Re: [syzbot] [net?] [nfc?] WARNING in nfc_rfkill_set_block

[syzbot <syzbot+535bbe83dfc3ae8d4be3@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    c8bc81a52d5a Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1508ce34580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bd9738e00c1bbfb4
dashboard link: https://syzkaller.appspot.com/bug?extid=535bbe83dfc3ae8d4be3
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=11019a62580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1308ce34580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e617000fa273/disk-c8bc81a5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ae3a3f4924d/vmlinux-c8bc81a5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d68d297e1f87/bzImage-c8bc81a5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+535bbe83dfc3ae8d4be3@syzkaller.appspotmail.com

Bluetooth: hci0: Opcode 0x0c1a failed: -110
Bluetooth: hci0: Error when powering off device on rfkill (-110)
------------[ cut here ]------------
rtmutex deadlock detected
WARNING: CPU: 0 PID: 6084 at kernel/locking/rtmutex.c:1674 rt_mutex_handle_deadlock+0x28/0xb0 kernel/locking/rtmutex.c:1674
Modules linked in:
CPU: 0 UID: 0 PID: 6084 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rt_mutex_handle_deadlock+0x28/0xb0 kernel/locking/rtmutex.c:1674
Code: 90 90 41 57 41 56 41 55 41 54 53 83 ff dd 0f 85 8c 00 00 00 48 89 f7 e8 c6 2c 01 00 90 48 c7 c7 80 08 0b 8b e8 79 78 8a f6 90 <0f> 0b 90 90 4c 8d 3d 00 00 00 00 65 48 8b 1c 25 08 e0 f5 91 4c 8d
RSP: 0018:ffffc90003a8f950 EFLAGS: 00010246
RAX: 4a17b3cdcfcd8c00 RBX: ffffc90003a8f9e0 RCX: ffff888034b23b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003a8fb00 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1017104863 R12: 1ffff92000751f38
R13: ffffffff8af8b119 R14: ffff88802b77f098 R15: dffffc0000000000
FS:  00007f918c68e6c0(0000) GS:ffff8881268c2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558db6b05168 CR3: 0000000040f42000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x692/0x6e0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
 mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
 device_lock include/linux/device.h:911 [inline]
 nfc_dev_down net/nfc/core.c:143 [inline]
 nfc_rfkill_set_block+0x50/0x2e0 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+0x284/0xb40 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/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f918d01ebe9
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:00007f918c68e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f918d255fa0 RCX: 00007f918d01ebe9
RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007f918d0a1e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f918d256038 R14: 00007f918d255fa0 R15: 00007ffcb32fa318
 </TASK>


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