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Date: Mon, 1 Aug 2011 13:24:14 +0800
From: Wu Fengguang <fengguang.wu@intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
        Andrew Morton <akpm@linux-foundation.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: xfstests 073 regression
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On Mon, Aug 01, 2011 at 07:47:49AM +0800, Dave Chinner wrote:
> On Sun, Jul 31, 2011 at 11:10:14PM +0800, Wu Fengguang wrote:
> > On Sat, Jul 30, 2011 at 09:44:22PM +0800, Christoph Hellwig wrote:
> > > This patch fixes the hang for me.
> > 
> > Thanks. It'd be better to get the _simple and tested_ fix into 3.1-rc1.
> > (if anyone find major problems with the fix, please speak up)
> 
> Yes, I already have, a couple of hours before you sent this:
> 
> http://www.spinics.net/lists/linux-fsdevel/msg47357.html

Err I found it in my spam folder.. and added you to the white list :)

> We haven't found the root cause of the problem, and writeback cannot
> hold off grab_super_passive() because writeback only holds read
> locks on s_umount, just like grab_super_passive. So if
> grab_super_passive is failing, there is some other, not yet
> unidentified actor causing this problem....

Yeah sorry, I totally overlooked the read lock. Since Linus has
pointed out the possibility of read-write-read deadlock, I'll jump
to your more recent email for the root cause.

Thanks,
Fengguang