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From: Omar Sandoval <osandov@osandov.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@fb.com>, linux-fsdevel@vger.kernel.org
Subject: Re: [BUG] Oops in inode_to_bdi()
Date: Fri, 23 Jan 2015 17:22:09 -0800	[thread overview]
Message-ID: <20150124012209.GA4893@mew> (raw)
In-Reply-To: <20150121192949.GA24787@infradead.org>

On Wed, Jan 21, 2015 at 11:29:49AM -0800, Christoph Hellwig wrote:
> On Wed, Jan 21, 2015 at 12:17:07PM -0700, Jens Axboe wrote:
> > Christoph,
> > 
> > Ran into this one while testing. Looks like mapping->host is NULL, off
> > the shmem_writepage().
> 
> Hmm.  Not sure how this can happen, but for a NULL inode we can
> always just return noop_backing_dev_info safely, I'll cook up a patch.

Just in case anyone is still wondering, this happens because for a
swapcache page, page_mapping() returns the corresponding address_space
out of swapper_spaces, which doesn't have a valid host pointer. Before
getting rid of backing_dev_info, we would've used swap_backing_dev_info,
which it looks like you replaced with noop_backing_dev_info in your
series, so Jens' fix should be right.

-- 
Omar

      parent reply	other threads:[~2015-01-24  1:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-21 19:17 [BUG] Oops in inode_to_bdi() Jens Axboe
2015-01-21 19:29 ` Christoph Hellwig
2015-01-21 19:33   ` Jens Axboe
2015-01-21 20:04     ` Jens Axboe
2015-01-24  1:22   ` Omar Sandoval [this message]

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