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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 8A068C32789 for ; Tue, 6 Nov 2018 14:17:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5078220685 for ; Tue, 6 Nov 2018 14:17:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5078220685 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 S1730767AbeKFXnQ (ORCPT ); Tue, 6 Nov 2018 18:43:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44070 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730663AbeKFXnP (ORCPT ); Tue, 6 Nov 2018 18:43:15 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5452537E87; Tue, 6 Nov 2018 14:17:49 +0000 (UTC) Received: from llong.remote.csb (ovpn-124-84.rdu2.redhat.com [10.10.124.84]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3841C60470; Tue, 6 Nov 2018 14:17:36 +0000 (UTC) Subject: Re: [PATCH v14 05/12] cpuset: Add an error state to cpuset.sched.partition To: Peter Zijlstra 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 , Tom Hromatka References: <1539635377-22335-1-git-send-email-longman@redhat.com> <1539635377-22335-6-git-send-email-longman@redhat.com> <20181106113712.GL22431@hirez.programming.kicks-ass.net> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181106113712.GL22431@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 06 Nov 2018 14:17:49 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/06/2018 06:37 AM, Peter Zijlstra wrote: > On Mon, Oct 15, 2018 at 04:29:30PM -0400, Waiman Long wrote: >> Handling error returned by update_parent_subparts_cpumask() in >> update_cpumasks_hier() is problematic as the states may become >> inconsistent. To avoid that and increase flexibility in handling other >> error cases, a new error state (-1) is added to the partition_root_state >> flag. This new error state is set internally and user cannot write this >> value to "cpuset.sched.partition". >> >> In this error state, the partition root becomes an erroneous one. It is >> no longer a real partition root, but the CS_CPU_EXCLUSIVE flag will >> still be set as it can be changed back to a real one if appropriate >> change happens later on. > I feel this Changelog should be much more explicit about the reasons > this -1 state can happen. As is, I've got no clue. OK, I will elaborate more on this changelog. Cheers, Longman