From 03657519851cd180983db4bd0c38eaeed4aa2962 Mon Sep 17 00:00:00 2001
From: Kyle McMartin <kyle@treachery.i.jkkm.org>
Date: Mon, 11 Jan 2010 08:25:12 -0500
Subject: linux-2.6-debug-vm-would-have-oomkilled.patch

---
 kernel/sysctl.c |    8 ++++++++
 mm/oom_kill.c   |    7 +++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a68b24..72a4ff1 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -71,6 +71,7 @@ extern int sysctl_overcommit_ratio;
 extern int sysctl_panic_on_oom;
 extern int sysctl_oom_kill_allocating_task;
 extern int sysctl_oom_dump_tasks;
+extern int sysctl_would_have_oomkilled;
 extern int max_threads;
 extern int core_uses_pid;
 extern int suid_dumpable;
@@ -973,6 +974,13 @@ static struct ctl_table vm_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 	{
+		.procname	= "would_have_oomkilled",
+		.data		= &sysctl_would_have_oomkilled,
+		.maxlen		= sizeof(sysctl_would_have_oomkilled),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+	{
 		.procname	= "overcommit_ratio",
 		.data		= &sysctl_overcommit_ratio,
 		.maxlen		= sizeof(sysctl_overcommit_ratio),
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f52481b..a892f07 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -31,6 +31,7 @@
 int sysctl_panic_on_oom;
 int sysctl_oom_kill_allocating_task;
 int sysctl_oom_dump_tasks;
+int sysctl_would_have_oomkilled;
 static DEFINE_SPINLOCK(zone_scan_lock);
 /* #define DEBUG */
 
@@ -396,6 +397,12 @@ static void __oom_kill_task(struct task_struct *p, int verbose)
 		return;
 	}
 
+	if (sysctl_would_have_oomkilled == 1) {
+		printk(KERN_ERR "Would have killed process %d (%s). But continuing instead.\n",
+				task_pid_nr(p), p->comm);
+		return;
+	}
+
 	if (verbose)
 		printk(KERN_ERR "Killed process %d (%s) "
 		       "vsz:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
-- 
1.6.5.2