syzbot

============================================
WARNING: possible recursive locking detected
6.0.0-rc5-syzkaller-00094-ga335366bad13 #0 Not tainted
--------------------------------------------
syz-executor417/3619 is trying to acquire lock:
ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1712 [inline]
ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x69/0x3a0 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1712 [inline]
ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_shutdown+0x52/0x210 net/bluetooth/rfcomm/sock.c:902

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz-executor417/3619:
 #0: ffff88806c2498d0 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #0: ffff88806c2498d0 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x280 net/socket.c:649
 #1: ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1712 [inline]
 #1: ffff888076423130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_shutdown+0x52/0x210 net/bluetooth/rfcomm/sock.c:902
 #2: ffffffff8d9f4a48 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x2f/0x240 net/bluetooth/rfcomm/core.c:507
 #3: ffff888076422128 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x15d/0x890 net/bluetooth/rfcomm/core.c:487

stack backtrace:
CPU: 0 PID: 3619 Comm: syz-executor417 Not tainted 6.0.0-rc5-syzkaller-00094-ga335366bad13 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2988 [inline]
 check_deadlock kernel/locking/lockdep.c:3031 [inline]
 validate_chain kernel/locking/lockdep.c:3816 [inline]
 __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5053
 lock_acquire kernel/locking/lockdep.c:5666 [inline]
 lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
 lock_sock_nested+0x36/0xf0 net/core/sock.c:3393
 lock_sock include/net/sock.h:1712 [inline]
 rfcomm_sk_state_change+0x69/0x3a0 net/bluetooth/rfcomm/sock.c:73
 __rfcomm_dlc_close+0x1b1/0x890 net/bluetooth/rfcomm/core.c:489
 rfcomm_dlc_close+0x1e5/0x240 net/bluetooth/rfcomm/core.c:520
 __rfcomm_sock_close+0x13c/0x250 net/bluetooth/rfcomm/sock.c:220
 rfcomm_sock_shutdown+0xcc/0x210 net/bluetooth/rfcomm/sock.c:905
 rfcomm_sock_release+0x64/0x140 net/bluetooth/rfcomm/sock.c:925
 __sock_release+0xcd/0x280 net/socket.c:650
 sock_close+0x18/0x20 net/socket.c:1365
 __fput+0x277/0x9d0 fs/file_table.c:320
 task_work_run+0xdd/0x1a0 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xad5/0x29b0 kernel/exit.c:795
 do_group_exit+0xd2/0x2f0 kernel/exit.c:925
 get_signal+0x238c/0x2610 kernel/signal.c:2857
 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869
 exit_to_user_mode_loop kernel/entry/common.c:166 [inline]
 exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6679f86c09
Code: Unable to access opcode bytes at RIP 0x7f6679f86bdf.
RSP: 002b:00007ffc21cd91f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007f6679f86c09
RDX: 000000000000000a RSI: 0000000020000000 RDI: 0000000000000003
RBP: 0000000000000003 R08: 000000ff21cd9228 R09: 000000ff21cd9228
R10: 000000ff21cd9228 R11: 0000000000000246 R12: 00005555566c12b8
R13: 0000000000000000 R14: 00007ffc21cd9260 R15: 0000000000000003
 </TASK>