From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx158.postini.com [74.125.245.158]) by kanga.kvack.org (Postfix) with SMTP id 3D2536B007D for ; Fri, 22 Mar 2013 05:48:35 -0400 (EDT) Date: Fri, 22 Mar 2013 10:48:32 +0100 From: Michal Hocko 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> Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Li Zefan , Tejun Heo , LKML , Cgroups , linux-mm@kvack.org, KAMEZAWA Hiroyuki , Johannes Weiner 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, 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