diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -1259,6 +1259,12 @@
 	 * if so find the root of the mounted filesystem.
 	 */
 	do {
+		/*
+		 * Ensure that the v_mounthere update from
+		 * vfs_domount() is visible if we saw the
+		 * VIRF_MOUNTPOINT flag.
+		 */
+		atomic_thread_fence_acq();
 		mp = dp->v_mountedhere;
 		KASSERT(mp != NULL,
 		    ("%s: NULL mountpoint for VIRF_MOUNTPOINT vnode", __func__));
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1202,8 +1202,9 @@
 	MNT_IUNLOCK(mp);
 
 	VI_LOCK(vp);
-	vn_irflag_set_locked(vp, VIRF_MOUNTPOINT);
 	vp->v_mountedhere = mp;
+	atomic_thread_fence_rel();	/* see vfs_lookup() */
+	vn_irflag_set_locked(vp, VIRF_MOUNTPOINT);
 	VI_UNLOCK(vp);
 	cache_purge(vp);