From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: ext4fs error "ext4_mb_generate_buddy:741:group 16, 8160 clusters in bitmap, 4064 in gd" (with repro) Date: Thu, 9 Aug 2012 13:06:40 -0400 Message-ID: <20120809170640.GA6607@thunk.org> References: <50238A29.3060808@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Paolo Bonzini , "Linux Kernel Mailinlinux-ext4@vger.kernel.orgg List" , linux-ext4@vger.kernel.org To: Lukas Czerner Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:43843 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751756Ab2HIRGn (ORCPT ); Thu, 9 Aug 2012 13:06:43 -0400 Content-Disposition: inline In-Reply-To: <50238A29.3060808@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Aug 09, 2012 at 12:00:09PM +0200, Paolo Bonzini wrote: > Here is how to reproduce it. It happens during fstrim. I found other > occurrences of the error in the mailing list, but they were not related > to trim so they may be something different. > > modprobe scsi_debug dev_size_mb=256 lbpws=1 > dd if=/dev/zero of=/dev/sdb bs=1M > fdisk /dev/sdb > >> create a new partition accepting all defaults > fdisk -lu /dev/sdb|tail -1 > >> should show: /dev/sdb1 57 524285 262114+ 83 Linux > > mkfs.ext4 /dev/sdb1 > mkdir test > mount /dev/sdb1 test > fstrim ./test I can confirm that this accurately reproduces file system corruption using a 3.5 kernel. It looks like some block allocation bitmap blocks is getting trimmed when it shouldn't have been. Lukas, can you take a look at this? - Ted