From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752218AbdGRWJT (ORCPT ); Tue, 18 Jul 2017 18:09:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34340 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513AbdGRWJS (ORCPT ); Tue, 18 Jul 2017 18:09:18 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B90E980476 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 B90E980476 Subject: Re: [PATCH cgroup/for-4.13-fixes] cgroup: create dfl_root files on subsys registration To: Tejun Heo Cc: Li Zefan , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <1500406336-29512-1-git-send-email-longman@redhat.com> <20170718195148.GC3365493@devbig577.frc2.facebook.com> <539870d2-8b85-2f54-61bd-4ba068e75ce0@redhat.com> <20170718201229.GD3365493@devbig577.frc2.facebook.com> <255cc198-2c10-af76-98ca-086807d11540@redhat.com> <20170718205009.GE3365493@devbig577.frc2.facebook.com> <20170718210658.GF3365493@devbig577.frc2.facebook.com> <20170718215746.GG3365493@devbig577.frc2.facebook.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Tue, 18 Jul 2017 18:09:16 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20170718215746.GG3365493@devbig577.frc2.facebook.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 18 Jul 2017 22:09:17 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/18/2017 05:57 PM, Tejun Heo wrote: > On subsystem registration, css_populate_dir() is not called on the new > root css, so the interface files for the subsystem on cgrp_dfl_root > aren't created on registration. This is a residue from the days when > cgrp_dfl_root was used only as the parking spot for unused subsystems, > which no longer is true as it's used as the root for cgroup2. > > This is often fine as later operations tend to create them as a part > of mount (cgroup1) or subtree_control operations (cgroup2); however, > it's not difficult to mount cgroup2 with the controller interface > files missing as Waiman found out. > > Fix it by invoking css_populate_dir() on the root css on subsys > registration. > > Signed-off-by: Tejun Heo > Reported-by: Waiman Long > Cc: stable@vger.kernel.org # v4.5+ > --- > Hello, Waiman. > > Can you please verify that this fixes the bug? > Yes, this patch fix the problem. Tested-by: Waiman Long