From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754529AbZEGIEj (ORCPT ); Thu, 7 May 2009 04:04:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753082AbZEGIEV (ORCPT ); Thu, 7 May 2009 04:04:21 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:54808 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752232AbZEGIET (ORCPT ); Thu, 7 May 2009 04:04:19 -0400 Message-ID: <4A029634.303@cn.fujitsu.com> Date: Thu, 07 May 2009 16:05:08 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Gui Jianfeng CC: Vivek Goyal , nauman@google.com, dpshah@google.com, mikew@google.com, fchecconi@gmail.com, paolo.valente@unimore.it, jens.axboe@oracle.com, ryov@valinux.co.jp, fernando@oss.ntt.co.jp, s-uchida@ap.jp.nec.com, taka@valinux.co.jp, jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, righi.andrea@gmail.com, agk@redhat.com, dm-devel@redhat.com, snitzer@redhat.com, m-ikeda@ds.jp.nec.com, akpm@linux-foundation.org Subject: Re: [PATCH 05/18] io-controller: Common hierarchical fair queuing code in elevaotor layer References: <1241553525-28095-1-git-send-email-vgoyal@redhat.com> <1241553525-28095-6-git-send-email-vgoyal@redhat.com> <4A0290ED.7080506@cn.fujitsu.com> In-Reply-To: <4A0290ED.7080506@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Gui Jianfeng wrote: > Vivek Goyal wrote: >> This patch enables hierarchical fair queuing in common layer. It is >> controlled by config option CONFIG_GROUP_IOSCHED. > ... >> +} >> + >> +void iocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup) >> +{ >> + struct io_cgroup *iocg = cgroup_to_io_cgroup(cgroup); >> + struct hlist_node *n, *tmp; >> + struct io_group *iog; >> + >> + /* >> + * Since we are destroying the cgroup, there are no more tasks >> + * referencing it, and all the RCU grace periods that may have >> + * referenced it are ended (as the destruction of the parent >> + * cgroup is RCU-safe); bgrp->group_data will not be accessed by >> + * anything else and we don't need any synchronization. >> + */ >> + hlist_for_each_entry_safe(iog, n, tmp, &iocg->group_data, group_node) >> + io_destroy_group(iocg, iog); >> + >> + BUG_ON(!hlist_empty(&iocg->group_data)); >> + > > Hi Vivek, > > IMHO, free_css_id() needs to be called here. > Right. Though alloc_css_id() is called by cgroup core in cgroup_create(), free_css_id() should be called by subsystem itself. This is a bit strange, but it's required by memory cgroup. Normally, free_css_id() is called in destroy() handler, but memcg calls it when a mem_cgroup's refcnt goes to 0. When a cgroup is destroyed, the mem_cgroup won't be destroyed (refcnt > 0) if it has records on swap-entry. >> + kfree(iocg); >> +} >> + >> +void io_disconnect_groups(struct elevator_queue *e) >> +{ >> + struct hlist_node *pos, *n; >> + struct io_group *iog; >> + struct elv_fq_data *efqd = &e->efqd; >> + >> + hlist_for_each_entry_safe(iog, pos, n, &efqd->group_list, >> + elv_data_node) { >> + hlist_del(&iog->elv_data_node); >> + >