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[2003:d8:2f1a:3700:2982:b5f7:a04e:4cb4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a568a54e71sm2425465f8f.1.2025.06.13.06.52.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Jun 2025 06:52:10 -0700 (PDT) Message-ID: <51756190-f379-4faa-a4b1-56fd88d776e1@redhat.com> Date: Fri, 13 Jun 2025 15:52:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] mm,hugetlb: Change mechanism to detect a COW on private mapping To: Oscar Salvador , Andrew Morton Cc: Muchun Song , James Houghton , Peter Xu , Gavin Guo , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250612134701.377855-1-osalvador@suse.de> <20250612134701.377855-2-osalvador@suse.de> 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: <20250612134701.377855-2-osalvador@suse.de> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: wsIXfRcs0ep1tRBGIakI1D82SIKuYHAufXgqTRJO2zU_1749822731 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 0A55EA0003 X-Stat-Signature: oqjqfod3o1xur3sqduponkyeq7gjyokw X-HE-Tag: 1749822733-129882 X-HE-Meta: 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 78CSKuln 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 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 12.06.25 15:46, Oscar Salvador wrote: > hugetlb_wp() checks whether the process is trying to COW on a private mapping > in order to know whether the reservation for that address was already consumed > or not. > If it was consumed and we are the ownner of the mapping, the folio will have to > be unmapped from the other processes. > > Currently, that check is done by looking up the folio in the pagecache and > compare it to the folio which is mapped in our pagetables. > If it differs, it means we already mapped it privately before, consuming a > reservation on the way. > All we are interested in is whether the mapped folio is anonymous, so we can > simplify and check for that instead. > > Also, we transition from a trylock to a folio_lock, since the former was only > needed when hugetlb_fault() had to lock both folios, in order to avoid deadlock. > > Closes: https://lore.kernel.org/lkml/20250513093448.592150-1-gavinguo@igalia.com/ If there is a Closes: there should probably be a Fixes: and a Reported-by: > Signed-off-by: Oscar Salvador > Suggested-by: Peter Xu > --- Nothing jumped at me, we'll learn if we missed anything soon I guess :) Acked-by: David Hildenbrand -- Cheers, David / dhildenb