Messages in this thread | | | Date | Tue, 19 May 2015 15:11:34 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem |
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On Tue, 19 May 2015, Aleksa Sarai wrote:
> >> 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.
Thanks,
tglx
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