From 9c44bc03fff44ff04237a7d92e35304a0e50c331 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 12 May 2008 21:21:04 +0200
Subject: [PATCH] softlockup: allow panic on lockup
allow users to configure the softlockup detector to generate a panic
instead of a warning message.
high-availability systems might opt for this strict method (combined
with panic_timeout= boot option/sysctl), instead of generating
softlockup warnings ad infinitum.
also, automated tests work better if the system reboots reliably (into
a safe kernel) in case of a lockup.
The full spectrum of configurability is supported: boot option, sysctl
option and Kconfig option.
it's default-disabled.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
Documentation/kernel-parameters.txt | 3 +++
include/linux/sched.h | 3 ++-
kernel/softlockup.c | 21 +++++++++++++++++++++
kernel/sysctl.c | 11 +++++++++++
lib/Kconfig.debug | 26 +++++++++++++++++++++++++-
5 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e07c432c731ff..042588fa12e5c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1971,6 +1971,9 @@ and is between 256 and 4096 characters. It is defined in the file
snd-ymfpci= [HW,ALSA]
+ softlockup_panic=
+ [KNL] Should the soft-lockup detector generate panics.
+
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/sonypi.txt
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5395a6176f4be..71f5972dc48e0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -294,7 +294,8 @@ extern void softlockup_tick(void);
extern void spawn_softlockup_task(void);
extern void touch_softlockup_watchdog(void);
extern void touch_all_softlockup_watchdogs(void);
-extern unsigned long softlockup_thresh;
+extern unsigned int softlockup_panic;
+extern unsigned long softlockup_thresh;
extern unsigned long sysctl_hung_task_check_count;
extern unsigned long sysctl_hung_task_timeout_secs;
extern unsigned long sysctl_hung_task_warnings;
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 01b6522fd92bc..78e0ad21cb0c0 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -27,6 +27,21 @@ static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
static int __read_mostly did_panic;
unsigned long __read_mostly softlockup_thresh = 60;
+/*
+ * Should we panic (and reboot, if panic_timeout= is set) when a
+ * soft-lockup occurs:
+ */
+unsigned int __read_mostly softlockup_panic =
+ CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
+
+static int __init softlockup_panic_setup(char *str)
+{
+ softlockup_panic = simple_strtoul(str, NULL, 0);
+
+ return 1;
+}
+__setup("softlockup_panic=", softlockup_panic_setup);
+
static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
@@ -120,6 +135,9 @@ void softlockup_tick(void)
else
dump_stack();
spin_unlock(&print_lock);
+
+ if (softlockup_panic)
+ panic("softlockup: hung tasks");
}
/*
@@ -172,6 +190,9 @@ static void check_hung_task(struct task_struct *t, unsigned long now)
t->last_switch_timestamp = now;
touch_nmi_watchdog();
+
+ if (softlockup_panic)
+ panic("softlockup: blocked tasks");
}
/*
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 29116652dca82..2d3b388c402db 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -727,6 +727,17 @@ static struct ctl_table kern_table[] = {
},
#endif
#ifdef CONFIG_DETECT_SOFTLOCKUP
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "softlockup_panic",
+ .data = &softlockup_panic,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_doulongvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
{
.ctl_name = CTL_UNNUMBERED,
.procname = "softlockup_thresh",
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d2099f41aa1eb..509ae35a9ef5c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -147,7 +147,7 @@ config DETECT_SOFTLOCKUP
help
Say Y here to enable the kernel to detect "soft lockups",
which are bugs that cause the kernel to loop in kernel
- mode for more than 10 seconds, without giving other tasks a
+ mode for more than 60 seconds, without giving other tasks a
chance to run.
When a soft-lockup is detected, the kernel will print the
@@ -159,6 +159,30 @@ config DETECT_SOFTLOCKUP
can be detected via the NMI-watchdog, on platforms that
support it.)
+config BOOTPARAM_SOFTLOCKUP_PANIC
+ bool "Panic (Reboot) On Soft Lockups"
+ depends on DETECT_SOFTLOCKUP
+ help
+ Say Y here to enable the kernel to panic 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.
+
+ The panic can be used in combination with panic_timeout,
+ to cause the system to reboot automatically after a
+ lockup has been detected. 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_PANIC_VALUE
+ int
+ depends on DETECT_SOFTLOCKUP
+ range 0 1
+ default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
+ default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
+
config SCHED_DEBUG
bool "Collect scheduler debugging info"
depends on DEBUG_KERNEL && PROC_FS
--
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