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[2003:cb:c734:9600:af27:4326:a216:2bfb]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43bbbff18b3sm57280375e9.24.2025.03.03.08.46.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Mar 2025 08:46:30 -0800 (PST) Message-ID: Date: Mon, 3 Mar 2025 17:46:29 +0100 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?] kernel BUG in try_to_unmap_one To: Hillf Danton , syzbot Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, Zi Yan References: <20250301234002.2893-1-hdanton@sina.com> Content-Language: en-US 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: <20250301234002.2893-1-hdanton@sina.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 02.03.25 00:40, Hillf Danton wrote: > On Sat, 01 Mar 2025 14:41:20 -0800 >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: e5d3fd687aac Add linux-next specific files for 20250218 >> git tree: linux-next >> console output: https://syzkaller.appspot.com/x/log.txt?x=12faf7f8580000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=4e945b2fe8e5992f >> dashboard link: https://syzkaller.appspot.com/bug?extid=fb86166504f57eff29d7 >> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 >> >> Unfortunately, I don't have any reproducer for this issue yet. >> >> Downloadable assets: >> disk image: https://storage.googleapis.com/syzbot-assets/ef079ccd2725/disk-e5d3fd68.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/99f2123d6831/vmlinux-e5d3fd68.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/eadfc9520358/bzImage-e5d3fd68.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+fb86166504f57eff29d7@syzkaller.appspotmail.com >> >> evict+0x4e8/0x9a0 fs/inode.c:806 >> __dentry_kill+0x20d/0x630 fs/dcache.c:660 >> dput+0x19f/0x2b0 fs/dcache.c:902 >> __fput+0x60b/0x9f0 fs/file_table.c:472 >> task_work_run+0x24f/0x310 kernel/task_work.c:227 >> resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] >> exit_to_user_mode_loop kernel/entry/common.c:114 [inline] >> exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] >> __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] >> syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218 >> do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> ------------[ cut here ]------------ >> kernel BUG at mm/rmap.c:1858! >> Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI >> CPU: 1 UID: 0 PID: 6053 Comm: syz.4.27 Not tainted 6.14.0-rc3-next-20250218-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 >> RIP: 0010:try_to_unmap_one+0x3d0d/0x3fa0 mm/rmap.c:1858 >> Code: c7 c7 80 93 c3 8e 48 89 da e8 ef f3 19 03 e9 68 ca ff ff e8 b5 12 ab ff 48 8b 7c 24 20 48 c7 c6 80 17 36 8c e8 94 d2 f5 ff 90 <0f> 0b e8 9c 12 ab ff 48 8b 7c 24 18 48 c7 c6 40 1c 36 8c e8 7b d2 >> RSP: 0018:ffffc9000b1be9c0 EFLAGS: 00010246 >> RAX: 367eb4645686ad00 RBX: 00000000f4000000 RCX: ffffc9000b1be503 >> RDX: 0000000000000004 RSI: ffffffff8c2aaf60 RDI: ffffffff8c8156e0 >> RBP: ffffc9000b1bedf0 R08: ffffffff903da477 R09: 1ffffffff207b48e >> R10: dffffc0000000000 R11: fffffbfff207b48f R12: 8000000053c008e7 >> R13: dffffc0000000000 R14: ffffea00014f0000 R15: ffffea00014f0030 >> FS: 00007f4d2783e6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000000110c465fa1 CR3: 000000002a1f6000 CR4: 00000000003526f0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> Call Trace: >> >> __rmap_walk_file+0x420/0x5f0 mm/rmap.c:2774 >> try_to_unmap+0x219/0x2e0 >> unmap_folio+0x183/0x1f0 mm/huge_memory.c:3053 >> __folio_split+0x849/0x16d0 mm/huge_memory.c:3696 >> truncate_inode_partial_folio+0x9b1/0xdc0 mm/truncate.c:234 >> shmem_undo_range+0x82f/0x1820 mm/shmem.c:1143 > > Given folio_test_hugetlb(folio) [1], what is weird is hugetlb page in a > shmem mapping. > Right, the problem begins when we call __folio_split() on a hugetlb folio, and the issue is that we seem to find that in the pagecache. I wonder if there is some weird interaction with out recent folio split changes in next. Maybe, for some reason, we end up adding a wrong folio to the pagecache during a split (truncation), and a follow-up split (truncation) finds the wrong folio. Just a guess, though. CCing Zi Yan. -- Cheers, David / dhildenb