From 7a0e26cd13a61905a0734ff093a9026c6ee63400 Mon Sep 17 00:00:00 2001
From: andrew <andrew@NetBSD.org>
Date: Wed, 30 Jun 1993 03:48:25 +0000
Subject: [PATCH] Paul Kranenburg's VM deadlock patches (from patchkit 00147,
 parts 3 & 4). Prevent dirty objects from being cached, and prevent
 vm_page_alloc() from allocating too much memory to non-kernel objects.

---
 sys/vm/vm_object.c | 23 ++++++++++++++++++++++-
 sys/vm/vm_page.c   | 10 +++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 61325dedd32d..1c01709e701d 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vm_object.c	7.4 (Berkeley) 5/7/91
- *	$Id: vm_object.c,v 1.3 1993/05/20 03:59:35 cgd Exp $
+ *	$Id: vm_object.c,v 1.4 1993/06/30 03:48:26 andrew Exp $
  *
  *
  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
@@ -249,6 +249,26 @@ void vm_object_deallocate(object)
 		 */
 
 		if (object->can_persist) {
+			register vm_page_t	p;
+
+			/*
+			 * Check for dirty pages in object
+			 * Print warning as this may signify kernel bugs
+			 * pk@cs.few.eur.nl	- 4/15/93
+			 */
+			p = (vm_page_t) queue_first(&object->memq);
+			while (!queue_end(&object->memq, (queue_entry_t) p)) {
+				VM_PAGE_CHECK(p);
+
+				if (pmap_is_modified(VM_PAGE_TO_PHYS(p)) ||
+								!p->clean) {
+
+					printf("vm_object_dealloc: persistent object %x isn't clean\n", object);
+					goto cant_persist;
+				}
+
+				p = (vm_page_t) queue_next(&p->listq);
+			}
 
 			queue_enter(&vm_object_cached_list, object,
 				vm_object_t, cached_list);
@@ -261,6 +281,7 @@ void vm_object_deallocate(object)
 			vm_object_cache_trim();
 			return;
 		}
+	cant_persist:;
 
 		/*
 		 *	Make sure no one can look us up now.
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 3f19dd74fe0e..1add5abc262a 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vm_page.c	7.4 (Berkeley) 5/7/91
- *	$Id: vm_page.c,v 1.4 1993/05/20 03:59:37 cgd Exp $
+ *	$Id: vm_page.c,v 1.5 1993/06/30 03:48:25 andrew Exp $
  *
  *
  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
@@ -548,6 +548,14 @@ vm_page_t vm_page_alloc(object, offset)
 
 	spl = splimp();				/* XXX */
 	simple_lock(&vm_page_queue_free_lock);
+	if (	object != kernel_object &&
+		object != kmem_object	&&
+		vm_page_free_count <= vm_page_free_reserved) {
+
+		simple_unlock(&vm_page_queue_free_lock);
+		splx(spl);
+		return(NULL);
+	}
 	if (queue_empty(&vm_page_queue_free)) {
 		simple_unlock(&vm_page_queue_free_lock);
 		splx(spl);