linux-kernel - Re: Regression in next with ext4 oops

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Message-ID: <20161004144439.olirtskevgwlace7@atomide.com>
Date:   Tue, 4 Oct 2016 07:44:39 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Eric Biggers <ebiggers@...gle.com>,
        Andreas Dilger <adilger@...ger.ca>,
        Jaegeuk Kim <jaegeuk@...nel.org>, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        Al Viro <viro@...IV.linux.org.uk>
Subject: Re: Regression in next with ext4 oops

* Theodore Ts'o <tytso@....edu> [161004 07:04]:
> On Tue, Oct 04, 2016 at 11:00:41AM +0200, Jan Kara wrote:
> > Never seen this but I suspect it is a fallout from Al's directory locking
> > changes. In particular ext4_htree_fill_tree() builds rb-tree of found
> > directory entries in file->private_data (and generally modifies the
> > structure stored there) but after Al's changes we don't have exclusive
> > access to struct file if I'm right so if two processes end up calling
> > getdents() for the same 'struct file' we are doomed.
> 
> I haven't seen it either, and I've been doing a lot of testing on the
> ext4 test branch.  So I'm guessing Tony has the only reliable repro
> for the problem at the moment.  That being said, it shouldn't be that
> hard to create a test case for this and add it to xfstests.
> 
> I'm pretty sure Jan is right about this, though, but it would be great
> to a get a quick confirmation from Tony if at all possible.

Looks like Jan's patch somehow makes things worse for me.

Regards,

Tony