From fef2c9bc1b54c0261324a96e948c0b849796e896 Mon Sep 17 00:00:00 2001
From: Don Zickus <dzickus@redhat.com>
Date: Tue, 22 Mar 2011 16:34:16 -0700
Subject: [PATCH] kernel/watchdog.c: allow hardlockup to panic by default
When a cpu is considered stuck, instead of limping along and just printing
a warning, it is sometimes preferred to just panic, let kdump capture the
vmcore and reboot. This gets the machine back into a stable state quickly
while saving the info that got it into a stuck state to begin with.
Add a Kconfig option to allow users to set the hardlockup to panic
by default. Also add in a 'nmi_watchdog=nopanic' to override this.
[akpm@linux-foundation.org: fix strncmp length]
Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/kernel-parameters.txt | 5 +++--
kernel/watchdog.c | 5 ++++-
lib/Kconfig.debug | 17 +++++++++++++++++
3 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a3b688287a8d..e9261e938f6a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1597,11 +1597,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Format: [state][,regs][,debounce][,die]
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
- Format: [panic,][num]
+ Format: [panic,][nopanic,][num]
Valid num: 0
0 - turn nmi_watchdog off
When panic is specified, panic when an NMI watchdog
- timeout occurs.
+ timeout occurs (or 'nopanic' to override the opposite
+ default).
This is useful when you use a panic=... timeout and
need the box quickly up again.
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 18bb15776c57..054a67cca9da 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -48,12 +48,15 @@ static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
* Should we panic when a soft-lockup or hard-lockup occurs:
*/
#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static int hardlockup_panic;
+static int hardlockup_panic =
+ CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
static int __init hardlockup_panic_setup(char *str)
{
if (!strncmp(str, "panic", 5))
hardlockup_panic = 1;
+ else if (!strncmp(str, "nopanic", 7))
+ hardlockup_panic = 0;
else if (!strncmp(str, "0", 1))
watchdog_enabled = 0;
return 1;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 191c5c4c89fc..fb0afeff9436 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -171,6 +171,23 @@ config HARDLOCKUP_DETECTOR
def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
!ARCH_HAS_NMI_WATCHDOG
+config BOOTPARAM_HARDLOCKUP_PANIC
+ bool "Panic (Reboot) On Hard Lockups"
+ depends on LOCKUP_DETECTOR
+ help
+ Say Y here to enable the kernel to panic on "hard lockups",
+ which are bugs that cause the kernel to loop in kernel
+ mode with interrupts disabled for more than 60 seconds.
+
+ Say N if unsure.
+
+config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
+ int
+ depends on LOCKUP_DETECTOR
+ range 0 1
+ default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
+ default 1 if BOOTPARAM_HARDLOCKUP_PANIC
+
config BOOTPARAM_SOFTLOCKUP_PANIC
bool "Panic (Reboot) On Soft Lockups"
depends on LOCKUP_DETECTOR
--
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