From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752504Ab2KRA3d (ORCPT ); Sat, 17 Nov 2012 19:29:33 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:37977 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752436Ab2KRA3d (ORCPT ); Sat, 17 Nov 2012 19:29:33 -0500 From: Sasha Levin To: mingo@kernel.org Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Sasha Levin Subject: [PATCH] watchdog: Inject NMI when locked up and going to panic Date: Sat, 17 Nov 2012 19:28:53 -0500 Message-Id: <1353198533-24473-1-git-send-email-sasha.levin@oracle.com> X-Mailer: git-send-email 1.8.0 X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Send an NMI to all CPUs when a lockup is detected and the lockup watchdog code is configured to panic. This gives us a fairly uptodate snapshot of all CPUs in the system. This lets us get stack trace of all CPUs which makes life easier trying to debug a deadlock, and the NMI doesn't change anything since the next step is a kernel panic. Signed-off-by: Sasha Levin --- kernel/watchdog.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 9d4c8d5..26a5f88 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -239,10 +239,12 @@ static void watchdog_overflow_callback(struct perf_event *event, if (__this_cpu_read(hard_watchdog_warn) == true) return; - if (hardlockup_panic) + if (hardlockup_panic) { + trigger_all_cpu_backtrace(); panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); - else + } else { WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); + } __this_cpu_write(hard_watchdog_warn, true); return; @@ -323,8 +325,10 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) else dump_stack(); - if (softlockup_panic) + if (softlockup_panic) { + trigger_all_cpu_backtrace(); panic("softlockup: hung tasks"); + } __this_cpu_write(soft_watchdog_warn, true); } else __this_cpu_write(soft_watchdog_warn, false); -- 1.8.0