lkml.org 
[lkml]   [2011]   [Aug]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] cgroups: Don't attach task to subsystem if migration failed
On Fri, Aug 26, 2011 at 05:38:44PM +0200, Frederic Weisbecker wrote:
> 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 <bblum@andrew.cmu.edu>
> >
> > awaiting useful changelog...
> >
>
> Here is the patch with a (trial of a) useful changelog. Subject
> has been changed as well:

This description is much better than my original one - thanks!

I'd ack it, but my name is already there. :P

-- Ben

>
> ---
> From a9b84e395a0355cd1aa5ee0f525cd682b16dad63 Mon Sep 17 00:00:00 2001
> From: Ben Blum <bblum@andrew.cmu.edu>
> 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 <oleg@redhat.com>
> Signed-off-by: Ben Blum <bblum@andrew.cmu.edu>
> Acked-by: Paul Menage <paul@paulmenage.org>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Tejun Heo <tj@kernel.org>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> 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
>
>
>


\
 
 \ /
  Last update: 2011-08-26 19:31    [W:0.035 / U:2.356 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site