Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem

[Aleksa Sarai]

>> 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]).

--
Aleksa Sarai (cyphar)
www.cyphar.com
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