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 BE7E3C54E94 for ; Tue, 24 Jan 2023 17:26:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CCFFB6B0072; Tue, 24 Jan 2023 12:26:16 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C80CD6B0073; Tue, 24 Jan 2023 12:26:16 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B6EBA6B0074; Tue, 24 Jan 2023 12:26:16 -0500 (EST) 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 A86A96B0072 for ; Tue, 24 Jan 2023 12:26:16 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 5D94F406D1 for ; Tue, 24 Jan 2023 17:26:16 +0000 (UTC) X-FDA: 80390371152.20.18158CC Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf23.hostedemail.com (Postfix) with ESMTP id 3B925140014 for ; Tue, 24 Jan 2023 17:26:14 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eA4CPmdY; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf23.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1674581174; 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=x1//lKxOSoW8HByrjyrd9SNUigcEe/d5fAJWdteeAwY=; b=Z6QY12D+mgCOOFGl1qyKHplPLz5qcfR0Sw6jRZlRoW8UXAz9/k1MKlRdNz0z78gtwpjRxG slp94FXr5/h0yhgmagCAbhwScJf60dVLDAqSdPw9WPc4q7AItolLz+m9EnCeqiGIEd9m1T II9O7tZy4PcUoPqKifD5rULHEbAkTg8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eA4CPmdY; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf23.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1674581174; a=rsa-sha256; cv=none; b=RnE3mqlh+W1gPx3a2SCYrEVkdpAIYXQV7/CuyAhi0zvsgeMiVvFYgLw7ViJFj4T4niYJjf etcS1bL0DtC3CR/ZJ+cbPTV7kNpTymrwsYu3R2POwunwVFzCFsBecv3OByBZFRCBChTPMl NSxOiLSc8L7IXlMI5wrmZac9CCIHnrM= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674581173; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=x1//lKxOSoW8HByrjyrd9SNUigcEe/d5fAJWdteeAwY=; b=eA4CPmdYLdBkEdb03f5ztZPN2GoIevibFfTKykADN+rSdyfzZPZoEt9Vd/WSUajFVoRhjt Q7GCulxG8Xw5H4cd883tZGKQmZWncQuHjs/16xl5XbPKMSylU0xu6Odpb+hDwmLx59SHn4 1Gq6nj7fp3zwUN2bmbjrrw4T8HmF0Xo= Received: from mail-yw1-f199.google.com (mail-yw1-f199.google.com [209.85.128.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-537-NGm7N72VOcC-KL81TyyPsQ-1; Tue, 24 Jan 2023 12:26:12 -0500 X-MC-Unique: NGm7N72VOcC-KL81TyyPsQ-1 Received: by mail-yw1-f199.google.com with SMTP id 00721157ae682-4fa63c84621so160882197b3.20 for ; Tue, 24 Jan 2023 09:26:12 -0800 (PST) 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 :message-id:reply-to; bh=x1//lKxOSoW8HByrjyrd9SNUigcEe/d5fAJWdteeAwY=; b=fOWdkRrpkV92dtr39lGb4tH7rJmOsQDZVcFVVcP/cIKPRzJWzVaKMrUWcRq0bll1lY jCjqnUCCYzbjsD8VNhIgfaXB0IgjE8EOprenLW9zno3aNipL+iPY8VVL4qaFlHWO3geX lQplF0h+Bf+mmuB46A9PSM9CkfKuq0Xz3zAXwpZAZEIZQBXNMtc+OpH9Kg8MVhA3cBI8 GeKQieXvalxw8LkwJZ0c1CvrqsnTTR4fRLZAAF4fsgeeZmlD2KO8SWBZQUfY51pS4MmH ofkVy9Fz2QHYBhjZNEr1NP7862IrS/tf+f/wVN8ZAEcyHsAW4vblQrx/6eapRIETZDCK WvuA== X-Gm-Message-State: AFqh2kpUJlKiJhzOWMIDjbhOcopk7vX6oKpy1uNWglU0X0EMboEe/eDM 9OGS6QV0ipixbPmTZJ04s5T3Bo4IWgQk+FXIEHbKurKRcd2X3wFJ3rH0h0nEJVvyiQFwAKVIOlv fKMm0o4ilBnA= X-Received: by 2002:a81:8187:0:b0:466:b529:e379 with SMTP id r129-20020a818187000000b00466b529e379mr20203138ywf.27.1674581171811; Tue, 24 Jan 2023 09:26:11 -0800 (PST) X-Google-Smtp-Source: AMrXdXuntBE/q4AbbQoO+OesA9EZ1i3Bp0xsn0vakOkRw+wyHlq3Frgixzl4rdgMcorwGfrkChzC1w== X-Received: by 2002:a81:8187:0:b0:466:b529:e379 with SMTP id r129-20020a818187000000b00466b529e379mr20203110ywf.27.1674581171581; Tue, 24 Jan 2023 09:26:11 -0800 (PST) Received: from x1n (bras-base-aurron9127w-grc-56-70-30-145-63.dsl.bell.ca. [70.30.145.63]) by smtp.gmail.com with ESMTPSA id n22-20020a05620a223600b006fa22f0494bsm1736320qkh.117.2023.01.24.09.26.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 09:26:10 -0800 (PST) Date: Tue, 24 Jan 2023 12:26:08 -0500 From: Peter Xu To: Muhammad Usama Anjum Cc: David Hildenbrand , Andrew Morton , =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Andrei Vagin , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , Mike Rapoport , Nadav Amit , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: Re: [PATCH v7 1/4] userfaultfd: Add UFFD WP Async support Message-ID: References: <20230109064519.3555250-1-usama.anjum@collabora.com> <20230109064519.3555250-2-usama.anjum@collabora.com> <0bed5911-48b9-0cc2-dfcf-d3bc3b0e8388@collabora.com> <328f54c1-171f-22a1-10c9-8b7a25bd8027@collabora.com> MIME-Version: 1.0 In-Reply-To: <328f54c1-171f-22a1-10c9-8b7a25bd8027@collabora.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3B925140014 X-Stat-Signature: j8g3qum18rshxbpb35fd9fk7ks5u9yfr X-HE-Tag: 1674581174-441176 X-HE-Meta: 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 31ogyGYl ZuSUZ1t87EbL3OUbIMBj+cO9tCfKCmHsGXTqDAlei76HEAFvaPeWhuohRNTFfzOaxBmfiw3BMGZTyRAsb/F0CjLYLNV2Q2XZDU0ufHzPXrAj4AqQDAmMRbjpHdMl/PYp74J9OG0FoOZEKd+GF+OSi56s6WhyJayxcQn2/qGcenqAW3kts72SIONap+pUdahy1v4YZLu90IGcYhgWgVqhdIOPkE1VmHf2G6eJwbfoxjYVJDIrf1gEV2jtESnUz6IB2jztHE8ZxiGkMtdUueKFV3X/6s5EwvABJOgWd4m9kI1AYkWwJWz/9pN+uHCStmVarHlKJ0ynQVCPHZw1mx4bo12tOOYVr+Uf+vHYFS7XJV6n+5QrByLfhU7S+mrTqns6huzfqllq5Do/sYrZUF1xZtOF8VbqnsaXnYJtG2bfoBRofhda6Kr14SwIHMQ== 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 Mon, Jan 23, 2023 at 03:11:20PM +0500, Muhammad Usama Anjum wrote: > > One thing worth mention is, I think for async wp it doesn't need to be > > restricted by UFFD_USER_MODE_ONLY, because comparing to the sync messages > > it has no risk of being utilized for malicious purposes. > I think with updated handling path updated in do_wp_page() and > wp_huge_pmd() in version, UFFD_USER_MODE_ONLY will not affect us. This is more or less a comment for the design, the new code should work (by bypassing handle_userfaultfd(), where this bit was checked). We'll need an man page update if this feature will be merged [1], and if so it'll need to be updated for the UFFD_USER_MODE_ONLY section regarding to async uffd-wp support too. I think that can also be worked out after the series being accepted first, so just a heads up. [1] https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git -- Peter Xu