From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752049AbdGRUMf (ORCPT ); Tue, 18 Jul 2017 16:12:35 -0400 Received: from mail-qk0-f182.google.com ([209.85.220.182]:34254 "EHLO mail-qk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513AbdGRUMd (ORCPT ); Tue, 18 Jul 2017 16:12:33 -0400 Date: Tue, 18 Jul 2017 16:12:29 -0400 From: Tejun Heo To: Waiman Long Cc: Li Zefan , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cgroup: Show control files in cgroup2 root after mount Message-ID: <20170718201229.GD3365493@devbig577.frc2.facebook.com> References: <1500406336-29512-1-git-send-email-longman@redhat.com> <20170718195148.GC3365493@devbig577.frc2.facebook.com> <539870d2-8b85-2f54-61bd-4ba068e75ce0@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <539870d2-8b85-2f54-61bd-4ba068e75ce0@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Jul 18, 2017 at 04:00:45PM -0400, Waiman Long wrote: > From my own debugging, the controller files (e.g. the debug controller) > were indirectly populated by the rebind_subsystems() call. > > [ 1.628103] css_populate_dir: init subsystem debug ... > [ 1.654975] cgroup_apply_control_enable+0x103/0x340 > [ 1.657719] cgroup_apply_control+0x1a/0x30 > [ 1.658521] rebind_subsystems+0x18a/0x3b0 ... But there's kernfs_activate() call at the end of rebind_subsystems(), so if the files were being added there, it should have been activated there and I can confirm that the files are correctly added / removed from the cgroup2 root directory when controllers are attached to / detached from it. > For the default cgroup2 root, kernfs_activate() was only called at the > beginning in cgroup_init() with only the base cgroup files added. No > more call after that until I touched the cgroup.subtree_control file. Hmm... we're activating at the end of * cgroup_setup_root() * rebind_subsystems() * cgroup_subtree_control_write() * cgroup_apply_cftypes() after successful addition * cgroup_mkdir() I *think* this should cover everything. Just in case, are you looking at the mainline kernel? Can you share how you can reproduce the issue? Thanks. -- tejun