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Date: Sun, 16 Feb 2003 18:41:46 +0100
From: Manfred Spraul <manfred@colorfullife.com>
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To: "Martin J. Bligh" <mbligh@aracnet.com>
CC: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@transmeta.com>,
       Anton Blanchard <anton@samba.org>,
       Zwane Mwaikambo <zwane@holomorphy.com>
Subject: Re: Fw: 2.5.61 oops running SDET
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>
>
>OK, I did the following, which is what I think you wanted, plus Zwane's
>observation that task_state acquires the task_struct lock (we're the only 
>caller, so I just removed it), but I still get the same panic and this time
>the box hung.
>

AFAICS both exec and exit rely on write_lock_irq(tasklist_lock) for 
synchronization of changes to tsk->sig{,hand}.
I bet an __exit_sighand occurs in the middle of proc_pid_status() - 
after the NULL test, before the access in task_sig.

Martin, could you check what happens if you do not release the 
tasklist_lock until after the task_sig()?

--
    Manfred