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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56E66C433FE for ; Fri, 22 Oct 2021 09:31:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E978B610C8 for ; Fri, 22 Oct 2021 09:31:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E978B610C8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 74026900003; Fri, 22 Oct 2021 05:31:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6F09A900002; Fri, 22 Oct 2021 05:31:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5DFA3900003; Fri, 22 Oct 2021 05:31:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0026.hostedemail.com [216.40.44.26]) by kanga.kvack.org (Postfix) with ESMTP id 4F387900002 for ; Fri, 22 Oct 2021 05:31:24 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1249F2BA9D for ; Fri, 22 Oct 2021 09:31:24 +0000 (UTC) X-FDA: 78723555288.23.6FE6418 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf09.hostedemail.com (Postfix) with ESMTP id D181F300011D for ; Fri, 22 Oct 2021 09:31:20 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 2C5202197A; Fri, 22 Oct 2021 09:31:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1634895082; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Re6Z+hD2OCPgbW5Kbd7cCqLbxFmo37eYAN4KtUFAFdY=; b=m3OJaBmhfXfIBurvZYW6QASEO3Y1IOBs2uS0m6VSU227lq8QSDYK0b1hRJ254SqGMu2HuF tTSfj8pdJVs8mpBk/SxYc+DwdV3osyIdjSYTs2S6SRtW1O73fr/HDHlwUzVqRUIO7qy5BR TLTyW55h+MKnjSA2bLC969Y2hQjensU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1634895082; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Re6Z+hD2OCPgbW5Kbd7cCqLbxFmo37eYAN4KtUFAFdY=; b=dOwa8ZJKDumhBngx2/KcSiE6iS0CJYsP39w0K5Nw5HtWCu+3SQY8oGYzA5pFUr7TucUUgA 9lsYz/psuyzLiMDg== Received: from quack2.suse.cz (unknown [10.100.224.230]) by relay2.suse.de (Postfix) with ESMTP id D2BCCA3B83; Fri, 22 Oct 2021 09:31:20 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id B61191E11B6; Fri, 22 Oct 2021 11:31:20 +0200 (CEST) Date: Fri, 22 Oct 2021 11:31:20 +0200 From: Jan Kara To: Zhengyuan Liu Cc: Jan Kara , viro@zeniv.linux.org.uk, Andrew Morton , tytso@mit.edu, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, =?utf-8?B?5YiY5LqR?= , Zhengyuan Liu Subject: Re: Problem with direct IO Message-ID: <20211022093120.GG1026@quack2.suse.cz> References: <20211020173729.GF16460@quack2.suse.cz> <20211021080304.GB5784@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: D181F300011D Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=m3OJaBmh; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=dOwa8ZJK; spf=pass (imf09.hostedemail.com: domain of jack@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=jack@suse.cz; dmarc=none X-Stat-Signature: rkf4hbzda8wsngtnbw777xhebipi4a8g X-Rspamd-Server: rspam06 X-HE-Tag: 1634895080-696835 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 21-10-21 20:11:43, Zhengyuan Liu wrote: > On Thu, Oct 21, 2021 at 4:03 PM Jan Kara wrote: > > > > On Thu 21-10-21 10:21:55, Zhengyuan Liu wrote: > > > On Thu, Oct 21, 2021 at 1:37 AM Jan Kara wrote: > > > > On Wed 13-10-21 09:46:46, Zhengyuan Liu wrote: > > > > > we are encounting following Mysql crash problem while importing tables : > > > > > > > > > > 2021-09-26T11:22:17.825250Z 0 [ERROR] [MY-013622] [InnoDB] [FATAL] > > > > > fsync() returned EIO, aborting. > > > > > 2021-09-26T11:22:17.825315Z 0 [ERROR] [MY-013183] [InnoDB] > > > > > Assertion failure: ut0ut.cc:555 thread 281472996733168 > > > > > > > > > > At the same time , we found dmesg had following message: > > > > > > > > > > [ 4328.838972] Page cache invalidation failure on direct I/O. > > > > > Possible data corruption due to collision with buffered I/O! > > > > > [ 4328.850234] File: /data/mysql/data/sysbench/sbtest53.ibd PID: > > > > > 625 Comm: kworker/42:1 > > > > > > > > > > Firstly, we doubled Mysql has operating the file with direct IO and > > > > > buffered IO interlaced, but after some checking we found it did only > > > > > do direct IO using aio. The problem is exactly from direct-io > > > > > interface (__generic_file_write_iter) itself. > > > > > > > > > > ssize_t __generic_file_write_iter() > > > > > { > > > > > ... > > > > > if (iocb->ki_flags & IOCB_DIRECT) { > > > > > loff_t pos, endbyte; > > > > > > > > > > written = generic_file_direct_write(iocb, from); > > > > > /* > > > > > * If the write stopped short of completing, fall back to > > > > > * buffered writes. Some filesystems do this for writes to > > > > > * holes, for example. For DAX files, a buffered write will > > > > > * not succeed (even if it did, DAX does not handle dirty > > > > > * page-cache pages correctly). > > > > > */ > > > > > if (written < 0 || !iov_iter_count(from) || IS_DAX(inode)) > > > > > goto out; > > > > > > > > > > status = generic_perform_write(file, from, pos = iocb->ki_pos); > > > > > ... > > > > > } > > > > > > > > > > From above code snippet we can see that direct io could fall back to > > > > > buffered IO under certain conditions, so even Mysql only did direct IO > > > > > it could interleave with buffered IO when fall back occurred. I have > > > > > no idea why FS(ext3) failed the direct IO currently, but it is strange > > > > > __generic_file_write_iter make direct IO fall back to buffered IO, it > > > > > seems breaking the semantics of direct IO. > > > > > > > > > > The reproduced environment is: > > > > > Platform: Kunpeng 920 (arm64) > > > > > Kernel: V5.15-rc > > > > > PAGESIZE: 64K > > > > > Mysql: V8.0 > > > > > Innodb_page_size: default(16K) > > > > > > > > Thanks for report. I agree this should not happen. How hard is this to > > > > reproduce? Any idea whether the fallback to buffered IO happens because > > > > iomap_dio_rw() returns -ENOTBLK or because it returns short write? > > > > > > It is easy to reproduce in my test environment, as I said in the previous > > > email replied to Andrew this problem is related to kernel page size. > > > > Ok, can you share a reproducer? > > I don't have a simple test case to reproduce, the whole procedure shown as > following is somewhat complex. > > 1. Prepare Mysql installation environment > a. Prepare a SSD partition (at least 100G) as the Mysql data > partition, format to Ext3 and mount to /data > # mkfs.ext3 /dev/sdb1 > # mount /dev/sdb1 /data > b. Create Mysql user and user group > # groupadd mysql > # useradd -g mysql mysql > c. Create Mysql directory > # mkdir -p /data/mysql > # cd /data/mysql > # mkdir data tmp run log > > 2. Install Mysql > a. Download mysql-8.0.25-1.el8.aarch64.rpm-bundle.tar from > https://downloads.mysql.com/archives/community/ > b. Install Mysql > # tar -xvf mysql-8.0.25-1.el8.aarch64.rpm-bundle.tar > # yum install openssl openssl-devel > # rpm -ivh mysql-community-common-8.0.25-1.el8.aarch64.rpm > mysql-community-client-plugins-8.0.25-1.el8.aarch64.rpm \ > mysql-community-libs-8.0.25-1.el8.aarch64.rp > mysql-community-client-8.0.25-1.el8.aarch64.rpm \ > mysql-community-server-8.0.25-1.el8.aarch64.rpm > mysql-community-devel-8.0.25-1.el8.aarch64.rpm > > 3. Configure Mysql > a. # chown mysql:mysql /etc/my.cnf > b. # vim /etc/my.cnf > innodb_flush_method = O_DIRECT > default-storage-engine=INNODB > datadir=/data/mysql/data > socket=/data/mysql/run/mysql.sock > tmpdir=/data/mysql/tmp > log-error=/data/mysql/log/mysqld.log > pid-file=/data/mysql/run/mysqld.pid > port=3306 > user=mysql > c. initialize Mysql (problem may reproduce at this stage) > # mysqld --defaults-file=/etc/my.cnf --initialize > d. Start Mysql > # mysqld --defaults-file=/etc/my.cnf & > e. Login into Mysql > # mysql -uroot -p -S /data/mysql/run/mysql.sock > You can see the temporary password from step 3.c > f. Configure access > mysql> alter user 'root'@'localhost' identified by "123456"; > mysql> create user 'root'@'%' identified by '123456'; > mysql> grant all privileges on *.* to 'root'@'%'; flush privileges; > mysql> create database sysbench; > > 4. Use sysbench to test Mysql > a. Install sysbench from https://github.com/akopytov/sysbench/archive/master.zip > b. Use following script to reproduce problem (may need dozens of minutes) > while true ; do > sysbench /usr/local/share/sysbench/oltp_write_only.lua > --table-size=1000000 --tables=100 \ > --threads=32 --db-driver=mysql --mysql-db=sysbench > --mysql-host=127.0.0.1 --mysql- port=3306 \ > --mysql-user=root --mysql-password=123456 > --mysql-socket=/var/lib/mysql/mysql.sock prepare > > sleep 5 > sysbench /usr/local/share/sysbench/oltp_write_only.lua > --table-size=1000000 --tables=100 \ > --threads=32 --db-driver=mysql --mysql-db=sysbench > --mysql-host=127.0.0.1 --mysql- port=3306 \ > --mysql-user=root --mysql-password=123456 > --mysql-socket=/var/lib/mysql/mysql.sock cleanup > > sleep 5 > done > > If you can't reproduce, we could provide a remote environment for you or > connect to your machine to build a reproduced environment. Ah, not that simple, also it isn't that easy to get arm64 machine for experiments for me. Connecting to your environment would be possible but let's try remote debugging for a bit more ;) > > > > Can you post output of "dumpe2fs -h " for the filesystem where the > > > > problem happens? Thanks! > > > > > > Sure, the output is: > > > > > > # dumpe2fs -h /dev/sda3 > > > dumpe2fs 1.45.3 (14-Jul-2019) > > > Filesystem volume name: > > > Last mounted on: /data > > > Filesystem UUID: 09a51146-b325-48bb-be63-c9df539a90a1 > > > Filesystem magic number: 0xEF53 > > > Filesystem revision #: 1 (dynamic) > > > Filesystem features: has_journal ext_attr resize_inode dir_index > > > filetype needs_recovery sparse_super large_file > > > > Thanks for the data. OK, a filesystem without extents. Does your test by > > any chance try to do direct IO to a hole in a file? Because that is not > > (and never was) supported without extents. Also the fact that you don't see > > the problem with ext4 (which means extents support) would be pointing in > > that direction. > > I am not sure if it trys to do direct IO to a hole or not, is there any > way to check? If you have a simple test to reproduce please let me know, > we are glad to try. Can you enable following tracing? echo 1 >/sys/kernel/debug/tracing/events/ext4/ext4_ind_map_blocks_exit/enable echo iomap_dio_rw >/sys/kernel/debug/tracing/set_ftrace_filter echo "function_graph" >/sys/kernel/debug/tracing/current_tracer And then gather output from /sys/kernel/debug/tracing/trace_pipe. Once the problem reproduces, you can gather the problematic file name from dmesg, find inode number from "stat " and provide that all to me? Thanks! Honza -- Jan Kara SUSE Labs, CR