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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 B0028C3B188 for ; Thu, 13 Feb 2020 07:45:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6216021734 for ; Thu, 13 Feb 2020 07:45:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=rasmusvillemoes.dk header.i=@rasmusvillemoes.dk header.b="biWiIy6c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729890AbgBMHpd (ORCPT ); Thu, 13 Feb 2020 02:45:33 -0500 Received: from mail-lf1-f66.google.com ([209.85.167.66]:38613 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729706AbgBMHpd (ORCPT ); Thu, 13 Feb 2020 02:45:33 -0500 Received: by mail-lf1-f66.google.com with SMTP id r14so3540086lfm.5 for ; Wed, 12 Feb 2020 23:45:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=tccHDFw8Be0tCiwLFmvqNHBCYLNSpms3aI/0Nu1Lkcw=; b=biWiIy6cSpYBYseYC5rG9zg0yZrhQDMcxudJjex+4XKfDJs5X9uRsoByIs3ZPg2On5 jo9rIt6nZQenqD3JNRPCsh+HcCyg6TQGtIvpn6dorob+z2JtRRyIsV08SbF1Ftkt+eMX +sSnpaCuqr43G996HOyFc+XyiKQV+fRGDUvsQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=tccHDFw8Be0tCiwLFmvqNHBCYLNSpms3aI/0Nu1Lkcw=; b=aK+9hZVJ/jZ3AtaQoFM+VsQ9idI+IAnND46fNp6CGN9X6dvESmD7BwONDkkY6uzgYI GGuDbHvdvWRhbs2Gj30ATf/UAl8buznB7rz5tmkWtJivcihk5Vkp+nWglV3H64THiAV8 XtDOIfCDrrSnuU8ndoyOO8EPynQYnryzRg9gD0Ds/xcquftBQpvbbc6jB2isX5tw1au3 L8+qxfFlqb0nV6Q57DdIumIxEC8R9xJKbkdEbAXrqydzy7SQZXWRK591weOw5urMWsXB iIC3vOyBdHx9qacILvVHz8yIcbtQyIAoOL0FQBtlh3/tcp8NYaZhe2EfFh/MMFVMTh4B fteg== X-Gm-Message-State: APjAAAUDOxM0rrLRbKG8MAyE7bAYy5NRiYWABKnIHj2dUDedWlMwwNUN 79PQHrHJd5j2101fc9MlXQ3VAWreVb9d4FPB X-Google-Smtp-Source: APXvYqw0quAloIVavV+0KAsCtOQX6LMqkFeiTVZoBqg/BRZSHx3nU8/X33CUk+TdrSB1k2JH4qEHWg== X-Received: by 2002:ac2:5391:: with SMTP id g17mr6979327lfh.93.1581579930294; Wed, 12 Feb 2020 23:45:30 -0800 (PST) Received: from [172.16.11.50] ([81.216.59.226]) by smtp.gmail.com with ESMTPSA id h7sm745141lfj.29.2020.02.12.23.45.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Feb 2020 23:45:29 -0800 (PST) Subject: Re: [Regression 5.6-rc1][Bisected b6231ea2b3c6] Powerpc 8xx doesn't boot anymore To: Christophe Leroy , Li Yang , Qiang Zhao , Greg Kroah-Hartman Cc: "linuxppc-dev@lists.ozlabs.org" , Scott Wood , linux-arm-kernel@lists.infradead.org, LKML References: <0d45fa64-51ee-0052-cb34-58c770c5b3ce@c-s.fr> From: Rasmus Villemoes Message-ID: Date: Thu, 13 Feb 2020 08:45:28 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <0d45fa64-51ee-0052-cb34-58c770c5b3ce@c-s.fr> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/02/2020 15.24, Christophe Leroy wrote: > Hi Rasmus, > > Kernel 5.6-rc1 silently fails on boot. > > I bisected the problem to commit b6231ea2b3c6 ("soc: fsl: qe: drop > broken lazy call of cpm_muram_init()") > > I get a bad_page_fault() for an access at address 8 in > cpm_muram_alloc_common(), called from cpm_uart_console_setup() via > cpm_uart_allocbuf() Sorry about that. But I'm afraid I don't see what I could have done differently - the patch series, including b6231ea2b3c6, has been in -next since 20191210, both you and ppc-dev were cc'ed on the entire series (last revision sent November 28). And I've been dogfooding the patches on both arm- and ppc-derived boards ever since (but obviously only for a few cpus). > Reverting the guilty commit on top of 5.6-rc1 is not trivial. > > In your commit text you explain that cpm_muram_init() is called via > subsys_initcall. But console init is done before that, so it cannot work. No, but neither did the code I removed seem to work - how does doing spin_lock_init on a held spinlock, and then unlocking it, work? Is everything-spinlock always a no-op in your configuration? And even so, I'd think a GFP_KERNEL allocation under spin_lock_irqsave() would trigger some splat somewhere? Please note I'm not claiming my patch is not at fault, it clearly is, I just want to try to understand how I could have been wrong about the "nobody can have been relying on it" part. > Do you have a fix for that ? Not right now, but I'll have a look. It's true that the patch probably doesn't revert cleanly, but it shouldn't be hard to add back those few lines in the appropriate spot, with a big fat comment that this does something very fishy (at least as a temporary measure if we don't find a proper solution soonish). Rasmus