linux-kernel - Re: [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry

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Message-ID: <4FE20C97.2060401@redhat.com>
Date:	Wed, 20 Jun 2012 13:47:03 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Mel Gorman <mgorman@...e.de>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>,
	Linux-Netdev <netdev@...r.kernel.org>,
	Linux-NFS <linux-nfs@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Neil Brown <neilb@...e.de>,
	Christoph Hellwig <hch@...radead.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Christie <michaelc@...wisc.edu>,
	Eric B Munson <emunson@...bm.net>
Subject: Re: [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free
 for network storage

On 06/20/2012 05:38 AM, Mel Gorman wrote:
> Commit [b3a27d: swap: Add swap slot free callback to
> block_device_operations] dereferences p->bdev->bd_disk but this is a
> NULL dereference if using swap-over-NFS. This patch checks SWP_BLKDEV
> on the swap_info_struct before dereferencing.
>
> With reference to this callback, Christoph Hellwig stated "Please
> just remove the callback entirely.  It has no user outside the staging
> tree and was added clearly against the rules for that staging tree".
> This would also be my preference but there was not an obvious way of
> keeping zram in staging/ happy.
>
> Signed-off-by: Xiaotian Feng<dfeng@...hat.com>
> Signed-off-by: Mel Gorman<mgorman@...e.de>

Acked-by: Rik van Riel<riel@...hat.com>

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