Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755220AbbESK4q (ORCPT ); Tue, 19 May 2015 06:56:46 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:55275 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754616AbbESK4m (ORCPT ); Tue, 19 May 2015 06:56:42 -0400 Date: Tue, 19 May 2015 12:56:31 +0200 From: Peter Zijlstra To: Aleksa Sarai Cc: Tejun Heo , lizefan@huawei.com, mingo@redhat.com, richard@nod.at, =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH v12 8/8] cgroup: implement the PIDs subsystem Message-ID: <20150519105631.GH19282@twins.programming.kicks-ass.net> References: <1431960667-26593-1-git-send-email-cyphar@cyphar.com> <1431960667-26593-9-git-send-email-cyphar@cyphar.com> <20150519080055.GA3644@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1178 Lines: 28 On Tue, May 19, 2015 at 06:44:39PM +1000, Aleksa Sarai wrote: > >> However, it should be noted that organisational operations (adding and > >> removing tasks from a PIDs hierarchy) will *not* be prevented. > > > > This is how you spell: broken controller. > > This has been discussed before. Organisational operations (i.e. > attaching to a cgroup) are not to be blocked by a cgroup controller in > the unified hierarchy. That's utterly insane. As argued at length in threads like: lkml.kernel.org/r/alpine.DEB.2.11.1505061100040.4225@nanos This breaks fundamental control rules and makes life for a number of controllers impossible. Also, I'll NAK each and every patch that will attempt to remove failing can_attach from the cgroup core as it will fundamentally break some scheduler controllers. So please use it, it doesn't make any bloody sense to 'control' the number of PIDs but then allow it to overrun the set point. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/