IPVS: ftp: loaded support on port[0] = 21
============================================
WARNING: possible recursive locking detected
4.14.290-syzkaller #0 Not tainted
--------------------------------------------
swapper/1/0 is trying to acquire lock:
(&port_lock_key){-.-.}, at: [<ffffffff835a6fe9>] uart_write+0x109/0x560 drivers/tty/serial/serial_core.c:611
but task is already holding lock:
(&port_lock_key){-.-.}, at: [<ffffffff835c2480>] serial8250_handle_irq.part.0+0x20/0x330 drivers/tty/serial/8250/8250_port.c:1891
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
3 locks held by swapper/1/0:
#0: (&(&i->lock)->rlock){-.-.}, at: [<ffffffff835af80a>] spin_lock include/linux/spinlock.h:317 [inline]
#0: (&(&i->lock)->rlock){-.-.}, at: [<ffffffff835af80a>] serial8250_interrupt+0x3a/0x210 drivers/tty/serial/8250/8250_core.c:119
#1: (&port_lock_key){-.-.}, at: [<ffffffff835c2480>] serial8250_handle_irq.part.0+0x20/0x330 drivers/tty/serial/8250/8250_port.c:1891
#2: (&tty->ldisc_sem){++++}, at: [<ffffffff83554d4b>] tty_ldisc_ref+0x1b/0x80 drivers/tty/tty_ldisc.c:305
stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.290-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
print_deadlock_bug kernel/locking/lockdep.c:1800 [inline]
check_deadlock kernel/locking/lockdep.c:1847 [inline]
validate_chain kernel/locking/lockdep.c:2448 [inline]
__lock_acquire.cold+0x180/0x97c kernel/locking/lockdep.c:3491
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160
uart_write+0x109/0x560 drivers/tty/serial/serial_core.c:611
n_hdlc_send_frames+0x241/0x410 drivers/tty/n_hdlc.c:404
n_hdlc_tty_wakeup+0x95/0xb0 drivers/tty/n_hdlc.c:480
tty_wakeup+0xc3/0xf0 drivers/tty/tty_io.c:533
tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:49
serial8250_tx_chars+0x3fe/0xc70 drivers/tty/serial/8250/8250_port.c:1828
serial8250_handle_irq.part.0+0x28d/0x330 drivers/tty/serial/8250/8250_port.c:1915
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1888 [inline]
serial8250_default_handle_irq+0x8a/0x1f0 drivers/tty/serial/8250/8250_port.c:1931
serial8250_interrupt+0xf3/0x210 drivers/tty/serial/8250/8250_core.c:129
__handle_irq_event_percpu+0xee/0x7f0 kernel/irq/handle.c:147
handle_irq_event_percpu kernel/irq/handle.c:187 [inline]
handle_irq_event+0xed/0x240 kernel/irq/handle.c:204
handle_edge_irq+0x224/0xc40 kernel/irq/chip.c:770
generic_handle_irq_desc include/linux/irqdesc.h:159 [inline]
handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87
do_IRQ+0x93/0x1d0 arch/x86/kernel/irq.c:230
common_interrupt+0x93/0x93 arch/x86/entry/entry_64.S:576
</IRQ>
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x50/0x80 kernel/locking/spinlock.c:200
RSP: 0018:ffff8880b5487d58 EFLAGS: 00000282 ORIG_RAX: ffffffffffffffc8
RAX: 1ffffffff11e1343 RBX: ffff8880b5478380 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff8880b5478c04
RBP: ffff8880ba534400 R08: ffffffff8b9a1e98 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880ba534400
R13: ffff8880b54b8500 R14: ffff888097deac80 R15: ffff8880ba534d50
finish_lock_switch kernel/sched/sched.h:1346 [inline]
finish_task_switch+0x178/0x610 kernel/sched/core.c:2678
context_switch kernel/sched/core.c:2814 [inline]
__schedule+0x893/0x1de0 kernel/sched/core.c:3387
schedule_idle+0x53/0x80 kernel/sched/core.c:3458
do_idle+0x127/0x3c0 kernel/sched/idle.c:269
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:351
start_secondary+0x4db/0x670 arch/x86/kernel/smpboot.c:272
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240