Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 4 Nov 2019 12:33:09 -0800 (PST)
From:   David Rientjes <rientjes@google.com>
To:     John Hubbard <jhubbard@nvidia.com>
cc:     Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Alex Williamson <alex.williamson@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        =?UTF-8?Q?Bj=C3=B6rn_T=C3=B6pel?= <bjorn.topel@intel.com>,
        Christoph Hellwig <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Chinner <david@fromorbit.com>,
        David Airlie <airlied@linux.ie>,
        "David S . Miller" <davem@davemloft.net>,
        Ira Weiny <ira.weiny@intel.com>, Jan Kara <jack@suse.cz>,
        Jason Gunthorpe <jgg@ziepe.ca>, Jens Axboe <axboe@kernel.dk>,
        Jonathan Corbet <corbet@lwn.net>,
        =?UTF-8?Q?J=C3=A9r=C3=B4me_Glisse?= <jglisse@redhat.com>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Michal Hocko <mhocko@suse.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Paul Mackerras <paulus@samba.org>,
        Shuah Khan <shuah@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>, bpf@vger.kernel.org,
        dri-devel@lists.freedesktop.org, kvm@vger.kernel.org,
        linux-block@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-media@vger.kernel.org, linux-rdma@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org,
        linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and
 FOLL_PIN
In-Reply-To: <20191103211813.213227-6-jhubbard@nvidia.com>
Message-ID: <alpine.DEB.2.21.1911041231520.74801@chino.kir.corp.google.com>
References: <20191103211813.213227-1-jhubbard@nvidia.com> <20191103211813.213227-6-jhubbard@nvidia.com>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On Sun, 3 Nov 2019, 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()
> 
> All pages that are pinned via the above calls, must be unpinned via
> put_user_page().
> 

Hi John,

I'm curious what consideration is given to what pageblock migrate types 
that FOLL_PIN and FOLL_LONGTERM pages originate from, assuming that 
longterm would want to originate from MIGRATE_UNMOVABLE pageblocks for the 
purposes of anti-fragmentation?