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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 621AAC433B4 for ; Fri, 7 May 2021 07:33:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25781601FF for ; Fri, 7 May 2021 07:33:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232868AbhEGHe1 (ORCPT ); Fri, 7 May 2021 03:34:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229849AbhEGHeW (ORCPT ); Fri, 7 May 2021 03:34:22 -0400 Received: from mail-lj1-x234.google.com (mail-lj1-x234.google.com [IPv6:2a00:1450:4864:20::234]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0310BC061574 for ; Fri, 7 May 2021 00:33:23 -0700 (PDT) Received: by mail-lj1-x234.google.com with SMTP id w4so10341132ljw.9 for ; Fri, 07 May 2021 00:33:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=bApySWlmTsfizudeVmUm2CRbJWPswhG/6Y0dhbrJr7E=; b=VcQuqnwfp4qDEkS+zK9V3j86OHrLkqmVnGXei5/r3lgE7od3meqaBsckUS2Kt0xMCS yJCYFvuF9t+7+cFmoMNa3dg4wVYrZowROrwPc4GMov1TXU2E85p7VnrBvKeVBwmnrkVB z9VO2fEhXGKD0vp1Z1vt36cXiK6c+1jrhI69Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bApySWlmTsfizudeVmUm2CRbJWPswhG/6Y0dhbrJr7E=; b=nG2v7A7+pGHC//JlbLZJUyZy3pC6iQwnVxn8pe70O3vnqbBoqfK9F2MzCOSEqwhpWP /u7jxUa6GC9Q9wsH39QOU2k5VlDFrpeakUCgJ791zuNVuF2isWeUyhjjxT9LnA1sH3gA tGI+t930ub9FDNtgZyxF0b/lf2ohIeecE8X3hL/82EaUuOIzmK3x/kyco1kA4SvBhbTP OLexTZXosD2TKTjBmEEj3Za8T/2esInFN4ELhQtO8V/IZB5f36iJDOJtflNo92YZdSs0 raA9Oyt1VY5hzIZEV6Y9QOIpgZu2d5inrmdXUwjmd9K4iUxR5TRR5wIipFXw0sKPopf9 LoZw== X-Gm-Message-State: AOAM531dy9qUkD6ydSrM2yBflw2VLBd2dugBvbEyQN5QXadCLn+RlZzk MYHMn/mP2+MfHdWq9aP5lgPCoY/gqgiIQm59TJc= X-Google-Smtp-Source: ABdhPJy8xj4MmaXWj4Ln8dc9AVAwHvZsmKkeHwFbJbm+lkKT7UWTsXEJmvE4caaG5ZK+KY+y6v6yaA== X-Received: by 2002:a2e:8596:: with SMTP id b22mr6546471lji.482.1620372801320; Fri, 07 May 2021 00:33:21 -0700 (PDT) Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com. [209.85.167.43]) by smtp.gmail.com with ESMTPSA id y20sm1283327lfe.162.2021.05.07.00.33.21 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 07 May 2021 00:33:21 -0700 (PDT) Received: by mail-lf1-f43.google.com with SMTP id x19so11469881lfa.2 for ; Fri, 07 May 2021 00:33:21 -0700 (PDT) X-Received: by 2002:ac2:5f92:: with SMTP id r18mr5567590lfe.253.1620372345069; Fri, 07 May 2021 00:25:45 -0700 (PDT) MIME-Version: 1.0 References: <20210506180126.03e1baee7ca52bedb6cc6003@linux-foundation.org> <20210507010432.IN24PudKT%akpm@linux-foundation.org> In-Reply-To: <20210507010432.IN24PudKT%akpm@linux-foundation.org> From: Linus Torvalds Date: Fri, 7 May 2021 00:25:29 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 48/91] kernel/crash_core: add crashkernel=auto for vmcore creation To: Andrew Morton Cc: Andrey Konovalov , Baoquan He , Christian Brauner , Colin King , Jonathan Corbet , dyoung@redhat.com, Frederic Weisbecker , gpiccoli@canonical.com, john.p.donnelly@oracle.com, Josh Poimboeuf , Kees Cook , Linux-MM , Masahiro Yamada , Mauro Carvalho Chehab , Mike Kravetz , Ingo Molnar , mm-commits@vger.kernel.org, "Paul E. McKenney" , Peter Zijlstra , Randy Dunlap , Steven Rostedt , Mike Rapoport , saeed.mirzamohammadi@oracle.com, Sami Tolvanen , Stephen Boyd , Thomas Gleixner , Vivek Goyal , yifeifz2@illinois.edu Content-Type: text/plain; charset="UTF-8" Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org On Thu, May 6, 2021 at 6:04 PM Andrew Morton wrote: > > From: Saeed Mirzamohammadi > Subject: kernel/crash_core: add crashkernel=auto for vmcore creation > > This adds crashkernel=auto feature to configure reserved memory for vmcore > creation. CONFIG_CRASH_AUTO_STR is defined to be set for different kernel > distributions and different archs based on their needs. Ugh. I didn't realize how nasty this was until after I'd applied this patch. I'm going to drop this patch, because the Kconfig thing for it is an unmitigated mess. I was confused by the question, and then the help message was actively misleading. This is wrong for so many reasons: - this is a classic case of "you shouldn't ask a user this". The question makes no sense to any normal person, it certainly didn't to me. Don't ask questions that don't have sane answers. - the config help text is actively misleading, and claims that the option is about how much memory is reserved for a crash kernel Not so. It's the default string for when somebody uses "crashkernel=auto" - this shouldn't be a config option at all, it's clearly a distro setting, and should be on the kernel command line with the other distro settings. So I'm dropping this, and I don't see it ever being applied in this form for the above reasons. People, I've said this before, and apparently I need to say it again: the kernel config is likely the nastiest part of building a local kernel, and the biggest impediment to people actually building their own kernels. And people building their own kernel is the first step to becoming a kernel developer. So the kernel configuration is already one of the less pleasant parts of the kernel, but that does NOT mean that we should strive to make it even worse. Obscure, odd, strange config questions like this are a no-no. We're not making an already bad experience wose for something like this. Linus