[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.52' (ECDSA) to the list of known hosts. syzkaller login: [ 38.730495] IPVS: ftp: loaded support on port[0] = 21 executing program [ 39.128195] [ 39.129806] ============================================ [ 39.135226] WARNING: possible recursive locking detected [ 39.140652] 4.14.300-syzkaller #0 Not tainted [ 39.145119] -------------------------------------------- [ 39.150537] swapper/1/0 is trying to acquire lock: [ 39.155431] (&port_lock_key){-.-.}, at: [] uart_write+0x109/0x560 [ 39.163292] [ 39.163292] but task is already holding lock: [ 39.169230] (&port_lock_key){-.-.}, at: [] serial8250_handle_irq.part.0+0x20/0x390 [ 39.178561] [ 39.178561] other info that might help us debug this: [ 39.185192] Possible unsafe locking scenario: [ 39.185192] [ 39.191217] CPU0 [ 39.193790] ---- [ 39.196339] lock(&port_lock_key); [ 39.199934] lock(&port_lock_key); [ 39.203528] [ 39.203528] *** DEADLOCK *** [ 39.203528] [ 39.209561] May be due to missing lock nesting notation [ 39.209561] [ 39.216461] 3 locks held by swapper/1/0: [ 39.220505] #0: (&(&i->lock)->rlock){-.-.}, at: [] serial8250_interrupt+0x3a/0x210 [ 39.229931] #1: (&port_lock_key){-.-.}, at: [] serial8250_handle_irq.part.0+0x20/0x390 [ 39.239702] #2: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref+0x1b/0x80 [ 39.248166] [ 39.248166] stack backtrace: [ 39.252636] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.300-syzkaller #0 [ 39.259703] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 [ 39.269028] Call Trace: [ 39.271583] [ 39.273706] dump_stack+0x1b2/0x281 [ 39.277306] __lock_acquire.cold+0x180/0x97c [ 39.281686] ? __lock_acquire+0x2190/0x3f20 [ 39.285976] ? trace_hardirqs_on+0x10/0x10 [ 39.290179] ? trace_hardirqs_on+0x10/0x10 [ 39.294384] ? trace_hardirqs_on+0x10/0x10 [ 39.298587] lock_acquire+0x170/0x3f0 [ 39.302361] ? uart_write+0x109/0x560 [ 39.306132] _raw_spin_lock_irqsave+0x8c/0xc0 [ 39.310598] ? uart_write+0x109/0x560 [ 39.314371] uart_write+0x109/0x560 [ 39.317968] ? n_hdlc_buf_get+0x194/0x220 [ 39.322087] ? __uart_start.isra.0+0x1b0/0x1b0 [ 39.326639] n_hdlc_send_frames+0x241/0x410 [ 39.330930] n_hdlc_tty_wakeup+0x95/0xb0 [ 39.334960] ? n_hdlc_tty_open+0x4d0/0x4d0 [ 39.339168] tty_wakeup+0xc3/0xf0 [ 39.342594] tty_port_default_wakeup+0x26/0x40 [ 39.347151] serial8250_tx_chars+0x3fe/0xc70 [ 39.351532] serial8250_handle_irq.part.0+0x2c7/0x390 [ 39.356691] serial8250_default_handle_irq+0x8a/0x1f0 [ 39.361850] serial8250_interrupt+0xf3/0x210 [ 39.366229] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 39.371649] ? serial8250_backup_timeout+0x440/0x440 [ 39.376724] __handle_irq_event_percpu+0xee/0x7f0 [ 39.381535] handle_irq_event+0xed/0x240 [ 39.385568] ? handle_irq_event_percpu+0x110/0x110 [ 39.390467] handle_edge_irq+0x224/0xc40 [ 39.394498] handle_irq+0x35/0x50 [ 39.397923] do_IRQ+0x93/0x1d0 [ 39.401088] common_interrupt+0x93/0x93 [ 39.405028] [ 39.407240] ? native_safe_halt+0xe/0x10 [ 39.411269] ? default_idle+0x47/0x370 [ 39.415136] ? do_idle+0x250/0x3c0 [ 39.418644] ? cpu_startup_entry+0x14/0x20 [ 39.422848] ? start_secondary+0x4db/0x670 [ 39.427053] ? set_cpu_sibling_map+0x1680/0x1680 [ 39.431778] ? secondary_startup_64+0xa5/0xb0