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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 DEA4FC6786F for ; Mon, 29 Oct 2018 01:32:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ADCAA20827 for ; Mon, 29 Oct 2018 01:32:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ADCAA20827 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fromorbit.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726580AbeJ2KSn (ORCPT ); Mon, 29 Oct 2018 06:18:43 -0400 Received: from ipmail03.adl2.internode.on.net ([150.101.137.141]:26562 "EHLO ipmail03.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725886AbeJ2KSn (ORCPT ); Mon, 29 Oct 2018 06:18:43 -0400 Received: from ppp59-167-129-252.static.internode.on.net (HELO dastard) ([59.167.129.252]) by ipmail03.adl2.internode.on.net with ESMTP; 29 Oct 2018 11:51:00 +1030 Received: from dave by dastard with local (Exim 4.80) (envelope-from ) id 1gGwEl-0003YU-1M; Mon, 29 Oct 2018 12:20:59 +1100 Date: Mon, 29 Oct 2018 12:20:59 +1100 From: Dave Chinner To: Anatoly Trosinenko Cc: "Darrick J. Wong" , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: XFS: Hang and dmesg flood on mounting invalid FS image Message-ID: <20181029012058.GK19305@dastard> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 28, 2018 at 08:50:46PM +0300, Anatoly Trosinenko wrote: > Hello, > > When mounting a broken XFS image, the kernel hangs and floods dmesg > with stack traces. How did the corruption occur? $ sudo xfs_logprint -d /dev/vdc xfs_logprint: data device: 0xfd20 log device: 0xfd20 daddr: 131112 length: 6840 0 HEADER Cycle 1 tail 1:000000 len 512 ops 1 [00000 - 00000] Cycle 0xffffffff New Cycle 0x00000001 2 HEADER Cycle 1 tail 1:000002 len 512 ops 5 4 HEADER Cycle 1 tail -2147483647:000002 len 512 ops 1 ^^^^^^^^^^^^ 6 HEADER Cycle 0 tail 1:000000 len 0 ops 0 [00000 - 00006] Cycle 0x00000001 New Cycle 0x00000000 7 HEADER Cycle 0 tail 1:000000 len 0 ops 0 Ok, so from this the head of the log is block 4, and it has a corrupt tail pointer it points to: $ sudo xfs_logprint -D -s 4 /dev/vdc |head -10 xfs_logprint: data device: 0xfd20 log device: 0xfd20 daddr: 131112 length: 6840 BLKNO: 4 0 bebaedfe 1000000 2000000 20000 1000000 3610000 1000080 2000000 ^^^^^^^ ^ ^ wrong wrong wrong 8 2f27bae6 2000000 1000000 dabdbab0 0 0 0 0 10 0 0 0 0 0 0 0 0 18 0 0 0 0 0 0 0 0 20 0 0 0 0 0 0 0 0 They decode as: cycle: 1 version: 2 lsn: 1,24835 tail_lsn: 2147483649,2 So the tail LSN points to an invalid log cycle and the previous block. IOWs, the block number in the tail indicates the whole log is valid and needs to be scanned. but the cycle is not valid. And that's the problem. Neither the head or tail blocks are validated before they are used. CRC checking of the head and tail blocks comes later.... Cheers, Dave. -- Dave Chinner david@fromorbit.com