From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id D57386B0002 for ; Wed, 27 Mar 2013 11:19:22 -0400 (EDT) Message-ID: <51530E1E.3010100@parallels.com> Date: Wed, 27 Mar 2013 19:19:58 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name() References: <1364373399-17397-1-git-send-email-mhocko@suse.cz> <20130327145727.GD29052@cmpxchg.org> <20130327151104.GK16579@dhcp22.suse.cz> In-Reply-To: <20130327151104.GK16579@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Johannes Weiner , Tejun Heo , Li Zefan , KAMEZAWA Hiroyuki , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org On 03/27/2013 07:11 PM, 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. theoretically, this is PATH_MAX + max cache name. -- 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/ . Don't email: email@kvack.org