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>
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@ -1597,11 +1597,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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Format: [state][,regs][,debounce][,die]
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nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
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Format: [panic,][num]
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Format: [panic,][nopanic,][num]
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Valid num: 0
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0 - turn nmi_watchdog off
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When panic is specified, panic when an NMI watchdog
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timeout occurs.
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timeout occurs (or 'nopanic' to override the opposite
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default).
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This is useful when you use a panic=... timeout and
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need the box quickly up again.
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@ -48,12 +48,15 @@ static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
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* Should we panic when a soft-lockup or hard-lockup occurs:
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*/
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static int hardlockup_panic;
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static int hardlockup_panic =
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CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
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static int __init hardlockup_panic_setup(char *str)
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{
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if (!strncmp(str, "panic", 5))
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hardlockup_panic = 1;
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else if (!strncmp(str, "nopanic", 7))
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hardlockup_panic = 0;
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else if (!strncmp(str, "0", 1))
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watchdog_enabled = 0;
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return 1;
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@ -171,6 +171,23 @@ config HARDLOCKUP_DETECTOR
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def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
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!ARCH_HAS_NMI_WATCHDOG
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config BOOTPARAM_HARDLOCKUP_PANIC
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bool "Panic (Reboot) On Hard Lockups"
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depends on LOCKUP_DETECTOR
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help
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Say Y here to enable the kernel to panic on "hard lockups",
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which are bugs that cause the kernel to loop in kernel
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mode with interrupts disabled for more than 60 seconds.
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Say N if unsure.
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config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
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int
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depends on LOCKUP_DETECTOR
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range 0 1
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default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
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default 1 if BOOTPARAM_HARDLOCKUP_PANIC
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config BOOTPARAM_SOFTLOCKUP_PANIC
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bool "Panic (Reboot) On Soft Lockups"
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depends on LOCKUP_DETECTOR
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