From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD83CC43141 for ; Thu, 21 Jun 2018 09:20:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F9B220652 for ; Thu, 21 Jun 2018 09:20:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="L35dYrdR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F9B220652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932838AbeFUJUb (ORCPT ); Thu, 21 Jun 2018 05:20:31 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46862 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932591AbeFUJU2 (ORCPT ); Thu, 21 Jun 2018 05:20:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=clYijeDdCIi1ndl/s6LkWqPSsod6X7UFEYG/DR5QN18=; b=L35dYrdRofas/fU/r57FjG1Ob mhozuLtakh+eaIcfFquS9u1mc76DKd8s8iPWA6qPV9PHD1VSgGBk+RvotN8NMZjh6fuV4UfGX5A9s nSeySgxTeXZbA37BvbxyKc1UgmuvL/u6y9mb17g0vcehp/qhsDilEDM0VBwP50uW3BbKEgV/X9zzL 28t2NSe3SMb7kz48nL3lxEL/MuC5an1TXO4xv3sb2yomEC5p1CSqgdixW++csskaWvLOqEfpif/8Y hFlQp8qk3WPubAgdfSayNnA/C1jaYm1acRUYvlesjXDWnTwwOxGXPg+JVF1zJMJATMrDjsHFfF3wU jYCkGbaag==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fVvlI-0006jm-94; Thu, 21 Jun 2018 09:20:16 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EC0652029F1DB; Thu, 21 Jun 2018 11:20:13 +0200 (CEST) Date: Thu, 21 Jun 2018 11:20:13 +0200 From: Peter Zijlstra To: Waiman Long Cc: Tejun Heo , Li Zefan , Johannes Weiner , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith , torvalds@linux-foundation.org, Roman Gushchin , Juri Lelli , Patrick Bellasi Subject: Re: [PATCH v10 2/9] cpuset: Add new v2 cpuset.sched.domain_root flag Message-ID: <20180621092013.GU2494@hirez.programming.kicks-ass.net> References: <1529295249-5207-1-git-send-email-longman@redhat.com> <1529295249-5207-3-git-send-email-longman@redhat.com> <20180620142735.GM2494@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 21, 2018 at 03:58:06PM +0800, Waiman Long wrote: > As for the inconsistency between the real root and the container root, > this is true for almost all the controllers. So it is a generic problem. > One possible solution is to create a kind a pseudo root cgroup for the > container that looks and feels like a real root. But is there really a > need to do that? I don't really know. I thought the idea was to make containers indistinguishable from a real system. Now I know we're really rather far away from that in reality, and I really have no clue how important all that is. It all depends on how exactly this works; is it like I assumed, that this file is owned by the parent instead of the current directory? And that if you namespace this, you have an effective read-only file? Then fixing the inconsistency is trivial; simply provide a read-only file for the actual root cgroup too. And if the solution is trivial, I don't see a good reason not to do it.