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Date: Wed, 2 Apr 2008 14:28:15 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>, paulmck@linux.vnet.ibm.com,
       Ingo Molnar <mingo@elte.hu>, Vegard Nossum <vegard.nossum@gmail.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Randy Dunlap <randy.dunlap@oracle.com>
Subject: Re: kmemcheck caught read from freed memory (cfq_free_io_context)
Message-ID: <20080402122814.GF12774@kernel.dk>
References: <20080402110718.GU12774@kernel.dk> <1207134536.8514.773.camel@twins> <20080402111422.GW12774@kernel.dk> <1207135212.8514.782.camel@twins> <20080402113258.GY12774@kernel.dk> <1207136230.8514.791.camel@twins> <20080402114243.GZ12774@kernel.dk> <1207136867.8514.796.camel@twins> <20080402115337.GD12774@kernel.dk> <1207138422.8514.799.camel@twins>
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On Wed, Apr 02 2008, Peter Zijlstra wrote:
> On Wed, 2008-04-02 at 13:53 +0200, Jens Axboe wrote:
> 
> > > Yeah, SLAB_DESTROY_BY_RCU should have a _HUGE_ comment explaining it,
> > > I'm sure this is not the first (nor the last) time people get that
> > > wrong.
> > 
> > It should, SLAB_DESTROY_BY_RCU is definitely useful, but it is expected
> > to be an 'easier' way of doing the call_rcu() manually. So it definitely
> > needs more documentation.
> > 
> 
> Ok I gave it a go, how bad is this text?

I think it looks good. The key point is this:

"This delays freeing the SLAB page by a grace period, it does _NOT_ delay
object freeing."

which is right in the front of the text and with sample validation
below. So you can add my acked-by to that, if you want.

-- 
Jens Axboe