From c82b01813e76de4e88702e49695f3d173f523544 Mon Sep 17 00:00:00 2001
From: John Dyson <dyson@FreeBSD.org>
Date: Mon, 10 Jun 1996 00:25:40 +0000
Subject: [PATCH] Keep the vm_fault/vm_pageout from getting into an "infinite
 paging loop", by reserving "cached" pages before waking up the pageout
 daemon.  This will reserve the faulted page, and keep the system from
 thrashing itself to death given this condition.

---
 sys/vm/vm_fault.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index d76fcc58444a..c9a6c8cb392c 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -66,7 +66,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_fault.c,v 1.48 1996/06/01 20:50:57 dyson Exp $
+ * $Id: vm_fault.c,v 1.49 1996/06/08 06:48:32 dyson Exp $
  */
 
 /*
@@ -261,6 +261,7 @@ RetryFault:;
 	while (TRUE) {
 		m = vm_page_lookup(object, pindex);
 		if (m != NULL) {
+			int queue;
 			/*
 			 * If the page is being brought in, wait for it and
 			 * then retry.
@@ -280,18 +281,21 @@ RetryFault:;
 				goto RetryFault;
 			}
 
+			queue = m->queue;
+			vm_page_unqueue_nowakeup(m);
+
 			/*
 			 * Mark page busy for other processes, and the pagedaemon.
 			 */
-			if ((m->queue == PQ_CACHE) &&
+			if ((queue == PQ_CACHE) &&
 			    (cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
+				vm_page_activate(m);
 				UNLOCK_AND_DEALLOCATE;
 				VM_WAIT;
 				goto RetryFault;
 			}
 
 			m->flags |= PG_BUSY;
-			vm_page_unqueue_nowakeup(m);
 
 			if (m->valid &&
 				((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&