From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=zn05=5G=vger.kernel.org=linux-kselftest-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no
	autolearn_force=no version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id F0EF4C4332E
	for <linux-kselftest@archiver.kernel.org>; Sat, 21 Mar 2020 08:20:45 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id C632C20658
	for <linux-kselftest@archiver.kernel.org>; Sat, 21 Mar 2020 08:20:45 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1728040AbgCUIUp (ORCPT
        <rfc822;linux-kselftest@archiver.kernel.org>);
        Sat, 21 Mar 2020 04:20:45 -0400
Received: from verein.lst.de ([213.95.11.211]:51189 "EHLO verein.lst.de"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1727961AbgCUIUo (ORCPT <rfc822;linux-kselftest@vger.kernel.org>);
        Sat, 21 Mar 2020 04:20:44 -0400
Received: by verein.lst.de (Postfix, from userid 2407)
        id C3FCA68AFE; Sat, 21 Mar 2020 09:20:41 +0100 (CET)
Date:   Sat, 21 Mar 2020 09:20:41 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Ralph Campbell <rcampbell@nvidia.com>,
        Christoph Hellwig <hch@lst.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Bharata B Rao <bharata@linux.ibm.com>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Jerome Glisse <jglisse@redhat.com>, kvm-ppc@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        nouveau@lists.freedesktop.org, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 3/4] mm: simplify device private page handling in
 hmm_range_fault
Message-ID: <20200321082041.GA28613@lst.de>
References: <7256f88d-809e-4aba-3c46-a223bd8cc521@nvidia.com> <20200317121536.GQ20941@ziepe.ca> <20200317122445.GA11662@lst.de> <20200317122813.GA11866@lst.de> <20200317124755.GR20941@ziepe.ca> <20200317125955.GA12847@lst.de> <24fca825-3b0f-188f-bcf2-fadcf3a9f05a@nvidia.com> <20200319181716.GK20941@ziepe.ca> <89e33770-a0ab-e1ec-d5e5-535edefd3fd3@nvidia.com> <20200320000345.GO20941@ziepe.ca>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200320000345.GO20941@ziepe.ca>
User-Agent: Mutt/1.5.17 (2007-11-01)
Sender: linux-kselftest-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kselftest.vger.kernel.org>
X-Mailing-List: linux-kselftest@vger.kernel.org

On Thu, Mar 19, 2020 at 09:03:45PM -0300, Jason Gunthorpe wrote:
> > Should tests enable the feature or the feature enable the test?
> > IMHO, if the feature is being compiled into the kernel, that should
> > enable the menu item for the test. If the feature isn't selected,
> > no need to test it :-)
> 
> I ment if DEVICE_PRIVATE should be a user selectable option at all, or
> should it be turned on when a driver like nouveau is selected.

I don't think it should be user selectable.  This is an implementation
detail users can't know about.

> Is there some downside to enabling DEVICE_PRIVATE?

The option itself adds a little more code to the core kernel, and
introduces a few additional branches in core mm code.

But more importantly it pulls in the whole pgmap infrastructure.