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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 F1A2AC433DF for ; Tue, 19 May 2020 03:29:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D088D204EF for ; Tue, 19 May 2020 03:29:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726407AbgESD3U (ORCPT ); Mon, 18 May 2020 23:29:20 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:33578 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbgESD3U (ORCPT ); Mon, 18 May 2020 23:29:20 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07488;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Tz-O038_1589858957; Received: from admindeMacBook-Pro-2.local(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0Tz-O038_1589858957) by smtp.aliyun-inc.com(127.0.0.1); Tue, 19 May 2020 11:29:17 +0800 Subject: Re: [PATCH RFC] ext4: fix partial cluster initialization when splitting extent To: Eric Whitney Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, joseph.qi@linux.alibaba.com References: <1589444097-38535-1-git-send-email-jefflexu@linux.alibaba.com> <20200514222120.GB4710@localhost.localdomain> <20200518220804.GA20248@localhost.localdomain> From: JeffleXu Message-ID: <9b526ae9-cba6-35dd-0424-61e8fa5ab016@linux.alibaba.com> Date: Tue, 19 May 2020 11:29:17 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200518220804.GA20248@localhost.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 5/19/20 6:08 AM, Eric Whitney wrote: > Hi, Jeffle: > > What kernel were you running when you observed your failures? Does your > patch resolve all observed failures, or do any remain? Do you have a > simple test script that reproduces the bug? > > I've made almost 1000 runs of shared/298 on various bigalloc configurations > using Ted's test appliance on 5.7-rc5 and have not observed a failure. > Several auto group runs have also passed without failures. Ideally, I'd > like to be able to reproduce your failure to be sure we fully understand > what's going on. It's still the case that the "2" is wrong, but I think > that code in rm_leaf may be involved in an unexpected way. > > Thanks, > Eric Hi Eric, Following on is my test environment. kernel: 5.7-rc4-git-eb24fdd8e6f5c6bb95129748a1801c6476492aba e2fsprog: latest release version 1.45.6 (20-Mar-2020) xfstests: git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git, master branch, latest commit 1. Test device I run the test in a VM and the VM is setup by qemu. The size of vdb is 1G, ``` #lsblk NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT vdb    254:16   0   1G  0 disk ``` and is initialized by: ``` qemu-img create -f qcow2 /XX/disk1.qcow2 1G qemu-kvm -drive file=/XX/disk1.qcow2,if=virtio,format=qcow2 ... ``` 2. Test script local.config of xfstests is like: export TEST_DEV=/dev/vdb export TEST_DIR=/mnt/test export SCRATCH_DEV=/dev/vdc export SCRATCH_MNT=/mnt/scratch Following on is an example script to reproduce the failure: ```sh #!/bin/bash for i in `seq 100`; do         echo y | mkfs.ext4 -O bigalloc -C 16K /dev/vdb         ./check shared/298         status=$?         if [[ $status == 1 ]]; then                 echo "$i exit"                 exit         fi done ``` Indeed the failure occurs occasionally. Sometimes the script stops at iteration 4, or sometimes at iteration 2, 7, 24. The failure occurs with the following dmesg report: ``` [  387.471876] EXT4-fs error (device vdb): mb_free_blocks:1457: group 1, block 158084:freeing already freed block (bit 6753); block bitmap corrupt. [  387.473729] EXT4-fs error (device vdb): ext4_mb_generate_buddy:747: group 1, block bitmap and bg descriptor inconsistent: 19550 vs 19551 free clusters ``` 3. About the applied patch The applied patch does fix the failure in my test environment. At least the failure doesn't occur after running the full 100 iterations. Thanks Jeffle