From: Tejun Heo <tj@kernel.org>
To: Matt Helsley <matthltc@us.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
rjw@sisk.pl, paul@paulmenage.org,
containers@lists.linux-foundation.org,
linux-pm@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] freezer: kill unused set_freezable_with_signal()
Date: Sun, 11 Sep 2011 10:37:42 +0900 [thread overview]
Message-ID: <20110911013742.GJ29319@htj.dyndns.org> (raw)
In-Reply-To: <20110908180159.GA4197@count0.beaverton.ibm.com>
Hello, Matt.
On Thu, Sep 08, 2011 at 11:01:59AM -0700, Matt Helsley wrote:
> Looking at the code and docs I realize I didn't explicitly mention that
> kthreads could not be frozen by the cgroup freezer. However, the code did
> not allow it. When freezing tasks the cgroup freezer always did:
>
> freeze_task(task, true)
>
> which would only freeze tasks without PF_FREEZER_NOSIG due to the second
> "sig_only" parameter. I believe this means it could not be used to
> freeze kthreads.
>
> My feeling is kthreads should not be "managed" directly by userspace.
> Especially if that includes the ability to arbitrarily stop or freeze them.
> So it seems more appropriate to explicitly disallow freezing of kthreads
> via the cgroup freezer.
Oh yeah, that's what we should do and maybe that's what the current
code intends to achieve too but currently it ends up triggering
BUG_ON().
Thanks.
--
tejun
next prev parent reply other threads:[~2011-09-11 1:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-02 18:27 [PATCHSET pm-freezer] freezer: fixes & simplifications Tejun Heo
2011-09-02 18:27 ` [PATCH 1/6] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() Tejun Heo
2011-09-04 18:02 ` Oleg Nesterov
2011-09-04 18:11 ` Tejun Heo
2011-09-04 18:20 ` Oleg Nesterov
2011-09-02 18:27 ` [PATCH 2/6] freezer: set PF_NOFREEZE on a dying task right before TASK_DEAD " Tejun Heo
2011-09-02 18:27 ` [PATCH 3/6] freezer: restructure __refrigerator() Tejun Heo
2011-09-02 18:27 ` [PATCH 4/6] freezer: use lock_task_sighand() in fake_signal_wake_up() Tejun Heo
2011-09-02 18:27 ` [PATCH 5/6] freezer: remove unused @sig_only from freeze_task() Tejun Heo
2011-09-02 18:27 ` [PATCH 6/6] freezer: kill unused set_freezable_with_signal() Tejun Heo
2011-09-04 18:46 ` Oleg Nesterov
2011-09-05 2:33 ` Tejun Heo
2011-09-05 2:35 ` Tejun Heo
2011-09-05 16:21 ` Oleg Nesterov
2011-09-05 16:20 ` Oleg Nesterov
2011-09-06 3:28 ` Tejun Heo
2011-09-06 15:18 ` Oleg Nesterov
2011-09-06 15:25 ` Oleg Nesterov
2011-09-06 15:53 ` Tejun Heo
2011-09-07 18:21 ` [PATCH 0/1] freezer: fix wait_event_freezable/__thaw_task races Oleg Nesterov
2011-09-07 18:22 ` [PATCH 1/1] " Oleg Nesterov
2011-09-08 1:05 ` Tejun Heo
2011-09-08 17:59 ` Oleg Nesterov
2011-09-11 1:54 ` Tejun Heo
2011-09-11 18:29 ` Oleg Nesterov
2011-09-11 18:41 ` Oleg Nesterov
2011-09-08 18:01 ` [PATCH 6/6] freezer: kill unused set_freezable_with_signal() Matt Helsley
2011-09-11 1:37 ` Tejun Heo [this message]
2011-09-04 18:48 ` [PATCHSET pm-freezer] freezer: fixes & simplifications Oleg Nesterov
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