From fef2c9bc1b54c0261324a96e948c0b849796e896 Mon Sep 17 00:00:00 2001 From: Don Zickus 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 Acked-by: Peter Zijlstra Reviewed-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 a3b6882..e9261e9 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 18bb157..054a67c 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 191c5c4..fb0afef 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 -- 2.7.4