Re: cgroups(7): documenting /sys/kernel/cgroup files

[Michael Kerrisk (man-pages)]

Hello Tejun,

On 10 January 2018 at 15:02, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
>
> On Wed, Jan 10, 2018 at 04:44:14AM -0800, Roman Gushchin wrote:
>> cgroup.threads is not listed because it's not delegatable (doesn't have
>> CFTYPE_NS_DELEGATABLE flag set). I don't know if it was intended or just
>> an accident (I believe the latter).
>
> So, thread mode isn't delegatble.  Marking a cgroup as threaded turns
> that subtree threaded and join the parent's domain, so we can't allow
> delegation roots to be turned threaded - just like we can't mark the
> root cgroup threaded, and I'm not really not sure what it means to
> delegate a portion of threaded subtree.

So, I am confused. According to Documentation/cgroup-v2.txt,
cgoup.threads is delegated:

[[
Model of Delegation
~~~~~~~~~~~~~~~~~~~

A cgroup can be delegated in two ways.  First, to a less privileged
user by granting write access of the directory and its "cgroup.procs",
"cgroup.threads" and "cgroup.subtree_control" files to the user.
Second, if the "nsdelegate" mount option is set, automatically to a
cgroup namespace on namespace creation.
]]

So, is that a mistake in that text file?

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/