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Date: Sun, 11 Dec 2011 14:48:55 -0800
From: Vincent Li <vincent.mc.li@...il.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Don Zickus <dzickus@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Andrew Morton <akpm@...ux-foundation.org>,
Mandeep Singh Baines <msb@...omium.org>,
linux-kernel@...r.kernel.org, Vincent Li <vincent.mc.li@...il.com>
Subject: [PATCH] Softlockup (out of cpu) killer
In kernel, there is out of memory (OOM) killer, why not make an out of cpu (OOC) killer?
I tested following patch by running an user-space cpu hogging process and the softlockukp
detector killed the process successfully.
Softlockup could be caused by user-space process hogging cpu, add softlockup_kill kernel
config to allow kernel to kill the user space cpu hogging process. this feature is
useful for high availability systems that have uptime gurantees and where a softlockup
must be resolved ASAP
echo 1 > /proc/sys/kernel/softlockukp_kill to enable cpu hog process killer
echo 0 > /proc/sys/kernel/softlockup_kill to disable cpu hog process killer
Signed-off-by: Vincent Li <vincent.mc.li@...il.com>
---
Documentation/kernel-parameters.txt | 4 ++++
include/linux/sched.h | 1 +
kernel/sysctl.c | 9 +++++++++
kernel/watchdog.c | 18 ++++++++++++++++++
lib/Kconfig.debug | 21 +++++++++++++++++++++
5 files changed, 53 insertions(+), 0 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 81c287f..1609387 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2418,6 +2418,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
[KNL] Should the soft-lockup detector generate panics.
Format: <integer>
+ softlockup_panic=
+ [KNL] Should the soft-lockup detector kill cpu hog process.
+ Format: <integer>
+
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/laptops/sonypi.txt
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1c4f3e9..4783fac 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -315,6 +315,7 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos);
extern unsigned int softlockup_panic;
+extern unsigned int softlockup_kill;
void lockup_detector_init(void);
#else
static inline void touch_softlockup_watchdog(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ae27196..e79ea9c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -770,6 +770,15 @@ static struct ctl_table kern_table[] = {
.extra2 = &one,
},
{
+ .procname = "softlockup_kill",
+ .data = &softlockup_kill,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+ {
.procname = "nmi_watchdog",
.data = &watchdog_enabled,
.maxlen = sizeof (int),
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1d7bca7..5832a90 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -75,6 +75,17 @@ static int __init softlockup_panic_setup(char *str)
}
__setup("softlockup_panic=", softlockup_panic_setup);
+unsigned int __read_mostly softlockup_kill =
+ CONFIG_BOOTPARAM_SOFTLOCKUP_KILL_VALUE;
+
+static int __init softlockup_kill_setup(char *str)
+{
+ softlockup_kill = simple_strtoul(str, NULL, 0);
+
+ return 1;
+}
+__setup("softlockup_kill=", softlockup_kill_setup);
+
static int __init nowatchdog_setup(char *str)
{
watchdog_enabled = 0;
@@ -306,6 +317,13 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
else
dump_stack();
+ if (softlockup_kill) {
+ printk(KERN_ERR "Kill softlockup process [%s:%d] on CPU#%d\n",
+ current->comm, task_pid_nr(current),
+ smp_processor_id());
+ force_sig(SIGKILL, current);
+ }
+
if (softlockup_panic)
panic("softlockup: hung tasks");
__this_cpu_write(soft_watchdog_warn, true);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 82928f5..e4afc98 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -224,6 +224,27 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
+config BOOTPARAM_SOFTLOCKUP_KILL
+ bool "Kill (cpu hog process) On Soft Lockups"
+ depends on LOCKUP_DETECTOR
+ help
+ Say Y here to enable the kernel to kill cpu hog process on
+ "soft lockups", which are bugs that cause the kernel to
+ loop in kernel mode for more than 60 seconds, without giving
+ other tasks a chance to run.
+
+ This feature is useful for high-availability systems that
+ have uptime guarantees and where a lockup must be resolved ASAP.
+
+ Say N if unsure.
+
+config BOOTPARAM_SOFTLOCKUP_KILL_VALUE
+ int
+ depends on LOCKUP_DETECTOR
+ range 0 1
+ default 0 if !BOOTPARAM_SOFTLOCKUP_KILL
+ default 1 if BOOTPARAM_SOFTLOCKUP_KILL
+
config DETECT_HUNG_TASK
bool "Detect Hung Tasks"
depends on DEBUG_KERNEL
--
1.7.0.4
--
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