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[2003:cb:c743:ad00:d0f3:7f1d:5dd4:a961]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-432dab72085sm170925915e9.3.2024.11.18.11.42.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Nov 2024 11:42:38 -0800 (PST) Message-ID: Date: Mon, 18 Nov 2024 20:42:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: memfd and transparent hugepages To: Avi Kivity , linux-mm References: <2f7b4534689ec00dc9dd139ec2845c79d1617514.camel@scylladb.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: <2f7b4534689ec00dc9dd139ec2845c79d1617514.camel@scylladb.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: W5OZ-ecuDyS9z5QrPMI2GoHpatMRWV3vUXHAqI9fQsc_1731958960 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: mi9uwmdc3yew9xwkkzopcpti1gpgx16x X-Rspam-User: X-Rspamd-Queue-Id: CD0AF40016 X-Rspamd-Server: rspam02 X-HE-Tag: 1731958900-283294 X-HE-Meta: U2FsdGVkX1/n6E4irE9W9YsPIkCaljx3swOx//9wu5Tcw35TSFPYI5EQRHgRhKg491wjQhpBmEZH34yOlooCyGMagWMLsR5fFvkX4wcmrxQzCDMKoQfOc3rc0eY1RBKBwYJwfyXDoQ/PUCuAGG1mVPzwpjL/WPrq5otzIzj9xu86WC8koHJb7DsRGetfqkQK2EmIz5W9Upl2rmj1778A7NU8N8W9aNcXDO2xQjGugV8tLC2Y3O5N4Ufry5DPJFxx8Rk7nBpoOnx+R/3AMSRFAYCOUaJfYQxg8V7X1vvAiABkBCWCJMot2RxIFcP/QxHK/58Qm6MiZ2G5SObiGFZcIg3jw7WS43Hu8Br+nUd19yVBbwVhjHLokLznaBPqJ+u9TvYMkc5cXhVZoBqgira9dayEnMeb9GK7+X0xuHvTGLoodlUSw38MYtyivukYTHXXhp5wOstVbQT9NVnnKys8vbFk8aZMKpHKES4Av7pjoFkSyJyw2PxwtA/4YXBqGhm0050/Cqsob7enVyrMNFYiJJdmNTVoJ15Ruo5tFv9XiypdA1y0xxhraOsC79guFacQMwbE/6ajHkLV3IBBhn4JmCOiplHBpw+GL7jXdtGGIMt2VUddPPZFyxVAs1wVb2du7HCsN1OLRlVgQwhv7UsfNHNfSPIlPfsEmKVSyXvqLmLesbek+Ay/VnPx371G9QzicSY7U1QoGNp6OtxWE1wcfTbuN3MooGafsazV3ERlcL8ujhyEeo0R1OGGSX6hCL8TZ01mrezTLMBI2rA5BNY8HxZTXbHWctPoj8hb7Tl9qeBtru14ETC2wnxG+Abo4PYPTp/2jd/FuGXWG3vBnuF1I/CWl5bJfeVzcD20kLzgBpTVMLyc1AfZbv4FFnf144W1+oHHhY4K+yi7a7W0V9+hsASibFph78cnd8fr32r0N+u3xByIVssbYmM6RdnYVG7I8q2QlPxWfRF3Nfws1iK UiNilK6D QQX2hZKlDIz1VjbB9QFRXUdqPR1JNJ0+B/7ZS/mcXflpGHlRt4VpFU6fRRbKJZwibm0R2baNJoDgE0NcX+FCQoRgzG/0D+Ht9zFOoLQPDcOXeBmWpwA9EReiD0+149CaG3XLxMNSTnINTVVcKVfQEq9hpf7lPY6fDrq27EWqEbj45SfmeHgXykppWfKk93haw9hvT0NflN3QUevEMQGrDoyzD539U9TsMPniPl1SRAhyJvj9UCx5+06VickzukrKkwIjppaphZHsSJwkUaSaG3iNxqtCxAwHEgClh5ob6gyI6Hk/pXIVA6sIimpLQKME5y01kQMcF75kconzdLUPl3/29dDqcaHzdAPyyWedjlXUSQS0VHBX60eRq5kDACyMYG/hAG6ZGp+XkUho= 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 18.11.24 15:13, Avi Kivity wrote: > #define _GNU_SOURCE > #include > #include > #include > #include > > int main(int ac, char** av) { > size_t memsz = (size_t)2048 << 20; > int fd = memfd_create("memory", MFD_CLOEXEC); > ftruncate(fd, memsz); > void* p = mmap((void*)0x40000000, memsz, PROT_READ|PROT_WRITE, > MAP_PRIVATE|MAP_FILE, fd, 0); > madvise(p, memsz, MADV_HUGEPAGE); > madvise(p, memsz, MADV_POPULATE_WRITE); > madvise(p, memsz, MADV_COLLAPSE); > pause(); > return 0; > } Hi, > > While memfd is documented as using anonymous pages, AnonHugePages shows > as zero. it's an anonymous file, not anonymous memory. memfd is shmem in diguise. > > If memfd incompatible with transparent hugepages? Shmem supports THP. But you have one flaws in your program: you have to mmap it MAP_SHARED. It's shmem. Otherwise during MADV_POPULATE_WRITE you're simply allocating a shmem page (pageache), and the COW it to map an anonymous page in your page tables, resulting in a double memory consumption (pagecache+anonymous memory). khugepaged does currently not operate on such VMAs. If you use MAP_SHARED in your example above: $ cat /proc/`pgrep tst`/smaps_rollup 00400000-7ffc2770d000 ---p 00000000 00:00 0 [rollup] Rss: 2098460 kB Pss: 2097269 kB Pss_Dirty: 2097248 kB Pss_Anon: 96 kB Pss_File: 21 kB Pss_Shmem: 2097152 kB Shared_Clean: 1200 kB Shared_Dirty: 0 kB Private_Clean: 12 kB Private_Dirty: 2097248 kB Referenced: 2098460 kB Anonymous: 96 kB KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 2097152 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB -- Cheers, David / dhildenb