From: tytso@mit.edu Subject: Re: 2.6.33-rc1: kernel BUG at fs/ext4/inode.c:1063 (sparc) Date: Thu, 24 Dec 2009 18:15:11 -0500 Message-ID: <20091224231511.GB32757@thunk.org> References: <20091224230512.GA32757@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Alexander Beregalov , Linux Kernel Mailing List , linux-ext4@vger.kernel.org, Jens Axboe Return-path: Received: from THUNK.ORG ([69.25.196.29]:58121 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751498AbZLXXPP (ORCPT ); Thu, 24 Dec 2009 18:15:15 -0500 Content-Disposition: inline In-Reply-To: <20091224230512.GA32757@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Dec 24, 2009 at 06:05:12PM -0500, tytso@MIT.EDU wrote: > On Fri, Dec 25, 2009 at 01:28:34AM +0300, Alexander Beregalov wrote: > > > > Kernel is 2.6.33-rc1-00366-g2f99f5c > > Ext4 mounts ext3 filesystem > > > > kernel BUG at fs/ext4/inode.c:1063! > > OK, that's this BUG which is triggering: > > if (mdb_free) { > /* Account for allocated meta_blocks */ > mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks; > BUG_ON(mdb_free < mdb_claim); <------- BUG triggered > mdb_free -= mdb_claim; > > Can you replicate this? If so, I'd like to ask you to replicate with > the following debugging patch applied: Here's a revised version of the patch which should avoid the BUG_ON, which should make it be less annoying. We should really figure out what's going on and fix it, though. It may be fixed by the recently pushed quota race fixes, or at least there's a good chace that it's related to a ext4 quota-releated WARN_ON that people have been complaining about. - Ted --- /tmp/inode.c 2009-12-24 17:55:03.736366001 -0500 +++ /tmp/inode.c.new 2009-12-24 18:13:07.716366002 -0500 @@ -1060,8 +1060,14 @@ if (mdb_free) { /* Account for allocated meta_blocks */ mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks; - BUG_ON(mdb_free < mdb_claim); - mdb_free -= mdb_claim; + if (mdb_free < mdb_claim) { + ext4_msg(inode->i_sb, KERN_ERR, "inode #%lu: " + "mdb_free (%d) < mdb_claim (%d) BUG\n", + inode->i_ino, mdb_free, mdb_claim); + WARN_ON(1); + mdb_free = 0; + } else + mdb_free -= mdb_claim; /* update fs dirty blocks counter */ percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);