From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751991AbbASLYE (ORCPT ); Mon, 19 Jan 2015 06:24:04 -0500 Received: from mx2.parallels.com ([199.115.105.18]:36094 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751651AbbASLXv (ORCPT ); Mon, 19 Jan 2015 06:23:51 -0500 From: Vladimir Davydov To: Andrew Morton CC: Johannes Weiner , Michal Hocko , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Dave Chinner , Al Viro , , , Subject: [PATCH -mm v2 3/7] cgroup: release css->id after css_free Date: Mon, 19 Jan 2015 14:23:21 +0300 Message-ID: <4d7447a920522c1085ff96c08b2be71e0eb5d896.1421664712.git.vdavydov@parallels.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, we release css->id in css_release_work_fn, right before calling css_free callback, so that when css_free is called, the id may have already been reused for a new cgroup. I am going to use css->id to create unique names for per memcg kmem caches. Since kmem caches are destroyed only on css_free, I need css->id to be freed after css_free was called to avoid name clashes. This patch therefore moves css->id removal to css_free_work_fn. To prevent css_from_id from returning a pointer to a stale css, it makes css_release_work_fn replace the css ptr at css_idr:css->id with NULL. Signed-off-by: Vladimir Davydov --- kernel/cgroup.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 6ffd3ae52bf8..7bd3e0f0f341 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4373,16 +4373,20 @@ static void css_free_work_fn(struct work_struct *work) { struct cgroup_subsys_state *css = container_of(work, struct cgroup_subsys_state, destroy_work); + struct cgroup_subsys *ss = css->ss; struct cgroup *cgrp = css->cgroup; percpu_ref_exit(&css->refcnt); - if (css->ss) { + if (ss) { /* css free path */ + int id = css->id; + if (css->parent) css_put(css->parent); - css->ss->css_free(css); + ss->css_free(css); + cgroup_idr_remove(&ss->css_idr, id); cgroup_put(cgrp); } else { /* cgroup free path */ @@ -4434,7 +4438,7 @@ static void css_release_work_fn(struct work_struct *work) if (ss) { /* css release path */ - cgroup_idr_remove(&ss->css_idr, css->id); + cgroup_idr_replace(&ss->css_idr, NULL, css->id); if (ss->css_released) ss->css_released(css); } else { -- 1.7.10.4