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=-5.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 599CFC48BE8 for ; Mon, 14 Jun 2021 05:27:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A1A0461105 for ; Mon, 14 Jun 2021 05:27:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1A0461105 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 207236B006C; Mon, 14 Jun 2021 01:27:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1B7C56B006E; Mon, 14 Jun 2021 01:27:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 058706B0070; Mon, 14 Jun 2021 01:27:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0185.hostedemail.com [216.40.44.185]) by kanga.kvack.org (Postfix) with ESMTP id C8D3D6B006C for ; Mon, 14 Jun 2021 01:27:25 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0C5AB40F4 for ; Mon, 14 Jun 2021 05:27:25 +0000 (UTC) X-FDA: 78251196450.18.D60E7FD Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) by imf24.hostedemail.com (Postfix) with ESMTP id D1284A000247 for ; Mon, 14 Jun 2021 05:27:15 +0000 (UTC) Received: from localhost (mailhub3.si.c-s.fr [192.168.12.233]) by localhost (Postfix) with ESMTP id 4G3KhV14cZzBDBP; Mon, 14 Jun 2021 07:27:22 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UWgPplpQZ_8c; Mon, 14 Jun 2021 07:27:22 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4G3KhV017RzBDBC; Mon, 14 Jun 2021 07:27:22 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E6CCB8B789; Mon, 14 Jun 2021 07:27:21 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id t7pqco8zY48P; Mon, 14 Jun 2021 07:27:21 +0200 (CEST) Received: from [172.25.230.102] (po15451.idsi0.si.c-s.fr [172.25.230.102]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B6FFB8B763; Mon, 14 Jun 2021 07:27:21 +0200 (CEST) Subject: Re: [PATCH 5/6] mm/mremap: Use pmd/pud_poplulate to update page table entries To: "Aneesh Kumar K.V" , Matthew Wilcox Cc: linuxppc-dev , Nick Piggin , Linux-MM , Kalesh Singh , Joel Fernandes , "Kirill A . Shutemov" , Andrew Morton , Linus Torvalds References: <20210610083549.386085-1-aneesh.kumar@linux.ibm.com> <20210610083549.386085-6-aneesh.kumar@linux.ibm.com> <87wnqy9lru.fsf@linux.ibm.com> From: Christophe Leroy Message-ID: Date: Mon, 14 Jun 2021 07:27:19 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D1284A000247 Authentication-Results: imf24.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf24.hostedemail.com: domain of christophe.leroy@csgroup.eu designates 93.17.236.30 as permitted sender) smtp.mailfrom=christophe.leroy@csgroup.eu X-Stat-Signature: n8s16m7k9q3j6gj1ocxat6oa5scotnto X-HE-Tag: 1623648435-967757 Content-Transfer-Encoding: quoted-printable 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: Le 13/06/2021 =C3=A0 13:13, Aneesh Kumar K.V a =C3=A9crit=C2=A0: > On 6/13/21 4:20 PM, Matthew Wilcox wrote: >> On Sun, Jun 13, 2021 at 02:36:13PM +0530, Aneesh Kumar K.V wrote: >>> IIUC the reason why we do have pmd_pgtable() is that pgtable_t type >>> is arch dependent. On some architecture it is pte_t * and on the othe= r >>> struct page *. The reason being highmem and level 4 page table can >>> be located in highmem. >> >> That is ahistorical.=C2=A0 See 2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b= 4 -- >> we have pgtable_t for the benefit of s390's crazy sub-page page table >> sizes. >=20 > That is also true with ppc64. We do sub-page page table size. I was try= ing to explain why it can't=20 > be pte_t * everywhere and why we have > it as struct page *. ppc32 as well. On the 8xx, with 16k size pages, the HW still use 4k page = tables, so we do use sub-pages. In order too keep the code simple, we have converted all powerpc to sub-p= ages for that, allthough=20 some powerpc platforms have only one sub-page per page. Christophe