Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755476Ab3CVJsg (ORCPT ); Fri, 22 Mar 2013 05:48:36 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41205 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754959Ab3CVJsf (ORCPT ); Fri, 22 Mar 2013 05:48:35 -0400 Date: Fri, 22 Mar 2013 10:48:32 +0100 From: Michal Hocko To: Glauber Costa Cc: Li Zefan , Tejun Heo , LKML , Cgroups , linux-mm@kvack.org, KAMEZAWA Hiroyuki , Johannes Weiner Subject: Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name() Message-ID: <20130322094832.GG31457@dhcp22.suse.cz> References: <514A60CD.60208@huawei.com> <20130321090849.GF6094@dhcp22.suse.cz> <20130321102257.GH6094@dhcp22.suse.cz> <514BB23E.70908@huawei.com> <20130322080749.GB31457@dhcp22.suse.cz> <514C1388.6090909@huawei.com> <514C14BF.3050009@parallels.com> <20130322093141.GE31457@dhcp22.suse.cz> <514C2754.4080701@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <514C2754.4080701@parallels.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1510 Lines: 50 On Fri 22-03-13 13:41:40, Glauber Costa wrote: > On 03/22/2013 01:31 PM, Michal Hocko wrote: > > On Fri 22-03-13 12:22:23, Glauber Costa wrote: > >> On 03/22/2013 12:17 PM, Li Zefan wrote: > >>>> GFP_TEMPORARY groups short lived allocations but the mem cache is not > >>>>> an ideal candidate of this type of allocations.. > >>>>> > >>> I'm not sure I'm following you... > >>> > >>> char *memcg_cache_name() > >>> { > >>> char *name = alloc(); > >>> return name; > >>> } > >>> > >>> kmem_cache_dup() > >>> { > >>> name = memcg_cache_name(); > >>> kmem_cache_create_memcg(name); > >>> free(name); > >>> } > >>> > >>> Isn't this a short lived allocation? > >>> > >> > >> Hi, > >> > >> Thanks for identifying and fixing this. > >> > >> Li is right. The cache name will live long, but this is because the > >> slab/slub caches will strdup it internally. So the actual memcg > >> allocation is short lived. > > > > OK, I have totally missed that. Sorry about the confusion. Then all the > > churn around the allocation is pointless, no? > > What about: > > If we're really not concerned about stack, then yes. Even if always > running from workqueues, a PAGE_SIZEd stack variable seems risky to me. This is not on stack. It is static -- Michal Hocko SUSE Labs -- 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/