Message-ID: <49AF28C4.1000300@cn.fujitsu.com>
Date: Thu, 05 Mar 2009 09:20:04 +0800
From: Lai Jiangshan <laijs@cn.fujitsu.com>
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To: Christoph Lameter <cl@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>,
       Pekka Enberg <penberg@cs.helsinki.fi>, Nick Piggin <npiggin@suse.de>,
       "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
       Manfred Spraul <manfred@colorfullife.com>, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm 3/6] slub: introduce __kfree_rcu
References: <49AD343E.6010903@cn.fujitsu.com> <alpine.DEB.1.10.0903041003200.3850@qirst.com>
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Christoph Lameter wrote:
> On Tue, 3 Mar 2009, Lai Jiangshan wrote:
> 
>> +
>> +void __kfree_rcu(const void *x, struct rcu_head *rcu)
>> +{
>> +	call_rcu(rcu, kfree_rcu_callback);
>> +}
>> +EXPORT_SYMBOL(__kfree_rcu);
>> +
> 
> The parameter x is unused why require it? I see that SLOB needs it. Cant
> you do a similar trick as in SLUB just calculating the start address of
> the object from the rcu address?
> 


The first parameter of __kfree_rcu() is unused in slab,slub,slqb.
(I used it before, for CONFIG_SLUB_DEBUG=y ...etc. But I found
these debugging code is needless)

Object sizes of the memory objects in slob's kmalloc-slab are various.
We hardly calculate the start address of the object from the rcu address.

Lai


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