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 12:41:55 -0500
From:   Jerome Glisse <jglisse@redhat.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>,
        =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <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>,
        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 08/18] mm/process_vm_access: set FOLL_PIN via
 pin_user_pages_remote()
Message-ID: <20191104174155.GE5134@redhat.com>
References: <20191103211813.213227-1-jhubbard@nvidia.com>
 <20191103211813.213227-9-jhubbard@nvidia.com>
MIME-Version: 1.0
In-Reply-To: <20191103211813.213227-9-jhubbard@nvidia.com>
User-Agent: Mutt/1.12.1 (2019-06-15)
Content-Type: text/plain; charset=WINDOWS-1252
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, Nov 03, 2019 at 01:18:03PM -0800, John Hubbard wrote:
> Convert process_vm_access to use the new pin_user_pages_remote()
> call, which sets FOLL_PIN. Setting FOLL_PIN is now required for
> code that requires tracking of pinned pages.
>=20
> Also, release the pages via put_user_page*().
>=20
> Also, rename "pages" to "pinned_pages", as this makes for
> easier reading of process_vm_rw_single_vec().
>=20
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Reviewed-by: J=E9r=F4me Glisse <jglisse@redhat.com>

> ---
>  mm/process_vm_access.c | 28 +++++++++++++++-------------
>  1 file changed, 15 insertions(+), 13 deletions(-)
>=20
> diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
> index 357aa7bef6c0..fd20ab675b85 100644
> --- a/mm/process_vm_access.c
> +++ b/mm/process_vm_access.c
> @@ -42,12 +42,11 @@ static int process_vm_rw_pages(struct page **pages,
>  =09=09if (copy > len)
>  =09=09=09copy =3D len;
> =20
> -=09=09if (vm_write) {
> +=09=09if (vm_write)
>  =09=09=09copied =3D copy_page_from_iter(page, offset, copy, iter);
> -=09=09=09set_page_dirty_lock(page);
> -=09=09} else {
> +=09=09else
>  =09=09=09copied =3D copy_page_to_iter(page, offset, copy, iter);
> -=09=09}
> +
>  =09=09len -=3D copied;
>  =09=09if (copied < copy && iov_iter_count(iter))
>  =09=09=09return -EFAULT;
> @@ -96,7 +95,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
>  =09=09flags |=3D FOLL_WRITE;
> =20
>  =09while (!rc && nr_pages && iov_iter_count(iter)) {
> -=09=09int pages =3D min(nr_pages, max_pages_per_loop);
> +=09=09int pinned_pages =3D min(nr_pages, max_pages_per_loop);
>  =09=09int locked =3D 1;
>  =09=09size_t bytes;
> =20
> @@ -106,14 +105,15 @@ static int process_vm_rw_single_vec(unsigned long a=
ddr,
>  =09=09 * current/current->mm
>  =09=09 */
>  =09=09down_read(&mm->mmap_sem);
> -=09=09pages =3D get_user_pages_remote(task, mm, pa, pages, flags,
> -=09=09=09=09=09      process_pages, NULL, &locked);
> +=09=09pinned_pages =3D pin_user_pages_remote(task, mm, pa, pinned_pages,
> +=09=09=09=09=09=09     flags, process_pages,
> +=09=09=09=09=09=09     NULL, &locked);
>  =09=09if (locked)
>  =09=09=09up_read(&mm->mmap_sem);
> -=09=09if (pages <=3D 0)
> +=09=09if (pinned_pages <=3D 0)
>  =09=09=09return -EFAULT;
> =20
> -=09=09bytes =3D pages * PAGE_SIZE - start_offset;
> +=09=09bytes =3D pinned_pages * PAGE_SIZE - start_offset;
>  =09=09if (bytes > len)
>  =09=09=09bytes =3D len;
> =20
> @@ -122,10 +122,12 @@ static int process_vm_rw_single_vec(unsigned long a=
ddr,
>  =09=09=09=09=09 vm_write);
>  =09=09len -=3D bytes;
>  =09=09start_offset =3D 0;
> -=09=09nr_pages -=3D pages;
> -=09=09pa +=3D pages * PAGE_SIZE;
> -=09=09while (pages)
> -=09=09=09put_page(process_pages[--pages]);
> +=09=09nr_pages -=3D pinned_pages;
> +=09=09pa +=3D pinned_pages * PAGE_SIZE;
> +
> +=09=09/* If vm_write is set, the pages need to be made dirty: */
> +=09=09put_user_pages_dirty_lock(process_pages, pinned_pages,
> +=09=09=09=09=09  vm_write);
>  =09}
> =20
>  =09return rc;
> --=20
> 2.23.0
>=20