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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 73554C43460 for ; Sun, 16 May 2021 14:43:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4885960C3F for ; Sun, 16 May 2021 14:43:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234255AbhEPOox (ORCPT ); Sun, 16 May 2021 10:44:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:44170 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230324AbhEPOox (ORCPT ); Sun, 16 May 2021 10:44:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5082AB07B; Sun, 16 May 2021 14:43:37 +0000 (UTC) Subject: Re: PROBLEM: bcache related kernel BUG() since Linux 5.12 To: Matthias Ferdinand , Thorsten Knabe Cc: linux-bcache@vger.kernel.org References: <58f92cd7-38d1-bc16-2b5f-b68b2db2233b@thorsten-knabe.de> From: Coly Li Message-ID: <1f1c49d2-6291-f8b5-3627-08ed88114e88@suse.de> Date: Sun, 16 May 2021 22:43:33 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/mixed; boundary="------------2FA4DE397A0807C8B37B1358" Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org This is a multi-part message in MIME format. --------------2FA4DE397A0807C8B37B1358 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 5/16/21 4:42 PM, Matthias Ferdinand wrote: > On Sat, May 15, 2021 at 09:06:07PM +0200, Thorsten Knabe wrote: >> Hello. >> >> Starting with Linux 5.12 bcache triggers a BUG() after a few minutes of >> usage. >> >> Linux up to 5.11.x is not affected by this bug. >> >> Environment: >> - Debian 10 AMD 64 >> - Kernel 5.12 - 5.12.4 >> - Filesystem ext4 >> - Backing device: degraded software RAID-6 (MD) with 3 of 4 disks active >> (unsure if the degraded RAID-6 has an effect or not) >> - Cache device: Single SSD > > Sorry I can't immediately help with bcache, but for DRBD, there was a > similar problem with DRBD on degraded md-raid fixed just recently: > > https://lists.linbit.com/pipermail/drbd-user/2021-May/025904.html > > Although they had silent data corruption AFAICT, not a loud BUG(), and > they stated problems started with kernel 4.3. > > For DRBD it had to do with split BIOs and readahead, which degraded > md-raid may or may not fail, and missing a fail on parts of a split-up > readahead BIO. > > Matthias > This is caused by a hidden issue which is triggered by the bio code change in v5.12. The attached patch can help to avoid the panic, and the finally fixes are under testing and will be posted very soon. 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