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,URIBL_BLOCKED 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 8DF2FC46460 for ; Wed, 15 Aug 2018 11:00:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40E2921580 for ; Wed, 15 Aug 2018 11:00:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40E2921580 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.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 S1729074AbeHONvm (ORCPT ); Wed, 15 Aug 2018 09:51:42 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:54086 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728576AbeHONvl (ORCPT ); Wed, 15 Aug 2018 09:51:41 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 51B8F18A; Wed, 15 Aug 2018 03:59:59 -0700 (PDT) Received: from [0.0.0.0] (e107985-lin.emea.arm.com [10.4.12.239]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0005E3F5BC; Wed, 15 Aug 2018 03:59:55 -0700 (PDT) Subject: Re: [PATCH v3 03/14] sched/core: uclamp: add CPU's clamp groups accounting To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan References: <20180806163946.28380-1-patrick.bellasi@arm.com> <20180806163946.28380-4-patrick.bellasi@arm.com> <20180814164905.GG2605@e110439-lin> <7c45c1a8-24cb-6798-5b6f-3b5dfc9b490d@arm.com> <20180815105428.GA7388@e110439-lin> From: Dietmar Eggemann Message-ID: Date: Wed, 15 Aug 2018 12:59:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180815105428.GA7388@e110439-lin> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/15/2018 12:54 PM, Patrick Bellasi wrote: > On 15-Aug 11:37, Dietmar Eggemann wrote: >> On 08/14/2018 06:49 PM, Patrick Bellasi wrote: >>> Hi Dietmar! >>> >>> On 14-Aug 17:44, Dietmar Eggemann wrote: >>>> On 08/06/2018 06:39 PM, Patrick Bellasi wrote: [..] >> If this is only for testing/debugging, I would suggest a simple one line >> BUG_ON() > > These are (eventually) considered as recoverable errors... thus, > AFAIK, using BUG_ON is overkilling and discouraged: > https://elixir.bootlin.com/linux/latest/source/include/asm-generic/bug.h#L42 Not sure about that. If this refcounting is out of sync, that's indicating a serious issue here for me which should be fixed. >> You find CONFIG_SCHED_DEBUG=y in production kernels as well. > > AFAIK, that setting is discouraged for production kernels... > Moreover, it's still better to WARN sometimes on a production kernel > the crash the device, isnt't it? IMHO, if this is something which should not happen at all, a BUG_ON() is the right thing to do here. And you get the call stack to investigate why it hit.