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charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: b927546677c8 Merge tag 'dma-mapping-6.19-2025-12-22' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11dc8b92580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a94030c847137a18 dashboard link: https://syzkaller.appspot.com/bug?extid=71fcf20f7c1e5043d78c compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10515f1a580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/b27369f4b013/disk-b9275466.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3b2d81c4be86/vmlinux-b9275466.xz kernel image: https://storage.googleapis.com/syzbot-assets/89c2ad4f36b6/bzImage-b9275466.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+71fcf20f7c1e5043d78c@syzkaller.appspotmail.com ------------[ cut here ]------------ WARNING: block/blk-wbt.c:741 at wbt_init_enable_default+0x4e/0x60 block/blk-wbt.c:741, CPU#0: syz.1.439/7602 Modules linked in: CPU: 0 UID: 0 PID: 7602 Comm: syz.1.439 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:wbt_init_enable_default+0x4e/0x60 block/blk-wbt.c:741 Code: ff 89 c6 e8 e4 e4 40 fd 85 db 75 18 e8 9b e0 40 fd 5b e9 20 2c 90 fc cc e8 8f e0 40 fd 5b e9 14 2c 90 fc cc e8 83 e0 40 fd 90 <0f> 0b 90 5b e9 04 2c 90 fc cc 0f 1f 84 00 00 00 00 00 90 90 90 90 RSP: 0018:ffffc90004ab7ab8 EFLAGS: 00010293 RAX: ffffffff848014fd RBX: 00000000fffffff4 RCX: ffff88802a78bd00 RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000 RBP: 1ffff11004165212 R08: ffffffff8f822277 R09: 1ffffffff1f0444e R10: dffffc0000000000 R11: fffffbfff1f0444f R12: 0000000000000000 R13: 1ffff110051e05f7 R14: ffff888020b29000 R15: ffff888028f02fa8 FS: 00007f3ce68426c0(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f999a972100 CR3: 000000007b2b2000 CR4: 0000000000350ef0 Call Trace: blk_register_queue+0x36a/0x3f0 block/blk-sysfs.c:935 __add_disk+0x677/0xd50 block/genhd.c:528 add_disk_fwnode+0xfc/0x480 block/genhd.c:597 add_disk include/linux/blkdev.h:785 [inline] loop_add+0x7f0/0xad0 drivers/block/loop.c:2093 loop_control_get_free drivers/block/loop.c:2209 [inline] loop_control_ioctl+0x2f2/0x5a0 drivers/block/loop.c:2224 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3ce598f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3ce6842038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3ce5be6090 RCX: 00007f3ce598f749 RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000006 RBP: 00007f3ce5a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3ce5be6128 R14: 00007f3ce5be6090 R15: 00007ffd72edd058 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status 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 syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. 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