Index: sys/kern/sys_pipe.c
===================================================================
--- sys/kern/sys_pipe.c	(revision 228073)
+++ sys/kern/sys_pipe.c	(working copy)
@@ -569,12 +569,6 @@
 		/* If we're not backing this pipe, no need to do anything. */
 		error = 0;
 	}
-	if (error == 0) {
-		pipe->pipe_ino = alloc_unr(pipeino_unr);
-		if (pipe->pipe_ino == -1)
-			/* pipeclose will clear allocated kva */
-			error = ENOMEM;
-	}
 	return (error);
 }
 
@@ -1399,6 +1393,7 @@
 	struct thread *td;
 {
 	struct pipe *pipe = fp->f_data;
+	int new_unr;
 #ifdef MAC
 	int error;
 
@@ -1408,6 +1403,12 @@
 	if (error)
 		return (error);
 #endif
+	if (pipe->pipe_ino == 0) {
+		new_unr = alloc_unr(pipeino_unr);
+		if (new_unr == -1)
+			return (ENOMEM);
+		pipe->pipe_ino = new_unr;
+	}
 	bzero(ub, sizeof(*ub));
 	ub->st_mode = S_IFIFO;
 	ub->st_blksize = PAGE_SIZE;
@@ -1554,7 +1555,7 @@
 	} else
 		PIPE_UNLOCK(cpipe);
 
-	if (ino > 0)
+	if (ino != 0)
 		free_unr(pipeino_unr, cpipe->pipe_ino);
 }