From 7608362b58a1485e1ea1e5e91492bbc33e8a7bf3 Mon Sep 17 00:00:00 2001
From: yamt <yamt@NetBSD.org>
Date: Thu, 7 Feb 2008 12:24:16 +0000
Subject: [PATCH] swapcluster_flush: handle nused==0, which can happen if
 swapcluster_add failed. PR/37669 from Andrew Doran.

---
 sys/uvm/uvm_pdaemon.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/sys/uvm/uvm_pdaemon.c b/sys/uvm/uvm_pdaemon.c
index 7cac2f934785..38ee3cc720aa 100644
--- a/sys/uvm/uvm_pdaemon.c
+++ b/sys/uvm/uvm_pdaemon.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: uvm_pdaemon.c,v 1.90 2008/01/28 12:22:47 yamt Exp $	*/
+/*	$NetBSD: uvm_pdaemon.c,v 1.91 2008/02/07 12:24:16 yamt Exp $	*/
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -71,7 +71,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.90 2008/01/28 12:22:47 yamt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.91 2008/02/07 12:24:16 yamt Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_readahead.h"
@@ -533,10 +533,12 @@ swapcluster_flush(struct swapcluster *swc, bool now)
 	 * now start the pageout.
 	 */
 
-	uvmexp.pdpageouts++;
-	uvm_pageout_start(nused);
-	error = uvm_swap_put(slot, swc->swc_pages, nused, 0);
-	KASSERT(error == 0);
+	if (nused > 0) {
+		uvmexp.pdpageouts++;
+		uvm_pageout_start(nused);
+		error = uvm_swap_put(slot, swc->swc_pages, nused, 0);
+		KASSERT(error == 0);
+	}
 
 	/*
 	 * zero swslot to indicate that we are