kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup
In many cases of hardlockup reports, it's actually not possible to know
why it triggered, because the CPU that got stuck is usually waiting on a
resource (with IRQs disabled) in posession of some other CPU is holding.
IOW, we are often looking at the stacktrace of the victim and not the
actual offender.
Introduce sysctl / cmdline parameter that makes it possible to have
hardlockup detector perform all-CPU backtrace.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 78488e0..7ec5b86 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -73,6 +73,7 @@
extern int watchdog_thresh;
extern unsigned long *watchdog_cpumask_bits;
extern int sysctl_softlockup_all_cpu_backtrace;
+extern int sysctl_hardlockup_all_cpu_backtrace;
struct ctl_table;
extern int proc_watchdog(struct ctl_table *, int ,
void __user *, size_t *, loff_t *);