Quoting Tejun Heo (tj@kernel.org):

Hello,

On Fri, Jun 24, 2016 at 12:22:54AM +0000, Topi Miettinen wrote:

quoted

quoted

This doesn't have anything to do with resource control and I don't
think it's a good idea to add arbitrary monitoring mechanisms to
cgroup just because it's easy to add interface there.  Given that
capabilities are inherited and modified through the process hierarchy,
shouldn't this be part of that?

With per process tracking, it's easy to miss if a short-lived process
exercised capabilities. Especially with ambient capabilities, the parent
process could be a shell script which might not use capabilities at all,
but its children do the heavy lifting.

But isn't being recursive orthogonal to using cgroup?  Why not account
usages recursively along the process hierarchy?  Capabilities don't
have much to do with cgroup but everything with process hierarchy.
That's how they're distributed and modified.  If monitoring their
usages is necessary, it makes sense to do it in the same structure.

That was my argument against using cgroups to enforce a new bounding
set.  For tracking though, the cgroup process tracking seems as applicable
to this as it does to systemd tracking of services.  It tracks a task and
the children it forks.