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[149.14.88.26]) by smtp.gmail.com with ESMTPSA id bv26-20020a0560001f1a00b0033e03a6b1ecsm701426wrb.18.2024.02.28.02.46.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Feb 2024 02:46:57 -0800 (PST) Message-ID: Date: Wed, 28 Feb 2024 11:46:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails To: Suren Baghdasaryan , Andrew Morton Cc: Qi Zheng , aarcange@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20240222080815.46291-1-zhengqi.arch@bytedance.com> <20240222130005.c3f24eed1c1a27c66947e9df@linux-foundation.org> 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: 8bit X-Rspamd-Queue-Id: 423F7C0013 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: an8iepnpjw5pmfohnegbq1despb13j6x X-HE-Tag: 1709117221-280018 X-HE-Meta: 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 5qUn13zQ KHQ7zpeK7mVjM/AbFIDhAkX6TTMiFT+hyV//lMQPhCIflPtP8BcSqbkTedUhnsJsAPdLhiJY7/XjXZg8MAwEOAwNWGxvJ0fiKhO+McGq6vFBsMc3lYO2PO7RFLOCUNswD6wrUjzy9J8/zbNyUIDtgLWSqQeWtbn0rNJoWqp1NtJ4uQvfFCH9DR9tVv+7jowxKkFpAM+JKOCxmK1e2kNSoW8SlGQ== 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 22.02.24 22:56, Suren Baghdasaryan wrote: > On Thu, Feb 22, 2024 at 1:00 PM Andrew Morton wrote: >> >> On Thu, 22 Feb 2024 16:08:15 +0800 Qi Zheng wrote: >> >>> After ptep_clear_flush(), if we find that src_folio is pinned we will fail >>> UFFDIO_MOVE and put src_folio back to src_pte entry, but the change to >>> src_folio->{mapping,index} is not restored in this process. This is not >>> what we expected, so fix it. >>> >>> Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") >> >> What are the expected worst-case userspace-visible runtime effects of >> this flaw? > > It can cause rmap for that page to be invalid. I guess memory > corruption might be the visible effect? At least swapout+migration would no longer work, because we might fail to locate the mappings of that folio. Memory corruption, not sure. -- Cheers, David / dhildenb