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kernel/watchdog.c: allow hardlockup to panic by default

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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>
This commit is contained in:
Don Zickus 2011-03-22 16:34:16 -07:00 committed by Linus Torvalds
parent b1b5f65e53
commit fef2c9bc1b
3 changed files with 24 additions and 3 deletions
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5
Documentation/kernel-parameters.txt
View File

@ -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.

5
kernel/watchdog.c
View File

@ -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;

17
lib/Kconfig.debug
View File

@ -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