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 B229DC83F26 for ; Fri, 25 Jul 2025 10:10:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 564D76B007B; Fri, 25 Jul 2025 06:10:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5158E6B0088; Fri, 25 Jul 2025 06:10:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B6146B0089; Fri, 25 Jul 2025 06:10:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 2BB356B007B for ; Fri, 25 Jul 2025 06:10:16 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id D224E1405AC for ; Fri, 25 Jul 2025 10:10:15 +0000 (UTC) X-FDA: 83702366790.27.1F2D1E3 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf29.hostedemail.com (Postfix) with ESMTP id 66A6712000C for ; Fri, 25 Jul 2025 10:10:13 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HY7QbDuK; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1753438213; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RCv5vRN+V3N36ln4l/qk+no8mmBtq9CdsJugmAnVBHc=; b=LfnWMX0JC/kq7Wbb6GeUkqi0qSursjqNQyNbzEBsZHeNv6KpJEXCP8/PDKa5lur6ogZzad pFk57oLXQgEqZxwkCKSBsATtZUVCxYL2Orr8zj2dso0BqzB+tFSlynCADG+IBPauoZ21AS 4oEz0ZjoNYuT0S07ehnaXzKYed7uTnU= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HY7QbDuK; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1753438213; a=rsa-sha256; cv=none; b=x5LfjeYPrTEwUah94PrNkhsEsxChWqC7xpep/1AYxtg38tx2yZopqofXGys9W3R9iaYZOR fLT7RJg3J8/72hAM4W69zveRQbfErdlscx2dnFc0JIoAbVHkZM3tikCxZJHQFD22s50t/z vsZeYqrlnklkure+zRPiRORgPrzR4sQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753438212; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=RCv5vRN+V3N36ln4l/qk+no8mmBtq9CdsJugmAnVBHc=; b=HY7QbDuK444Im40cKsmRZmvna/JDGoKmFAHEhda6K2zlqcTzsN2jqH3AabmvLN8B9URn3O gVr1ugv8S7DzzlopqW1xOKI8qZRRTldk54W4LG+iAwXiIf5AhdfpFwLlgzITp0fC5Kd7DE zagKFVGAIElnHmE38PMUA8iOoFobC94= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-387-IBUj4I5SMqy0SAorgP6KFw-1; Fri, 25 Jul 2025 06:10:11 -0400 X-MC-Unique: IBUj4I5SMqy0SAorgP6KFw-1 X-Mimecast-MFC-AGG-ID: IBUj4I5SMqy0SAorgP6KFw_1753438210 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-45359bfe631so10670205e9.0 for ; Fri, 25 Jul 2025 03:10:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753438210; x=1754043010; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=RCv5vRN+V3N36ln4l/qk+no8mmBtq9CdsJugmAnVBHc=; b=OA1nwbnWnrYjeVPcjLA6+wCnum8j7w1/EBmhRuK7EN9hTPwV/SMNt440+jJvHBXMNB z40NRoMRO+VKs6Za3mlGLxkYiWWNpumTjMh+OA4LCoG1powm9PVY6f0Vs3Wk6Ljm1tpT wYqWhivkPe9vZ481DSMuTP/55axBQv5CFZdIFkKlXkQ6rEQ1yRvAZQrGk61YmfzpQ6ya 0ur3uCM7xtNsYGuyXJqvYvZDSqPX6J0hnFYRAz5GdKL8Rrzb8IVaCdXFQDmt6NiRoFtc pXRwXIo4ZGlmVq5NdARn2mjN45yWgUNIY68UVkEEP9JK0jcCiYnmRoUpq0VcuF6fkqAj 5qbQ== X-Forwarded-Encrypted: i=1; AJvYcCV5DnUvrNOsuK63ii72QhidmYObOCHQDMXW4fCKsGlwM1mCz/liev212GxrUpOavY3GcSWlVIL/MA==@kvack.org X-Gm-Message-State: AOJu0YwRfjVUN0TsRClc/hwAEKgfjSkldRzin5gI8ydZlLDolbFQ54A8 k7PMmlyEIEl78hhOGuS/7SuzrSsCrnRADa1vsXoynWEHAT0aXwDYYLFbz77azeof4fZ0DffZ4Gg DIT4Thvo9UzI4K1e4YmF0Ujvl+xhU4T+LU5IvlivwlgBRZVesk2dT X-Gm-Gg: ASbGnctT6o/+C9kOUzOtGVtX96pyjT8a22WY6H9c8C5uqHSH73TXaWIZ7JzReO2Rr+j GBhnsQrZpMXPlun53CPEdqJvNTfC8tQ22NpRES3f6NlCYA7sKCdL/sWudz+vLGDiGIUDTbDN8aP L0ClQJNxo8apgZt2hUlhmf4lLaeNORhdCH+qB+fGdp2MQajtISq2JUoN2+MAiNNdjtT2iQrJO/9 wcAHE6TRm1S5zremnypa1CLoTpYmoAJFq1AvnXGXnbgweUvCaUfjk7I4e1ApHBnckYoXlRSbIyZ ZDQQfRsLY45rvWtpCAYF7xpYqp7y12Va1/SdSXJHzOC7AIjNKuqSFd0wmePnDx8dabNpkAUaND5 t7F7a2FkSmfsf/mg60UAF35V8BbPX3Vbwsz/rT9m2qK9FqQRgnQ1hokg3+EDUkm6wLCI= X-Received: by 2002:a05:600c:6088:b0:442:dc75:5625 with SMTP id 5b1f17b1804b1-458762f07eemr12140615e9.5.1753438209998; Fri, 25 Jul 2025 03:10:09 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFK7mwDSWg8+ygksCm6dpsZRM8Kza275xhyDlqpfynlyccXvQz3lJi4ZoaZcr76pXUpb8kLzw== X-Received: by 2002:a05:600c:6088:b0:442:dc75:5625 with SMTP id 5b1f17b1804b1-458762f07eemr12140215e9.5.1753438209561; Fri, 25 Jul 2025 03:10:09 -0700 (PDT) Received: from ?IPV6:2003:d8:2f1a:f400:5a9f:b1bf:4bb3:99b1? (p200300d82f1af4005a9fb1bf4bb399b1.dip0.t-ipconnect.de. [2003:d8:2f1a:f400:5a9f:b1bf:4bb3:99b1]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b76fcacf0bsm4625237f8f.38.2025.07.25.03.10.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Jul 2025 03:10:08 -0700 (PDT) Message-ID: <649565be-eab2-4783-9595-b4263ac50310@redhat.com> Date: Fri, 25 Jul 2025 12:10:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/5] mm/mseal: update madvise() logic To: Lorenzo Stoakes Cc: Andrew Morton , "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jeff Xu References: <4f66d89a-631a-43eb-b4f9-c9a0b44caaae@redhat.com> <692f9624-e440-4cf2-8202-861c679ddb73@lucifer.local> <0ad414a1-9a57-4050-a7b6-fdea08aebbd1@redhat.com> <507a09cf-291c-4886-92e7-9d9cc294a247@lucifer.local> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: VJaQHorUGAAZPKBeVAOh4ch3k8flP0O4oCntSlywSNI_1753438210 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 66A6712000C X-Rspamd-Server: rspam06 X-Stat-Signature: w3nfz175w8kr3wowur356b5psmsq1ezd X-HE-Tag: 1753438213-276090 X-HE-Meta: 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 0WLMvzIt AGGflgW5CG3rZ6I6m3DYuxgAe3Dgnrs5U5z6PohCXLRFvdZ5URoOqyrfNf8il/6u+hG7/3OjfOyb0yE4BrzBatn+G6eMUaH+nqSjl7OGW3hobRkmOZQSMm4xC8AOUgVl+iACZyFCN4B14BEvv3b2C7PDFJvvh7HgAVeiFkeF4usBeMWjfR0bxqliBLXjirE5p5v+p4sRgiZmxrCdt26jejSuxNV6NuiXzrx1nB6w5RAtQSl2evLHBWD8exKkRAxyc5txLR0IlNkUxzYwvUaoVjSFvvD0eTTnqJI8eoTTcT0L5nShcZvRdBgGolLtxO0crK2mKwaMxujVffOE1qfQTeHLZ3VQg00+KBraDLuouvgwPkRu6uCyyhoPC7oPARca6MLrZU3oNEm6Q2+yU72A10mZdifbMWgBVsQ9dEieWo6jAy+RxhSvZN8uQ6V1VfiCgR7FCtGfQJRipRBeqR85FKbdN1w== 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: List-Subscribe: List-Unsubscribe: >>> So - we explicitly disallow FOLL_FORCE write override for CoW file-backed >>> mappings. >>> >>> Obviously if FOLL_FORCE is not set, then we're ALSO not allowed to get past a >>> FOLL_WRITE and !VM_WRITE situation. >>> >>>> >>>>> >>>>> Hmm maybe I'll soften on this anon_vma idea then. Maybe it is a 'cheap fix' to >>>>> rule out the _usual_ cases. >>>> >>>> Yeah, something to evaluate. >>> >>> I'm thinking more and more we're probably actually safe with !vma->anon_vma || >>> !(vma->vm_flags & VM_MAYWRITE). >> >> I think there are possible races, the question is how much you care about >> them. > > Yes I was just wrong. Please just disregard. > > I mean racing with MADV_POPULATE_WRITE seems a niche thing to worry about, and > so what if you did, it's writing a... copy of the underlying file-backed folios > no? MADV_POPULATE_WRITE does not apply. It's only racing with FOLL_FORCE, like debugger access. Again, a race one probably shouldn't worry about in the context of mseal. -- Cheers, David / dhildenb