linux-kernel - Re: [PATCH 5/7] cgroup_freezer: allow moving tasks in and out of a frozen cgroup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20121023161414.GA18138@redhat.com>
Date:	Tue, 23 Oct 2012 18:14:14 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	rjw@...k.pl, linux-kernel@...r.kernel.org, lizefan@...wei.com,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org
Subject: Re: [PATCH 5/7] cgroup_freezer: allow moving tasks in and out of a
	frozen cgroup

On 10/22, Tejun Heo wrote:
>
> Hello,
>
> On Mon, Oct 22, 2012 at 09:25:06PM +0200, Oleg Nesterov wrote:
> > > @@ -190,12 +201,12 @@ static void freezer_fork(struct task_struct *task)
> > >  		goto out;
> > >
> > >  	spin_lock_irq(&freezer->lock);
> > > -	BUG_ON(freezer->state == CGROUP_FROZEN);
> > > -
> > > -	/* Locking avoids race with FREEZING -> THAWED transitions. */
> > > -	if (freezer->state == CGROUP_FREEZING)
> > > +	/*
> > > +	 * @task might have been just migrated into a FROZEN cgroup.
> >
> > Confused. If it was migrated, then freezer_attach() should take care
> > do freeze_task?
>
> Hmmm... there's a window where a task is migrated but ->attach()
> hasn't completed yet, so freezer_attach() might not have kicked in
> yet.

Yes, I see.

Indeed, cgroup_task_migrate() is called before ->attach().

Thanks!

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/