From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933677AbdEXSSA convert rfc822-to-8bit (ORCPT ); Wed, 24 May 2017 14:18:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46402 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933130AbdEXSRz (ORCPT ); Wed, 24 May 2017 14:17:55 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 29E83C04B948 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=longman@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 29E83C04B948 Subject: Re: [RFC PATCH v2 13/17] cgroup: Allow fine-grained controllers control in cgroup v2 To: Tejun Heo References: <1494855256-12558-1-git-send-email-longman@redhat.com> <1494855256-12558-14-git-send-email-longman@redhat.com> <20170519205550.GD15279@wtj.duckdns.org> <6fe07727-e611-bfcd-8382-593a51bb4888@redhat.com> <20170524173144.GI24798@htj.duckdns.org> <29bc746d-f89b-3385-fd5c-314bcd22f9f7@redhat.com> <20170524175600.GL24798@htj.duckdns.org> Cc: Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, efault@gmx.de From: Waiman Long Organization: Red Hat Message-ID: Date: Wed, 24 May 2017 14:17:50 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170524175600.GL24798@htj.duckdns.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8BIT X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 24 May 2017 18:17:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/24/2017 01:56 PM, Tejun Heo wrote: > 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. > I would allow enabling the controller in subtree_control if granted from the parent and not explicitly disabled. IOW, both B and C can "echo +memory" to their subtree_control to grant memory controller to their children, but not A. A has to re-enable memory controller or set it to pass-through mode before it can enable it in subtree_control. I need to clarify that "echo +memory > cgroup.controllers" is allowed to re-enable it, but not without the granting from its parent. Cheers, Longman