Re: [RFC PATCH v2 13/17] cgroup: Allow fine-grained controllers control in cgroup v2

[Tejun Heo]

Hello,

On Wed, May 24, 2017 at 01:49:46PM -0400, Waiman Long wrote:
> What I am saying is as follows:
>     / A
> P - B
>    \ C
> 
> # echo +memory > P/cgroups.subtree_control
> # echo -memory > P/A/cgroup.controllers
> # echo "#memory" > P/B/cgroup.controllers
> 
> The parent grants the memory controller to its children - A, B and C.
> Child A has the memory controller explicitly disabled. Child B has the
> memory controller in pass-through mode, while child C has the memory
> controller enabled by default. "echo +memory > cgroup.controllers" is
> not allowed. There are 2 possible choices with regard to the '-' or '#'
> prefixes. We can allow them before the grant from the parent or only
> after that. In the former case, the state remains dormant until after
> the grant from the parent.

Ah, I see, you want cgroup.controllers to be able to mask available
controllers by the parent.  Can you expand your example with further
nesting and how #memory on cgroup.controllers would affect the nested
descendant?

Thanks.

-- 
tejun