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[2003:cb:c70c:de00:1200:8636:b63b:f43]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-432f643b299sm54461735e9.0.2024.11.21.01.55.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Nov 2024 01:55:05 -0800 (PST) Message-ID: <6b8351f6-39bb-4312-b3ff-000eb1f1fe90@redhat.com> Date: Thu, 21 Nov 2024 10:55:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] BUG: Bad page state in iomap_write_begin From: David Hildenbrand To: syzbot , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Cc: David Howells References: <673d9fc5.050a0220.363a1b.0007.GAE@google.com> <7bab1234-45d7-43f6-8ebf-4a2c923c6a46@redhat.com> 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: <7bab1234-45d7-43f6-8ebf-4a2c923c6a46@redhat.com> X-Mimecast-Spam-Score: 1 X-Mimecast-MFC-PROC-ID: 8C9FmBz1b9B4fK8Wy1BB59tRMgkpcZ4ygAIjRuIvzmM_1732182907 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 709894000D X-Stat-Signature: krgcjmu1z8r6st36y1azbqn7fnzmf6zy X-Rspam-User: X-HE-Tag: 1732182870-648397 X-HE-Meta: U2FsdGVkX1+Gn1RyjUiFYw9hwy9cpiLlBSTWbRvM8JWHh2YoTL+9iq1gb79PTobULAn5wbOzUexwI4MRu8LAwcqiHoVCzQiuOjvYvcKZNGrLEIHQFXgNBnYELp8coyWJMwjo46VYM7zEiXTdQGQ/ueSe1AlY0aPBGzF4qq8qEk1+aQ3JHWJdMbNeT66qYPlNBH9+/1o9DHOsvTRzeELzrRgtDzTFrP1pS8fSPQnVrr1foBbVwDbRB6EcJVB/e7XIlyy7x50KGXVaX6gLLjPX5prWuZHjw3lewLkXYP7umzNWQf//raKu/V+q/SUuq6lozmhCw0yDW+TzhNH69HVD3gWY5yq7Aj/PiMrjE8SOyqqeARUI9LZQr1iphCr52iVscYqABxhM25TzVHEQRwJ2i2uO3GuBnDIb2bMEe4juPIB5pCBleo0K6oNSxNrJAmegeSIadQltUkgFqKFNz9/ZGI6fSj6JFtuIo6Q2/8cKb0iyDSbOJhQtx3hRdHBGWUrT9BUmv00fRYbgwXMB4qboYYPg/IVMUY1BJmgPebQJdWICXdDSsme0ujXAJBbrjIaT4mua1nfayhK9Etsdhi/UBiFYgNXCjtHWnnzR0wh6DGGwTmMo50ZOBwR8e/sqJNQ6VgVXHWBRmZInCbIcGEETmvgE/QV6nO2L9F7o+Y9KzpmpzMIe+A2ZE+NgRNpcOmS1mpdAHXxFRhWst3ksbxissaceDlqrI4vLQIuk9trSMAbysiE3XpBIYQyIhlw19TpnxFv4wgy5lTIoEywJVBOvdT8Z2lqadyJ1OSbLpsMxYy+U/Op6To7XHRTbTYNTpn4LlNbnjJ0XTLeOk7KskMxSgt6+cKfMs34By/rkem1CLwzye88LPWYT+/UGLw+M7pqQO66nJjOTreQ5R2Zb3/K8i+RP76m1FcYZe7lOx9+S3ABvA4oLrrVrFfSQ1JtwHwMEgN8lVBPBb+xZikYq3Ef XdI+MP/K 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 M2ZEYoe9 bkcAJGaA7QUgUesRcHQZVzrMW6/skKq16KOBFNMLMjdzKBy0IqE/KhR/itoX7Oca5GRsw2h1Xh0= 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 21.11.24 10:46, David Hildenbrand wrote: > On 21.11.24 10:26, David Hildenbrand wrote: >> On 20.11.24 09:37, syzbot wrote: >>> Hello, >>> >>> syzbot found the following issue on: >>> >>> HEAD commit: e8bdb3c8be08 Merge tag 'riscv-for-linus-6.12-rc8' of git:/.. >>> git tree: upstream >>> console output: https://syzkaller.appspot.com/x/log.txt?x=1644d2c0580000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=d2aeec8c0b2e420c >>> dashboard link: https://syzkaller.appspot.com/bug?extid=c317c107c68f8bc257d9 >>> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1144d2c0580000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=176252e8580000 >>> >>> Downloadable assets: >>> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-e8bdb3c8.raw.xz >>> vmlinux: https://storage.googleapis.com/syzbot-assets/fcae16ff0e0f/vmlinux-e8bdb3c8.xz >>> kernel image: https://storage.googleapis.com/syzbot-assets/758973beace8/bzImage-e8bdb3c8.xz >>> mounted in repro #1: https://storage.googleapis.com/syzbot-assets/a097a300c8a9/mount_0.gz >>> mounted in repro #2: https://storage.googleapis.com/syzbot-assets/36b9fff6ab5e/mount_6.gz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+c317c107c68f8bc257d9@syzkaller.appspotmail.com >>> >>> BUG: Bad page state in process syz-executor315 pfn:49e01 >>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x49e01 >>> head: order:0 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:-1 >> >> So, we have a pincount underflow on a large folio (order-9). We >> allocated the folio in iomap_write_begin()->__iomap_get_folio(). Nothing >> special. >> >> [...] >> >>> >>> BUG: Bad page state in process syz-executor315 pfn:49e00 >>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x49e00 >>> head: order:0 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 >>> flags: 0x4fff0000000004d(locked|referenced|uptodate|head|node=1|zone=1|lastcpupid=0x7ff) >>> raw: 04fff0000000004d dead000000000100 dead000000000122 0000000000000000 >>> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff0000000004d dead000000000100 dead000000000122 0000000000000000 >>> head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff00000000000 0000000000000000 ffffffffffffffff 0000000000000000 >>> head: 0000000000000200 0000000000000000 00000000ffffffff 0000000000000000 >>> page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set >> >> And we seem to have an unexpected flag set on the head page of the same >> large folio. Likely PG_locked. >> >> ... >> >>> XFS (loop0): Unmounting Filesystem 9f1cad42-11bd-4e12-8f0b-f07876b81d9a >>> BUG: Bad page state in process syz-executor315 pfn:49c01 >>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x49c01 >>> head: order:0 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:-1 >>> flags: 0x4fff0000000004d(locked|referenced|uptodate|head|node=1|zone=1|lastcpupid=0x7ff) >>> raw: 04fff00000000000 ffffea0001270001 ffffffffffffffff ffffffff00000000 >>> raw: 0000000000000200 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff0000000004d dead000000000100 dead000000000122 0000000000000000 >>> head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff00000000000 ffffea0001270001 ffffffffffffffff ffffffff00000000 >>> head: 0000000000000200 0000000000000000 00000000ffffffff 0000000000000000 >>> page dumped because: nonzero pincount >> >> [...] >> >>> >>> BUG: Bad page state in process syz-executor315 pfn:49c00 >>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x49c00 >>> head: order:0 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 >>> flags: 0x4fff0000000004d(locked|referenced|uptodate|head|node=1|zone=1|lastcpupid=0x7ff) >>> raw: 04fff0000000004d dead000000000100 dead000000000122 0000000000000000 >>> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff0000000004d dead000000000100 dead000000000122 0000000000000000 >>> head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 >>> head: 04fff00000000000 0000000000000000 ffffffffffffffff 0000000000000000 >>> head: 0000000000000200 0000000000000000 00000000ffffffff 0000000000000000 >>> page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set >>> page_owner tracks the page as allocated >> >> Same thing, different folio. >> >> >> So we seem to be repeatedly freeing a large folio that >> (a) Is locked >> (b) Has a pincount underflow >> >> Likely because we have an unbalanced unpin, that happens before >> evicting/truncating the folio. If we then evict/truncate the (locked) >> folio, we free the folio before unlocking it and dropping the actual >> last reference. >> >> Not sure why we see a comparable thing with small folios (pincount part >> of refcount, but on unpin our refcount should seriously underflow >> immediately) >> >> CCing David > > If I get the reproducer right, it does: > > (1) Create a temporary folder and chdir into it > > (2) Mounts an (XFS?) image (syz_mount_image() magic ) > > (3) Opens a file1 in there > > (4) Writes some data into it using write(). Likely this allocates the > folios. > > (5) Mmaps the file1 (MAP_UNINITIALIZED|MAP_LOCKED|MAP_FIXED|MAP_SHARED) > > (6) Creates a socket -- socket() -- and binds it -- bind(). > > (7) Writes some more data into the mmap of file1 using memcpy. > > (8) Mounts another (?) image (syz_mount_image() magic ) > > (9) Opens a file2 in there with O_SYNC|O_DIRECT|O_CREAT|O_RDWR. > > (10) Calls ioctl(0xc0185879) on the file2 > > (11) Calls sendmsg() on the socket. msghdr and all data seems to reside > completely in the mmap of file1. > > (12) Calls symlink(0,0) > > (13) Calls rename(0,0) > > > I doubt 12+13 are relevant. Likely (11) is the problematic bit: we are > performing direct-io on folios allocated during (4) from file1 into file2. > > I have not deciphered yet what the ioctl in (10) does. Seems to be FITRIM. -- Cheers, David / dhildenb