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Howlett" , Suren Baghdasaryan , Matthew Wilcox , Rik van Riel , Harry Yoo , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Jakub Matena , Wei Yang , Barry Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <7e51e1e2-7272-48d5-9457-40ab87ad7694@redhat.com> <76zi626uk53dtfzmezzt6cfz45ansam2gpcumddqxnipnw5jkh@qwfzoxgi255b> <68d8c7ad-aea0-4556-be63-9b67d70e4386@redhat.com> <58560256-58da-4fa6-a953-d2c4695ffba8@lucifer.local> <5ff81ef9-e755-4a75-bcce-92c4a4d1da6e@redhat.com> <7ae2e19c-10f6-4121-bc15-dd07c11b197a@lucifer.local> 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: <7ae2e19c-10f6-4121-bc15-dd07c11b197a@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 9vzdGuR4tzTDIVP3YdS3EgrbT0wN7wLX9qCiKoEG1qo_1750766759 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: rspam08 X-Rspamd-Queue-Id: A09C0180008 X-Stat-Signature: t646kiwpq5hufwy1h7j4dnh9r931hoca X-Rspam-User: X-HE-Tag: 1750766762-182392 X-HE-Meta: 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 774+X13e 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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: >>>> >>>> Or: separate but maybe awful idea, but if the problem is the number of VMAs >>>> maybe we could try harder based on the map count? i.e if >>>> map_count > (max_map_count / 2), try to relocate anon. >>> >>> Interesting, though that'd make some things randomly merge and other stuff not, >>> and you really have to consistently do this stuff to make things mergeable. >> >> Yes, I'd prefer if we can make it more predictable. >> >> (Of course, the VMA region size could also be used as an input to a policy. >> e.g., small move -> much fragmentation -> merge, large move -> less >> fragmentation -> don't care. Knowing about the use cases that use mremap() >> of anon memory and how they might be affected could be very valuable. Maybe >> it's mostly moving a handful of pages where we most care about this >> optimization?). > > I think fundamentally there are two problems: > > 1. Unexpected VMA fragmentation leading to later mremap() failure. > 2. Unnecessary VMA proliferation. > > So we could fix 1 with a 'allow multiple VMAs to be moved if no resize' > patch. Yes. Which might end up easier (well, okay, different level of complexity, at least not messing with folio->) And of course the relocate anon stuff is about 2. > > In theory we could combine it, but things could become complicated as then > it's mulitple VMA/anon_vma merges. Yes. -- Cheers, David / dhildenb