Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751352AbZFWEqI (ORCPT ); Tue, 23 Jun 2009 00:46:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750788AbZFWEp5 (ORCPT ); Tue, 23 Jun 2009 00:45:57 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:36911 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745AbZFWEp4 (ORCPT ); Tue, 23 Jun 2009 00:45:56 -0400 Date: Tue, 23 Jun 2009 13:44:20 +0900 From: KAMEZAWA Hiroyuki To: Daisuke Nishimura Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "balbir@linux.vnet.ibm.com" , "menage@google.com" Subject: Re: [RFC][PATCH] cgroup: fix permanent wait in rmdir Message-Id: <20090623134420.9103eac5.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090623131333.be387c84.nishimura@mxp.nes.nec.co.jp> References: <20090622183707.dd9e665b.kamezawa.hiroyu@jp.fujitsu.com> <20090623092223.a44e7b20.kamezawa.hiroyu@jp.fujitsu.com> <20090623131333.be387c84.nishimura@mxp.nes.nec.co.jp> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1970 Lines: 62 On Tue, 23 Jun 2009 13:13:33 +0900 Daisuke Nishimura wrote: > On Tue, 23 Jun 2009 09:22:23 +0900, KAMEZAWA Hiroyuki wrote: > > On Mon, 22 Jun 2009 18:37:07 +0900 > > KAMEZAWA Hiroyuki wrote: > > > > > previous discussion was this => http://marc.info/?t=124478543600001&r=1&w=2 > > > > > > I think this is a minimum fix (in code size and behavior) and because > > > we can take a BIG LOCK, this kind of check is necessary, anyway. > > > Any comments are welcome. > > > > I'll split this into 2 patches...and I found I should check page-migration, too. > I'll wait a new version, but can you explain in advance this page-migration case ? > Not far from swap-in case. Assume cgroup "A" which includes file caches. A task in other group mmap file caches and do page migration and rmdir against "A" is called at the same time. In mem_cgroup_prepare_migration(), following check is used. == lock_page_cgroup(pc); if (PageCgroupUsed(pc)) { mem = pc->mem_cgroup; css_get(&mem->css); } unlock_page_cgroup(pc); <======================================(*) if (mem) { <==============================(**) try_charge(); ... } == At (*), we grab css refcnt which can be under pre_destroy() and At (**), pre_destroy may returns 0 but charge may be done after the end of pre_destroy(). > > > +static int mem_cgroup_retry_rmdir(struct cgroup_subsys *ss, > > > + struct cgroup *cont) > > > +{ > > > + struct mem_cgroup *mem = mem_cgroup_from_cont(cont); > > > + > > > + if (res_counter_read_u64(&memcg->res, RES_USAGE)) > It should be &mem->res. > yes. too many typos in my patches in these days.. Thanks, -Kame -- 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/