From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 846EF1A0D77 for ; Tue, 24 Feb 2015 14:30:49 +1100 (AEDT) From: Anton Blanchard To: Andrew Morton , Steven Rostedt , Michael Ellerman , Paul Mackerras , Benjamin Herrenschmidt , sam.bobroff@au1.ibm.com, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Russell King , peterz@infradead.org, Don Zickus Subject: [PATCH 5/7] watchdog: Serialise soft lockup errors with die_spin_lock_{irqsave, irqrestore} Date: Tue, 24 Feb 2015 14:30:32 +1100 Message-Id: <1424748634-9153-6-git-send-email-anton@samba.org> In-Reply-To: <1424748634-9153-1-git-send-email-anton@samba.org> References: <1424748634-9153-1-git-send-email-anton@samba.org> Cc: x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , A simple kernel module was used to create concurrent soft and hard lockups: http://ozlabs.org/~anton/junkcode/badguy.tar.gz Signed-off-by: Anton Blanchard --- kernel/watchdog.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 70bf118..dd161e3 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -313,6 +314,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) struct pt_regs *regs = get_irq_regs(); int duration; int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; + unsigned long flags; /* kick the hardlockup detector */ watchdog_interrupt_count(); @@ -384,6 +386,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) } } + die_spin_lock_irqsave(flags); pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); @@ -394,6 +397,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) show_regs(regs); else dump_stack(); + die_spin_unlock_irqrestore(flags); if (softlockup_all_cpu_backtrace) { /* Avoid generating two back traces for current -- 2.1.0