From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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=-7.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 44AF4C10F07 for ; Wed, 20 Feb 2019 23:58:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 130CC20880 for ; Wed, 20 Feb 2019 23:58:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="dmqbfBMw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726986AbfBTX6x (ORCPT ); Wed, 20 Feb 2019 18:58:53 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:3883 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725989AbfBTX6w (ORCPT ); Wed, 20 Feb 2019 18:58:52 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 20 Feb 2019 15:58:58 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 20 Feb 2019 15:58:52 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 20 Feb 2019 15:58:52 -0800 Received: from [10.2.169.124] (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 20 Feb 2019 23:58:51 +0000 Subject: Re: [PATCH 02/10] mm/hmm: do not erase snapshot when a range is invalidated To: , CC: , Andrew Morton , Ralph Campbell References: <20190129165428.3931-1-jglisse@redhat.com> <20190129165428.3931-3-jglisse@redhat.com> From: John Hubbard Message-ID: Date: Wed, 20 Feb 2019 15:58:40 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190129165428.3931-3-jglisse@redhat.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1550707138; bh=jP+wiat2XSsdStfjMflPAPZ0y6VSuTquKiZkpsPA0wk=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=dmqbfBMwvjaiDm4+ShTJ/pUB6RmCQ/z4LdRkHsxmLjQ13SeSj75L5H16XUZNvEgI5 KEuJ9clung0YkN8Juhf52xYrG7rcjUYdiVcxmOWAgxJXFACrSuhAy3Dh+RZRJAWjGl v5f2fKZFcdS75UivGyHgoA0Agrlufs+52Go8uJmzob84TdtuO7FpQIoizsu33g8cET EAAQoIID1RfvmJ6mYYiR/7gFk0CgqV+Ytoxt5dYrpbJtgk1CTKd68Z6eSYBuHR0DzG 5+b6jYldNox+246RO7rJN2dpYw6rxa07YhZVJ0rWzaR8cMYihE2hggXo2yOumsXtc2 QhGMT+ce258jA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/29/19 8:54 AM, jglisse@redhat.com wrote: > From: J=C3=A9r=C3=B4me Glisse >=20 > Users of HMM might be using the snapshot information to do > preparatory step like dma mapping pages to a device before > checking for invalidation through hmm_vma_range_done() so > do not erase that information and assume users will do the > right thing. >=20 > Signed-off-by: J=C3=A9r=C3=B4me Glisse > Cc: Andrew Morton > Cc: Ralph Campbell > Cc: John Hubbard > --- > mm/hmm.c | 6 ------ > 1 file changed, 6 deletions(-) >=20 > diff --git a/mm/hmm.c b/mm/hmm.c > index b9f384ea15e9..74d69812d6be 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -170,16 +170,10 @@ static int hmm_invalidate_range(struct hmm *hmm, bo= ol device, > =20 > spin_lock(&hmm->lock); > list_for_each_entry(range, &hmm->ranges, list) { > - unsigned long addr, idx, npages; > - > if (update->end < range->start || update->start >=3D range->end) > continue; > =20 > range->valid =3D false; > - addr =3D max(update->start, range->start); > - idx =3D (addr - range->start) >> PAGE_SHIFT; > - npages =3D (min(range->end, update->end) - addr) >> PAGE_SHIFT; > - memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages); > } > spin_unlock(&hmm->lock); > =20 >=20 Seems harmless to me. I really cannot see how this could cause a problem, so you can add: Reviewed-by: John Hubbard thanks, --=20 John Hubbard NVIDIA