Re: [PATCH] lockdep: fix delayacct locking bug

[Oleg Nesterov <oleg@tv-sign.ru>]

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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