Debian GNU/Linux 9 syzkaller ttyS0
Warning: Permanently added '10.128.0.30' (ECDSA) to the list of known hosts.
syzkaller login: [ 33.028285] IPVS: ftp: loaded support on port[0] = 21
executing program
[ 33.418955]
[ 33.420587] ============================================
[ 33.426012] WARNING: possible recursive locking detected
[ 33.431438] 4.19.211-syzkaller #0 Not tainted
[ 33.435905] --------------------------------------------
[ 33.441327] swapper/1/0 is trying to acquire lock:
[ 33.446229] 000000005a4695cc (&port_lock_key){-.-.}, at: uart_write+0x1ce/0x6f0
[ 33.453659]
[ 33.453659] but task is already holding lock:
[ 33.459602] 000000005a4695cc (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0
[ 33.468514]
[ 33.468514] other info that might help us debug this:
[ 33.475160] Possible unsafe locking scenario:
[ 33.475160]
[ 33.481196] CPU0
[ 33.483752] ----
[ 33.486565] lock(&port_lock_key);
[ 33.490179] lock(&port_lock_key);
[ 33.493780]
[ 33.493780] *** DEADLOCK ***
[ 33.493780]
[ 33.499813] May be due to missing lock nesting notation
[ 33.499813]
[ 33.506716] 3 locks held by swapper/1/0:
[ 33.510776] #0: 0000000088525b6d (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x3a/0x240
[ 33.519770] #1: 000000005a4695cc (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0
[ 33.529108] #2: 00000000f5223691 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x1d/0x80
[ 33.537141]
[ 33.537141] stack backtrace:
[ 33.541618] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.211-syzkaller #0
[ 33.548688] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
[ 33.558013] Call Trace:
[ 33.560573]
[ 33.562702] dump_stack+0x1fc/0x2ef
[ 33.566307] __lock_acquire.cold+0x121/0x57e
[ 33.570698] ? mark_held_locks+0xf0/0xf0
[ 33.574751] ? mark_held_locks+0xf0/0xf0
[ 33.578791] lock_acquire+0x170/0x3c0
[ 33.582584] ? uart_write+0x1ce/0x6f0
[ 33.586372] _raw_spin_lock_irqsave+0x8c/0xc0
[ 33.590848] ? uart_write+0x1ce/0x6f0
[ 33.594626] uart_write+0x1ce/0x6f0
[ 33.598238] ? lock_downgrade+0x720/0x720
[ 33.602364] ? lock_acquire+0x170/0x3c0
[ 33.606495] ? __uart_start.isra.0+0x1c0/0x1c0
[ 33.611055] ? _raw_spin_unlock_irqrestore+0x66/0xe0
[ 33.616134] ? n_hdlc_buf_get+0x1ab/0x240
[ 33.620341] ? __uart_start.isra.0+0x1c0/0x1c0
[ 33.624900] n_hdlc_send_frames+0x278/0x470
[ 33.629199] n_hdlc_tty_wakeup+0xa0/0xc0
[ 33.633240] ? n_hdlc_tty_open+0x510/0x510
[ 33.637448] tty_wakeup+0xd4/0x110
[ 33.640969] tty_port_default_wakeup+0x26/0x40
[ 33.645528] serial8250_tx_chars+0x490/0xaf0
[ 33.649914] serial8250_handle_irq.part.0+0x31f/0x3d0
[ 33.655079] serial8250_default_handle_irq+0xae/0x220
[ 33.660245] serial8250_interrupt+0x101/0x240
[ 33.664718] ? serial8250_backup_timeout+0x4d0/0x4d0
[ 33.669798] __handle_irq_event_percpu+0x27e/0x8e0
[ 33.674706] handle_irq_event+0x102/0x290
[ 33.678830] ? handle_irq_event_percpu+0x160/0x160
[ 33.683734] ? handle_edge_irq+0x29/0xcf0
[ 33.687863] handle_edge_irq+0x260/0xcf0
[ 33.691910] handle_irq+0x35/0x50
[ 33.695346] do_IRQ+0x93/0x1c0
[ 33.698552] common_interrupt+0xf/0xf
[ 33.702325]
[ 33.704543] RIP: 0010:native_safe_halt+0xe/0x10
[ 33.709188] Code: 48 89 df e8 f4 20 7f f9 e9 2e ff ff ff 48 89 df e8 e7 20 7f f9 eb 82 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 14 43 4e 00 fb f4 90 e9 07 00 00 00 0f 00 2d 04 43 4e 00 f4 c3 90 90 41 56 41 55
[ 33.728067] RSP: 0018:ffff8880b5a9fd40 EFLAGS: 00000282 ORIG_RAX: ffffffffffffffd2
[ 33.735754] RAX: 1ffffffff13e3054 RBX: dffffc0000000000 RCX: 0000000000000000
[ 33.742999] RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff8880b5a86c44
[ 33.750257] RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
[ 33.757504] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89f18290
[ 33.764747] R13: 1ffff11016b53fb2 R14: 0000000000000000 R15: 0000000000000000
[ 33.772003] default_idle+0x49/0x310
[ 33.775696] do_idle+0x2ec/0x4b0
[ 33.779037] ? arch_cpu_idle_exit+0x70/0x70
[ 33.783334] ? _raw_spin_unlock_irqrestore+0x79/0xe0
[ 33.788429] ? lockdep_hardirqs_on+0x3a8/0x5c0
[ 33.792995] cpu_startup_entry+0xc5/0xe0
[ 33.797032] ? cpu_in_idle+0x20/0x20
[ 33.800722] ? _raw_spin_unlock_irqrestore+0x79/0xe0
[ 33.805805] ? lockdep_hardirqs_on+0x3a8/0x5c0
[ 33.810362] start_secondary+0x435/0x5c0
[ 33.814402] ? set_cpu_sibling_map+0x17b0/0x17b0
[ 33.819137] secondary_startup_64+0xa4/0xb0