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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 79F04C433E2 for ; Tue, 1 Sep 2020 09:36:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62F7A2087D for ; Tue, 1 Sep 2020 09:36:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726764AbgIAJgi convert rfc822-to-8bit (ORCPT ); Tue, 1 Sep 2020 05:36:38 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:51232 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726679AbgIAJge (ORCPT ); Tue, 1 Sep 2020 05:36:34 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-198-0_ckY7SzOmm2B0gV5icsSA-1; Tue, 01 Sep 2020 10:36:30 +0100 X-MC-Unique: 0_ckY7SzOmm2B0gV5icsSA-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Tue, 1 Sep 2020 10:36:29 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Tue, 1 Sep 2020 10:36:29 +0100 From: David Laight To: 'Norbert Preining' , "linux-kernel@vger.kernel.org" Subject: RE: kernel hard lockups wit 5.9-rc{2,3} Thread-Topic: kernel hard lockups wit 5.9-rc{2,3} Thread-Index: AQHWf177xf+hBGUvkEWCmoTo7Rvn6alThq5g Date: Tue, 1 Sep 2020 09:36:29 +0000 Message-ID: <85b60791227e4719ae98ef08d1200af2@AcuMS.aculab.com> References: <20200831053847.GA5022@bulldog.preining.info> In-Reply-To: <20200831053847.GA5022@bulldog.preining.info> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Norbert Preining > I am seeing hard lockups with 5.9-rc2 and -rc3, while 5.8.N (1,2,3,4,5) > work without any problems. > > THe lockups are hard to debug, since not even Sysrq works anymore. The > screen freezes completely, no reaction. Ports are also dead, ssh into > the machine is not possible. > > Hangs are repeatable, but not triggerable (at least I didn't find a > way). Last time I left the screen locked and went shopping to find it > locked up coming back. In total I got about 10 lock ups. I've had a random lockup on a pre-rc1 kernel. But that might be one of our own drivers - OTOH they 'normally' generate OOPS tracebacks. Have you tried setting up a serial console? It might contain some useful messages. Sysrq is more likely to work with a PS2 keyboard (not USB). IIRC the 'caps lock' light only needs PS2 keyboard interrupts to be working - a useful check on how dead a system it. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)