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To: Alexei Starovoitov , bpf@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, memxor@gmail.com, eddyz87@gmail.com, tj@kernel.org, brho@google.com, hannes@cmpxchg.org, lstoakes@gmail.com, akpm@linux-foundation.org, urezki@gmail.com, hch@infradead.org, linux-mm@kvack.org, kernel-team@fb.com References: <20240209040608.98927-1-alexei.starovoitov@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: <20240209040608.98927-1-alexei.starovoitov@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: C30C812001A X-Rspam-User: X-Stat-Signature: rceph9bnbxncf61foif99sp6kfprbtud X-Rspamd-Server: rspam01 X-HE-Tag: 1707747287-431459 X-HE-Meta: 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 o3M6hBHL xkBBZlqXrtu0AZlzXYV1SedcjboSUF0ImJGWw08x2xTVXRYYQB3klq99TD74KDgEthrfn7N94SlrgL8O8irszSDIl8vTrJzSLzrUiXMFAI081cK3vUSzm4TPR4maKPe9GfgPW5dlUz2v6/WLsTP35qteyl+diDkGWqDRNfuQNDSLc4SjDo3I6SdG2ge46AcECShJJfjSL3qOdCROWOhsnAo4G0yfSnjHkNQP0iZjKgnpR3Sg= 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 09.02.24 05:05, Alexei Starovoitov wrote: > From: Alexei Starovoitov > > v1->v2: > - Improved commit log with reasons for using vmap_pages_range() in bpf_arena. > Thanks to Johannes > - Added support for __arena global variables in bpf programs > - Fixed race conditions spotted by Barret > - Fixed wrap32 issue spotted by Barret > - Fixed bpf_map_mmap_sz() the way Andrii suggested > > The work on bpf_arena was inspired by Barret's work: > https://github.com/google/ghost-userspace/blob/main/lib/queue.bpf.h > that implements queues, lists and AVL trees completely as bpf programs > using giant bpf array map and integer indices instead of pointers. > bpf_arena is a sparse array that allows to use normal C pointers to > build such data structures. Last few patches implement page_frag > allocator, link list and hash table as bpf programs. > > v1: > bpf programs have multiple options to communicate with user space: > - Various ring buffers (perf, ftrace, bpf): The data is streamed > unidirectionally from bpf to user space. > - Hash map: The bpf program populates elements, and user space consumes them > via bpf syscall. > - mmap()-ed array map: Libbpf creates an array map that is directly accessed by > the bpf program and mmap-ed to user space. It's the fastest way. Its > disadvantage is that memory for the whole array is reserved at the start. > > Introduce bpf_arena, which is a sparse shared memory region between the bpf > program and user space. > > Use cases: > 1. User space mmap-s bpf_arena and uses it as a traditional mmap-ed anonymous > region, like memcached or any key/value storage. The bpf program implements an > in-kernel accelerator. XDP prog can search for a key in bpf_arena and return a > value without going to user space. Just so I understand it correctly: this is all backed by unmovable and unswappable memory. Is there any (existing?) way to restrict/cap the memory consumption via this interface? How easy is this to access+use by unprivileged userspace? arena_vm_fault() seems to allocate new pages simply via alloc_page(GFP_KERNEL | __GFP_ZERO); No memory accounting, mlock limit checks etc. We certainly don't want each and every application to be able to break page compaction, swapping etc, that's why I am asking. -- Cheers, David / dhildenb