Index: sys/cam/nvme/nvme_da.c
===================================================================
--- sys/cam/nvme/nvme_da.c
+++ sys/cam/nvme/nvme_da.c
@@ -986,7 +986,19 @@
 out:
 		start_ccb->ccb_h.flags |= CAM_UNLOCKED;
 		softc->outstanding_cmds++;
-		softc->refcount++;
+		/*
+		 * Take two references out. One guards against the completion
+		 * routine triggered by start_ccb finishing, triggering a geom
+		 * wither and call to daclose before we can get to the
+		 * cam_periph_lock.  The other reference guards against us
+		 * returning, wither + ndaclose because geom falsely thinks all
+		 * its transactions are done (it shouldn't do this, but it's
+		 * better to fail safe in the face of geom bugs and it's easy to
+		 * do with an extra reference here) and then this transaction
+		 * completing.
+		 */
+		softc->refcount++;			/* For submission */
+		softc->refcount++;			/* For completion */
 		cam_periph_unlock(periph);
 		xpt_action(start_ccb);
 		cam_periph_lock(periph);
@@ -1059,6 +1071,8 @@
 			cam_iosched_bio_complete(softc->cam_iosched, bp, done_ccb);
 			xpt_release_ccb(done_ccb);
 			ndaschedule(periph);
+			KASSERT(softc->refcount >= 1, ("ndadone softc %p refcount %d", softc, softc->refcount));
+			softc->refcount--; /* Release the periph refcount taken in ndastart() for each CCB. *.
 			cam_periph_unlock(periph);
 			biodone(bp);
 		} else { /* state == NDA_CCB_TRIM */
@@ -1086,6 +1100,8 @@
 			cam_iosched_bio_complete(softc->cam_iosched, bp1, done_ccb);
 			xpt_release_ccb(done_ccb);
 			ndaschedule(periph);
+			KASSERT(softc->refcount >= 1, ("ndadone softc %p refcount %d", softc, softc->refcount));
+			softc->refcount--; /* Release the periph refcount taken in ndastart() for each CCB. *.
 			cam_periph_unlock(periph);
 			while ((bp2 = TAILQ_FIRST(&queue)) != NULL) {
 				TAILQ_REMOVE(&queue, bp2, bio_queue);
@@ -1100,11 +1116,6 @@
 				biodone(bp2);
 			}
 		}
-		/*
-		 * Release the periph refcount taken in mdastart() for each CCB.
-		 */
-		KASSERT(softc->refcount >= 1, ("ndadone softc %p refcount %d", softc, softc->refcount));
-		softc->refcount--;
 		return;
 	}
 	case NDA_CCB_DUMP: