Commit fef2c9bc authored by Don Zickus's avatar Don Zickus Committed by Linus Torvalds
Browse files

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: default avatarDon Zickus <dzickus@redhat.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b1b5f65e

Documentation/kernel-parameters.txt

+3 −2
Original line number Diff line number Diff line
@@ -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.

kernel/watchdog.c

+4 −1
Original line number Diff line number Diff line
@@ -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;

lib/Kconfig.debug

+17 −0
Original line number Diff line number Diff line
@@ -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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