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

[Roman Gushchin]

Hello Michael,

On Wed, Jan 10, 2018 at 05:23:32AM +0100, Michael Kerrisk (man-pages) wrote:
> Hello Roman,
> 
> On 8 January 2018 at 22:11, Michael Kerrisk (man-pages)
> <mtk.manpages@xxxxxxxxx> wrote:
> > Hello Roman,
> >
> > I wrote cgroups(7) text below to document the files added by you in
> > Linux 4.15. Could you let me know if the following text is okay please:
> >
> >    /sys/kernel/cgroup files
> >        /sys/kernel/cgroup/delegate (since Linux 4.15)
> >               This file exports a list of the cgroups v2 files  (one  per
> >               line) that are delegatable (i.e., whose ownership should be
> >               changed to the user ID of the delegatee).  In  the  future,
> >               the  set  of delegatable files may change or grow, and this
> >               file provides a way for the  kernel  to  inform  user-space
> >               applications of which files must be delegated.  As at Linux
> >               4.15, one sees the following when inspecting this file:
> >
> >                   $ cat /sys/kernel/cgroup/delegate
> >                   cgroup.procs
> >                   cgroup.subtree_control
> 
> I have a question about /sys/kernel/cgroup/delegate: why does this
> file not list cgroup.threads, since that is also a file that
> (potentially) should be delegated?

cc Tejun

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).

Thanks!

PS In the latter case the following patch should fix it: