Date: Sun, 27 Nov 2005 13:28:14 +0100
From: Ingo Molnar <mingo@elte.hu>
To: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, wfg@mail.ustc.edu.cn,
       levon@movementarian.org
Subject: Re: [PATCH] Make RCU task_struct safe for oprofile
Message-ID: <20051127122814.GA22692@elte.hu>
References: <20051126210726.GA5277@us.ibm.com>
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* Paul E. McKenney <paulmck@us.ibm.com> wrote:

> Hello!
> 
> Applying RCU to the task structure broke oprofile, because 
> free_task_notify() can now be called from softirq.  This means that 
> the task_mortuary lock must be acquired with irq disabled in order to 
> avoid intermittent self-deadlock.  Since irq is now disabled, the 
> critical section within process_task_mortuary() has been restructured 
> to be O(1) in order to maximize scalability and minimize realtime 
> latency degradation.
> 
> Kudos to Wu Fengguang for finding this problem!

thanks, i applied this to the -rt tree.

	Ingo
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