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(p200300cbc72fed009dc21adbd1334434.dip0.t-ipconnect.de. [2003:cb:c72f:ed00:9dc2:1adb:d133:4434]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36878684773sm11116875f8f.7.2024.07.23.03.12.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Jul 2024 03:12:20 -0700 (PDT) Message-ID: <50a581c9-0e59-4282-859b-922d02b3870e@redhat.com> Date: Tue, 23 Jul 2024 12:12:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/x86/pat: Only untrack the pfn range if unmap region To: Peter Xu , "Liam R. Howlett" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Alex Williamson , Jason Gunthorpe , Al Viro , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "Kirill A . Shutemov" , x86@kernel.org, Yan Zhao , Kevin Tian , Pei Li , David Wang <00107082@163.com>, Bert Karwatzki , Sergey Senozhatsky References: <20240712144244.3090089-1-peterx@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-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A565F180016 X-Stat-Signature: k4iq4xmnof96xczy9ku4n8hsme8638pr X-HE-Tag: 1721729547-636520 X-HE-Meta: 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 Smnzj529 ym860m1meUfT3lL/iTmwkqPxyL0AeUqSoOqaqjH2yhdFv8AGfGAyfO7QNDldpxDIl0CnGQLLFpQ4ln3+e3uaRUm2jzn6laWQPXGLFiL1WIQLRw7niwb2tkgkFsmqGnAR7ptTVbQbFc8/LQQq+Z1BOwO/l+QdE9SUQPjZGUlDNg16Q+zpWFU9XzU1PV3Al3GrT1bTtC4yN9yhUjqqc77Ck38QCAguNlOAm7Nk68Q+bKYc/OepQDaYWrihqNf5dlQiYB8MqyD49HvJAwZ2MYj8BpvkixPwyTq+MH4BAlyGkebRfE6V8zM7/vmydr4nGYiDu/o9sy9ABnBz2S9Ut8Kxwn9pmajzes6Dt4gcM3kmsu7gszsL3TaZT4bA5SfOYv5Oce6M+7JVl+oHcFgkOUYS1uEaXNCd3xksQ1lWtUU1DLUP9V9NkT+zA4unCMDRBTk4Zw2et 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 22.07.24 23:17, Peter Xu wrote: > On Mon, Jul 22, 2024 at 04:22:45PM -0400, Liam R. Howlett wrote: >> The problem report from [2] and [3] is that we are getting to a call >> path that includes unmap_single_vma() without the mmap lock. This patch >> fails to address that issue, it only takes the caller with the assert >> out of the call path. >> >> Removing the function with the lock check doesn't fix the locking issue. >> If there is no locking issue here, please state the case in the commit >> log as you feel it is safe to use a vma pointer without the mmap_lock >> held. > > Could you please state why there's a locking issue, and why this patch (of > a x86 PAT specific issue...) would need any documentation on that? > > I thought it was pretty common that file truncation (or anything similar) > does a file rmap walk over vmas that mapping this file, and vmas need to be > alive during the rmap walk, no? Right, I was also assuming that the rmap locking (from where we obtained that VMA -- rmap interval tree) makes sure that using the VMA is safe. -- Cheers, David / dhildenb