From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E5AF2C3274 for ; Wed, 16 Jul 2025 10:44:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752662671; cv=none; b=c5QBgSo9z5yldt+ptT9XZKdFDKidv0o3ifIQflMny+i4HBPQl9dZ4rtO70K2DbQLyqRtvaqUHHx9x3HojU/zChoNiG/xNr89Q52PzD8ev6kdngGTIHbYf3+DVJ9O4yDeMlL0K8ksC4TxJL2tKxCWhffAoDsO5VwbLHMB/evGOdM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752662671; c=relaxed/simple; bh=BM2RWK92PKISCA1wSUFtzN01XGb8/Ifi8vvkpRHlV08=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WiHeMiaqTQ0/wLSmv7h/CYBoBQc+CYma7p7RrMuH7yCl94WrQFvi/L64P4J0u+0ZxQu+HvBQNP4bDX9EKnO4I+V5uaEyKEcnhFRiy+0Iw6g9FjG759HxDewOl1e7pNENoToVJoOSDCeJ1TkrgRkax6eXR3RgEtTChb17fA11f7c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=L39BvBFl; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="L39BvBFl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752662669; 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=H0DrpHFYox10/T2b5Nsf8Ll/oRGOI12jubzByP7raXI=; b=L39BvBFllidsUC/enfPK4/uhzEzfZkiB2thYoEBoBqqVCz5kKcEkr/hTl0DqFP4Tvm9uKm 0tsEuFU6ETbZTxS5DviUb4MRuxWsnkT9KfEiINevgUmU06y0FNhDdtTqJrKaLhg+2kuYBP mzugBpPklrG6Az44xTrEqzjR6cmAjQs= 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-381-nFBNjgkdNdSDjAwks8hPQg-1; Wed, 16 Jul 2025 06:44:27 -0400 X-MC-Unique: nFBNjgkdNdSDjAwks8hPQg-1 X-Mimecast-MFC-AGG-ID: nFBNjgkdNdSDjAwks8hPQg_1752662666 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-451d30992bcso51341185e9.2 for ; Wed, 16 Jul 2025 03:44:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752662666; x=1753267466; 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=H0DrpHFYox10/T2b5Nsf8Ll/oRGOI12jubzByP7raXI=; b=p23cOjnv5sPy2im+TUNnzHXZhXECrAHcVcJsbI07vgfzc/JXxJbsT9lBi5AJK4fkZz rwcm22yb3lD+ZtlNARRqNbRXG3OPiQTAnDFZv9iBFNGBqE6vmjCiSLCG72xZ6OsxmVQH trovBSJgLz+3ttjCFBaRi7CiWc5nzZMna2pU7gkUP2/M1idvvgUeybWqG1hhmmAaavZN l/8AGX5HvsTDXURjopCuY8s1mPRG934+dQBVckv2zvkaStZCs/3QxZbNeXRnzQWqeahD ZPdcxhN0tSTc2EWg8GPmBX9fhUjXvGDQz+KhP/UxDw12nYZTZvH3/PGw9SucUviqhZC8 cKSw== X-Forwarded-Encrypted: i=1; AJvYcCU00LF3HrLjtqeXNu6LjwW6OtTvwFVTi2T7CfNB9vzHwAiTbHJOjxbuogpyfyjCAYD6yOn1hYLglhUXMQc=@vger.kernel.org X-Gm-Message-State: AOJu0YzI8Aq5W8c63TkD4Ysb9Vhcet9L5NxQnsNbYXqlPHVj1BZK3eo+ j1dlbQYMUh4d0F4Ro8Um9rjucmzzaFGnVwQ5JLb8BXa3atQU4Sxd2Stjii66hAOLBlaQxBXqx61 0g6Rwz7e+lOzlrtj6peAEvaTDOMNc140zWiYS80n2bculQFxQTrbgLYhDNQNLxaz0Uw== X-Gm-Gg: ASbGncuU60YjhUeFtkvM40O3PDroS/YPRcwoPBJig9Bv6gBSIiy1xhLzYsmm2Ik1mZ8 gYI6g+fId5hJFOu9tl2RG52Rqjd6gNh57PgDPogCtIOtch/0J5dsmw3OkiPkyhTzv4p8zrI+P0F Zkf0NpoaES4gMgZJVwesGZPe2nN/mmJU6MPfThjix4YhNdAHocrWbXON72u42e6jQUy1HVDrlsX poUTm119CqTf9OZNUFtbi0hqB4usCd0h+/YIq3Ve94NID/jvDXpBJeDkCcFZO5+ujntD6VF4iBJ JmhGpG3ioMb4yZjZkyFTla6yWx6izV0PNXMh2CUU38x52o/KdyiX6aNxz0iFBCX5Ss0TV0v8T8N 8vU1iobrArloFwHPDhKmGrdwfoegFGmYj4mHZEk3I61aGmyi6M3lyvEmVxl+InFX1Vh8= X-Received: by 2002:a05:6000:3cb:b0:3a4:e629:6504 with SMTP id ffacd0b85a97d-3b60e5246a5mr1354312f8f.49.1752662666356; Wed, 16 Jul 2025 03:44:26 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEWua8wVVW9bKulQ0ObMl//Eo2vwfpPgEkZ+TqYQycNsZHWW4bjQYPv7qQsGur2N+pi10FAMQ== X-Received: by 2002:a05:6000:3cb:b0:3a4:e629:6504 with SMTP id ffacd0b85a97d-3b60e5246a5mr1354275f8f.49.1752662665920; Wed, 16 Jul 2025 03:44:25 -0700 (PDT) Received: from ?IPV6:2003:d8:2f1d:ed00:1769:dd7c:7208:eb33? (p200300d82f1ded001769dd7c7208eb33.dip0.t-ipconnect.de. [2003:d8:2f1d:ed00:1769:dd7c:7208:eb33]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4562eb63551sm16517585e9.24.2025.07.16.03.44.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Jul 2025 03:44:25 -0700 (PDT) Message-ID: Date: Wed, 16 Jul 2025 12:44:23 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 1/7] selftests/proc: add /proc/pid/maps tearing from vma split test To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, aha310510@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org References: <20250716030557.1547501-1-surenb@google.com> <20250716030557.1547501-2-surenb@google.com> From: David Hildenbrand Content-Language: en-US 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: <20250716030557.1547501-2-surenb@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 16.07.25 05:05, Suren Baghdasaryan wrote: > The /proc/pid/maps file is generated page by page, with the mmap_lock > released between pages. This can lead to inconsistent reads if the > underlying vmas are concurrently modified. For instance, if a vma split > or merge occurs at a page boundary while /proc/pid/maps is being read, > the same vma might be seen twice: once before and once after the change. > This duplication is considered acceptable for userspace handling. > However, observing a "hole" where a vma should be (e.g., due to a vma > being replaced and the space temporarily being empty) is unacceptable. > > Implement a test that: > 1. Forks a child process which continuously modifies its address space, > specifically targeting a vma at the boundary between two pages. > 2. The parent process repeatedly reads the child's /proc/pid/maps. > 3. The parent process checks the last vma of the first page and > the first vma of the second page for consistency, looking for the > effects of vma splits or merges. > > The test duration is configurable via the -d command-line parameter > in seconds to increase the likelihood of catching the race condition. > The default test duration is 5 seconds. > > Example Command: proc-maps-race -d 10 > > Signed-off-by: Suren Baghdasaryan Why is this selftest not making use of any kselftest framework? I'm sure there is a very good reason :) Reading assert() feels very weird compared to other selftests. -- Cheers, David / dhildenb