On 27.08.2025 18:42, Joanne Koong wrote: > On Wed, Aug 27, 2025 at 6:45 AM Aleksandr Nogikh <nogikh@xxxxxxxxxx> wrote: >> I've bisected the problem to the following commit: >> >> commit 167f21a81a9c4dbd6970a4ee3853aecad405fa7f (HEAD) >> Author: Joanne Koong <joannelkoong@xxxxxxxxx> >> Date: Mon Jul 7 16:46:06 2025 -0700 >> >> mm: remove BDI_CAP_WRITEBACK_ACCT >> >> There are no users of BDI_CAP_WRITEBACK_ACCT now that fuse doesn't do >> its own writeback accounting. This commit removes >> BDI_CAP_WRITEBACK_ACCT. >> >> Joanne Koong, could you please take a look at the syzbot report below? > Hi Aleksandr, > > Thanks for bisecting this. This is a duplicate of what Marek reported > in [1]. His patch in [2] fixes the warning getting triggered. > > Marek, could you submit your patch formally to the mm tree so it could > be picked up? I've already did that: https://lore.kernel.org/all/20250826130948.1038462-1-m.szyprowski@xxxxxxxxxxx/ > > Thanks, > Joanne > > > [1] https://lore.kernel.org/linux-fsdevel/a91010a8-e715-4f3d-9e22-e4c34efc0408@xxxxxxxxxxx/T/#u > [2] https://lore.kernel.org/linux-fsdevel/a91010a8-e715-4f3d-9e22-e4c34efc0408@xxxxxxxxxxx/T/#m3aa6506ee7de302242e64861f8e2199f24e4ad46 > >> On Fri, Aug 22, 2025 at 12:09 PM syzbot >> <syzbot+0630e71306742d4b2aea@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: >>> Hello, >>> >>> syzbot found the following issue on: >>> >>> HEAD commit: 0f4c93f7eb86 Add linux-next specific files for 20250822 >>> git tree: linux-next >>> console output: https://protect2.fireeye.com/v1/url?k=1fb70741-7eccadc9-1fb68c0e-74fe4860018a-55254c3abc8830cc&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fx%2Flog.txt%3Fx%3D172c07bc580000 >>> kernel config: https://protect2.fireeye.com/v1/url?k=7674b464-170f1eec-76753f2b-74fe4860018a-dc792d3947085adc&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fx%2F.config%3Fx%3D21eed27c0deadb92 >>> dashboard link: https://protect2.fireeye.com/v1/url?k=cc82c51b-adf96f93-cc834e54-74fe4860018a-15cd3914e26f6b7e&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fextid%3D0630e71306742d4b2aea >>> compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 >>> >>> Downloadable assets: >>> disk image: https://protect2.fireeye.com/v1/url?k=e6bff250-87c458d8-e6be791f-74fe4860018a-800b933a7034a696&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fstorage.googleapis.com%2Fsyzbot-assets%2F669ede8f5d66%2Fdisk-0f4c93f7.raw.xz >>> vmlinux: https://protect2.fireeye.com/v1/url?k=2603018e-4778ab06-26028ac1-74fe4860018a-9b89a99c7853c7f0&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fstorage.googleapis.com%2Fsyzbot-assets%2F50feda89fe89%2Fvmlinux-0f4c93f7.xz >>> kernel image: https://protect2.fireeye.com/v1/url?k=420b962e-23703ca6-420a1d61-74fe4860018a-a965e5c8c6b4614a&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fstorage.googleapis.com%2Fsyzbot-assets%2F317a0d3516fb%2FbzImage-0f4c93f7.xz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+0630e71306742d4b2aea@xxxxxxxxxxxxxxxxxxxxxxxxx >>> >>> ------------[ cut here ]------------ >>> WARNING: ./include/linux/backing-dev.h:243 at inode_to_wb include/linux/backing-dev.h:239 [inline], CPU#1: kworker/u8:6/2949 >>> WARNING: ./include/linux/backing-dev.h:243 at __folio_start_writeback+0x9d5/0xb70 mm/page-writeback.c:3027, CPU#1: kworker/u8:6/2949 >>> Modules linked in: >>> CPU: 1 UID: 0 PID: 2949 Comm: kworker/u8:6 Not tainted syzkaller #0 PREEMPT(full) >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 >>> Workqueue: writeback wb_workfn (flush-8:0) >>> RIP: 0010:inode_to_wb include/linux/backing-dev.h:239 [inline] >>> RIP: 0010:__folio_start_writeback+0x9d5/0xb70 mm/page-writeback.c:3027 >>> Code: 28 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 ce a2 29 00 49 8b 07 25 ff 3f 00 00 e9 1b fa ff ff e8 7c 04 c6 ff 90 <0f> 0b 90 e9 d6 fb ff ff e8 6e 04 c6 ff 48 c7 c7 a0 f8 5f 8e 4c 89 >>> RSP: 0018:ffffc9000bb06ea0 EFLAGS: 00010293 >>> RAX: ffffffff81fad344 RBX: ffffea00050de8c0 RCX: ffff88802ee29e00 >>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 >>> RBP: ffffc9000bb07010 R08: ffffc9000bb06f97 R09: 0000000000000000 >>> R10: ffffc9000bb06f80 R11: fffff52001760df3 R12: ffffea00050de8c8 >>> R13: 0000000000000000 R14: ffff888023060880 R15: ffff888023060660 >>> FS: 0000000000000000(0000) GS:ffff8881258c3000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 00007f7354907000 CR3: 000000000e338000 CR4: 00000000003526f0 >>> Call Trace: >>> <TASK> >>> __block_write_full_folio+0x75f/0xe10 fs/buffer.c:1928 >>> blkdev_writepages+0xd1/0x170 block/fops.c:484 >>> do_writepages+0x32e/0x550 mm/page-writeback.c:2604 >>> __writeback_single_inode+0x145/0xff0 fs/fs-writeback.c:1680 >>> writeback_sb_inodes+0x6c7/0x1010 fs/fs-writeback.c:1976 >>> __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2047 >>> wb_writeback+0x44f/0xaf0 fs/fs-writeback.c:2158 >>> wb_check_old_data_flush fs/fs-writeback.c:2262 [inline] >>> wb_do_writeback fs/fs-writeback.c:2315 [inline] >>> wb_workfn+0xaef/0xef0 fs/fs-writeback.c:2343 >>> process_one_work kernel/workqueue.c:3236 [inline] >>> process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 >>> worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 >>> kthread+0x711/0x8a0 kernel/kthread.c:463 >>> ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148 >>> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >>> </TASK> >>> >>> >>> --- >>> This report is generated by a bot. It may contain errors. >>> See https://protect2.fireeye.com/v1/url?k=d9d7c080-b8ac6a08-d9d64bcf-74fe4860018a-5a4a20c239e4ea82&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fgoo.gl%2FtpsmEJ for more information about syzbot. >>> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. >>> >>> syzbot will keep track of this issue. See: >>> https://protect2.fireeye.com/v1/url?k=03a49fa8-62df3520-03a514e7-74fe4860018a-9a57f917485c2c59&q=1&e=3aa7e54d-e6d6-43e9-ade0-0a94ae0545e0&u=https%3A%2F%2Fgoo.gl%2FtpsmEJ%23status for how to communicate with syzbot. >>> >>> If the report is already addressed, let syzbot know by replying with: >>> #syz fix: exact-commit-title >>> >>> If you want to overwrite report's subsystems, reply with: >>> #syz set subsystems: new-subsystem >>> (See the list of subsystem names on the web dashboard) >>> >>> If the report is a duplicate of another one, reply with: >>> #syz dup: exact-subject-of-another-report >>> >>> If you want to undo deduplication, reply with: >>> #syz undup >>> Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
