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From: Nick Piggin <nickpiggin@yahoo.com.au>
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
Date: Sat, 05 Feb 2005 09:15:40 +1100	[thread overview]
Message-ID: <4203F40C.8040707@yahoo.com.au> (raw)
In-Reply-To: <42036C2C.5040503@fujitsu-siemens.com>

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.


  reply	other threads:[~2005-02-05  0:34 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-03 12:51 Bodo Stroesser
2005-02-04  0:27 ` Nick Piggin
2005-02-04 12:35   ` Bodo Stroesser
2005-02-04 22:15     ` Nick Piggin [this message]
2005-02-04 22:39       ` Andrew Morton
2005-02-04 23:15         ` Nick Piggin
2005-02-05  4:35           ` Nick Piggin
2005-02-06  3:26             ` [PATCH] fix wait_task_inactive race (was Re: Race condition in ptrace) Nick Piggin
2005-02-06  7:19               ` Ingo Molnar
2005-02-06  7:36                 ` Nick Piggin
2005-02-06  7:47                   ` Nick Piggin
2005-02-14 16:07                   ` Bodo Stroesser

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