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[2003:cb:c749:6600:b73a:466c:e610:686]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a1c829235sm1916215f8f.15.2024.12.19.08.41.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Dec 2024 08:41:38 -0800 (PST) Message-ID: <968d3543-d8ac-4b5a-af8e-e6921311d5cf@redhat.com> Date: Thu, 19 Dec 2024 17:41:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 4/5] mm/migrate: skip migrating folios under writeback with AS_WRITEBACK_INDETERMINATE mappings To: Shakeel Butt Cc: Zi Yan , Joanne Koong , miklos@szeredi.hu, linux-fsdevel@vger.kernel.org, jefflexu@linux.alibaba.com, josef@toxicpanda.com, bernd.schubert@fastmail.fm, linux-mm@kvack.org, kernel-team@meta.com, Matthew Wilcox , Oscar Salvador , Michal Hocko References: <20241122232359.429647-1-joannelkoong@gmail.com> <20241122232359.429647-5-joannelkoong@gmail.com> <43e13556-18a4-4250-b4fe-7ab736ceba7d@redhat.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-MFC-PROC-ID: FCFRT4Vz6oQTqGoVkmSfurN3ckj7ctu9oOHz8gyjFhY_1734626500 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: 3m5mto7c6hymmtfkxhwacndskkeocsaa X-Rspam-User: X-Rspamd-Queue-Id: DA8861C0004 X-Rspamd-Server: rspam08 X-HE-Tag: 1734626489-673602 X-HE-Meta: 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 U6bh/KGS PBfys0AnxOowEwImTOY45hJ3pvsFNuzAQxP628QL7VxoXBBvZOHSg488VSWtlLB4mhDqq0peVUF4ciXoIQfGS0b2QF9YAQ7Mf393CoXsNyZUxzKiTdfLxpX9hYx/81nXN+qAlBo7dqCFT+FrG3jFLP0zcEthttGCxjvfOGiKfRlOQwi2sG13AQbWrICNrAXTHhtCZb4aDFBtuCIUgTnHylm3KH5hLEFb9zGrYW/BaRzGM4WobmCeAlkwcAsCexz7VirthD5AwjkoyTpk+wFCNvqJGWOSoBcNf7dSz9U0+OgUL2l9CUTvI/nOI30KorP+vVJULLkHLVitVZgQTp9shfSwor1WOGbih/Jpeo5uMO03yjJNMEnpnixeE9PG6BqBWe1UL+ehiSRcLrMZuWJ9Az97ITs+EG3NCNhI+9sEe0W48JF56KoDt75ZRYkNkrOd7wCTs X-Bogosity: Ham, tests=bogofilter, spamicity=0.212636, 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 19.12.24 17:40, Shakeel Butt wrote: > On Thu, Dec 19, 2024 at 05:29:08PM +0100, David Hildenbrand wrote: > [...] >>> >>> If you check the code just above this patch, this >>> mapping_writeback_indeterminate() check only happen for pages under >>> writeback which is a temp state. Anyways, fuse folios should not be >>> unmovable for their lifetime but only while under writeback which is >>> same for all fs. >> >> But there, writeback is expected to be a temporary thing, not possibly: >> "AS_WRITEBACK_INDETERMINATE", that is a BIG difference. >> >> I'll have to NACK anything that violates ZONE_MOVABLE / ALLOC_CMA >> guarantees, and unfortunately, it sounds like this is the case here, unless >> I am missing something important. >> > > It might just be the name "AS_WRITEBACK_INDETERMINATE" is causing > the confusion. The writeback state is not indefinite. A proper fuse fs, > like anyother fs, should handle writeback pages appropriately. These > additional checks and skips are for (I think) untrusted fuse servers. Can unprivileged user space provoke this case? -- Cheers, David / dhildenb