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[79.224.255.169]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b8e1cb7deesm11542751f8f.2.2025.08.06.00.55.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 06 Aug 2025 00:55:55 -0700 (PDT) Message-ID: <50ad6ed2-2f4b-44b1-8b78-8eb3993834f0@redhat.com> Date: Wed, 6 Aug 2025 09:55:54 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] WARNING in follow_page_pte To: syzbot , akpm@linux-foundation.org, jgg@ziepe.ca, jhubbard@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, peterx@redhat.com, syzkaller-bugs@googlegroups.com References: <68930511.050a0220.7f033.003a.GAE@google.com> From: David Hildenbrand Content-Language: en-US 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/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: <68930511.050a0220.7f033.003a.GAE@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 06.08.25 09:32, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 7e161a991ea7 Merge tag 'i2c-for-6.17-rc1-part2' of git://g.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=16d385bc580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=75e522434dc68cb9 > dashboard link: https://syzkaller.appspot.com/bug?extid=57bcc752f0df8bb1365c > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13fa96a2580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1083c434580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/85ce789ac77a/disk-7e161a99.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/4d1fd8fed61a/vmlinux-7e161a99.xz > kernel image: https://storage.googleapis.com/syzbot-assets/9bd5f709ed6f/bzImage-7e161a99.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+57bcc752f0df8bb1365c@syzkaller.appspotmail.com > > do_initcall_level+0x104/0x190 init/main.c:1331 > do_initcalls+0x59/0xa0 init/main.c:1347 > kernel_init_freeable+0x334/0x4b0 init/main.c:1579 > kernel_init+0x1d/0x1d0 init/main.c:1469 > ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 5866 at mm/gup.c:869 follow_page_pte+0xe3c/0x13e0 mm/gup.c:868 That's the VM_WARN_ON_ONCE_PAGE((flags & FOLL_PIN) && PageAnon(page) && !PageAnonExclusive(page), page); [ 89.134725][ T5866] page: refcount:507 mapcount:1 mapping:0000000000000000 index:0x200000009 pfn:0x70809 [ 89.144633][ T5866] head: order:9 mapcount:505 entire_mapcount:0 nr_pages_mapped:505 pincount:2 [ 89.153655][ T5866] memcg:ffff88801b6f8000 [ 89.157938][ T5866] anon flags: 0xfff6000002007c(referenced|uptodate|dirty|lru|head|swapbacked|node=0|zone=1|lastcpupid=0x7ff) [ 89.170337][ T5866] raw: 00fff00000000000 ffffea0001c20001 dead000000000122 dead000000000400 [ 89.179013][ T5866] raw: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 89.188218][ T5866] head: 00fff6000002007c ffffea0001c52088 ffffea0001cc9988 ffff88807c250551 [ 89.196996][ T5866] head: 0000000200000000 0000000000000000 000001fbffffffff ffff88801b6f8000 [ 89.205866][ T5866] head: 00fff00000010a09 ffffea0001c20001 000001f9000001f8 00000002ffffffff [ 89.214719][ T5866] head: ffffffff000001f8 0000000000000015 0000000000000000 0000000000000200 So it's a pte-mapped THP, whereby the folio is pinned two times. The warning indicates that we likely have !exclusive anon page that is mapped writable into the page table. xdp_umem_pin_pages calls pin_user_pages(FOLL_WRITE | FOLL_LONGTERM). Let me dig, the reproducer seems to involve fork, io_uring, mprotect and setsockopt. -- Cheers, David / dhildenb