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 CB5482581 for ; Mon, 23 Jun 2025 13:49:11 +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=1750686553; cv=none; b=bNm2SvBJ5hNLDf/FYYvY6Z9ugS3qxsvieZUdHCTXquI6SKHHgznSvHZO2wvZYVidozjnfTznCF96vyUsJdUzX5ZsVXO6Y7y2YqI2BPCRCzUWlLDaR/An44edF4OmlvaUF+Xv50nK2qUXi4zSIv/l3LkovtGg9pxg2mszMZPvU4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750686553; c=relaxed/simple; bh=f7aOklejQbZ7G0VrNNG8wxBtdwtA0mLdvOXgTTgiXNQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AjPjlgCpnAu++iKdG7x2pBjWy1kLFOew6n4oc6ragiCpEZTY8Ts4mhNmwNe2Hdw/S/zyORNHjG76g4WxN8IN4BRdYeSt3vfaDKBVtoxEXL6VIF8NLEhFeVNS+t7AA1rdozJ7NrDDUrniTKumZkQEmSP6oHgKCasaZYUje9EaLdQ= 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=MS+2CCAA; 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="MS+2CCAA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750686550; 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=jsKHRipSf0W3kGdVFY9Q0sc/VyJxrNO7AzDAt8FfuEs=; b=MS+2CCAApaWOLkSSrLG6493/zDNUQYZh+W45RVRZTdLwRS/1fIjHSKDnHt9lVEdZAOdfup YQnPOWkU7CgKYPcGxpiV3hsP8HGv57geH8qaoD+f6kW6q6KWl50YkA4FOHXafpRKm8YQ0X vhKEJ7e+0mbhJvcLHdRBeWNd7cmei4M= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-651-zdXElxDYNNat5iBNhuWudA-1; Mon, 23 Jun 2025 09:49:08 -0400 X-MC-Unique: zdXElxDYNNat5iBNhuWudA-1 X-Mimecast-MFC-AGG-ID: zdXElxDYNNat5iBNhuWudA_1750686548 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-453018b4ddeso26916405e9.3 for ; Mon, 23 Jun 2025 06:49:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750686547; x=1751291347; 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=jsKHRipSf0W3kGdVFY9Q0sc/VyJxrNO7AzDAt8FfuEs=; b=fMh0XWeOI3F1vhl8kulBxU8ndBjjWVCTLjPQEWNCMtmQNBjy21V+29G1ZCd8JDKEeg co92rZfACIHWRsNgp534jdp5UbWxZZsgDcGN7q6TQ67zxZdhcI8c++H1HvwmtL0f/fQ6 LUNvFNUDSq4U8NFOvLX9ibakwuNzA1MZpQyENQknQHJ0zIlDK60V/bkxaepWjB6o1E+4 wWTSnWIVNIbdR4G4CTnWsuI07jQTtqeoHkhlaXek5qOwXsMj5uasawI3btijeAPWLC/J cCHh2mDBjov6FI94QNgVzKWcB+WyClbUWM31hTgZHPfObgGJnusnYOq+msf5IpwB1Rgj n0rw== X-Forwarded-Encrypted: i=1; AJvYcCUs5UQ3ca+4Q71PIEzESekNZvIZjpRf/ulJlxwLxuSThsbMsnA+5RuFc6cJJqTODPAUkLZmeyEqN3NPF3I=@vger.kernel.org X-Gm-Message-State: AOJu0YwpKjrWKJWVPXLeBX/wSgD326CbfG8poSZAKrgnGI86HWuvAjL0 1iLxEfXnGrEGzpJA6bnC7Nv2jD8NiG9kFMDQqka2ElMs4z64F8DToNsobnpkYsrCzyT+XpuPC6C LIJRo0w/r1eIEWwgu8m/TRnmh4XM0kTO3bMnuR3jV7JS3hygSiUrPPbq39FeAk/6JPw== X-Gm-Gg: ASbGncutmoCjrFSzgVDMF/9NGt7/2DvfLDT7SspH6PeN4TomAWcuxtixL/6pue3/xAf JJ3avMYL7xC/JN3WvpyD6akx2wrrESeBtF3vQ+aj+ckg+OIgrIhG/QZuQmXR+2QNK8z5XDragLr mTTlAhq1+zWkiBVVVjbI/5skF69No/lfu/SpIAFpK/KP91A5uVVdWkWv/NLTBOG71U1itLf/qOW hYwT9oskpv0euNyxUTWbeGh6nXMERJVQWZUf38YRiifTff9GB1VJdXFmoeINtkv0YznEruuU4Fk ukmMpV5olp1RS8TTUFTtsCo5uHgFBsH6eclLpyY214JySbhqIWU5Zfe1i6kuUUeBWkNK9u5craL OJlRdY0FLNHyE3Z9ZSIn1jHzk7anafIpT9I2d8Wj4PbKXjfxG2A== X-Received: by 2002:a05:600c:1910:b0:442:f482:c432 with SMTP id 5b1f17b1804b1-453654c931amr124139635e9.18.1750686547516; Mon, 23 Jun 2025 06:49:07 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG03KKPfAZFSoUe/FDMvp2k1XbIBgN8Sc2WFAhxNfiQpaPmKu3c2IwVA1FchvOgoQIZkih1FA== X-Received: by 2002:a05:600c:1910:b0:442:f482:c432 with SMTP id 5b1f17b1804b1-453654c931amr124139425e9.18.1750686547124; Mon, 23 Jun 2025 06:49:07 -0700 (PDT) Received: from ?IPV6:2003:d8:2f4e:fd00:8e13:e3b5:90c8:1159? (p200300d82f4efd008e13e3b590c81159.dip0.t-ipconnect.de. [2003:d8:2f4e:fd00:8e13:e3b5:90c8:1159]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a6d1189977sm9378431f8f.82.2025.06.23.06.49.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Jun 2025 06:49:06 -0700 (PDT) Message-ID: Date: Mon, 23 Jun 2025 15:49:05 +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] selftests/mm: add test for (BATCH_PROCESS)MADV_DONTNEED To: Lorenzo Stoakes , wang lian Cc: Andrew Morton , Shuah Khan , Christian Brauner , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, SeongJae Park , zijing.zhang@proton.me, ryncsn@gmail.com, p1ucky0923@gmail.com, gkwang@linx-info.com, "Liam R. Howlett" , Vlastimil Babka , Jann Horn References: <20250621133003.4733-1-lianux.mm@gmail.com> <8fb737cc-ba83-4949-b4fb-2a2e1af0967a@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: <8fb737cc-ba83-4949-b4fb-2a2e1af0967a@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23.06.25 14:35, Lorenzo Stoakes wrote: > +cc Liam, David, Vlastimil, Jann > > (it might not be obvious from get_maintainers.pl but please cc > maintainers/reviewers of the thing you are adding a test for, thanks!) > > Overall I'm not in favour of us taking this patch. > > There are a number of issues with it (explained inline below), but those aside, > it seems to be: > > - Checking whether a simple anon buffer of arbitrary size is zapped by > MADV_DONTNEED. > > - Printing out a dubious microbenchmark that seems to be mostly asserting that > fewer sycalls are faster when using process_madvise() locally. > > And I'm struggling to see the value of that. We have other tests that should already severely break if MADV_DONTNEED doesn't work ... but sure, we could think about more elaborate functional tests when they provide a clear benefit. (zapping all kinds of memory types, anon/ksm/huge zeropage/pagecache/hugetlb/ ... and using /proc/self/pagemap to see if the page table mappings are already gone) I don't think we have a lot of process_madvise selftests, right? hugtlb handling that was added recently is already tested to some degree in hugetlb-madvise.c. In general, I'm not a fan of selftests that measure syscall performance ... -- Cheers, David / dhildenb