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[91.12.110.230]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42ba639643esm106955475e9.1.2024.08.31.02.59.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 31 Aug 2024 02:59:14 -0700 (PDT) Message-ID: Date: Sat, 31 Aug 2024 11:59:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC] mm: entirely reuse the whole anon mTHP in do_wp_page To: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Barry Song , Chuanhua Han , Baolin Wang , Ryan Roberts , Zi Yan , Chris Li , Kairui Song , Kalesh Singh , Suren Baghdasaryan References: <20240831092339.66085-1-21cnbao@gmail.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: <20240831092339.66085-1-21cnbao@gmail.com> 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-Rspamd-Queue-Id: 94CB81C0009 X-Stat-Signature: n617xno58a7zy3t7k8bxeyjdqb3qweia X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1725098359-752048 X-HE-Meta: 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 0nPKKmul 9P7vZob9voXz3Qdie9nhxurFIK54xcW/bVshmSCgUkKizXp9qOBtVA26jMHeWxr0PAhQE7T2LQgjTdNoV0cV9pesmgwaVm85l6x07qJjchuqny/zphPDdf4+bQAosqocbeb4X4uOrpX6DQFLMRfDQkKQwRhC5/TeCfsq4q2mm0+DFS6tedakJWjTvo7oYkqBaa2ChLbAML1E3GY64Gn+Frfi/Yr74JhzGGaG98jb3URUjiKSfIR3JLLwJCOwveqhnsHpXs/4V4vupHwflb/blh5f+Vu/A5oXrxr2zC13HtWaBGJaya+Rh6Fk0b3/1Xru/cvUxMd7Ssfhd61RiNAsgRn4x9Eewiv/dWPHxl9vsrFImH15cgG1p4FCgcbrbL4J9iPEMlvvDUZtn6eBuTvV3kLCvyQ51Ljevb6YUNUoNCSg7jUY3KFX0NAtrVTmJtCe9ncqzrmcz05tFvsYTK+S6cx4a9OQVLhhbi7bP/A9FnK7A314= 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: > + idx = folio_page_idx(folio, vmf->page); > + folio_start = address - idx * PAGE_SIZE; > + folio_end = folio_start + nr * PAGE_SIZE; > + > + if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start))) > + return false; > + if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end))) > + return false; > + folio_ptep = vmf->pte - idx; > + folio_pte = ptep_get(folio_ptep); > + if (!pte_present(folio_pte) || pte_pfn(folio_pte) != folio_pfn(folio)) > + return false; > + if (folio_pte_batch(folio, folio_start, folio_ptep, folio_pte, nr, 0, > + NULL, NULL, NULL) != nr) > + return false; > + if (folio_mapcount(folio) != nr) > + return false; BTW, you're not checking against the refcount (and it's all a bit racy on concurrent unmapping!). So you're re-introducing the vmsplice child->parent attak. -- Cheers, David / dhildenb