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From: Li Zhong <zhong@linux.vnet.ibm.com>
To: Glauber Costa <glommer@parallels.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>, linux-mm <linux-mm@kvack.org>,
	Paul Mackerras <paulus@samba.org>, Matt Mackall <mpm@selenic.com>,
	Christoph Lameter <cl@linux.com>,
	PowerPC email list <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH powerpc 2/2] kfree the cache name  of pgtable cache if SLUB is used
Date: Thu, 05 Jul 2012 17:29:38 +0800	[thread overview]
Message-ID: <1341480578.23916.7.camel@ThinkPad-T420> (raw)
In-Reply-To: <4FF54F18.50300@parallels.com>

On Thu, 2012-07-05 at 12:23 +0400, Glauber Costa wrote:
> On 07/05/2012 05:41 AM, Li Zhong wrote:
> > 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. 
> 
> If you really need to kfree the string, or even if it is easier for you
> this way, it can be done. As a matter of fact, this is the case for me.
> Just that your patch is not enough. Christoph has a patch that makes
> this behavior consistent over all allocators.

Sorry, I didn't know that. Seems I don't need to continue the half-done
work in slab. If possible, would you please give me a link of the patch?
Thank you. 

> This just needs to be pushed again to the tree.
> 

WARNING: multiple messages have this Message-ID (diff)
From: Li Zhong <zhong@linux.vnet.ibm.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>, linux-mm <linux-mm@kvack.org>,
	PowerPC email list <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH powerpc 2/2] kfree the cache name  of pgtable cache if SLUB is used
Date: Thu, 05 Jul 2012 17:29:38 +0800	[thread overview]
Message-ID: <1341480578.23916.7.camel@ThinkPad-T420> (raw)
In-Reply-To: <4FF54F18.50300@parallels.com>

On Thu, 2012-07-05 at 12:23 +0400, Glauber Costa wrote:
> On 07/05/2012 05:41 AM, Li Zhong wrote:
> > 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. 
> 
> If you really need to kfree the string, or even if it is easier for you
> this way, it can be done. As a matter of fact, this is the case for me.
> Just that your patch is not enough. Christoph has a patch that makes
> this behavior consistent over all allocators.

Sorry, I didn't know that. Seems I don't need to continue the half-done
work in slab. If possible, would you please give me a link of the patch?
Thank you. 

> This just needs to be pushed again to the tree.
> 


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WARNING: multiple messages have this Message-ID (diff)
From: Li Zhong <zhong@linux.vnet.ibm.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>, linux-mm <linux-mm@kvack.org>,
	PowerPC email list <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH powerpc 2/2] kfree the cache name  of pgtable cache if SLUB is used
Date: Thu, 05 Jul 2012 17:29:38 +0800	[thread overview]
Message-ID: <1341480578.23916.7.camel@ThinkPad-T420> (raw)
In-Reply-To: <4FF54F18.50300@parallels.com>

On Thu, 2012-07-05 at 12:23 +0400, Glauber Costa wrote:
> On 07/05/2012 05:41 AM, Li Zhong wrote:
> > 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. 
> 
> If you really need to kfree the string, or even if it is easier for you
> this way, it can be done. As a matter of fact, this is the case for me.
> Just that your patch is not enough. Christoph has a patch that makes
> this behavior consistent over all allocators.

Sorry, I didn't know that. Seems I don't need to continue the half-done
work in slab. If possible, would you please give me a link of the patch?
Thank you. 

> This just needs to be pushed again to the tree.
> 



  reply	other threads:[~2012-07-05  9:29 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-25  9:53 [PATCH SLUB 1/2] duplicate the cache name in saved_alias list Li Zhong
2012-06-25  9:53 ` Li Zhong
2012-06-25  9:53 ` Li Zhong
2012-06-25  9:54 ` [PATCH powerpc 2/2] kfree the cache name of pgtable cache if SLUB is used Li Zhong
2012-06-25  9:54   ` Li Zhong
2012-06-25  9:54   ` Li Zhong
2012-06-29  0:45   ` Benjamin Herrenschmidt
2012-06-29  0:45     ` Benjamin Herrenschmidt
2012-06-29  0:45     ` Benjamin Herrenschmidt
2012-06-29  1:41     ` Zhong Li
2012-06-29  1:41       ` Zhong Li
2012-06-29  1:41       ` Zhong Li
2012-07-03 18:48   ` Christoph Lameter
2012-07-03 18:48     ` Christoph Lameter
2012-07-03 18:48     ` Christoph Lameter
2012-07-03 20:36     ` Christoph Lameter
2012-07-03 20:36       ` Christoph Lameter
2012-07-03 20:36       ` Christoph Lameter
2012-07-04  9:00       ` Li Zhong
2012-07-04  9:00         ` Li Zhong
2012-07-04  9:00         ` Li Zhong
2012-07-04 12:40         ` Glauber Costa
2012-07-04 12:40           ` Glauber Costa
2012-07-04 12:40           ` Glauber Costa
2012-07-05  1:41           ` Li Zhong
2012-07-05  1:41             ` Li Zhong
2012-07-05  1:41             ` Li Zhong
2012-07-05  8:23             ` Glauber Costa
2012-07-05  8:23               ` Glauber Costa
2012-07-05  8:23               ` Glauber Costa
2012-07-05  9:29               ` Li Zhong [this message]
2012-07-05  9:29                 ` Li Zhong
2012-07-05  9:29                 ` Li Zhong
2012-07-06 10:13                 ` Glauber Costa
2012-07-06 10:13                   ` Glauber Costa
2012-07-06 10:13                   ` Glauber Costa
2012-07-09  1:48                   ` Li Zhong
2012-07-09  1:48                     ` Li Zhong
2012-07-09  1:48                     ` Li Zhong
2012-06-25 10:54 ` [PATCH SLUB 1/2] duplicate the cache name in saved_alias list Wanlong Gao
2012-06-25 10:54   ` Wanlong Gao
2012-06-25 10:54   ` Wanlong Gao
2012-06-26  2:49   ` Li Zhong
2012-06-26  2:49     ` Li Zhong
2012-06-26  2:49     ` Li Zhong
2012-06-25 11:10 ` Glauber Costa
2012-06-25 11:10   ` Glauber Costa
2012-06-25 11:10   ` Glauber Costa
2012-06-26  2:58   ` Li Zhong
2012-06-26  2:58     ` Li Zhong
2012-06-26  2:58     ` Li Zhong
2012-06-27  7:53 ` [PATCH SLUB 1/2 v2] " Li Zhong
2012-06-27  7:53   ` Li Zhong
2012-06-27  7:53   ` Li Zhong

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