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 CE2E6C32771 for ; Wed, 28 Sep 2022 08:52:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1E5FA8E0135; Wed, 28 Sep 2022 04:52:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 194508E0120; Wed, 28 Sep 2022 04:52:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 05BA08E0135; Wed, 28 Sep 2022 04:52:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id ECA958E0120 for ; Wed, 28 Sep 2022 04:52:12 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id B29E2A11BB for ; Wed, 28 Sep 2022 08:52:12 +0000 (UTC) X-FDA: 79960877304.28.8950D34 Received: from mail-pj1-f42.google.com (mail-pj1-f42.google.com [209.85.216.42]) by imf13.hostedemail.com (Postfix) with ESMTP id 3C03520020 for ; Wed, 28 Sep 2022 08:52:11 +0000 (UTC) Received: by mail-pj1-f42.google.com with SMTP id 8-20020a17090a0b8800b00205d8564b11so1099467pjr.5 for ; Wed, 28 Sep 2022 01:52:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=YhKd/qqG3hYgCwHskWv+bTAHADkoBSPQyTs4xyUrQVI=; b=J/39CLLIHNbbdyLwo55aBZdPxMuVksxhxU12dvDDLDaKvLS6VPv7v931BU77Q1a1B6 xW/d7Ea1nvFFNO5PvVBhYufJpYccwEPApWWfHiWnfQbVV5X3WZZ+BhjXLxy3BqR9NTVE GCF9HQl6l805Y2WAq/Sg18KSEcQ75/UX+Qg81qIqqg+ANzt+xSsVlSYrJu48mG/tn0pn 4l+UIBhyu+9Ld/4aaLWSAAE3p7xKZTiuoav/lWw3a+h2BEocbnH6aosXQ2e0p1RJctBK qNqnZt3osniMHb5ksaZgTaIaPU51WQBXqR+xlhYFNrRDFITWd6BA4negrC6VG6EyIURM QVew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=YhKd/qqG3hYgCwHskWv+bTAHADkoBSPQyTs4xyUrQVI=; b=sy8FxOE09NYY8hciC57jfITxS4H/Qv9aXBclPRjn2wHvSHwZVb/tgftPKvNp3+VvTp dBzvvlRJkNt6rOFq2vk1VU9r0QkorAplESsrfhxaO+0gUCzvfuLNzt3jitUO0l2FnLw5 MinbqYxnh9hNUn0oTU6sTFDVkW/eJVHa6PrdI4JNBbCmBlBuZsw34uWGjnyD5Hjo7Pm8 Z/G5ywhQU0X20ghJKUt8lI4SoHMEkv38oFkVajFc1N6H5LcxeYg6i94NlUHxyGlJv9b/ 33QC95lOplbWKy9l2X1tt7Lpc3khRoJFYQevRuRcJLRiqmQrpU7JsmKcAT4qTP09bt/b JzEg== X-Gm-Message-State: ACrzQf1Wxic+IDz/nYv9ZER3snXI3Br0pxSQWtAMiwcAojAyU3bSRllG fM29efW3rrizcFs8f9IsAIc= X-Google-Smtp-Source: AMsMyM67XiMUXM9JXQrc/3ti18oFKIICmIsPNeCWVv8BA5XqIwNLPRe589oaCNlt/v5TcB+DTvIoBA== X-Received: by 2002:a17:90a:4588:b0:205:d605:8bcc with SMTP id v8-20020a17090a458800b00205d6058bccmr9146720pjg.205.1664355131012; Wed, 28 Sep 2022 01:52:11 -0700 (PDT) Received: from zhienlin-MBP ([140.121.198.208]) by smtp.gmail.com with ESMTPSA id k4-20020a17090a3e8400b002030d596ff7sm964068pjc.37.2022.09.28.01.52.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Sep 2022 01:52:10 -0700 (PDT) Date: Wed, 28 Sep 2022 16:52:02 +0800 From: Chih-En Lin To: John Hubbard Cc: Nadav Amit , Andrew Morton , Qi Zheng , David Hildenbrand , Matthew Wilcox , Christophe Leroy , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Luis Chamberlain , Kees Cook , Iurii Zaikin , Vlastimil Babka , William Kucharski , "Kirill A . Shutemov" , Peter Xu , Suren Baghdasaryan , Arnd Bergmann , Tong Tiangen , Pasha Tatashin , Li kunyu , Anshuman Khandual , Minchan Kim , Yang Shi , Song Liu , Miaohe Lin , Thomas Gleixner , Sebastian Andrzej Siewior , Andy Lutomirski , Fenghua Yu , Dinglan Peng , Pedro Fonseca , Jim Huang , Huichun Feng Subject: Re: [RFC PATCH v2 9/9] mm: Introduce Copy-On-Write PTE table Message-ID: References: <20220927162957.270460-1-shiyn.lin@gmail.com> <20220927162957.270460-10-shiyn.lin@gmail.com> <3D21021E-490F-4FE0-9C75-BB3A46A66A26@vmware.com> <10594124-b6b7-d202-d90b-72ac9d8bc9dc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10594124-b6b7-d202-d90b-72ac9d8bc9dc@nvidia.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664355132; a=rsa-sha256; cv=none; b=A2TOZQ6gMKMc6NM1u/8bR2JoqHU7rK0i1jGrLTEWvycADezqush5zB+I6amZ5xork2lXru UYBXuLvg07PNFLfuPkKOrLlJwj+VuIl95r38pTUx7H+d2SNI02I+PeYLQ86E35o98YljvT vKEOL+jr8jY5e+tm/6VuH40xlkHLGwQ= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b="J/39CLLI"; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of shiyn.lin@gmail.com designates 209.85.216.42 as permitted sender) smtp.mailfrom=shiyn.lin@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664355132; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=YhKd/qqG3hYgCwHskWv+bTAHADkoBSPQyTs4xyUrQVI=; b=fkyjVlEo3s+KyocVuNwrHZ87v2o3mo7/U5w9VCooNVf1f4RprkOnhMPcFI3cKK2cy7yujF FJ/+MJ3eEZ1g3QdVIoTWOtiNkDeUjPNbE08+G7UqsyurXmFFj2C33JfeufctAGsOhfgjlw i+Gle5a7p00f5nPDNwanden9i5zcbGM= X-Stat-Signature: pp7m661pmn33jdax7euxyx5brqpbwdbk X-Rspamd-Queue-Id: 3C03520020 X-Rspam-User: Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b="J/39CLLI"; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of shiyn.lin@gmail.com designates 209.85.216.42 as permitted sender) smtp.mailfrom=shiyn.lin@gmail.com X-Rspamd-Server: rspam11 X-HE-Tag: 1664355131-411454 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 Tue, Sep 27, 2022 at 02:26:19PM -0700, John Hubbard wrote: > On 9/27/22 12:53, Chih-En Lin wrote: > > I'm not familiar with THP right now. But we have a plan for looking > > at it to see what will happen with COW PTE. > > Currently, I can only say that I prefer to avoid involving the behavior > > of huge-page/THP. If there are any ideas here please tell us. > > > In order to be considered at all, this would have to at least behave > correctly in the presence of THP and hugetlbfs, IMHO. Those are no > longer niche features. > To make sure it will work well with them. During fork() and page fault, we put the mechanism after the hug-page/THP to make it doesn't mess up. It may have corner cases that I didn't handle. I will keep looking at it. Thanks, Chih-En lin