Index: head/sys/kern/uipc_mbuf2.c
===================================================================
--- head/sys/kern/uipc_mbuf2.c
+++ head/sys/kern/uipc_mbuf2.c
@@ -159,7 +159,7 @@
 	 * the target data is on <n, off>.
 	 * if we got enough data on the mbuf "n", we're done.
 	 */
-	if ((off == 0 || offp) && len <= n->m_len - off && writable)
+	if ((off == 0 || offp) && len <= n->m_len - off)
 		goto ok;
 
 	/*