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Date: Sun, 03 Aug 2008 01:14:40 -0700 (PDT)
Message-Id: <20080803.011440.137037332.davem@davemloft.net>
To: hugh@veritas.com
Cc: mingo@elte.hu, peterz@infradead.org, linux-kernel@vger.kernel.org
Subject: Re: combinatorial explosion in lockdep
From: David Miller <davem@davemloft.net>
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From: Hugh Dickins <hugh@veritas.com>
Date: Fri, 1 Aug 2008 12:57:27 +0100 (BST)

> @@ -113,6 +113,7 @@ static void __spin_lock_debug(spinlock_t
>  		/* lockup suspected: */
>  		if (print_once) {
>  			print_once = 0;
> +			oops_in_progress = 1;
>  			printk(KERN_EMERG "BUG: spinlock lockup on CPU#%d, "
>  					"%s/%d, %p\n",
>  				raw_smp_processor_id(), current->comm,
> @@ -121,6 +122,7 @@ static void __spin_lock_debug(spinlock_t
>  #ifdef CONFIG_SMP
>  			trigger_all_cpu_backtrace();
>  #endif
> +			oops_in_progress = 0;
>  		}
>  	}
>  }

It's probably best to not later clear oops_in_progress when we trigger
an event like this, to ensure that we do actually get any followon
messages on the console.