Date: Mon, 4 Dec 2017 13:47:10 -0800
From: Tejun Heo <tj@kernel.org>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: lkml <linux-kernel@vger.kernel.org>
Subject: Re: Writing "+pids" to cgroup.subtree_control flie yields EINVAL
Message-ID: <20171204214710.GM2421075@devbig577.frc2.facebook.com>
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Hello, Michael.

On Mon, Dec 04, 2017 at 10:35:13PM +0100, Michael Kerrisk (man-pages) wrote:
> I was trying to do some simple testing ot the CPU controller
> that is merged into 4.15, and ran immediately into some confusion.
> In the root cgroup on a freshly booted 4.150-rc1, I try the following:
> 
> # pwd
> /sys/fs/cgroup/unified
> # echo '+cpu' > cgroup.subtree_control 
> sh: echo: write error: Invalid argument
>
> What am I missing> I presume I'm missing something obvious, although
> nothing jumped out at me as I read the cgroups-v2.txt file.

Checking whether I messed up something really basic... hmmm doesn't
seem that way.  What do /sys/fs/cgroup/unified/cgroup.controllers and
/proc/cgroups say?

Thanks.

-- 
tejun