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 36420C48BE6 for ; Mon, 14 Jun 2021 05:27:50 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C4A4D613C2 for ; Mon, 14 Jun 2021 05:27:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C4A4D613C2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G3Kj107Rzz3cDv for ; Mon, 14 Jun 2021 15:27:49 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4G3Khf1Vpsz2xtt for ; Mon, 14 Jun 2021 15:27:27 +1000 (AEST) 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 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 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linus Torvalds , Nick Piggin , Linux-MM , Kalesh Singh , Joel Fernandes , "Kirill A . Shutemov" , Andrew Morton , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 13/06/2021 à 13:13, Aneesh Kumar K.V a écrit : > 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 other >>> struct page *. The reason being highmem and level 4 page table can >>> be located in highmem. >> >> That is ahistorical. See 2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4 -- >> we have pgtable_t for the benefit of s390's crazy sub-page page table >> sizes. > > That is also true with ppc64. We do sub-page page table size. I was trying to explain why it can't > 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-pages for that, allthough some powerpc platforms have only one sub-page per page. Christophe