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=-8.4 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_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 BE079C3A59C for ; Thu, 15 Aug 2019 19:23:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7757E20656 for ; Thu, 15 Aug 2019 19:23:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="P+RSFj2M" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7757E20656 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 270316B0281; Thu, 15 Aug 2019 15:23:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 21F186B0282; Thu, 15 Aug 2019 15:23:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 135BC6B0284; Thu, 15 Aug 2019 15:23:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0209.hostedemail.com [216.40.44.209]) by kanga.kvack.org (Postfix) with ESMTP id E884D6B0281 for ; Thu, 15 Aug 2019 15:23:47 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 6C081180AD7C3 for ; Thu, 15 Aug 2019 19:23:47 +0000 (UTC) X-FDA: 75825636894.15.bean02_3ea53e354361 X-HE-Tag: bean02_3ea53e354361 X-Filterd-Recvd-Size: 5230 Received: from hqemgate14.nvidia.com (hqemgate14.nvidia.com [216.228.121.143]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Thu, 15 Aug 2019 19:23:46 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 15 Aug 2019 12:23:47 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 15 Aug 2019 12:23:45 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 15 Aug 2019 12:23:45 -0700 Received: from rcampbell-dev.nvidia.com (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 15 Aug 2019 19:23:44 +0000 Subject: Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd() To: Jerome Glisse , Pingfan Liu CC: , Andrew Morton , Mel Gorman , Jan Kara , "Kirill A. Shutemov" , Michal Hocko , Mike Kravetz , Andrea Arcangeli , Matthew Wilcox , References: <20190807052858.GA9749@mypc> <1565167272-21453-1-git-send-email-kernelfans@gmail.com> <20190815171918.GC30916@redhat.com> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: Date: Thu, 15 Aug 2019 12:23:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190815171918.GC30916@redhat.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) 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=1565897027; bh=vkjRswpUjtZfCjVU2R9I+hlvzvOMVMgQk4AI8p27uwY=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=P+RSFj2MK6qwETLKT3U+Kgh8Zs/QjjEaL0NaxpNb2FGAew8lBC7SrZjoYTNsxIUBC sRqNyCTBmnUsDzC54aJbweOncfryqggz82LyC5JFGjngwplsubbikkOzZ6adhvbyfm NTC5la+MqrS4VXQRgugtcuB7+IFTLxd5VIbuak6jhvOI9uPTRM+jRB7FepjPo2S25t gfWzV2WehEd1RnVieZvPRERjdwuq1jhfHZ8cJftn4CDkCLF8s+Lp8Q7f+n4shOekD/ 3AnIjoPlvxEWtSGAzchogN8DcBDpOrFqqJHROWMLYQQ3oW3aoKWxRyCq9hqP+rhLpm s/RnpwxqsXG6A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 8/15/19 10:19 AM, Jerome Glisse wrote: > On Wed, Aug 07, 2019 at 04:41:12PM +0800, Pingfan Liu wrote: >> Clean up useless 'pfn' variable. >=20 > NAK there is a bug see below: >=20 >> >> Signed-off-by: Pingfan Liu >> Cc: "J=C3=A9r=C3=B4me Glisse" >> Cc: Andrew Morton >> Cc: Mel Gorman >> Cc: Jan Kara >> Cc: "Kirill A. Shutemov" >> Cc: Michal Hocko >> Cc: Mike Kravetz >> Cc: Andrea Arcangeli >> Cc: Matthew Wilcox >> To: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org >> --- >> mm/migrate.c | 9 +++------ >> 1 file changed, 3 insertions(+), 6 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 8992741..d483a55 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, >> pte_t pte; >> =20 >> pte =3D *ptep; >> - pfn =3D pte_pfn(pte); >> =20 >> if (pte_none(pte)) { >> mpfn =3D MIGRATE_PFN_MIGRATE; >> migrate->cpages++; >> - pfn =3D 0; >> goto next; >> } >> =20 >> if (!pte_present(pte)) { >> - mpfn =3D pfn =3D 0; >> + mpfn =3D 0; >> =20 >> /* >> * Only care about unaddressable device page special >> @@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, >> if (is_write_device_private_entry(entry)) >> mpfn |=3D MIGRATE_PFN_WRITE; >> } else { >> + pfn =3D pte_pfn(pte); >> if (is_zero_pfn(pfn)) { >> mpfn =3D MIGRATE_PFN_MIGRATE; >> migrate->cpages++; >> - pfn =3D 0; >> goto next; >> } >> page =3D vm_normal_page(migrate->vma, addr, pte); >> @@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, >> =20 >> /* FIXME support THP */ >> if (!page || !page->mapping || PageTransCompound(page)) { >> - mpfn =3D pfn =3D 0; >> + mpfn =3D 0; >> goto next; >> } >> - pfn =3D page_to_pfn(page); >=20 > You can not remove that one ! Otherwise it will break the device > private case. >=20 I don't understand. The only use of "pfn" I see is in the "else" clause above where it is set just before using it.