From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422672Ab2EKSN4 (ORCPT ); Fri, 11 May 2012 14:13:56 -0400 Received: from mx2.parallels.com ([64.131.90.16]:33612 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932215Ab2EKSNz (ORCPT ); Fri, 11 May 2012 14:13:55 -0400 Message-ID: <4FAD566C.3000804@parallels.com> Date: Fri, 11 May 2012 15:11:56 -0300 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: Christoph Lameter CC: , , , , Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , , Pekka Enberg Subject: Re: [PATCH v2 04/29] slub: always get the cache from its page in kfree References: <1336758272-24284-1-git-send-email-glommer@parallels.com> <1336758272-24284-5-git-send-email-glommer@parallels.com> <4FAD531D.6030007@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [187.105.248.83] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/11/2012 03:06 PM, Christoph Lameter wrote: > On Fri, 11 May 2012, Glauber Costa wrote: > >>> Adding a VM_BUG_ON may be useful to make sure that kmem_cache_free is >>> always passed the correct slab cache. >> >> Well, problem is , it isn't always passed the "correct" slab cache. >> At least not after this series, since we'll have child caches associated with >> the main cache. >> >> So we'll pass, for instance, kmem_cache_free(dentry_cache...), but will in >> fact free from the memcg copy of the dentry cache. > > Urg. But then please only do this for the MEMCG case and add a fat big > warning in kmem_cache_free. I can do that, of course. Another option if you don't oppose, is to add another field in the kmem_cache structure (I tried to keep them at a minimum), to record the parent cache we got created from. Then, it gets trivial to do the following: VM_BUG_ON(page->slab != s && page->slab != s->parent_cache); From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx114.postini.com [74.125.245.114]) by kanga.kvack.org (Postfix) with SMTP id E98D48D0020 for ; Fri, 11 May 2012 14:14:01 -0400 (EDT) Message-ID: <4FAD566C.3000804@parallels.com> Date: Fri, 11 May 2012 15:11:56 -0300 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v2 04/29] slub: always get the cache from its page in kfree References: <1336758272-24284-1-git-send-email-glommer@parallels.com> <1336758272-24284-5-git-send-email-glommer@parallels.com> <4FAD531D.6030007@parallels.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com, Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , devel@openvz.org, Pekka Enberg On 05/11/2012 03:06 PM, Christoph Lameter wrote: > On Fri, 11 May 2012, Glauber Costa wrote: > >>> Adding a VM_BUG_ON may be useful to make sure that kmem_cache_free is >>> always passed the correct slab cache. >> >> Well, problem is , it isn't always passed the "correct" slab cache. >> At least not after this series, since we'll have child caches associated with >> the main cache. >> >> So we'll pass, for instance, kmem_cache_free(dentry_cache...), but will in >> fact free from the memcg copy of the dentry cache. > > Urg. But then please only do this for the MEMCG case and add a fat big > warning in kmem_cache_free. I can do that, of course. Another option if you don't oppose, is to add another field in the kmem_cache structure (I tried to keep them at a minimum), to record the parent cache we got created from. Then, it gets trivial to do the following: VM_BUG_ON(page->slab != s && page->slab != s->parent_cache); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH v2 04/29] slub: always get the cache from its page in kfree Date: Fri, 11 May 2012 15:11:56 -0300 Message-ID: <4FAD566C.3000804@parallels.com> References: <1336758272-24284-1-git-send-email-glommer@parallels.com> <1336758272-24284-5-git-send-email-glommer@parallels.com> <4FAD531D.6030007@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Christoph Lameter Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Pekka Enberg On 05/11/2012 03:06 PM, Christoph Lameter wrote: > On Fri, 11 May 2012, Glauber Costa wrote: > >>> Adding a VM_BUG_ON may be useful to make sure that kmem_cache_free is >>> always passed the correct slab cache. >> >> Well, problem is , it isn't always passed the "correct" slab cache. >> At least not after this series, since we'll have child caches associated with >> the main cache. >> >> So we'll pass, for instance, kmem_cache_free(dentry_cache...), but will in >> fact free from the memcg copy of the dentry cache. > > Urg. But then please only do this for the MEMCG case and add a fat big > warning in kmem_cache_free. I can do that, of course. Another option if you don't oppose, is to add another field in the kmem_cache structure (I tried to keep them at a minimum), to record the parent cache we got created from. Then, it gets trivial to do the following: VM_BUG_ON(page->slab != s && page->slab != s->parent_cache);