linux-kernel - Re: lockdep: access percpu variable too early

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Message-ID: <20130306102057.GB6587@gmail.com>
Date:	Wed, 6 Mar 2013 11:20:57 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: lockdep: access percpu variable too early


* Ming Lei <ming.lei@...onical.com> wrote:

> Hi,
> 
> The percpu variables of 'lockdep_stats' and 'cpu_lock_stat' may be accessed before 
> percpu area is brought up in case of CONFIG_DEBUG_LOCKDEP/CONFIG_LOCK_STAT, so 
> these variables in non-boot CPUs will be initialized incorrectly.

What's the practical effect of it? Do we copy the value from the boot CPU and thus 
the secondary CPUs start with slightly increased stats?

Thanks,

	Ingo
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