From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:29553 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S932077AbbFOIKZ convert rfc822-to-8bit (ORCPT ); Mon, 15 Jun 2015 04:10:25 -0400 Subject: Re: kernel crashes with btrfs and busy database IO - how to debug? To: Tomasz Chmielewski References: <557A8691.6070908@cn.fujitsu.com> <73cb882c23a71c9039a0e7bbfddfab64@admin.virtall.com> <557AA1B9.9040009@cn.fujitsu.com> <40998423616120fecd531f31971b0b8b@admin.virtall.com> CC: linux-btrfs From: Qu Wenruo Message-ID: <557E8860.3080307@cn.fujitsu.com> Date: Mon, 15 Jun 2015 16:10:08 +0800 MIME-Version: 1.0 In-Reply-To: <40998423616120fecd531f31971b0b8b@admin.virtall.com> Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Now we can get the full backtrace. That's a step forward [45705.854778] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [45705.854824] IP: [] btrfs_wait_pending_ordered+0x5e/0x110 [btrfs] [45705.855615] Call Trace: [45705.855637] [] btrfs_commit_transaction+0x40b/0xb60 [btrfs] [45705.855671] [] ? prepare_to_wait_event+0x100/0x100 [45705.855698] [] btrfs_sync_file+0x313/0x380 [btrfs] [45705.855721] [] vfs_fsync_range+0x46/0xc0 [45705.855740] [] vfs_fsync+0x1c/0x20 [45705.855758] [] do_fsync+0x38/0x70 [45705.855777] [] SyS_fsync+0x10/0x20 [45705.855796] [] system_call_fastpath+0x16/0x75 Also the hang seems to be highly related to the bug, would you please send a new mail reporting the hang? Thanks, Qu 在 2015年06月14日 15:58, Tomasz Chmielewski 写道: > On 2015-06-14 09:30, Tomasz Chmielewski wrote: >> On 2015-06-13 08:23, Tomasz Chmielewski wrote: >> >>> I did get it from /var/crash/ though - is it more useful? I don't have >>> vmlinux for this kernel though, but have just built 4.1-rc7 with the >>> same config, can try to get the crash there. >> >> I've uploaded a crash dump and vmlinux here: >> >> http://www.virtall.com/files/temp/201506132321/ >> >> Let me know if it's anything useful or if you need more info. > > I've tried running it the same procedure to get one more crash, but it > didn't crash this time. > > Instead, btrfs is hanged on any writes - any processes trying to write > get into D state and never return; there is no write activity when > checking for example with iostat. "sync" command does not return. > > Reads from this btrfs filesystem are OK. > > I've uploaded the output of "echo w > /proc/sysrq-trigger" here: > > http://www.virtall.com/files/temp/dmesg.txt > > > Tomasz Chmielewski >