From 6390d0aecac09912beb617f9e153d72b86e0cb63 Mon Sep 17 00:00:00 2001
From: chs <chs@NetBSD.org>
Date: Sun, 30 Jan 2005 17:23:05 +0000
Subject: [PATCH] hack around a UVM problem that causes hangs when large
 processes fork. see PR 26908 for details.

---
 sys/uvm/uvm_amap.c    | 15 +++++++++++++--
 sys/uvm/uvm_pdaemon.c | 16 +++++++++++++---
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/sys/uvm/uvm_amap.c b/sys/uvm/uvm_amap.c
index f43567a22b37..68bd6b4c2bb4 100644
--- a/sys/uvm/uvm_amap.c
+++ b/sys/uvm/uvm_amap.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: uvm_amap.c,v 1.56 2005/01/01 21:00:06 yamt Exp $	*/
+/*	$NetBSD: uvm_amap.c,v 1.57 2005/01/30 17:23:05 chs Exp $	*/
 
 /*
  *
@@ -42,7 +42,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.56 2005/01/01 21:00:06 yamt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_amap.c,v 1.57 2005/01/30 17:23:05 chs Exp $");
 
 #undef UVM_AMAP_INLINE		/* enable/disable amap inlines */
 
@@ -204,6 +204,17 @@ fail2:
 	free(amap->am_slots, M_UVMAMAP);
 fail1:
 	pool_put(&uvm_amap_pool, amap);
+
+	/*
+	 * XXX hack to tell the pagedaemon how many pages we need,
+	 * since we can need more than it would normally free.
+	 */
+	if (waitf == M_NOWAIT) {
+		extern int uvm_extrapages;
+		uvm_extrapages += ((sizeof(int) * 2 +
+				    sizeof(struct vm_anon *)) *
+				   totalslots) >> PAGE_SHIFT;
+	}
 	return (NULL);
 }
 
diff --git a/sys/uvm/uvm_pdaemon.c b/sys/uvm/uvm_pdaemon.c
index f58b2f2e23dd..e5a6bbd7d08d 100644
--- a/sys/uvm/uvm_pdaemon.c
+++ b/sys/uvm/uvm_pdaemon.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: uvm_pdaemon.c,v 1.60 2004/10/03 08:47:48 enami Exp $	*/
+/*	$NetBSD: uvm_pdaemon.c,v 1.61 2005/01/30 17:23:05 chs 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 1.60 2004/10/03 08:47:48 enami Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.61 2005/01/30 17:23:05 chs Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -103,6 +103,11 @@ void		uvmpd_scan(void);
 void		uvmpd_scan_inactive(struct pglist *);
 void		uvmpd_tune(void);
 
+/*
+ * XXX hack to avoid hangs when large processes fork.
+ */
+int uvm_extrapages;
+
 /*
  * uvm_wait: wait (sleep) for the page daemon to free some pages
  *
@@ -183,6 +188,9 @@ uvmpd_tune(void)
 	if (uvmexp.freetarg <= uvmexp.freemin)
 		uvmexp.freetarg = uvmexp.freemin + 1;
 
+	uvmexp.freetarg += uvm_extrapages;
+	uvm_extrapages = 0;
+
 	/* uvmexp.inactarg: computed in main daemon loop */
 
 	uvmexp.wiredmax = uvmexp.npages / 3;
@@ -198,6 +206,7 @@ void
 uvm_pageout(void *arg)
 {
 	int bufcnt, npages = 0;
+	int extrapages = 0;
 	UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist);
 
 	UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0);
@@ -230,8 +239,9 @@ uvm_pageout(void *arg)
 		 */
 
 		uvm_lock_pageq();
-		if (npages != uvmexp.npages) {	/* check for new pages? */
+		if (npages != uvmexp.npages || extrapages != uvm_extrapages) {
 			npages = uvmexp.npages;
+			extrapages = uvm_extrapages;
 			uvmpd_tune();
 		}