From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031133Ab2CNVwg (ORCPT ); Wed, 14 Mar 2012 17:52:36 -0400 Received: from mail-pz0-f52.google.com ([209.85.210.52]:52389 "EHLO mail-pz0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031118Ab2CNVwd (ORCPT ); Wed, 14 Mar 2012 17:52:33 -0400 Date: Wed, 14 Mar 2012 14:52:28 -0700 From: Tejun Heo To: Li Zefan , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Frederic Weisbecker , Lennart Poettering Subject: [PATCH] cgroup: deprecate remount option changes and "name=" mount option Message-ID: <20120314215228.GI7349@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch removes the following features. * Rebinding subsys by remount: Never reached useful state - only works on empty hierarchies. * release_agent update by remount: release_agent itself will be replaced with conventional fsnotify notification. * "name=" mount option: This has been broken for years before Li fixed it recently. It has very marginal usefulness (plain bind mount can mostly replace it) and is quite unusual. Take the chance and mark for deprecation. Signed-off-by: Tejun Heo Cc: Li Zefan Cc: Lennart Poettering --- If you want these to survive, now is the time to scream. :) Thanks. Documentation/feature-removal-schedule.txt | 12 ++++++++++++ kernel/cgroup.c | 10 ++++++++++ 2 files changed, 22 insertions(+) Index: work/Documentation/feature-removal-schedule.txt =================================================================== --- work.orig/Documentation/feature-removal-schedule.txt +++ work/Documentation/feature-removal-schedule.txt @@ -510,3 +510,15 @@ Why: The pci_scan_bus_parented() interfa convert to using pci_scan_root_bus() so they can supply a list of bus resources when the bus is created. Who: Bjorn Helgaas + +---------------------------- + +What: cgroup option updates via remount, and "name=" mount option +When: March 2013 +Why: Remount currently allows changing bound subsystems and + release_agent. Rebinding is hardly useful as it only works + when the hierarchy is empty and release_agent itself should be + replaced with conventional fsnotify. "name=" option allows + mounting existing hierarchy by its name, which isn't useful + and has been broken for years without anyone noticing. +Who: Tejun Heo Index: work/kernel/cgroup.c =================================================================== --- work.orig/kernel/cgroup.c +++ work/kernel/cgroup.c @@ -1146,6 +1146,11 @@ static int parse_cgroupfs_options(char * } if (!strncmp(token, "name=", 5)) { const char *name = token + 5; + + /* See feature-removal-schedule.txt */ + pr_warning("cgroup: name= option is deprecated (pid=%d comm=%s name=%s)\n", + task_tgid_nr(current), current->comm, name); + /* Can't specify an empty name */ if (!strlen(name)) return -EINVAL; @@ -1294,6 +1299,11 @@ static int cgroup_remount(struct super_b if (ret) goto out_unlock; + /* See feature-removal-schedule.txt */ + if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent) + pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", + task_tgid_nr(current), current->comm); + /* Don't allow flags or name to change at remount */ if (opts.flags != root->flags || (opts.name && strcmp(opts.name, root->name))) {