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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 76910C2BBCF for ; Thu, 17 Dec 2020 21:31:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4CAAA23A56 for ; Thu, 17 Dec 2020 21:31:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729119AbgLQVbW (ORCPT ); Thu, 17 Dec 2020 16:31:22 -0500 Received: from mx3.molgen.mpg.de ([141.14.17.11]:41855 "EHLO mx1.molgen.mpg.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728336AbgLQVbW (ORCPT ); Thu, 17 Dec 2020 16:31:22 -0500 Received: from [192.168.0.8] (ip5f5aeed4.dynamic.kabel-deutschland.de [95.90.238.212]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: buczek) by mx.molgen.mpg.de (Postfix) with ESMTPSA id 5679C2000C03F; Thu, 17 Dec 2020 22:30:38 +0100 (CET) Subject: Re: v5.10.1 xfs deadlock To: Brian Foster Cc: linux-xfs@vger.kernel.org, Linux Kernel Mailing List , it+linux-xfs@molgen.mpg.de References: <20201217194317.GD2507317@bfoster> From: Donald Buczek Message-ID: <39b92850-f2ff-e4b6-0b2e-477ab3ec3c87@molgen.mpg.de> Date: Thu, 17 Dec 2020 22:30:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201217194317.GD2507317@bfoster> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.12.20 20:43, Brian Foster wrote: > On Thu, Dec 17, 2020 at 06:44:51PM +0100, Donald Buczek wrote: >> Dear xfs developer, >> >> I was doing some testing on a Linux 5.10.1 system with two 100 TB xfs filesystems on md raid6 raids. >> >> The stress test was essentially `cp -a`ing a Linux source repository with two threads in parallel on each filesystem. >> >> After about on hour, the processes to one filesystem (md1) blocked, 30 minutes later the process to the other filesystem (md0) did. >> >> root 7322 2167 0 Dec16 pts/1 00:00:06 cp -a /jbod/M8068/scratch/linux /jbod/M8068/scratch/1/linux.018.TMP >> root 7329 2169 0 Dec16 pts/1 00:00:05 cp -a /jbod/M8068/scratch/linux /jbod/M8068/scratch/2/linux.019.TMP >> root 13856 2170 0 Dec16 pts/1 00:00:08 cp -a /jbod/M8067/scratch/linux /jbod/M8067/scratch/2/linux.028.TMP >> root 13899 2168 0 Dec16 pts/1 00:00:05 cp -a /jbod/M8067/scratch/linux /jbod/M8067/scratch/1/linux.027.TMP >> >> Some info from the system (all stack traces, slabinfo) is available here: https://owww.molgen.mpg.de/~buczek/2020-12-16.info.txt >> >> It stands out, that there are many (549 for md0, but only 10 for md1) "xfs-conv" threads all with stacks like this >> >> [<0>] xfs_log_commit_cil+0x6cc/0x7c0 >> [<0>] __xfs_trans_commit+0xab/0x320 >> [<0>] xfs_iomap_write_unwritten+0xcb/0x2e0 >> [<0>] xfs_end_ioend+0xc6/0x110 >> [<0>] xfs_end_io+0xad/0xe0 >> [<0>] process_one_work+0x1dd/0x3e0 >> [<0>] worker_thread+0x2d/0x3b0 >> [<0>] kthread+0x118/0x130 >> [<0>] ret_from_fork+0x22/0x30 >> >> xfs_log_commit_cil+0x6cc is >> >> xfs_log_commit_cil() >> xlog_cil_push_background(log) >> xlog_wait(&cil->xc_push_wait, &cil->xc_push_lock); >> >> Some other threads, including the four "cp" commands are also blocking at xfs_log_commit_cil+0x6cc >> >> There are also single "flush" process for each md device with this stack signature: >> >> [<0>] xfs_map_blocks+0xbf/0x400 >> [<0>] iomap_do_writepage+0x15e/0x880 >> [<0>] write_cache_pages+0x175/0x3f0 >> [<0>] iomap_writepages+0x1c/0x40 >> [<0>] xfs_vm_writepages+0x59/0x80 >> [<0>] do_writepages+0x4b/0xe0 >> [<0>] __writeback_single_inode+0x42/0x300 >> [<0>] writeback_sb_inodes+0x198/0x3f0 >> [<0>] __writeback_inodes_wb+0x5e/0xc0 >> [<0>] wb_writeback+0x246/0x2d0 >> [<0>] wb_workfn+0x26e/0x490 >> [<0>] process_one_work+0x1dd/0x3e0 >> [<0>] worker_thread+0x2d/0x3b0 >> [<0>] kthread+0x118/0x130 >> [<0>] ret_from_fork+0x22/0x30 >> >> xfs_map_blocks+0xbf is the >> >> xfs_ilock(ip, XFS_ILOCK_SHARED); >> >> in xfs_map_blocks(). >> >> The system is low on free memory >> >> MemTotal: 197587764 kB >> MemFree: 2196496 kB >> MemAvailable: 189895408 kB >> >> but responsive. >> >> I have an out of tree driver for the HBA ( smartpqi 2.1.6-005 pulled from linux-scsi) , but it is unlikely that this blocking is related to that, because the md block devices itself are responsive (`xxd /dev/md0` ) >> >> I can keep the system in the state for a while. Is there an idea what was going from or an idea what data I could collect from the running system to help? I have full debug info and could walk lists or retrieve data structures with gdb. >> > > It might be useful to dump the values under /sys/fs/xfs//log/* for > each fs to get an idea of the state of the logs as well... root@deadbird:~# for f in /sys/fs/xfs/*/log/*; do echo $f : $(cat $f);done /sys/fs/xfs/md0/log/log_head_lsn : 5:714808 /sys/fs/xfs/md0/log/log_tail_lsn : 5:581592 /sys/fs/xfs/md0/log/reserve_grant_head : 5:365981696 /sys/fs/xfs/md0/log/write_grant_head : 5:365981696 /sys/fs/xfs/md1/log/log_head_lsn : 3:2963880 /sys/fs/xfs/md1/log/log_tail_lsn : 3:2772656 /sys/fs/xfs/md1/log/reserve_grant_head : 3:1517506560 /sys/fs/xfs/md1/log/write_grant_head : 3:1517506560 /sys/fs/xfs/sda1/log/log_head_lsn : 233:106253 /sys/fs/xfs/sda1/log/log_tail_lsn : 233:106251 /sys/fs/xfs/sda1/log/reserve_grant_head : 233:54403812 /sys/fs/xfs/sda1/log/write_grant_head : 233:54403812 /sys/fs/xfs/sda2/log/log_head_lsn : 84:5653 /sys/fs/xfs/sda2/log/log_tail_lsn : 84:5651 /sys/fs/xfs/sda2/log/reserve_grant_head : 84:2894336 /sys/fs/xfs/sda2/log/write_grant_head : 84:2894336 > > Brian > >> Best >> Donald >> > -- Donald Buczek buczek@molgen.mpg.de Tel: +49 30 8413 1433