linux-kernel - Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190814234959.GA463@iweiny-DESK2.sc.intel.com>
Date:   Wed, 14 Aug 2019 16:50:00 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     John Hubbard <jhubbard@...dia.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jérôme Glisse <jglisse@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages_remote()

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@...il.com wrote:
> >>>>> From: John Hubbard <jhubbard@...dia.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.

Ira

> 
> >>
> >> This overhead may be fine, not sure in this case, but I don't see everyone
> >> wanting it.
> 
> So now I see why you said that, but I will note that ODP hardware is rare,
> and will likely remain rare: replayable page faults require really special 
> hardware, and after all this time, we still only have CPUs, GPUs, and the
> Mellanox cards that do it.
> 
> That leaves a lot of other hardware to take care of.
> 
> thanks,
> -- 
> John Hubbard
> NVIDIA
>