linux-kernel - Re: [PATCH powerpc 2/2] kfree the cache name of pgtable cache if SLUB is used

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Date:	Thu, 05 Jul 2012 09:41:26 +0800
From:	Li Zhong <zhong@...ux.vnet.ibm.com>
To:	Glauber Costa <glommer@...allels.com>
Cc:	Christoph Lameter <cl@...ux.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	linux-mm <linux-mm@...ck.org>,
	PowerPC email list <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH powerpc 2/2] kfree the cache name  of pgtable cache if
 SLUB is used

On Wed, 2012-07-04 at 16:40 +0400, Glauber Costa wrote:
> On 07/04/2012 01:00 PM, Li Zhong wrote:
> > On Tue, 2012-07-03 at 15:36 -0500, Christoph Lameter wrote:
> >> > Looking through the emails it seems that there is an issue with alias
> >> > strings. 
> > To be more precise, there seems no big issue currently. I just wanted to
> > make following usage of kmem_cache_create (SLUB) possible:
> > 
> > 	name = some string kmalloced
> > 	kmem_cache_create(name, ...)
> > 	kfree(name);
> 
> Out of curiosity: Why?
> This is not (currently) possible with the other allocators (may change
> with christoph's unification patches), so you would be making your code
> slub-dependent.
> 

For slub itself, I think it's not good that: in some cases, the name
string could be kfreed ( if it was kmalloced ) immediately after calling
the cache create; in some other case, the name string needs to be kept
valid until some init calls finished. 

I agree with you that it would make the code slub-dependent, so I'm now
working on the consistency of the other allocators regarding this name
string duplicating thing. 


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