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[2003:cb:c733:f100:75e7:a0a4:9ac2:1abb]) by smtp.gmail.com with ESMTPSA id d7-20020adf9c87000000b0033d640c8942sm13253653wre.10.2024.03.04.14.04.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Mar 2024 14:04:37 -0800 (PST) Message-ID: <1299bd16-9171-407b-9882-db952db03b13@redhat.com> Date: Mon, 4 Mar 2024 23:04:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64/mm: Improve comment in contpte_ptep_get_lockless() To: Ryan Roberts , Catalin Marinas Cc: Andrew Morton , Mark Rutland , John Hubbard , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org References: <20240226120321.1055731-1-ryan.roberts@arm.com> <20240226120321.1055731-3-ryan.roberts@arm.com> <089f689d-f8dd-48ba-b6b0-6f91aa3b86f1@arm.com> From: David Hildenbrand 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: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: xcwowd75i65y36hzgfnw56er8u7dqjja X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A536640015 X-Rspam-User: X-HE-Tag: 1709589881-649665 X-HE-Meta: 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 JZJyYHL3 oAD4HUUq8EGr5XKPIyP5FOxzLebUdxx9hSsdLZuFlgkOlBR+io3MPqEaaX5qFJ7dfK7uysuxSDNzm9U+39T/ELsZBEHG7GBCxpdr7rQHrdjFzxvWjabibqMYxfuYBwPvsZ1ujIwj2w+giM+ayDvyIWX6axGiOM6BaZEwjC45Bs3pklw1Svv+IiRHC/RHfeJXyhEzZbhZLOxfCTeOwetHcwwK9Dct9OUF0BjZ4oLQti7PTV5x6ZI7a1qjsZf5/pKrOTUd0z75nU3Qlahti2bFDX1OPVabslkR5n2grK6xcs1ptnFiznt8VTaWhxgCwmAlujWLpnvN2B3jPqi1iPE2Es3ILatxA3tnrdLL6hZJ3CUunF0hvPS1367isaFmKndzedXCCqJOB3TJ2Z6kXSnUDMtDK4OQFEBggOloHpgAqEmhGFJqp+3xUbljpT5yXxp4N6yIAzAI+Xfm2V20GpqWy4jum27lldfzLm2K68IsFphpwOXs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04.03.24 19:40, Ryan Roberts wrote: > On 04/03/2024 17:37, Catalin Marinas wrote: >> On Mon, Mar 04, 2024 at 12:54:23PM +0000, Ryan Roberts wrote: >>> On 01/03/2024 18:47, Catalin Marinas wrote: >>>> On Mon, Feb 26, 2024 at 12:03:21PM +0000, Ryan Roberts wrote: >>>>> Make clear the atmicity/consistency requirements of the API and how we >>>>> achieve them. >>>>> >>>>> Link: https://lore.kernel.org/linux-mm/Zc-Tqqfksho3BHmU@arm.com/ >>>>> Signed-off-by: Ryan Roberts >>>>> --- >>>>> arch/arm64/mm/contpte.c | 24 ++++++++++++++---------- >>>>> 1 file changed, 14 insertions(+), 10 deletions(-) >> [...] >>>> Throughout the callers of this function, I couldn't find one where it >>>> matters. So I concluded that they don't need the dirty state. Normally >>>> the dirty state is passed to the page flags, so not lost after the pte >>>> has been cleaned. >>> >>> I agree we can simplify the semantics. But I think its better done in a separate >>> series (which I previously linked). >>> >>> What's the bottom line here? Are you ok with this comment as a short term >>> solution for now, or do you want something more radical (i.e. push to get the >>> series that does these simplifications reviewed and in time for v6.9). >>> >>> I still believe the current ptep_get_lockless() implementation is correct. So >>> given I have a plan to simplify in the long run, I hope we can still get this >>> series into v6.9 as planned. >> >> Yes, I'm fine with this patch. Assuming Andrew picked them up: >> >> Reviewed-by: Catalin Marinas > > Thanks! Yes, he did - they are in mm-unstable. > >> >> I'd like to get the simplification in as well at some point as I think >> our ptep_get_lockless() is unnecessarily complex for most use-cases. > > Yes, I'll keep pushing it. I know DavidH is keen for it. Maybe just sent a v1 (after the merge window?) if there is no further feedback. I still want to look into the details, but it's stuck deep in my inbox I'm afraid :) -- Cheers, David / dhildenb