From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.virtall.com ([178.63.195.102]:42212 "EHLO mail.virtall.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750762AbbFLIfN (ORCPT ); Fri, 12 Jun 2015 04:35:13 -0400 To: Qu Wenruo Subject: Re: kernel crashes with btrfs and busy database IO - how to debug? MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Date: Fri, 12 Jun 2015 17:35:11 +0900 From: Tomasz Chmielewski Cc: linux-btrfs In-Reply-To: <557A8691.6070908@cn.fujitsu.com> References: <557A8691.6070908@cn.fujitsu.com> Message-ID: <73cb882c23a71c9039a0e7bbfddfab64@admin.virtall.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2015-06-12 16:13, Qu Wenruo wrote: >> Remote syslog does not capture anything. > No backtrace? No (nothing saved on disk, don't have VNC access). The only way to capture anything is: while true; do dmesg -c ; done but that's usually incomplete. > Without backtrace, it's much harder to debug for us. > It's quite possible that some codes go mad and pass a NULL pointer, > and then wait_event() is called on the NULL->some_member. > > Anyway, backtrace is needed to debug this. > > If syslog can't help, what about kdump + crash to get the backtrace? I'll try to get a kdump + crash. -- Tomasz Chmielewski http://wpkg.org