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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 AAE88C76190 for ; Thu, 25 Jul 2019 22:33:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82942229F3 for ; Thu, 25 Jul 2019 22:33:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="JbPcWjQi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726890AbfGYWdE (ORCPT ); Thu, 25 Jul 2019 18:33:04 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:41200 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726704AbfGYWdD (ORCPT ); Thu, 25 Jul 2019 18:33:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: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=jssmfKZvvecRupRISlMgLXb+1mp99rJbmBQCtx9m1Y4=; b=JbPcWjQiZIeGbgUt8dvIirT/R APbfD5i7kBy+LUZztNOZWOzad3p22qKiLN4wicyDFoXmBFlgqcDQ7WDQt1qQU+ezehZvzWOtRR6gh 89I3k0jiHzWmqNLOT/unjyGwjQPeZbIaQht9b7Bto+GZyIX5X7Y95Cuk2N2D3sH8BoA8wfGKVFhj2 S03cfMTz8f01Q3z5TNubu0dimWllLwLPn7V9cJa8krxgbWiPpHE/hum7IpLToqQOCWQpt5mqqsZhw JU3W8Yxx9XPwm2DSunA3rxodmZk31ibQOQ6AJCpoaEvc4ASo2dnO+YL3OdEf2Lcr5L06Y7SbWlY4p 2ED5bl16A==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:37158) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hqmI7-0002i9-LP; Thu, 25 Jul 2019 23:32:51 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1hqmI5-000649-1S; Thu, 25 Jul 2019 23:32:49 +0100 Date: Thu, 25 Jul 2019 23:32:49 +0100 From: Russell King - ARM Linux admin To: "George G. Davis" Cc: "Eric W. Biederman" , Thomas Gleixner , Florian Fainelli , Allison Randal , Souptick Joarder , "moderated list:ARM PORT" , open list Subject: Re: [PATCH] ARM: Fix null die() string for unhandled data and prefetch abort cases Message-ID: <20190725223248.GO1330@shell.armlinux.org.uk> References: <1563589976-19004-1-git-send-email-george_davis@mentor.com> <20190720123023.GA1330@shell.armlinux.org.uk> <20190725213754.GA29898@mam-gdavis-lt> <20190725215540.GM1330@shell.armlinux.org.uk> <20190725222401.GB29898@mam-gdavis-lt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190725222401.GB29898@mam-gdavis-lt> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 25, 2019 at 06:24:01PM -0400, George G. Davis wrote: > Hello Russell, > > On Thu, Jul 25, 2019 at 10:55:40PM +0100, Russell King - ARM Linux admin wrote: > > On Thu, Jul 25, 2019 at 05:37:54PM -0400, George G. Davis wrote: > > > Hello Russell, > > > > > > Thanks for your prompt reply! > > > > > > On Sat, Jul 20, 2019 at 01:30:23PM +0100, Russell King - ARM Linux admin wrote: > > > > On Fri, Jul 19, 2019 at 10:32:55PM -0400, George G. Davis wrote: > > > > > When an unhandled data or prefetch abort occurs, the die() string > > > > > is empty resulting in backtrace messages similar to the following: > > > > > > > > > > Internal error: : 1 [#1] PREEMPT SMP ARM > > > > > > > > > > Replace the null string with the name of the abort handler in order > > > > > to provide more meaningful hints as to the cause of the fault. > > > > > > > > NAK. > > > > > > > > We already print the cause of the abort earlier in the dump, and we've > > > > also added a "cut here" marker to help people include all the necessary > > > > information when reporting a problem. > > > > > > For what it's worth, I often receive crash dumps which lack the pr_alert > > > messages and only include the pr_emerg messages which this change would at > > > least provide extra hints, since the "Internal error" as at EMERG level > > > wereas the initial messages are only at ALERT level. It's subtle but for > > > cases where the end user has set loglevel such that they only see EMERG > > > messages, the change is helpful, to me at least. > > > > > > > It's unfortunate that we have the additional colon in the oops dump, > > > > > > Agreed, it's rather unfortunate that the string is NULL in these cases. > > > > > > > but repeating the information that we've printed on one of the previous > > > > two lines is really not necessary. > > > > > > It depends on the loglevel the user has set. So perhaps it's not such a > > > bad thing to repeat the information? > > > > Or maybe we should arrange for consistent usage of the log levels? > > Unfortunately, some of the users that I work with have very specific limits > and requirements for kernel error message logging which are driven by > performance and/or storage limitations. So it's not always possible to "arrange > for consistent usage of the log levels" with some users. Meanwhile, these > messages do show up in logs without the pre-able headers, lacking the string > which is already available. It's hardly a big deal to re-use the same string, > especially for the !user_mode(regs) case, where the kernel will oops at > EMERG loglevel, leaving the NULL string as the reason. I can assure you that > I've tried to convince these users to change the loglevel but they have their > reasons for keeping it as they do and I'm unable to convince them otherwise. Sorry, but I really don't buy this. By your argument, we should get rid of the pre-amble headers because they're "not useful" in your eyes... -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up