From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754676Ab1HZPiw (ORCPT ); Fri, 26 Aug 2011 11:38:52 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:49324 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754248Ab1HZPiu (ORCPT ); Fri, 26 Aug 2011 11:38:50 -0400 Date: Fri, 26 Aug 2011 17:38:44 +0200 From: Frederic Weisbecker To: akpm@linux-foundation.org Cc: mm-commits@vger.kernel.org, bblum@andrew.cmu.edu, lizf@cn.fujitsu.com, oleg@redhat.com, paul@paulmenage.org, tj@kernel.org, LKML Subject: [PATCH v2] cgroups: Don't attach task to subsystem if migration failed Message-ID: <20110826153843.GE3298@somewhere> References: <201108252044.p7PKiaHd006997@imap1.linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201108252044.p7PKiaHd006997@imap1.linux-foundation.org> 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 On Thu, Aug 25, 2011 at 01:44:36PM -0700, akpm@linux-foundation.org wrote: > > The patch titled > cgroups: fix ordering of calls in cgroup_attach_proc > has been added to the -mm tree. Its filename is > cgroups-fix-ordering-of-calls-in-cgroup_attach_proc.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find > out what to do about this > > The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ > > ------------------------------------------------------ > Subject: cgroups: fix ordering of calls in cgroup_attach_proc > From: Ben Blum > > awaiting useful changelog... > Here is the patch with a (trial of a) useful changelog. Subject has been changed as well: --- >>From a9b84e395a0355cd1aa5ee0f525cd682b16dad63 Mon Sep 17 00:00:00 2001 From: Ben Blum Date: Thu, 25 Aug 2011 13:44:36 -0700 Subject: [PATCH] cgroups: Don't attach task to subsystem if migration failed If a task has exited to the point it has called cgroup_exit() already, then we can't migrate it to another cgroup anymore. This can happen when we are attaching a task to a new cgroup between the call to ->can_attach_task() on subsystems and the migration that is eventually tried in cgroup_task_migrate(). In this case cgroup_task_migrate() returns -ESRCH and we don't want to attach the task to the subsystems because the attachment to the new cgroup itself failed. Fix this by only calling ->attach_task() on the subsystems if the cgroup migration succeeded. Reported-by: Oleg Nesterov Signed-off-by: Ben Blum Acked-by: Paul Menage Cc: Li Zefan Cc: Tejun Heo Signed-off-by: Frederic Weisbecker --- kernel/cgroup.c | 15 +++++++++------ 1 files changed, 9 insertions(+), 6 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 1d2b6ce..84bdace 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2135,14 +2135,17 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) oldcgrp = task_cgroup_from_root(tsk, root); if (cgrp == oldcgrp) continue; - /* attach each task to each subsystem */ - for_each_subsys(root, ss) { - if (ss->attach_task) - ss->attach_task(cgrp, tsk); - } /* if the thread is PF_EXITING, it can just get skipped. */ retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, true); - BUG_ON(retval != 0 && retval != -ESRCH); + if (retval == 0) { + /* attach each task to each subsystem */ + for_each_subsys(root, ss) { + if (ss->attach_task) + ss->attach_task(cgrp, tsk); + } + } else { + BUG_ON(retval != -ESRCH); + } } /* nothing is sensitive to fork() after this point. */ -- 1.7.5.4