diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
@@ -781,6 +781,7 @@
 	znode_t *zdp = VTOZ(dvp);
 	znode_t *zp;
 	zfsvfs_t *zfsvfs = zdp->z_zfsvfs;
+	seqc_t dvp_seqc;
 	int	error = 0;
 
 	/*
@@ -806,6 +807,8 @@
 	ZFS_ENTER(zfsvfs);
 	ZFS_VERIFY_ZP(zdp);
 
+	dvp_seqc = vn_seqc_read_any(dvp);
+
 	*vpp = NULL;
 
 	if (flags & LOOKUP_XATTR) {
@@ -975,6 +978,24 @@
 		}
 	}
 
+	if ((cnp->cn_flags & ISDOTDOT) != 0) {
+		/*
+		 * FIXME: zfs_lookup_lock relocks vnodes and does nothing to
+		 * handle races. In particular different callers may end up
+		 * with different vnodes and will try to add conflicting
+		 * entries to the namecache.
+		 *
+		 * While finding different result may be acceptable in face
+		 * of concurrent modification, adding conflicting entries
+		 * trips over an assert in the namecache.
+		 *
+		 * Ultimately let an entry through once everything settles.
+		 */
+		if (!vn_seqc_consistent(dvp, dvp_seqc)) {
+			cnp->cn_flags &= ~MAKEENTRY;
+		}
+	}
+
 	/* Insert name into cache (as non-existent) if appropriate. */
 	if (zfsvfs->z_use_namecache && !zfsvfs->z_replay &&
 	    error == ENOENT && (cnp->cn_flags & MAKEENTRY) != 0)