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Date: Fri, 3 Nov 2006 21:14:21 +0300
From: Oleg Nesterov <oleg@tv-sign.ru>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kernel <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>,
       Linus Torvalds <torvalds@osdl.org>, Ingo Molnar <mingo@elte.hu>,
       arjan <arjan@infradead.org>
Subject: Re: [PATCH] lockdep: fix delayacct locking bug
Message-ID: <20061103181421.GA602@oleg>
References: <1162572527.26989.22.camel@twins>
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On 11/03, Peter Zijlstra wrote:
> 
> ======================================================
> [ INFO: soft-safe -> soft-unsafe lock order detected ]
> 2.6.19-rc4 #1
> ------------------------------------------------------
> mm_tester/1875 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
>  (&tsk->delays->lock){--..}, at: [<c0156652>] __delayacct_add_tsk+0x131/0x1d3
> 
> and this task is already holding:
>  (&sighand->siglock){.+..}, at: [<c0156b69>] taskstats_exit_send+0x52/0x3b2
> which would create a new lock dependency:
>  (&sighand->siglock){.+..} -> (&tsk->delays->lock){--..}

Thanks.

I introduced this bug in
	"[PATCH 5/6] taskstats: kill ->taskstats_lock in favor of ->siglock"

Oleg.

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