netdev - Re: [PATCH v4 09/23] mm/gup: introduce pin_user_pages*() and FOLL

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Message-ID: <d5b14492-45a9-914e-92db-29592c3634e5@nvidia.com>
Date:   Wed, 13 Nov 2019 12:24:32 -0800
From:   John Hubbard <jhubbard@...dia.com>
To:     Ira Weiny <ira.weiny@...el.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Alex Williamson <alex.williamson@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Björn Töpel <bjorn.topel@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Chinner <david@...morbit.com>,
        David Airlie <airlied@...ux.ie>,
        "David S . Miller" <davem@...emloft.net>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>,
        Jonathan Corbet <corbet@....net>,
        Jérôme Glisse <jglisse@...hat.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Hocko <mhocko@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Paul Mackerras <paulus@...ba.org>,
        Shuah Khan <shuah@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>, <bpf@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <kvm@...r.kernel.org>,
        <linux-block@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
        <linux-media@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <netdev@...r.kernel.org>,
        <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH v4 09/23] mm/gup: introduce pin_user_pages*() and FOLL_PIN

On 11/13/19 10:59 AM, Ira Weiny wrote:
> On Tue, Nov 12, 2019 at 08:26:56PM -0800, John Hubbard wrote:
>> Introduce pin_user_pages*() variations of get_user_pages*() calls,
>> and also pin_longterm_pages*() variations.
>>
>> These variants all set FOLL_PIN, which is also introduced, and
>> thoroughly documented.
>>
>> The pin_longterm*() variants also set FOLL_LONGTERM, in addition
>> to FOLL_PIN:
>>
>>      pin_user_pages()
>>      pin_user_pages_remote()
>>      pin_user_pages_fast()
>>
>>      pin_longterm_pages()
>>      pin_longterm_pages_remote()
>>      pin_longterm_pages_fast()
> 
> At some point in this conversation I thought we were going to put in "unpin_*"
> versions of these.
> 
> Is that still in the plans?
> 

Why yes it is! :)  Daniel Vetter and Jan Kara both already weighed in [1],
in favor of "unpin_user_page*()", rather than "put_user_page*()".

I'll change those names.

[1] https://lore.kernel.org/r/20191113101210.GD6367@quack2.suse.cz


thanks,
-- 
John Hubbard
NVIDIA