[PATCH] support for panic at OOM
This patch adds panic_on_oom sysctl under sys.vm.
When sysctl vm.panic_on_oom = 1, the kernel panics intead of killing rogue
processes. And if vm.panic_on_oom 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.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index a46c10f..2dc246a 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -29,6 +29,7 @@
- drop-caches
- zone_reclaim_mode
- zone_reclaim_interval
+- panic_on_oom
==============================================================
@@ -178,3 +179,15 @@
Reduce the interval if undesired off node allocations occur. However, too
frequent scans will have a negative impact onoff node allocation performance.
+=============================================================
+
+panic_on_oom
+
+This enables or disables panic on out-of-memory feature. If this is set to 1,
+the kernel panics when out-of-memory happens. If this is set to 0, the kernel
+will kill some rogue process, called oom_killer. Usually, oom_killer can kill
+rogue processes and system will survive. If you want to panic the system
+rather than killing rogue processes, set this to 1.
+
+The default value is 0.
+
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index cee944d..c713202 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -186,6 +186,7 @@
VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */
VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */
VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */
+ VM_PANIC_ON_OOM=33, /* panic at out-of-memory */
};
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0d656e6..072ac44 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -59,6 +59,7 @@
extern int C_A_D;
extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
+extern int sysctl_panic_on_oom;
extern int max_threads;
extern int sysrq_enabled;
extern int core_uses_pid;
@@ -702,6 +703,14 @@
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = VM_PANIC_ON_OOM,
+ .procname = "panic_on_oom",
+ .data = &sysctl_panic_on_oom,
+ .maxlen = sizeof(sysctl_panic_on_oom),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = VM_OVERCOMMIT_RATIO,
.procname = "overcommit_ratio",
.data = &sysctl_overcommit_ratio,
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 042e643..f9bb3cf 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -22,6 +22,7 @@
#include <linux/jiffies.h>
#include <linux/cpuset.h>
+int sysctl_panic_on_oom;
/* #define DEBUG */
/**
@@ -344,6 +345,8 @@
break;
case CONSTRAINT_NONE:
+ if (sysctl_panic_on_oom)
+ panic("out of memory. panic_on_oom is selected\n");
retry:
/*
* Rambo mode: Shoot down a process and hope it solves whatever