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(p200300cbc71b79008752fae3f9c9a07e.dip0.t-ipconnect.de. [2003:cb:c71b:7900:8752:fae3:f9c9:a07e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ec34a895fsm42201565e9.13.2025.04.04.03.29.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Apr 2025 03:29:48 -0700 (PDT) Message-ID: <67d4486b-658e-4f3f-9a67-8785616e6905@redhat.com> Date: Fri, 4 Apr 2025 12:29:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Does GUP page unpinning have to be done in the pinning context? To: David Howells , "Kirill A. Shutemov" , John Hubbard Cc: hch@infradead.org, willy@infradead.org, linux-mm@kvack.org References: <939183.1743762009@warthog.procyon.org.uk> 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: <939183.1743762009@warthog.procyon.org.uk> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: aru5zyLdcJOSWKPSFvRRqmgsKRHSmeiAl4f1s75VcSI_1743762589 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 4ADE5180010 X-Stat-Signature: 7wjn1d5heranucmhpee7m773qbgya1zb X-Rspam-User: X-HE-Tag: 1743762592-235756 X-HE-Meta: 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 JRuLl8/E nh2otZb9aWtc/uJUsvIqFXQIoxNzBKvbeMAs8DUtDemT94iR+0MCTWvSTYHz68h2RgXmwRJ9S7EW2G7rKCOK9ApYvl7RmxgL5hsaTBkoynZfj2m7otg/GHVdUw0r7WvV/jFQ4hJYJB5kKq99pUEchvSpyXVKffbK1Rik5/NoDJppeW2kcWObngQwZRYBjiTrGgfgmSD6dTDetzqEIXoR+gF89bfmBVSz0SgNrZ34NE1BLTUykzgeqdyMpe3SYg1akUBSHVkI1kbpNpl3eTksimqofhFI3NBNN+uk5BxF/axWI4Af4cr0psZBhoUx1oGWmBu52fYwMDMCEqH8JFRP3dzBJpg5sp2a+AfEIGotPM3ykbaonYlTR3LrHXy6yLmqJR9QzRmbB1aF2TdpD+BMfGiGs58SglsvXs+8JnyIWq+ZlWYL8GixDMLqDoy/CfsgVP4MhcUpwH/2F4/v6zUF1RMviT1kTmW4M8AH/ 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 04.04.25 12:20, David Howells wrote: > Hi Kirill, John, David, Hi, > > I don't know if you're the experts on GUP, but can you tell me if unpinning, > e.g. unpin_user_page(), needs to be done in the same MM context and/or the > same user context as the initial pinning? And, if so, is there some way to > break that link? gup_put_folio() seems to only rely on per-folio information (esp. node_stat_mod_folio). So there should not be such a context requirement. > > I'm looking at how I might extend page pinning into the socket layer and > sendmsg(MSG_ZEROCOPY). The problem is that sendmsg() merely queues the > buffers with no guarantee that it's finished with them by the time it's > returned. You get a SO_EE_ORIGIN_ZEROCOPY message to tell you that. > > I have to deal with the issue that the process that did the sendmsg(), the MM > context and the user context may all have ceased to exist by the time the > transmission completes if I don't pin them. AFAIKS that should work. -- Cheers, David / dhildenb