lkml.org 
[lkml]   [2006]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] support for panic at OOM
This patch adds a feature to panic at OOM, oom_die.

When sysctl vm.oom_die = 1, the kernel panics intead of killing
rogue processes. And if vm.oom_die is 0 the kernel will do
oom_kill() in the same way as it does today. Of course, the
default value is 0 and only root can modifies it.

In general, oom_killer works well and kill rogue processes. So
the whole system can survive. But there are environments where
panic is preferable rather than kill some processes.

For example, a failover system can replace a broken system with
back-up system immediately at panic, so it doesn't need oom_kill.

Considering a failover cluster system, a failover service puts
all nodes under its observation. When a node panics, the failover
system can replace it with new one immediately. But if oom_kill runs
and kills some processes, the system will go to partial broken
state. This partial broken state is sometimes difficult to be
detected. The worst case is that a failover daemon is killed
(possibility is not 0%), the whole system will be unstable.

Another case is crash-dump supported system. If the system panics
at OOM, crash dump can preserve *all* information about system.
Because SIGKILL cannot cause process coredump, oom killer cannot
preserve any hints except for the message log.

thanks,
-Kame
==

This patch adds oom_die sysctl under sys.vm.

When oom_die==1, system panic at out_of_memory istead of kill some
process. In some situation, I think panic is more useful than kill.
This patch is against 2.6.17-rc1-mm2.

Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Index: linux-2.6.17-rc1-mm2/kernel/sysctl.c
===================================================================
--- linux-2.6.17-rc1-mm2.orig/kernel/sysctl.c
+++ linux-2.6.17-rc1-mm2/kernel/sysctl.c
@@ -60,6 +60,7 @@ extern int proc_nr_files(ctl_table *tabl
extern int C_A_D;
extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
+extern int sysctl_oom_die;
extern int max_threads;
extern int sysrq_enabled;
extern int core_uses_pid;
@@ -718,6 +719,14 @@ static ctl_table vm_table[] = {
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = VM_OOM_DIE,
+ .procname = "oom_die",
+ .data = &sysctl_oom_die,
+ .maxlen = sizeof(sysctl_oom_die),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = VM_OVERCOMMIT_RATIO,
.procname = "overcommit_ratio",
.data = &sysctl_overcommit_ratio,
Index: linux-2.6.17-rc1-mm2/mm/oom_kill.c
===================================================================
--- linux-2.6.17-rc1-mm2.orig/mm/oom_kill.c
+++ linux-2.6.17-rc1-mm2/mm/oom_kill.c
@@ -23,7 +23,7 @@
#include <linux/cpuset.h>

/* #define DEBUG */
-
+int sysctl_oom_die = 0;
/**
* oom_badness - calculate a numeric value for how bad this task has been
* @p: task struct of which task we should calculate
@@ -290,6 +290,12 @@ static struct mm_struct *oom_kill_proces
return oom_kill_task(p, message);
}

+
+static void oom_die(void)
+{
+ panic("Panic: out of memory: oom_die is selected.");
+}
+
/**
* oom_kill - kill the "best" process when we run out of memory
*
@@ -331,6 +337,8 @@ void out_of_memory(struct zonelist *zone

case CONSTRAINT_NONE:
retry:
+ if (sysctl_oom_die)
+ oom_die();
/*
* Rambo mode: Shoot down a process and hope it solves whatever
* issues we may have.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-04-12 08:53    [W:0.682 / U:0.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site