From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751837AbdAMOpj (ORCPT <rfc822;w@1wt.eu>);
        Fri, 13 Jan 2017 09:45:39 -0500
Received: from mx1.redhat.com ([209.132.183.28]:32858 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751721AbdAMOph (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 13 Jan 2017 09:45:37 -0500
Date: Fri, 13 Jan 2017 09:45:08 -0500
From: Jerome Glisse <jglisse@redhat.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, John Hubbard <jhubbard@nvidia.com>,
        Russell King <linux@armlinux.org.uk>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Chris Metcalf <cmetcalf@mellanox.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [HMM v16 01/15] mm/memory/hotplug: convert device bool to int to
 allow for more flags v2
Message-ID: <20170113144508.GA3758@redhat.com>
References: <1484238642-10674-1-git-send-email-jglisse@redhat.com>
 <1484238642-10674-2-git-send-email-jglisse@redhat.com>
 <20170113135741.GA26827@localhost.localdomain>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20170113135741.GA26827@localhost.localdomain>
User-Agent: Mutt/1.7.1 (2016-10-04)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 13 Jan 2017 14:45:12 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Jan 13, 2017 at 07:27:41PM +0530, Balbir Singh wrote:
> On Thu, Jan 12, 2017 at 11:30:28AM -0500, Jérôme Glisse wrote:
> > When hotpluging memory we want more informations on the type of memory and
> > its properties. Replace the device boolean flag by an int and define a set
> > of flags.
> > 
> > New property for device memory is an opt-in flag to allow page migration
> > from and to a ZONE_DEVICE. Existing user of ZONE_DEVICE are not expecting
> > page migration to work for their pages. New changes to page migration i
> > changing that and we now need a flag to explicitly opt-in page migration.
> 
> Given that ZONE_DEVICE is dependent on X86_64, do we need to touch all
> architectures? I guess we could selectively enable things as we enable
> ZONE_DEVICE for other architectures?

Yes i need to change all architecture because the function prototype changes.

I add the bug stuff to be bullet proof from new feature added that might
cause trouble if arch does not handle them explicitly. If the bug stuff scares
people i can remove it.

Cheers,
Jérôme