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 EB0CE1EB188 for ; Thu, 20 Feb 2025 10:03:09 +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=1740045791; cv=none; b=lOrDQQVW97cpFIq9Y6Ng4b/dHjVYnLlTd2yjxTnB/FTkS6/YfMrzx/yjwWVYGil8zUBq+n8887Az4r1TE0/l13j5KXX+KfUNlbcckweE8cvocgllH/ru+QAurKylkmCsQWeNWLRRgQmohoN5mK1yyJMXmyPDFhqnr9DWZpkQjoc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740045791; c=relaxed/simple; bh=SBBn2UYvblwcq+tBRo29UULpxF9ovy4PTYY97hhd8Yc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sHogmBt21Kr5mF+XF8NM34MR76nFyEV2mXrSyf5dgFinEafOt4QMbT1fFd/KeEOFCvwi5ItL4KGMMBW/HB0Pm999/bARsRfP2xcyQ4FFTs06THd8FL3mlhqkLhdRJqEsXqaYlZB+1CKkKRn2bPjklBXannljnrtgRqjoHJhNhdA= 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=YZJicPt1; 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="YZJicPt1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1740045788; 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=d9nUyWvqcklnp2OI5prl7ETjXTJjb3fHnOT/VSvj7+A=; b=YZJicPt10CERJ+Iv/B+zumzMWde3Os5FW2+sE7KFneNu4c7K+sCgtilM4jvD5+dnRt9sz/ fw2rIMSymVLkwgVu4DJUAiQxO43mifNJjNAkj4ayw47cvFpHzh4ozTWUp2zLHMHNVSxadw wr45708ztEjtCU87ufdJVIjT7cmsRhM= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-450-sbtbarXNMfWLX4jGNVI6Cw-1; Thu, 20 Feb 2025 05:03:07 -0500 X-MC-Unique: sbtbarXNMfWLX4jGNVI6Cw-1 X-Mimecast-MFC-AGG-ID: sbtbarXNMfWLX4jGNVI6Cw_1740045786 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-38f628ff78eso322609f8f.1 for ; Thu, 20 Feb 2025 02:03:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740045786; x=1740650586; 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=d9nUyWvqcklnp2OI5prl7ETjXTJjb3fHnOT/VSvj7+A=; b=RYpgXAJ7SPZReNVBT1TWTZMkxv0rIbEuuXGi03JRDFnfyvI32/RJ+L6H+ciDBe+k8x loarn1TFXvvpiEiX4xAjEOAsEK/e8Sq0mQg544iLzl20iDJmmiF2SQtuJUjtCEY3TNxg gq0UKm6Fci26DDtGqEWenCegFU3kD3ngJNHaJeuAgHy92ZJy6qpLX0pauI36no50gFoO 15I/usEfCi3f7twokS72Kss7Jh65a2rDfKF51GF0q7koh2QOjCewCenjSzTeiwBYUCb7 TkM88z+AsBy51pn2kaKi/+jcIyJRrHSRXiO93GK9CGH5DNlkTYU8seY5MG4Ip2KHAj02 v+qg== X-Forwarded-Encrypted: i=1; AJvYcCX+NjlSUjUsf6gjsn6L01aRXhey9FG3bkeQt0IWZGkGklPpKvR/6OjVjU04wTB4PdnUthNEXL01jrQ=@vger.kernel.org X-Gm-Message-State: AOJu0YxndYRl1gD33jK5FbwfRmLsGmlhub8yUlR+MTAKTLLpI3pe3fkd URN04bD6LTcV+WsmaJZPrUYGm6GpN4nICldEIECzk+xJgHaxK/Gb0vA8RQOVrsqMlzrsZBHdrJu WTpAxo5tjgunhlDYEXAKJHHs2kmAn8647taziFd5wh/PcjI281nxnZLnXrA== X-Gm-Gg: ASbGncvJEcOBGap++wG4XnAnJrmVPHVtfOnXq04GC1z4Nubt0sIwi2NXrvoikI4DfXs hj55fjJKrN19KYCe7DqP5dsLVyENaTqGscIQEiWCvAYi/oWjphNfgCvx3RRKbSf1sntR30HFdyv sezaZbYgMkzBApkqbXIG6dJjQ+I5l485fg0TiuFMfx65iRcCAfchwpNMt9djJhlfba0+HMUXP0M EIR42MHIEN3W4KzC8uWST3zU4DBjd/urPCVtTG7fcIx50oWEL2reW2kKsKBBF+vavoIOGgR+tNG cj6ttlhRpEZwG98PYR83YfY1RIG1ycG7/27WSsBInIn7RsOjRhKI8CjnaARxgq2Ke+ChDpB5SHo Z0tQn2oDs1+oWUy2BCQE6bb9TE63Pnw== X-Received: by 2002:a05:6000:4608:b0:38d:dfdc:c874 with SMTP id ffacd0b85a97d-38f614b680cmr1912748f8f.10.1740045785932; Thu, 20 Feb 2025 02:03:05 -0800 (PST) X-Google-Smtp-Source: AGHT+IFgdMJuANrEX/DzcqMwK/DuM0WtW+B2wskdlKuHER6vA01Xbh8Jx5M/rko52SdDDMVuRR6sqA== X-Received: by 2002:a05:6000:4608:b0:38d:dfdc:c874 with SMTP id ffacd0b85a97d-38f614b680cmr1912713f8f.10.1740045785488; Thu, 20 Feb 2025 02:03:05 -0800 (PST) Received: from ?IPV6:2003:cb:c706:2000:e44c:bc46:d8d3:be5? (p200300cbc7062000e44cbc46d8d30be5.dip0.t-ipconnect.de. [2003:cb:c706:2000:e44c:bc46:d8d3:be5]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f258b412esm19828134f8f.1.2025.02.20.02.03.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Feb 2025 02:03:04 -0800 (PST) Message-ID: <4f5a9c19-9bdd-47eb-bb14-205e3dcced90@redhat.com> Date: Thu, 20 Feb 2025 11:03:02 +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 Cc: Kalesh Singh , Andrew Morton , Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , Vlastimil Babka , "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 References: <45297010-a0a4-4a42-84e8-6f4764eab3b3@lucifer.local> <41af4ffb-0383-4d00-9639-0bf16e1f5f37@redhat.com> <6e356431-5ac9-4363-b876-78a69ae7622a@lucifer.local> <4aa97b5c-3ddc-442b-8ec9-cc43ebe9e599@redhat.com> <387f3516-99f2-41e9-967e-4b051a8d21b8@redhat.com> <72e044ba-64af-49c0-8b87-ead508654fb7@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: <72e044ba-64af-49c0-8b87-ead508654fb7@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >> Your conclusion is 'did not participate with upstream'; I don't agree with >> that. But maybe you and Kalesh have a history on that that let's you react >> on his questions IMHO more emotionally than it should have been. > > This is wholly unfair, I have been very reasonable in response to this > thread. I have offered to find solutions, I have tried to understand the > problem in spite of having gone to great lengths to try to discuss the > limitations of the proposed approach in every venue I possibly could. > > I go out of my way to deal professionally and objectively with what is > presented. Nothing here is emotional. So I'd ask that you please abstain > from making commentary like this which has no basis. I appreciate everything you write below. But this request is just impossible. I will keep raising my opinion and misunderstandings will happen. Note that the whole "Honestly David you and the naming. .." thing could have been written as "I don't think it's a naming problem." >> >> >>> >>>> >>>> [...] >>>> >>>>> >>>>> As I said to you earlier, the _best_ we could do in smaps would be to add a >>>>> flag like 'Grd' or something to indicate some part of the VMA is >>>>> guarded. But I won't do that unless somebody has an -actual use case- for >>>>> it. >>>> >>>> Right, and that would limit where you have to manually scan. Something >>>> similar is being done with uffd-wp markers IIRC. >>> >>> Yeah that's a good point, but honestly if you're reading smaps that reads >>> the page tables, then reading /proc/$pid/pagemaps and reading page tables >>> TWICE that seems inefficient vs. just reading /proc/$pid/maps, then reading >>> /proc/$pid/pagemaps and reading page tables once. >> >> Right; I recently wished that we would have an interface to obtain more VMA >> flags without having to go through smaps > > Well maybe that lends itself to the idea of adding a whole new interface in > general... An extended "maps" interface might be reasonable, that allows for exposing more things without walking the page tables. (e.g., flags) Maybe one could have an indicator that says "ever had guard regions in this mapping" without actually walking the page tables. -- Cheers, David / dhildenb