Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages_remote()

From: John Hubbard <jhubbard@nvidia.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Dave Chinner" <david@fromorbit.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-rdma@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages_remote()
Date: Wed, 14 Aug 2019 17:02:17 -0700	[thread overview]
Message-ID: <2cbdf599-2226-99ae-b4d5-8909a0a1eadf@nvidia.com> (raw)
In-Reply-To: <20190814234959.GA463@iweiny-DESK2.sc.intel.com>

On 8/14/19 4:50 PM, Ira Weiny wrote:
> On Tue, Aug 13, 2019 at 05:56:31PM -0700, John Hubbard wrote:
>> On 8/13/19 5:51 PM, John Hubbard wrote:
>>> On 8/13/19 2:08 PM, Ira Weiny wrote:
>>>> On Mon, Aug 12, 2019 at 05:07:32PM -0700, John Hubbard wrote:
>>>>> On 8/12/19 4:49 PM, Ira Weiny wrote:
>>>>>> On Sun, Aug 11, 2019 at 06:50:44PM -0700, john.hubbard@gmail.com wrote:
>>>>>>> From: John Hubbard <jhubbard@nvidia.com>
>>>>> ...
>>>> Finally, I struggle with converting everyone to a new call.  It is more
>>>> overhead to use vaddr_pin in the call above because now the GUP code is going
>>>> to associate a file pin object with that file when in ODP we don't need that
>>>> because the pages can move around.
>>>
>>> What if the pages in ODP are file-backed?
>>>
>>
>> oops, strike that, you're right: in that case, even the file system case is covered.
>> Don't mind me. :)
> 
> Ok so are we agreed we will drop the patch to the ODP code?  I'm going to keep
> the FOLL_PIN flag and addition in the vaddr_pin_pages.
> 

Yes. I hope I'm not overlooking anything, but it all seems to make sense to
let ODP just rely on the MMU notifiers.

thanks,
-- 
John Hubbard
NVIDIA