============================================
WARNING: possible recursive locking detected
4.19.211-syzkaller #0 Not tainted
--------------------------------------------
sshd/8136 is trying to acquire lock:
000000008c9ae20f (&port_lock_key){-.-.}, at: uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591

but task is already holding lock:
000000008c9ae20f (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876

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

       CPU0
       ----
  lock(&port_lock_key);
  lock(&port_lock_key);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

ntfs: volume version 3.1.
3 locks held by sshd/8136:
 #0: 000000003b152831 (&(&i->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:329 [inline]
 #0: 000000003b152831 (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x3a/0x240 drivers/tty/serial/8250/8250_core.c:115
 #1: 000000008c9ae20f (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876
 #2: 000000003a7addc7 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x1d/0x80 drivers/tty/tty_ldisc.c:293

stack backtrace:
CPU: 1 PID: 8136 Comm: sshd Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 print_deadlock_bug kernel/locking/lockdep.c:1764 [inline]
 check_deadlock kernel/locking/lockdep.c:1808 [inline]
 validate_chain kernel/locking/lockdep.c:2404 [inline]
 __lock_acquire.cold+0x121/0x57e kernel/locking/lockdep.c:3416
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:152
 uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591
 n_hdlc_send_frames+0x278/0x470 drivers/tty/n_hdlc.c:403
 n_hdlc_tty_wakeup+0xa0/0xc0 drivers/tty/n_hdlc.c:479
 tty_wakeup+0xd4/0x110 drivers/tty/tty_io.c:534
 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:50
 serial8250_tx_chars+0x490/0xaf0 drivers/tty/serial/8250/8250_port.c:1813
 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1900
 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1873 [inline]
 serial8250_default_handle_irq+0xae/0x220 drivers/tty/serial/8250/8250_port.c:1916
 serial8250_interrupt+0x101/0x240 drivers/tty/serial/8250/8250_core.c:125
 __handle_irq_event_percpu+0x27e/0x8e0 kernel/irq/handle.c:149
 handle_irq_event_percpu kernel/irq/handle.c:189 [inline]
 handle_irq_event+0x102/0x290 kernel/irq/handle.c:206
 handle_edge_irq+0x260/0xcf0 kernel/irq/chip.c:800
 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline]
 handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87
 do_IRQ+0x93/0x1c0 arch/x86/kernel/irq.c:246
 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:670
 </IRQ>
RIP: 0033:0x55b215acdb40
Code: 07 c1 c7 0c 41 01 ca 41 01 fb 44 31 d2 44 31 de c1 c2 10 c1 c6 08 45 8d 3c 31 44 8d 4c 15 00 44 31 c9 44 31 ff 44 89 7c 24 08 <c1> c1 0c 41 89 ff 8b 7c 24 14 41 01 ca 41 c1 c7 07 44 31 d2 44 89
RSP: 002b:00007ffcf1529b40 EFLAGS: 00000286 ORIG_RAX: ffffffffffffffd5
RAX: 00000000170d1f49 RBX: 0000000036517a8f RCX: 0000000099a067b5
RDX: 000000000658586d RSI: 00000000f205de56 RDI: 0000000099c5ca44
RBP: 0000000081f3c6d4 R08: 00000000f8e9b5f1 R09: 00000000884c1f41
R10: 0000000031db1b5b R11: 000000000adf8133 R12: 00000000f930a2ca
R13: 00000000b907e069 R14: 000000001101856d R15: 00000000755f44ea