From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH v2] Add support for SCT Write Same
Date: Mon, 13 Jun 2016 01:02:43 -0700
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To: Shaun Tancheff <shaun.tancheff@seagate.com>
Cc: Christoph Hellwig <hch@infradead.org>, Shaun Tancheff <shaun@tancheff.com>, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>, "Martin K . Petersen" <martin.petersen@oracle.com>, Tejun Heo <tj@kernel.org>

On Thu, Jun 09, 2016 at 10:24:40PM -0500, Shaun Tancheff wrote:
> >  - The plain page_address above looks harmful, how do we know that
> >    the page is mapped into kernel memory?  This might actually be broken
> >    already, though.
> 
> I think it just happens to work because it's always used with a recently
> allocated page. Fixing it to include the (possible) offset is just a good thing.

I haven't spent much time with libata recently, but what prevents an
arbitrary user page ending up here through SG_IO?