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 0DC935479B for ; Mon, 30 Jun 2025 09:08:40 +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=1751274522; cv=none; b=RlNCe/lNl/FuNHXevf7ADAnqEWOBTBd5WR6z0RB3uEYWyhAp4YmTAb+W1r+uNR7nsYxVreWBxvotQ/nCRJ3r/TMdmvmxq4Q7L6GhCwOhdFizQM8btbxi0cyatpcLIEE+hwirbDGSqfhxZmyBAkXs6yulzKetFHYUSBzcAZPZlbQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751274522; c=relaxed/simple; bh=zKeTOXh3TvcxbRfpRjEUAS0qGLUUwsV5bYuNEJs8VZE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Cy8NGIq2Rp4g6WizcXmGOEV/9bf+8V70Nhj263meMSI5ULwYrQlKlRxmlmGRM9pxKPrTLVXfPdIRdARWkgiuoK0JgDvQMU+6yw38QH8wiFggRsuX+w2erDVSnv1F61Ec5ZAku17nCW+1hmUgL0SorD1k5C/5Utguf+sjpC/eDoQ= 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=cfQi8G8P; 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="cfQi8G8P" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1751274520; 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=64xC4zQ8+9vm0l1IYRTEX7hKYTJUCSlbYR5cwQZC1I0=; b=cfQi8G8PFrOg8Hpri64bjuOTT9zt5e6vhttx/jUs2mhg9f8mh4nZwvNcMFkUCdGgZdOyr4 Uq7NXBiUtF+lQHyHThihkZ9H8WjqHNIEAclZgHqtsLD3BVwO9/FMe+fz8KQRgTTDdF8KZY eN+Ao3TW3QiGw3MB9hcbWSK4euvySAc= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-657-cxItLjqhNyyzTJr1X_JMlg-1; Mon, 30 Jun 2025 05:08:38 -0400 X-MC-Unique: cxItLjqhNyyzTJr1X_JMlg-1 X-Mimecast-MFC-AGG-ID: cxItLjqhNyyzTJr1X_JMlg_1751274517 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3a4eeed54c2so1468264f8f.3 for ; Mon, 30 Jun 2025 02:08:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751274517; x=1751879317; 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=64xC4zQ8+9vm0l1IYRTEX7hKYTJUCSlbYR5cwQZC1I0=; b=DnIDTfidhxkRkJM9qj98+zwWismnm3GgFuaJ9lGm+bdudaS69QT6n6GyLEuX5wUiT0 b9MlTKqp+k9/fHBHrCwwwgkAfAPfvgr3W0rkGd2il+bWuPAlnCRgHncrYhqlPT8zWVvR YjkdN6RHwDMoCK2mDrA7jJzB/sxfa8Be+5MOVnaFMTEkAwnbbbVBpG0b8XCEluXk1CaU baifT/pO4N2Q6yvhNzE23nKBdFxuTzDKvSdTle0ZTlfIOSspWMA3N3MRO87j3dSUNNco 5y4/1jlK2BHD+VzUHf3HJgLOhOCnhepouvweQ5NaV2moj1oaHJCqlhpfLWsKKFd+6qjc PMHw== X-Forwarded-Encrypted: i=1; AJvYcCUZBNcOUwVwAcYEytc9p7KAO3tEkGiHAfMGichu2KnUGXSgjO8SyHNhIkPqNYRDyTUw+9dAYlTnYJBnYSg=@vger.kernel.org X-Gm-Message-State: AOJu0Yzkr/b8xfLf2qRtHv1eKJmQ7ZRqj4XEeyLkmaZLOcZZRtXdsbl0 1o1fYJuTgL05VCe1JHLuK7Do/RU1V9mDt27OhZaVZUGMBBHIRnqKvATaR7GeuHUgUotbmOXVEvE fTtc5LjdsvO7MnlOowZ5m0c/m7zTxd0C+GeFJj0Zv6mdp2Eqno1q35aN9mAmnbn2hTQ== X-Gm-Gg: ASbGncua2+hhNvb+98+TouU2vI6lJOUQs3s8oN/BpGygavgZP4/490nKDG7hHrtPYHR SaMnKzY/vNsB88sy+hw5tvX/XT+oPuXRkeH7Sbo2k8oehyVMrYVsbR0v8fQrbpnbyhuAik1D0QM R8xvonkoTymsi7JG1NwyB4ts91Yz6ozHiulAouBN+kNVCbLdDZ4hlwG9k9LkH0TNv6ADsGAOtHm wPcwfZhLqWLR6gMfImuINznkHJ6kqacLUeELZjWMVlbNYSzb56WXVr1dvZ4dlOqZH/ePjE1nmeH S8/lBW1kXDSNxurewmtI76V2yJNGHihm224rjlz6TBgUoLaybCH3cdhy7u0k0vIlVYaLauHxYcA QxIKGuM8uVaBLgIqbXWrzxCmT3sDoghel1CSIMPcz/oVehjkcOA== X-Received: by 2002:a05:6000:2807:b0:3a4:f892:de7f with SMTP id ffacd0b85a97d-3a8fee65129mr7468779f8f.36.1751274517047; Mon, 30 Jun 2025 02:08:37 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHJLXMZpwmNlVuaEbYCO/poMsOERDXHknjrrriyl3NfUpRhPKQc/NITgoCmhjRuusQcOSt1HA== X-Received: by 2002:a05:6000:2807:b0:3a4:f892:de7f with SMTP id ffacd0b85a97d-3a8fee65129mr7468743f8f.36.1751274516534; Mon, 30 Jun 2025 02:08:36 -0700 (PDT) Received: from ?IPV6:2003:d8:2f40:b300:53f7:d260:aff4:7256? (p200300d82f40b30053f7d260aff47256.dip0.t-ipconnect.de. [2003:d8:2f40:b300:53f7:d260:aff4:7256]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a88c80b5aesm9718838f8f.44.2025.06.30.02.08.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Jun 2025 02:08:35 -0700 (PDT) Message-ID: Date: Mon, 30 Jun 2025 11:08:34 +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 v1 1/4] mm: convert FPB_IGNORE_* into FPB_HONOR_* To: Ryan Roberts , Dev Jain , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Pedro Falcato , Rik van Riel , Harry Yoo References: <20250627115510.3273675-1-david@redhat.com> <20250627115510.3273675-2-david@redhat.com> <5c3428c6-25be-4a94-811a-6bb6718f6c58@arm.com> <5375208d-2c11-4579-a303-e8416ab07159@arm.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/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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 30.06.25 11:04, Ryan Roberts wrote: > On 30/06/2025 04:34, Dev Jain wrote: >> >> On 29/06/25 2:30 am, David Hildenbrand wrote: >>> On 28.06.25 05:37, Dev Jain wrote: >>>> >>>> On 27/06/25 5:25 pm, David Hildenbrand wrote: >>>>> Honoring these PTE bits is the exception, so let's invert the meaning. >>>>> >>>>> With this change, most callers don't have to pass any flags. >>>>> >>>>> No functional change intended. >>>> >>>> FWIW I had proposed this kind of change earlier to Ryan (CCed) and >>>> he pointed out: "Doesn't that argument apply in reverse if you want >>>> to ignore something new in future? >>>> >>>> By default we are comparing all the bits in the pte when determining the batch. >>>> The flags request to ignore certain bits. >>> >>> That statement is not true: as default we ignore the write and young bit. And >>> we don't have flags for that ;) >>> >>> Now we also ignore the dirty and soft-dity bit as default, unless told not to >>> do that by one very specific caller. >>> >>>> If we want to ignore extra bits in >>>> future, we add new flags and the existing callers don't need to be updated. >>> >>> What stops you from using FPB_IGNORE_* for something else in the future? >>> >>> As a side note, there are not that many relevant PTE bits to worry about in >>> the near future ;) >>> >>> I mean, uffd-wp, sure, ... and before we add a FPB_HONOR_UFFD_WP to all users >>> to be safe (and changing the default to ignore), you could add a >>> FPB_IGNORE_UFFD_WP first, to then check who really can tolerate just ignoring >>> it (most of them, I assume). >> I agree. > > Meh. Personally I think if you start mixing HONOR and IGNORE flags, it becomes > very confusing to work out what is being checked for and what is not. I stand by > my original view. But yeah, writable and young confuse it a bit... How about > generalizing by explicitly requiring IGNORE flags for write and young, then also > create a flags macro for the common case? > > #define FPB_IGNORE_COMMON (FPB_IGNORE_WRITE | FPB_IGNORE_YOUNG | \ > FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY) > > It's not a hill I'm going to die on though... How about we make this function simpler, not more complicated? ;) -- Cheers, David / dhildenb