From ef6020d18714af9f7540fd367ac87f7a831ecf99 Mon Sep 17 00:00:00 2001
From: Mike Silbersack <silby@FreeBSD.org>
Date: Tue, 19 Feb 2002 18:34:02 +0000
Subject: [PATCH] Changes to make the OOM killer much more effective:

- Allow the OOM killer to target processes currently locked in
  memory.  These very often are the ones doing the memory hogging.
- Drop the wakeup priority of processes currently sleeping while
  waiting for their page fault to complete.  In order for the OOM
  killer to work well, the killed process and other system processes
  waiting on memory must be allowed to wakeup first.

Reviewed by:	dillon
MFC after:	1 week
---
 sys/vm/vm_fault.c   |  4 ++--
 sys/vm/vm_page.c    | 23 +++++++++++++++++++++++
 sys/vm/vm_pageout.c |  3 +--
 sys/vm/vm_pageout.h |  2 ++
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 79e122420adf..77e161514c2d 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -347,7 +347,7 @@ RetryFault:;
 			if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) {
 				vm_page_activate(fs.m);
 				unlock_and_deallocate(&fs);
-				VM_WAIT;
+				VM_WAITPFAULT;
 				goto RetryFault;
 			}
 
@@ -388,7 +388,7 @@ RetryFault:;
 			}
 			if (fs.m == NULL) {
 				unlock_and_deallocate(&fs);
-				VM_WAIT;
+				VM_WAITPFAULT;
 				goto RetryFault;
 			}
 		}
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index abc419455841..2c0052b9c867 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -967,6 +967,7 @@ loop:
  *	vm_wait:	(also see VM_WAIT macro)
  *
  *	Block until free pages are available for allocation
+ *	- Called in various places before memory allocations.
  */
 
 void
@@ -988,6 +989,28 @@ vm_wait(void)
 	splx(s);
 }
 
+/*
+ *	vm_waitpfault:	(also see VM_WAITPFAULT macro)
+ *
+ *	Block until free pages are available for allocation
+ *	- Called only in vm_fault so that processes page faulting
+ *	  can be easily tracked.
+ */
+
+void
+vm_waitpfault(void)
+{
+	int s;
+
+	s = splvm();
+	if (!vm_pages_needed) {
+		vm_pages_needed = 1;
+		wakeup(&vm_pages_needed);
+	}
+	tsleep(&cnt.v_free_count, PUSER, "pfault", 0);
+	splx(s);
+}
+
 /*
  *	vm_page_activate:
  *
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index 57f22b2a8ba2..657f5e71a75c 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -1141,8 +1141,7 @@ rescan0:
 			/*
 			 * if this is a system process, skip it
 			 */
-			if ((p->p_flag & P_SYSTEM) || (p->p_lock > 0) ||
-			    (p->p_pid == 1) ||
+			if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
 			    ((p->p_pid < 48) && (vm_swap_size != 0))) {
 				PROC_UNLOCK(p);
 				continue;
diff --git a/sys/vm/vm_pageout.h b/sys/vm/vm_pageout.h
index bfcfbb110a3f..fc88589d5976 100644
--- a/sys/vm/vm_pageout.h
+++ b/sys/vm/vm_pageout.h
@@ -100,7 +100,9 @@ extern int vm_pageout_deficit;
 
 extern void pagedaemon_wakeup __P((void));
 #define VM_WAIT vm_wait()
+#define VM_WAITPFAULT vm_waitpfault()
 extern void vm_wait __P((void));
+extern void vm_waitpfault __P((void));
 
 #ifdef _KERNEL
 void vm_pageout_page __P((vm_page_t, vm_object_t));