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>

1 files changed, 3 insertions, 2 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.