Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751737AbeAJTOb (ORCPT + 1 other); Wed, 10 Jan 2018 14:14:31 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:38077 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbeAJTO2 (ORCPT ); Wed, 10 Jan 2018 14:14:28 -0500 X-Google-Smtp-Source: ACJfBotRLNSj1dLJu2Zpwl/py+WH0zxm9CYSXppyvvwRMahtBdwlw9KHUZaNN1DwZ7FE/tNakACN7g== Cc: mtk.manpages@gmail.com, "Serge E. Hallyn" , linux-man , lkml , "open list:CONTROL GROUP (CGROUP)" Subject: Re: cgroups(7): documenting /sys/kernel/cgroup files To: Tejun Heo , Roman Gushchin References: <20180110124407.GA26913@castle.DHCP.thefacebook.com> <20180110140239.GX3668920@devbig577.frc2.facebook.com> <20180110174457.GI3668920@devbig577.frc2.facebook.com> From: "Michael Kerrisk (man-pages)" Message-ID: <16c30b5d-d2c6-ffb0-9374-f48cb3bc154a@gmail.com> Date: Wed, 10 Jan 2018 20:14:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20180110174457.GI3668920@devbig577.frc2.facebook.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 01/10/2018 06:44 PM, Tejun Heo wrote: > On Wed, Jan 10, 2018 at 06:02:39AM -0800, Tejun Heo 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. > > Please disregard. > > Just like we can't mark the root cgroup threaded, we can't mark > delegated subtree root's threaded, so cgroup.type is not delegatable. > > However, the delegated root's children can definitely be marked > threadaed and they will join the delegated root's domain and the > threads are free to move between root and the threaded subtree. Exactly, so cgroup.threads in the threaded root must be made writable by the delegatee. Thanks, Tejun. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/