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b=dsH5SUzPgDHob1SA6hEhN3BHjfca8FM0rBsX8fSNPDZOrslpf3naZjnxtN71GBn2i 3CIgtiNa+0S0WaLNRULoJsFLUBk6sDuYlSlmOf1ZS7C+rSv7Dxu6nRcALtoT5JxKZq dTF6mEJJSjb0CUdbOFyLf5FhW1c6d6D1Nc3YhCoT0kdpTZ36Au+FjOr/9G4qHxeg03 ewaRmwxa0jj8aEKWtuk1LcIfnNA3D6Ahkh2ShBBGmxZQGF18AMwQ+As3nnpQYLFEGn CC2yBr2zCs4Rrb3lt/5xrfOL4ixVuU6vcMFSoHhPTLB4sJIoOn/Bur602OqR10h7ae eddo+u8P0Leyg== Message-ID: <1ddf6f68-4aff-4475-aa82-c2bf15c9706c@kernel.org> Date: Wed, 13 May 2026 13:44:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] possible deadlock in gup_fast_fallback (3) To: syzbot , akpm@linux-foundation.org, jgg@ziepe.ca, jhubbard@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, peterx@redhat.com, syzkaller-bugs@googlegroups.com References: <6a0321a3.050a0220.106bf4.0005.GAE@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <6a0321a3.050a0220.106bf4.0005.GAE@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 84611140002 X-Stat-Signature: 8zg5p6n6wud66gd1gs1wzsbanebdzmic X-HE-Tag: 1778672704-98522 X-HE-Meta: U2FsdGVkX1+ipB9Droxz5vdaVGZvAVSWdL1b3EQEHvs0PUt0kQdzeqot2EIIg/KLh6CgMWdZQlbrfheFsAMImmxhUqzjk8s4N48ouMC3ihsxVLBo0KkOaA2DipYoRPH+MDCKSgeVODVuGL0PedHwt4EJbxDYBG/L5z0La/Hgnb1HqY8Xwiy+wbk82qv+I9T5DELuvYYDWcNj7ZkPVj9gd6+4JcRwO30dfIqAPQVypekrJ7pYYqilubhIoCEDlS0Q7sR3tzLaqxA5mifa5eCSegHQghWLXC7bvif7qzHofjuo1e5gsKhmG3Z049oZVcC7mGHKYx9rIiIiXm84mUEOPW4CL4BL2ysRM80ChQB3AeP+UkXOq8I8TmDoSnmFqeW16mBk4owXWuAZzKTVQzZDygdpWpEHDN9EexK3TOoZAHKC9hQikpOlmljrluYyQF8pKR3VqPrlOLDL3zhYrqF586mMQxpOdDi+sPbhRldpXCr3hqRLuzqtDlswpXOmPw3Jn3os3XXurOfTiDb4f7suqsjkC2uLNxn2yWvPlACo7pvE4znEoP3UWFqRbXpDwb+OXrwUxIRlVIjGuHM0qRmpLWqgyOHsbMTMQtHco33yYByIlxP33PJ7fW1pJmnF91plW1oYnlEuB17qb0QSD0z8dh3++0gCStW24G526My4P2wdbS2c39UIvwqCMNqNzL5qS96lRyb34yNujJncdrRASsEb+B7GgaseIq9nt74WWBDmHWJDai72apnORv1w2w5dgllbYd9MZA/VDXKucpaxMCsfABGyCP3DKgm1JxyRPVFf4qYXs7gOATTmL74eU3zEg9vkZo4go7X6ZvAJwCUzHKN/xele4iH7wz0p/nKbJhi7F7UQJr73GR23zQa84zo8zcgtV9nKl7uwDdNfCQGjmbN1c93klcZXELoKyi8uTzL/ZiRRKTPJ+V2tbE0dNbe3+H6/OvUK4uNb/x25U2h vaIRBFSh 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/12/26 14:48, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 63751099502d Merge branch 'net-mlx5-steering-misc-enhancem.. > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1714fbce580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f2b487b72ffad035 > dashboard link: https://syzkaller.appspot.com/bug?extid=8edc46c9c781c802acf4 > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/1f8de738e2f8/disk-63751099.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/ae6cfb0d3b70/vmlinux-63751099.xz > kernel image: https://storage.googleapis.com/syzbot-assets/f00e218e1a55/bzImage-63751099.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+8edc46c9c781c802acf4@syzkaller.appspotmail.com > > ====================================================== > WARNING: possible circular locking dependency detected > syzkaller #0 Not tainted > ------------------------------------------------------ > syz.4.2801/16593 is trying to acquire lock: > ffff88802ae527f8 (&mm->mmap_lock){++++}-{4:4}, at: gup_fast_fallback+0x20d/0x20d0 mm/gup.c:3193 > > but task is already holding lock: > ffff888055ac9d60 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline] > ffff888055ac9d60 (sk_lock-AF_INET6){+.+.}-{0:0}, at: tls_sw_sendmsg+0x15d/0x2430 net/tls/tls_sw.c:1291 > > which lock already depends on the new lock. I don't know what going on here, but I know for sure that GUP is not to blame ;) -- Cheers, David