Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753948Ab3C0Pdx (ORCPT ); Wed, 27 Mar 2013 11:33:53 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:42143 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753365Ab3C0Pc5 (ORCPT ); Wed, 27 Mar 2013 11:32:57 -0400 Date: Wed, 27 Mar 2013 11:32:26 -0400 From: Johannes Weiner To: Michal Hocko Cc: Tejun Heo , Glauber Costa , Li Zefan , KAMEZAWA Hiroyuki , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name() Message-ID: <20130327153226.GF29052@cmpxchg.org> References: <1364373399-17397-1-git-send-email-mhocko@suse.cz> <20130327145727.GD29052@cmpxchg.org> <20130327151104.GK16579@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130327151104.GK16579@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 40 On Wed, Mar 27, 2013 at 04:11:04PM +0100, Michal Hocko wrote: > On Wed 27-03-13 10:58:25, Johannes Weiner wrote: > > On Wed, Mar 27, 2013 at 09:36:39AM +0100, Michal Hocko wrote: > [...] > > > + /* > > > + * kmem_cache_create_memcg duplicates the given name and > > > + * cgroup_name for this name requires RCU context. > > > + * This static temporary buffer is used to prevent from > > > + * pointless shortliving allocation. > > > + */ > > > + if (!tmp_name) { > > > + tmp_name = kmalloc(PAGE_SIZE, GFP_KERNEL); > > > + WARN_ON_ONCE(!tmp_name); > > > > Just use the page allocator directly and get a free allocation failure > > warning. > > WARN_ON_ONCE is probably pointless. > > > Then again, order-0 pages are considered cheap enough that they never > > even fail in our current implementation. > > > > Which brings me to my other point: why not just a simple single-page > > allocation? > > No objection from me. I was previously thinking about the "proper" > size for something that is a file name. So I originally wanted to use > PATH_MAX instead but ended up with PAGE_SIZE for reasons I do not > remember now. Maybe we can use NAME_MAX instead. I just do not like to > use page allocator directly when allocatating something like strings > etc... Don't grep for GFP_TEMPORARY then, we do it in a couple places :-) NAME_MAX is just for single dentry names, not path names, no? Might be a little short. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/