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Date: Mon, 9 Sep 2002 16:50:43 -0400
From: Daniel Jacobowitz <dan@debian.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@transmeta.com>, linux-kernel@vger.kernel.org
Subject: Re: do_syslog/__down_trylock lockup in current BK
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On Mon, Sep 09, 2002 at 10:43:51PM +0200, Ingo Molnar wrote:
> 
> the following assert triggers and catches the lockup:
> 
> --- linux/kernel/exit.c.orig	Mon Sep  9 21:59:24 2002
> +++ linux/kernel/exit.c	Mon Sep  9 22:38:44 2002
> @@ -461,6 +461,8 @@
>  		ptrace_unlink (p);
>  
>  		list_del_init(&p->sibling);
> +		if (p->parent == father && p->parent == p->real_parent)
> +			BUG();
>  		p->parent = p->real_parent;
>  		list_add_tail(&p->sibling, &p->parent->children);
>  	}
> 
> so somehow we can end up having parent == real_parent?

When is this happening?  It's not necessarily a bug.  If the process
was traced, then __ptrace_unlink will set p->parent = p->real_parent
when it unlinks.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer
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