diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 3eff780fd8da0a452197e036c4ed85247c07b8fa..3c9d19321df5728f3f119c67a1d8c394baded875 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -5420,9 +5420,14 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 		int len = xdr->buf->len - post_err_offset;
 
 		so->so_replay.rp_status = op->status;
-		so->so_replay.rp_buflen = len;
-		read_bytes_from_xdr_buf(xdr->buf, post_err_offset,
+		if (len <= NFSD4_REPLAY_ISIZE) {
+			so->so_replay.rp_buflen = len;
+			read_bytes_from_xdr_buf(xdr->buf,
+						post_err_offset,
 						so->so_replay.rp_buf, len);
+		} else {
+			so->so_replay.rp_buflen = 0;
+		}
 	}
 status:
 	*p = op->status;
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index cbddcf484dbac76ea55115ba18d734dbfaf99cf6..6ec195367113c2928c042922ae35d195f1224e49 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -430,11 +430,18 @@ struct nfs4_client_reclaim {
 	struct xdr_netobj	cr_princhash;
 };
 
-/* A reasonable value for REPLAY_ISIZE was estimated as follows:  
- * The OPEN response, typically the largest, requires 
- *   4(status) + 8(stateid) + 20(changeinfo) + 4(rflags) +  8(verifier) + 
- *   4(deleg. type) + 8(deleg. stateid) + 4(deleg. recall flag) + 
- *   20(deleg. space limit) + ~32(deleg. ace) = 112 bytes 
+/*
+ * REPLAY_ISIZE is sized for an OPEN response with delegation:
+ *   4(status) + 8(stateid) + 20(changeinfo) + 4(rflags) +
+ *   8(verifier) + 4(deleg. type) + 8(deleg. stateid) +
+ *   4(deleg. recall flag) + 20(deleg. space limit) +
+ *   ~32(deleg. ace) = 112 bytes
+ *
+ * Some responses can exceed this. A LOCK denial includes the conflicting
+ * lock owner, which can be up to 1024 bytes (NFS4_OPAQUE_LIMIT). Responses
+ * larger than REPLAY_ISIZE are not cached in rp_ibuf; only rp_status is
+ * saved. Enlarging this constant increases the size of every
+ * nfs4_stateowner.
  */
 
 #define NFSD4_REPLAY_ISIZE       112