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charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 8f0b4cce4481 Linux 6.19-rc1 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=102035c2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=1f2b6fe1fdf1a00b dashboard link: https://syzkaller.appspot.com/bug?extid=4ef89409a235d804c6c2 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=1101b91a580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=142035c2580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/ea3b19e4d883/disk-8f0b4cce.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/bd7c115820ba/vmlinux-8f0b4cce.xz kernel image: https://storage.googleapis.com/syzbot-assets/e5813cc1963f/bzImage-8f0b4cce.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+4ef89409a235d804c6c2@syzkaller.appspotmail.com ------------[ cut here ]------------ rtmutex deadlock detected WARNING: kernel/locking/rtmutex.c:1674 at rt_mutex_handle_deadlock+0x21/0xb0 kernel/locking/rtmutex.c:1674, CPU#1: syz.3.31/6310 Modules linked in: CPU: 1 UID: 0 PID: 6310 Comm: syz.3.31 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:rt_mutex_handle_deadlock+0x21/0xb0 kernel/locking/rtmutex.c:1674 Code: 90 90 90 90 90 90 90 90 90 41 57 41 56 41 55 41 54 53 83 ff dd 0f 85 86 00 00 00 48 89 f7 e8 66 3b 01 00 48 8d 3d 6f 83 08 04 <67> 48 0f b9 3a 4c 8d 3d 00 00 00 00 65 48 8b 1c 25 08 d0 b1 91 4c RSP: 0018:ffffc90004d97930 EFLAGS: 00010286 RAX: 0000000080000000 RBX: ffffc90004d979c0 RCX: 0000000000000000 RDX: 0000000000000006 RSI: ffffffff8ce0bc0c RDI: ffffffff8ede53f0 RBP: ffffc90004d97ad8 R08: ffffffff8edb3177 R09: 1ffffffff1db662e R10: dffffc0000000000 R11: fffffbfff1db662f R12: 1ffff920009b2f34 R13: ffffffff8ad5cb69 R14: ffff888037dc6098 R15: dffffc0000000000 FS: 000055557d26b500(0000) GS:ffff888126e03000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcf0a37f52 CR3: 00000000329d0000 CR4: 00000000003526f0 Call Trace: __rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline] __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline] rt_mutex_slowlock+0x666/0x6b0 kernel/locking/rtmutex.c:1800 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline] __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline] mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:552 device_lock include/linux/device.h:895 [inline] nfc_dev_down+0x3b/0x290 net/nfc/core.c:143 nfc_rfkill_set_block+0x2d/0x100 net/nfc/core.c:179 rfkill_set_block+0x1e5/0x450 net/rfkill/core.c:346 rfkill_fop_write+0x44e/0x580 net/rfkill/core.c:1301 vfs_write+0x287/0xb40 fs/read_write.c:684 ksys_write+0x14b/0x260 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f28f61cf749 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:00007fffd96926f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f28f6425fa0 RCX: 00007f28f61cf749 RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000004 RBP: 00007f28f6253f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f28f6425fa0 R14: 00007f28f6425fa0 R15: 0000000000000003 ---------------- Code disassembly (best guess): 0: 90 nop 1: 90 nop 2: 90 nop 3: 90 nop 4: 90 nop 5: 90 nop 6: 90 nop 7: 90 nop 8: 90 nop 9: 41 57 push %r15 b: 41 56 push %r14 d: 41 55 push %r13 f: 41 54 push %r12 11: 53 push %rbx 12: 83 ff dd cmp $0xffffffdd,%edi 15: 0f 85 86 00 00 00 jne 0xa1 1b: 48 89 f7 mov %rsi,%rdi 1e: e8 66 3b 01 00 call 0x13b89 23: 48 8d 3d 6f 83 08 04 lea 0x408836f(%rip),%rdi # 0x4088399 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: 4c 8d 3d 00 00 00 00 lea 0x0(%rip),%r15 # 0x36 36: 65 48 8b 1c 25 08 d0 mov %gs:0xffffffff91b1d008,%rbx 3d: b1 91 3f: 4c rex.WR --- 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.