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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 05513C2BA1A for ; Fri, 24 Apr 2020 08:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFCD320774 for ; Fri, 24 Apr 2020 08:11:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726582AbgDXILB (ORCPT ); Fri, 24 Apr 2020 04:11:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:52786 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726028AbgDXILA (ORCPT ); Fri, 24 Apr 2020 04:11:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 11D68AED2; Fri, 24 Apr 2020 08:10:59 +0000 (UTC) Message-ID: <1587715859.28179.17.camel@suse.cz> Subject: Re: [BISECTED] bug/regression, x86-64: completely unbootable machine From: Giovanni Gherdovich To: Rui Salvaterra , x86@kernel.org Cc: linux-kernel@vger.kernel.org Date: Fri, 24 Apr 2020 10:10:59 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-04-24 at 09:00 +0100, Rui Salvaterra wrote: > Hi, everyone, > > Starting with Linux 5.7-rc1, my Arrandale (Core i3-380M) laptop is > completely unbootable (the last messages on screen are GRUB's loading > kernel/initramfs). I was hoping someone would have noticed it before > 5.7-rc2 had been tagged, but alas. Anyway, I bisected it down to > commit 1567c3e3467cddeb019a7b53ec632f834b6a9239 (x86, sched: Add > support for frequency invariance). After reverting it, the machine > boots again, obviously. > > Let me know if you need any further info in order to fix this issue. > > Complete bisection log follows. > [...] Hello Rui, thanks for the report. The problem you encountered is due to a bug where the code doesn't work on machines with less than 4 physical CPU cores. It is fixed by this patch series: https://lore.kernel.org/lkml/20200416054745.740-1-ggherdovich@suse.cz/ The series has been merged in the branch sched/urgent of the "tip" tree (https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git), the commit fixing the bug you observed is 23ccee22e834 (x86, sched: Account for CPUs with less than 4 cores in freq. invariance), and will be merged in Linus' tree at some point. Thanks, Giovanni Gherdovich