Message-ID: <4203F40C.8040707@yahoo.com.au>
Date: Sat, 05 Feb 2005 09:15:40 +1100
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
CC: Roland Mc Grath <roland@redhat.com>, Jeff Dike <jdike@addtoit.com>,
       BlaisorBlade <blaisorblade_spam@yahoo.it>,
       user-mode-linux devel 
	<user-mode-linux-devel@lists.sourceforge.net>,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: Race condition in ptrace
References: <42021E35.8050601@fujitsu-siemens.com> <4202C18F.5010605@yahoo.com.au> <42036C2C.5040503@fujitsu-siemens.com>
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Bodo Stroesser wrote:
> Nick Piggin wrote:
> 
>> Bodo Stroesser wrote:

>> I don't see how this could help because AFAIKS, child->saving is only
>> set and cleared while the runqueue is locked. And the same runqueue lock
>> is taken by wait_task_inactive.
>>
> 
> Sorry, that not right. There are some routines called by sched(), that 
> release
> and reacquire the runqueue lock.
> 

Oh yeah, it is the wake_sleeping_dependent / dependent_sleeper crap.
Sorry, you are right. And that's definitely a bug in sched.c, because
it breaks wait_task_inactive, as you've rightly observed.

Andrew, IMO this is another bug to hold 2.6.11 for.

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