = sc->rtsx_write_count = 0;
-			RTSX_LOCK(sc);
-			sc->rtsx_mmc_dev = device_add_child(sc->rtsx_dev, "mmc", DEVICE_UNIT_ANY);
-			RTSX_UNLOCK(sc);
-			if (sc->rtsx_mmc_dev == NULL) {
-				device_printf(sc->rtsx_dev, "Adding MMC bus failed\n");
-			} else {
-				device_set_ivars(sc->rtsx_mmc_dev, sc);
-				device_probe_and_attach(sc->rtsx_mmc_dev);
-			}
+		sc->rtsx_read_count = sc->rtsx_write_count = 0;
+		child = device_add_child(sc->rtsx_dev, "mmc", DEVICE_UNIT_ANY);
+		if (child == NULL) {
+			device_printf(sc->rtsx_dev, "Adding MMC bus failed\n");
+		} else {
+			device_set_ivars(child, sc);
+			device_probe_and_attach(child);
 		}
-	} else {
+
+		RTSX_LOCK(sc);
+		sc->rtsx_mmc_dev = child;
+		sc->rtsx_flags |= RTSX_F_CARD_PRESENT;
+		RTSX_UNLOCK(sc);
+	} else if (!present && child != NULL) {
+		if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
+			device_printf(sc->rtsx_dev, "Card removed\n");
+		if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
+			device_printf(sc->rtsx_dev, "Read count: %jx, write count: %jx\n",
+			    (uintmax_t)sc->rtsx_read_count, (uintmax_t)sc->rtsx_write_count);
+
+		RTSX_LOCK(sc);
 		sc->rtsx_flags &= ~RTSX_F_CARD_PRESENT;
-		/* Card isn't present, detach if necessary. */
-		if (sc->rtsx_mmc_dev != NULL) {
-			if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
-				device_printf(sc->rtsx_dev, "Card removed\n");
+		sc->rtsx_mmc_dev = NULL;
+		RTSX_UNLOCK(sc);
 
-			if (sc->rtsx_debug_mask & RTSX_DEBUG_BASIC)
-				device_printf(sc->rtsx_dev, "Read count: %jx, write count: %jx\n",
-				    (uintmax_t)sc->rtsx_read_count,
-				    (uintmax_t)sc->rtsx_write_count);
-			if (device_delete_child(sc->rtsx_dev, sc->rtsx_mmc_dev))
-				device_printf(sc->rtsx_dev, "Detaching MMC bus failed\n");
-			sc->rtsx_mmc_dev = NULL;
-		}
+		if (device_delete_child(sc->rtsx_dev, child))
+			device_printf(sc->rtsx_dev, "Detaching MMC bus failed\n");
 	}
 }
 #endif /* MMCCAM */