Re: do_syslog/__down_trylock lockup in current BK

From: Daniel Jacobowitz (dan@debian.org)
Date: Mon Sep 09 2002 - 15:50:43 EST

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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