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authorDon Zickus <dzickus@redhat.com>2011-03-23 00:34:16 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-23 01:44:12 +0100
commitfef2c9bc1b54c0261324a96e948c0b849796e896 (patch)
treea4dd2733621d9fe1f8ec65d9ef30867ed09b640f
parentcalibrate: retry with wider bounds when converge seems to fail (diff)
downloadlinux-fef2c9bc1b54c0261324a96e948c0b849796e896.tar.xz
linux-fef2c9bc1b54c0261324a96e948c0b849796e896.zip
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>
-rw-r--r--Documentation/kernel-parameters.txt5
-rw-r--r--kernel/watchdog.c5
-rw-r--r--lib/Kconfig.debug17
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