From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 9619D1A238D for ; Tue, 25 Feb 2025 16:48:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740502106; cv=none; b=erzjIA0YiyDPWQAT+wl1rf31K/BQSTu9mLc9aTtLqUbw5KCMtuNHCoZ94jGiJdv8L+Yq2VykXSyq8D8mSR2uPIkbCsOgzzLc00wMAy/HSCEDx8F96GKbBZUR/XmWosUQrTP3BCt/4Ww0hNaD9wUTAVJUoBsWNrzPdKQhIIQVGt4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740502106; c=relaxed/simple; bh=QLeXofl8oz+1YDj2uHG9Af1DIWMS8S6ol/g/+nY++FQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OEEOq3EiO1sac3nWH/YhOUuW4tXsFfiMqGyPzFhhmzaxdMHOVfYjPFiiNwEGoRqcbA/hbhodSpMTUDGD9Clrvrua9Pp0imuFOboKCasa+tkHy4NnZcNLK3mx2GUeDqHsMqpb6SWEspyLWzDrSY301rM7+sCNtrmANQ4idf1oZOg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=Z4uUfH49; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="Z4uUfH49" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1740502103; 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=jw2CX8GJqxuLRFAFx88zTCcWlXcKTO/rHj8BJTgdWyk=; b=Z4uUfH494yPKf+qWMKBmLoNxiI948PB3j16TGiZaRDoTA6wdKzq/SC/oNJzzORITsJvrYv jrissvshBpo4KYV1rZfT5nfgKJ/MOIpjtOgj94kB4S6IQB8yREvzSo5VTTbV9YuoxFZWmH HSKcZuLTKMjUm2R9EKLP069+Ypfy5v4= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-164-2sxPO4_qN4KnthEY2M9aGw-1; Tue, 25 Feb 2025 11:48:21 -0500 X-MC-Unique: 2sxPO4_qN4KnthEY2M9aGw-1 X-Mimecast-MFC-AGG-ID: 2sxPO4_qN4KnthEY2M9aGw_1740502100 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4399304b329so27917305e9.3 for ; Tue, 25 Feb 2025 08:48:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740502100; x=1741106900; 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=jw2CX8GJqxuLRFAFx88zTCcWlXcKTO/rHj8BJTgdWyk=; b=qTxDtx0Dx1kHgWal7veB4I5XXf4NwXxpY7L240//J8fYRzsTY1tnBjkauJuuQbDLg9 YqweZ9wDLlmyM9zcuJy4EZ6s+OYaf1shBDnhtt2TPaX6O2f1MdNzgK1pOTZSCFz4tlwA yUE3Wjpol14c5Vrccdj4OS9TzNH4kTr/IYc5f2K444AEkjgCZFNMcPzGJNjSCeynXgvl SpYr5tL/SQJ6HQNVb7dPjqAUnnp8nc20aFrFkbQBQhGImKPst+I6iCCmaHfdBmnLTZtn m+nY1AMQFIg52DaILP3N2/ac33bgm5/LyMN2XclgeAXw8sJkMS1m+YW16l1iCHhyMr6S kjBg== X-Forwarded-Encrypted: i=1; AJvYcCWwXyMcjcXWI4W17yO8dM87fy0y5hObcwaz9WDArifh7Pfz0uCQqTwQbVNnZnMw3ItmeDMzkVXPn9k=@vger.kernel.org X-Gm-Message-State: AOJu0Yzmb9TNNANX+xePZLD84+iBUbyBWuCGO1tfQW5mdnyXuZWHHJfC AVGuwxAETxkwc/BXj0ezMCmWGLH6tlc3H54+NZWAhlB4N2eo+HYuJDeVlkHuR+zxuNfusI5AbHw bBsytE4+mUoTGkoUKl8uWyNQnjl/M2cxXIZgaIKvQwcajYmHUvppGkLnDDA== X-Gm-Gg: ASbGncvVSj1TpLAntHKT1Ps4MrC4CbClnZoOxY9ZvLN8qKl6CB9Yl7sNa6rGJ1sjDhL iLGfCD5cv0FaUrSnOqXQy9bSBzFhQWnpHcrZ+D9zrudNCpdcHrWaJNchnBlihagzrnut3kr8tVN LOiSRHG1ohvci3D5QzKEFdJg4NJ9LZsLPnZpa761r92CIekjLNUP08FgP+rnLXlQuNBc6pm7jwV AqWQ2TQKbqpnZeQtb9r3wb+ndPdUqXrHO4e0/QG4tfCgpDO4E4JqV4U7WAm9ne+QoL9YM1EuRij Kye5J7rj0UINr/49z8RsnzygKXaavFQcPJpCztU7cNiCqYNdt/6LsBjQE7bojYym/olTRrDMwt6 tu9G6RENjWM8frqDFcZLWIe3IaDvqrNqz/agSFAIu27c= X-Received: by 2002:a5d:59a3:0:b0:38d:e15e:17e9 with SMTP id ffacd0b85a97d-38f6f0b2161mr20087643f8f.35.1740502100267; Tue, 25 Feb 2025 08:48:20 -0800 (PST) X-Google-Smtp-Source: AGHT+IE8sdF4FkFqdZXDiyQJpYRdr9jotf0bgjSy0tUCoeN9Ynzu8FAq0ynzblVc1iJsuqV0PE3uGw== X-Received: by 2002:a5d:59a3:0:b0:38d:e15e:17e9 with SMTP id ffacd0b85a97d-38f6f0b2161mr20087605f8f.35.1740502099887; Tue, 25 Feb 2025 08:48:19 -0800 (PST) Received: from ?IPV6:2003:cb:c73e:aa00:c9db:441d:a65e:6999? (p200300cbc73eaa00c9db441da65e6999.dip0.t-ipconnect.de. [2003:cb:c73e:aa00:c9db:441d:a65e:6999]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ab15476f0sm32638635e9.23.2025.02.25.08.48.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 Feb 2025 08:48:19 -0800 (PST) Message-ID: <48ffe442-5015-44fe-bbd6-708ba8500505@redhat.com> Date: Tue, 25 Feb 2025 17:48:17 +0100 Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] mm: permit guard regions for file-backed/shmem mappings To: Lorenzo Stoakes , Vlastimil Babka Cc: Andrew Morton , Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , "Paul E . McKenney" , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Shuah Khan , linux-kselftest@vger.kernel.org, linux-api@vger.kernel.org, John Hubbard , Juan Yescas , Kalesh Singh References: <8d643393-ddc0-490d-8fad-ad0b2720afb1@lucifer.local> <37b606be-f1ef-4abf-83ff-c1f34567568e@redhat.com> <0db666da-10d3-4b2c-9b33-781fb265343f@redhat.com> <62c0ba1c-7724-4033-b1de-d62a59751ca5@lucifer.local> <6eb33b5d-3040-4637-b627-48f8f78e4e28@lucifer.local> <3102ab3b-67b6-4047-9db7-e83c3b9c1c53@lucifer.local> 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/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <3102ab3b-67b6-4047-9db7-e83c3b9c1c53@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >> As for compatibility with VM_LOCKONFAULT, do we need a new >> MADV_GUARD_INSTALL_LOCKED or can we say MADV_GUARD_INSTALL is new enough >> that it can be just retrofitted (like you retrofit file backed mappings)? >> AFAIU the only risk would be breaking somebody that already relies on a >> failure for VM_LOCKONFAULT, and it's unlikely there's such a somebody now. >> >> > > Hmm yeah I suppose. I guess just to be consistent with the other _LOCKED > variants? (which seem to be... undocumented at least in man pages :P, and yes I > realise this is me semi-volunteering to do that obviously...). > > But on the other hand, we could also expand this if you and I see also Dave feel > this makes sense and wouldn't be confusing. Just my 2 cents: one thing that came to mind: an existing library would have to be updated to use the _LOCKED variant if the app would be using mlockall(future), which is a bit unfortunate -- and if it could be avoided, it would be great. But yeah, devil is in the detail ... -- Cheers, David / dhildenb