From: Aleksa Sarai <cyphar@cyphar.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
"Tejun Heo" <tj@kernel.org>,
lizefan@huawei.com, mingo@redhat.com, richard@nod.at,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem
Date: Tue, 19 May 2015 23:43:21 +1000 [thread overview]
Message-ID: <CAOviyaiwGQZbA8w_TV0wXF7JaQK1LHGn8BC40R7ARR+mHHQf=Q@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1505191508530.4225@nanos>
>> >> However, it should be noted that organisational operations (adding and
>> >> removing tasks from a PIDs hierarchy) will *not* be prevented.
>> >
>> > This is how you spell: broken controller.
>>
>> This has been discussed before. Organisational operations (i.e.
>> attaching to a cgroup) are not to be blocked by a cgroup controller in
>> the unified hierarchy. You simply can't escape out of a parent
>> cgroup's limit through attaching to a child cgroup (because you will
>> attach either before the fork checks against the cgroup [in which case
>> the child's limit is followed -- which means you also follow the
>> parent's limit] or after it checks [which means you'll hit the
>> parent's limit and won't be able to fork]).
>
> That's complete and utter nonsense. What has the parent limit to do
> with the overflow of the child limit?
>
> parent: limit 100 usecnt 80
> child: limit 10 usecnt 10
>
> So moving anything into child is violating the constraints and has to
> be refused. Anything else is just dirty hackery.
Whoops. Yes, you're completely right. All right, I'll fix up the
patchset in a few days.
--
Aleksa Sarai (cyphar)
www.cyphar.com
next prev parent reply other threads:[~2015-05-19 13:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-18 14:50 [PATCH v12 0/8] cgroup: add pids subsystem Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 1/8] cgroup: switch to unsigned long for bitmasks Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 2/8] cgroup: use bitmask to filter for_each_subsys Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 3/8] cgroup: replace explicit ss_mask checking with for_each_subsys_which Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 4/8] cgroup, block: implement task_get_css() and use it in bio_associate_current() Aleksa Sarai
2015-05-18 21:59 ` Tejun Heo
2015-05-19 3:05 ` Aleksa Sarai
2015-05-28 20:47 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 5/8] cgroup: move enum cgroup_subsys_id definition Aleksa Sarai
2015-05-18 21:59 ` Tejun Heo
2015-05-19 1:25 ` Aleksa Sarai
2015-05-28 20:44 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 6/8] cgroup: allow a cgroup subsystem to reject a fork Aleksa Sarai
2015-05-18 22:12 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 7/8] cgroup: add a tset_get_css macro Aleksa Sarai
2015-05-18 21:34 ` Tejun Heo
2015-05-19 1:18 ` Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 8/8] cgroup: implement the PIDs subsystem Aleksa Sarai
2015-05-19 8:00 ` Peter Zijlstra
2015-05-19 8:44 ` Aleksa Sarai
2015-05-19 10:56 ` Peter Zijlstra
2015-05-28 20:33 ` Tejun Heo
2015-05-19 13:11 ` Thomas Gleixner
2015-05-19 13:43 ` Aleksa Sarai [this message]
2015-06-03 2:44 ` Aleksa Sarai
2015-05-28 20:40 ` Tejun Heo
2015-05-30 6:50 ` Aleksa Sarai
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