diff -r fd9b63dd9e3f external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c
--- external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c
+++ external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c
@@ -2370,6 +2370,8 @@ zfs_umount(vfs_t *vfsp, int fflag)
 #endif
 #ifdef __NetBSD__
 	cred_t *cr = CRED();
+	struct vnode_iterator *marker;
+	vnode_t *vp;
 #endif
 
 	ret = secpolicy_fs_unmount(cr, vfsp);
@@ -2412,12 +2414,27 @@ zfs_umount(vfs_t *vfsp, int fflag)
 	 */
 #ifdef __FreeBSD_kernel__
 	ret = vflush(vfsp, 0, (fflag & MS_FORCE) ? FORCECLOSE : 0, td);
+	if (ret != 0)
+		return (ret);
 #endif
 #ifdef __NetBSD__
-	ret = vflush(vfsp, NULL, (fflag & MS_FORCE) ? FORCECLOSE : 0);
+	/*
+	 * we loop here because zil_commit can bring some vnodes
+	 * back to mnt_vnodelist via zfs_get_data.
+	 */
+	vfs_vnode_iterator_init(vfsp, &marker);
+	while ((vp = vfs_vnode_iterator_next(marker, NULL, NULL))) {
+		VN_RELE(vp);
+		vfs_vnode_iterator_destroy(marker);
+		ret = vflush(vfsp, NULL, (fflag & MS_FORCE) ? FORCECLOSE : 0);
+		if (ret != 0)
+			return (ret);
+		if (zfsvfs->z_log)
+			zil_commit(zfsvfs->z_log, 0);
+		vfs_vnode_iterator_init(vfsp, &marker);
+	}
+	vfs_vnode_iterator_destroy(marker);
 #endif
-	if (ret != 0)
-		return (ret);
 
 #ifdef illumos
 	if (!(fflag & MS_FORCE)) {