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[2003:cb:c745:2300:653:c844:4858:570f]) by smtp.gmail.com with ESMTPSA id jx12-20020a05600c578c00b0041674bf7d4csm1952319wmb.48.2024.04.17.02.17.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 17 Apr 2024 02:17:25 -0700 (PDT) Message-ID: Date: Wed, 17 Apr 2024 11:17:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Request for clarification regarding huge pages and remapping of virtual to physical address To: sunil bhargo , "linux-mm@kvack.org" Cc: "mounesh.b@gmail.com" References: <245378552.87900.1713345083646.ref@mail.yahoo.com> <245378552.87900.1713345083646@mail.yahoo.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: <245378552.87900.1713345083646@mail.yahoo.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: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E98A2A0003 X-Stat-Signature: brp6sqfmiyk8sg3dnr5hcudtrqsu16ye X-HE-Tag: 1713345449-698395 X-HE-Meta: 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 Okl5GLBX hqev51qgbUBLIikdZW+liRstk3HSOzgKzqDBtAQqmVKTMN88nary25tIWPgqmmvhxWDn/IT6A3Qg30PvmgBklt+uJBpEJt3xJqJslQfP/ozMQF6GFsU7KJHHXs+0xJ73BbrSIMSkXEmYiBQAup3lgjLbBjoBYms+XcihvdcCtjYLc6g84w+9PC4tbv6qNoDkF8w+7y/4MInCzfguZZWBH+M6zf5KqT7mnoVciNPtibGGkuwc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000031, 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 17.04.24 11:11, sunil bhargo wrote: > Hi, > > We have an application which relies on virtual address to physical > address mapping to remain static. The buffer is allocated using > malloc. It is in user space and we were using the mlock thinking that as > it would prevent the swapping the va->pa address mapping would be > static. But it seems to be a faulty assumption. > > If the memory is allocated from huge pages by reserving space upfront at > the kernel boot up and then mmap’ing using MAP_HUGETLB, is it assured > that virtual address to physical mapping won’t be remapped and will be > static ? Unless you have a kernel that has page migration disabled, no. You could use secretmem (which is currently not migratabale/swappable/ ...), but that has very limited capabilities. A "hack" would be to register that (ordinary) memory using iouring as a fixed buffer. That way, it will be longterm pinned and can neither get migrated nor swapped out. -- Cheers, David / dhildenb