From: Jan Kara <jack@suse•cz>
To: Stephen Rothwell <sfr@canb•auug.org.au>
Cc: Andrew Morton <akpm@linux-foundation•org>,
Dave Chinner <david@fromorbit•com>,
Al Viro <viro@zeniv•linux.org.uk>,
linux-next@vger•kernel.org, LKML <linux-kernel@vger•kernel.org>,
Christoph Hellwig <hch@lst•de>, Jens Axboe <axboe@kernel•dk>,
Jan Kara <jack@suse•cz>
Subject: Re: linux-next: OOPS at boot time
Date: Wed, 21 Jul 2010 14:11:17 +0200 [thread overview]
Message-ID: <20100721121116.GD3447@quack.suse.cz> (raw)
In-Reply-To: <20100721174809.4781c244.sfr@canb.auug.org.au>
On Wed 21-07-10 17:48:09, Stephen Rothwell wrote:
> On Wed, 21 Jul 2010 00:29:07 -0700 Andrew Morton <akpm@linux-foundation•org> wrote:
> >
> > On Wed, 21 Jul 2010 15:20:07 +1000 Dave Chinner <david@fromorbit•com> wrote:
> >
> > > > and they were dirtied within dquot_free_space().
> > >
> > > AFAICT dquot_free_space() is called deep in the guts of
> > > ext3_truncate() via dquot_free_block(), which is called directly
> > > before end_writeback(). That should overwrite any state changes made
> > > inside ext3_truncate. I wonder if iput_final() is racing with
> > > something else here?
> > >
> >
> > This isn't a race. I type `make' and the warnings spew out at hundreds
> > per second - every unlink, I'd say.
>
> Bisected to:
>
> commit 8bfe4a06746e5f03c02afe3ceb97b5364c099f63
> Author: Al Viro <viro@zeniv•linux.org.uk>
> Date: Sun Jun 6 07:08:19 2010 -0400
>
> convert ext3 to ->evict_inode()
>
> Signed-off-by: Al Viro <viro@zeniv•linux.org.uk>
Thanks for bisecting this. The patch series indeed seems to uncover
some discrepancies.
Ext3 has always dirtied inode in it's ->delete_inode method (via quota
code). But previously clear_inode() just overwrote the state with I_CLEAR
and thus we never saw the BUG_ON. After Al's patches, i_state is set in
end_writeback() which happens earlier. In particular it happens before
ext3_free_inode() which dirties the inode through quota code while freeing
xattrs - they are accounted in i_blocks, so i_blocks are updated during
freeing and inode is dirtied.
Actually, ext3_mark_inode_dirty() called during each mark_inode_dirty()
call writes the inode state to the journal so the dirty flag in the inode
state is in fact stale and overwriting it with I_CLEAR never mattered. In
this sense, the BUG_ON triggered is a false positive. But I believe this is
a separate story.
I'm not sure how to really fix this. It seems a bit premature to me to
mark inode as I_CLEAR before the filesystem is actually done with it. So
maybe the line
inode->i_state = I_FREEING | I_CLEAR;
should be moved to evict() fuction?
Honza
--
Jan Kara <jack@suse•cz>
SUSE Labs, CR
next prev parent reply other threads:[~2010-07-21 12:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-20 6:41 linux-next: OOPS at boot time Stephen Rothwell
2010-07-20 10:36 ` Andrew Morton
2010-07-20 22:45 ` Dave Chinner
2010-07-21 0:44 ` Andrew Morton
2010-07-21 5:20 ` Dave Chinner
2010-07-21 7:29 ` Andrew Morton
2010-07-21 7:48 ` Stephen Rothwell
2010-07-21 12:11 ` Jan Kara [this message]
2010-07-21 17:49 ` Al Viro
2010-07-21 21:40 ` Al Viro
2010-07-23 10:04 ` Jan Kara
2010-07-24 12:27 ` Al Viro
2010-07-21 23:19 ` Dave Chinner
2010-07-21 12:19 ` Jan Kara
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