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kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup

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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>
This commit is contained in:
Jiri Kosina
2015-11-05 18:44:41 -08:00
committed by Linus Torvalds
parent ee7fed5405
commit 55537871ef
5 changed files with 55 additions and 5 deletions
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9
kernel/sysctl.c
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@ -898,6 +898,15 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
},
{
.procname = "hardlockup_all_cpu_backtrace",
.data = &sysctl_hardlockup_all_cpu_backtrace,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &one,
},
#endif /* CONFIG_SMP */
#endif
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)