Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200819110100.23504-1-song.bao.hua@hisilicon.com>
 <e4265ac0-793d-053b-81b1-15e57c04b830@nvidia.com> <CAFqt6zb2GjO9KOVdKT1P0P-Wn+isnArous5gpw-AJ3va+fi9rw@mail.gmail.com>
 <20200903183950.GF14765@casper.infradead.org>
In-Reply-To: <20200903183950.GF14765@casper.infradead.org>
From:   Souptick Joarder <jrdr.linux@gmail.com>
Date:   Sat, 5 Sep 2020 06:41:11 +0530
Message-ID: <CAFqt6zYBDEsHqdQtgh+eZUAf+ODet=+LS7gqSkX5JO9eqS=_TA@mail.gmail.com>
Subject: Re: [PATCH] mm/gup: don't permit users to call get_user_pages with FOLL_LONGTERM
To:     Matthew Wilcox <willy@infradead.org>
Cc:     John Hubbard <jhubbard@nvidia.com>,
        Barry Song <song.bao.hua@hisilicon.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>, linux-kernel@vger.kernel.org,
        linuxarm@huawei.com, Jan Kara <jack@suse.cz>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Jonathan Corbet <corbet@lwn.net>,
        Michal Hocko <mhocko@suse.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Shuah Khan <shuah@kernel.org>, Vlastimil Babka <vbabka@suse.cz>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Sep 4, 2020 at 12:09 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Sep 03, 2020 at 12:42:44PM +0530, Souptick Joarder wrote:
> > We can use is_valid_gup_flags() inside ->
> > get_user_pages_locked(),
> > get_user_pages_unlocked(),
> > pin_user_pages_locked() as well.
> >
> > Are you planning to add it in future patches ?
>
> If you're looking for a new project, adding a foll_t or gup_t or
> something for the FOLL flags (like we have for gfp_t or vm_fault_t)
> would be helpful.  We're inconsistent with our naming here.

Sure. I will start looking into this and come up with a RFC version.