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, 3 Feb 2020 16:09:40 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Brian Geffon <bgeffon@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, linux-api@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Sonny Rao <sonnyrao@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Yu Zhao <yuzhao@google.com>, Jesse Barnes <jsbarnes@google.com>
Subject: Re: [PATCH v2] mm: Add MREMAP_DONTUNMAP to mremap().
Message-ID: <20200203130940.enfvdsbn42hhoaki@box>
References: <20200123014627.71720-1-bgeffon@google.com>
 <20200124190625.257659-1-bgeffon@google.com>
 <20200126220650.i4lwljpvohpgvsi2@box>
 <CADyq12xCK_3MhGi88Am5P6DVZvrW8vqtyJMHO0zjNhvhYegm1w@mail.gmail.com>
 <20200129104655.egvpavc2tzozlbqe@box>
 <CADyq12xgnVByYOkL=GcszYYKzDpg254QEOFoW8=e1y=bmOCcFQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CADyq12xgnVByYOkL=GcszYYKzDpg254QEOFoW8=e1y=bmOCcFQ@mail.gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, Feb 02, 2020 at 05:17:53AM +0100, Brian Geffon wrote:
> On Wed, Jan 29, 2020 at 11:46 AM Kirill A. Shutemov
> <kirill@shutemov.name> wrote:
> > Any better options for the flag name? (I have none)
> 
> The other option is that it's broken up into two new flags the first
> MREMAP_MUSTMOVE which can be used regardless of whether or not you're
> leaving the original mapping mapped. This would do exactly what it
> describes: move the mapping to a new address with or without
> MREMAP_FIXED, this keeps consistency with MAYMOVE.
> 
> The second flag would be the new MREMAP_DONTUNMAP flag which requires
> MREMAP_MUSTMOVE, again with or without MREMAP_FIXED.
> 
> What are your thoughts on this?

Sounds reasonable.

MREMAP_DONTUNMAP doesn't really convey that you move pages to the new
mapping, but leave empty mapping behind. But I guess there's only so much
you can encode into the name. (Patch to the man page should do the rest)

-- 
 Kirill A. Shutemov