From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754768AbdGUUfY (ORCPT ); Fri, 21 Jul 2017 16:35:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7081 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996AbdGUUfW (ORCPT ); Fri, 21 Jul 2017 16:35:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com F33A680478 Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=longman@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com F33A680478 From: Waiman Long To: Tejun Heo , Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, efault@gmx.de, torvalds@linux-foundation.org, guro@fb.com, Waiman Long Subject: [PATCH v2 1/4] cgroup: Child cgroup creation not allowed on invalid domain Date: Fri, 21 Jul 2017 16:34:50 -0400 Message-Id: <1500669293-21792-2-git-send-email-longman@redhat.com> In-Reply-To: <1500669293-21792-1-git-send-email-longman@redhat.com> References: <1500669293-21792-1-git-send-email-longman@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 21 Jul 2017 20:35:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When thread mode is used, it is possible that some cgroups may be in an invalid state. Currently users may not be aware that they are invalid until they try to migrate tasks over. This patch disallows child cgroup creation on invalid domain. This adds one more failure point in reminding users that they are dealing with invalid domains. It also minimizes the number of invalid domains outstanding as much as possible. Signed-off-by: Waiman Long --- kernel/cgroup/cgroup.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e9a377d..5fc8133 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4664,6 +4664,14 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode) if (!parent) return -ENODEV; + /* + * New cgroup creation isn't allowed on an invalid domain parent. + */ + if (!cgroup_is_threaded(parent) && !cgroup_is_valid_domain(parent)) { + ret = -EOPNOTSUPP; + goto out_unlock; + } + cgrp = cgroup_create(parent); if (IS_ERR(cgrp)) { ret = PTR_ERR(cgrp); -- 1.8.3.1