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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BC18C433EF for ; Sat, 21 May 2022 03:50:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 832DD6B0072; Fri, 20 May 2022 23:50:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7E2A46B0073; Fri, 20 May 2022 23:50:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65BBC6B0074; Fri, 20 May 2022 23:50:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 538A66B0072 for ; Fri, 20 May 2022 23:50:16 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 1CBC333130 for ; Sat, 21 May 2022 03:50:16 +0000 (UTC) X-FDA: 79488372432.07.8668B3D Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) by imf20.hostedemail.com (Postfix) with ESMTP id 4417F1C0010 for ; Sat, 21 May 2022 03:50:02 +0000 (UTC) Received: by mail-pj1-f51.google.com with SMTP id z7-20020a17090abd8700b001df78c7c209so13006089pjr.1 for ; Fri, 20 May 2022 20:50:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=1thg0gD9LkoJN152HkT0OTmkJzX4+vIrjo7MEWofe+w=; b=jo+qEFyNr7yZv2BLra+Du20hufyMVTOka43o6y0X1kCVL+qxdrbSb5wGRDLDcy2mIC QKiAYZ0hDQOUN8R1P7p9IrIv0f8K8ABeeWf2kbJxnPoD9wUZYXXYODjWq6E3yzztuTCP fb3gCYiMvrJMqdFuPG+bzQHnbx++aq0T3HQB2VTzc2ClYYftzifKCX2hK6aX+iWrzYnh CEYyGv22r8ctZ6Dfk15ecRT9apCGJNWpiNjfTT3L2OJq+IR7EdVaau5CFLkBT8XmkSV4 pKnHnIKhCno5XvopZ4/Y12x6tzcUXnUVAmtpu97+601e7uTHdM8OOCSYK9HkuFiF4v6+ dSaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=1thg0gD9LkoJN152HkT0OTmkJzX4+vIrjo7MEWofe+w=; b=078fJzPJJCftuYmFTFN7p86gLKfKNeEIgPtY41a4oI3oPuUgFprfosqe8hfu9kMg5p erQyzOPLUvExOVGCU4G9nX2TjrIv3s8ZX8kasTnMzY+ovGwCEKKjqTgWwm7xr0T48UcO 0slPqCQzy79BfwhwDlyd6bp223Pez0jTj7rdgLNa6/fpBgJltR1dLdgVhWlZHlM+YxiB DMXQX0/osdJPmBmScFXqOLVhqG9dGtYd18BUUDxEhK8h/vFnwOfPUz8qYc6U6D+UuIxZ apmYwe/4c5RjCemGC6F8pvigUcNGzkiRAx/cnN1W/xf4hpU1wTedhwvnZqdHIA8dtpEi 8O1g== X-Gm-Message-State: AOAM530t70L6ByofnurQNm4JVPCW41CyIM/62AQ7Z9wH/e3eIEIN/Uos 5WQrgR956K6FmiQJPwlN8Yk= X-Google-Smtp-Source: ABdhPJwrmcJWaI5Mv2ARLKgUuuvw86bgEuR9UlPJEFOvrpvfOBAMVgMH/2LtnJltOwaKfoPbKAFROQ== X-Received: by 2002:a17:902:f647:b0:161:67af:6bf0 with SMTP id m7-20020a170902f64700b0016167af6bf0mr12093832plg.100.1653105014641; Fri, 20 May 2022 20:50:14 -0700 (PDT) Received: from strix-laptop (2001-b011-20e0-15d4-84b3-8c62-a0b8-199e.dynamic-ip6.hinet.net. [2001:b011:20e0:15d4:84b3:8c62:a0b8:199e]) by smtp.gmail.com with ESMTPSA id z15-20020a170903018f00b0015e8d4eb2easm445903plg.308.2022.05.20.20.50.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 May 2022 20:50:14 -0700 (PDT) Date: Sat, 21 May 2022 11:50:06 +0800 From: Chih-En Lin To: Christophe Leroy Cc: Andrew Morton , "linux-mm@kvack.org" , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Christian Brauner , "Matthew Wilcox (Oracle)" , Vlastimil Babka , William Kucharski , John Hubbard , Yunsheng Lin , Arnd Bergmann , Suren Baghdasaryan , Colin Cross , Feng Tang , "Eric W. Biederman" , Mike Rapoport , Geert Uytterhoeven , Anshuman Khandual , "Aneesh Kumar K.V" , Daniel Axtens , Jonathan Marek , Pasha Tatashin , Peter Xu , Andrea Arcangeli , Thomas Gleixner , Andy Lutomirski , Sebastian Andrzej Siewior , Fenghua Yu , David Hildenbrand , "linux-kernel@vger.kernel.org" , Kaiyang Zhao , Huichun Feng , Jim Huang Subject: Re: [RFC PATCH 2/6] mm: clone3: Add CLONE_COW_PGTABLE flag Message-ID: <20220521035006.GB1506735@strix-laptop> References: <20220519183127.3909598-1-shiyn.lin@gmail.com> <20220519183127.3909598-3-shiyn.lin@gmail.com> <7cb4c588-7a24-8557-6cd6-3ec59051c2b1@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7cb4c588-7a24-8557-6cd6-3ec59051c2b1@csgroup.eu> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4417F1C0010 X-Rspam-User: Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=jo+qEFyN; spf=pass (imf20.hostedemail.com: domain of shiyn.lin@gmail.com designates 209.85.216.51 as permitted sender) smtp.mailfrom=shiyn.lin@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: 77c7z7o7s4qziqithq7fomfezqcgqnxr X-HE-Tag: 1653105002-845250 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 Fri, May 20, 2022 at 02:13:25PM +0000, Christophe Leroy wrote: > > > Le 19/05/2022 à 20:31, Chih-En Lin a écrit : > > Add CLONE_COW_PGTABLE flag to support clone3() system call to enable the > > Copy-On-Write (COW) mechanism on the page table. > > Is that really something we want the user to decide ? Isn't it an > internal stuff that should be transparent for users ? > > As far as I know, there is no way today to decide whether you want COW > or not for main memory. Why should there be a choice for the COW of page > tables ? Agree. It should not expose to the user. COW of page table should become the configuration. Or, if the change is fine, it can even be the default setting. Thanks. --- Sorry I did not group reply the first time.