===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.15.0-rc1-syzkaller #0 Not tainted ----------------------------------------------------- kworker/u8:5/1078 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff8f575f78 (disc_data_lock#3){.+.+}-{3:3}, at: sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 and this task is already holding: ffffffff9ae25ff8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] ffffffff9ae25ff8 (&port_lock_key){-.-.}-{3:3}, at: uart_write+0x13b/0xb30 drivers/tty/serial/serial_core.c:626 which would create a new lock dependency: (&port_lock_key){-.-.}-{3:3} -> (disc_data_lock#3){.+.+}-{3:3} but this new dependency connects a HARDIRQ-irq-safe lock: (&port_lock_key){-.-.}-{3:3} ... which became HARDIRQ-irq-safe at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921 serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970 serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline] handle_irq arch/x86/kernel/irq.c:254 [inline] call_irq_handler arch/x86/kernel/irq.c:266 [inline] __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:80 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:748 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x148 to a HARDIRQ-irq-unsafe lock: (disc_data_lock#3){.+.+}-{3:3} ... which became HARDIRQ-irq-unsafe at: ... lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline] sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(disc_data_lock#3); local_irq_disable(); lock(&port_lock_key); lock(disc_data_lock#3); lock(&port_lock_key); *** DEADLOCK *** 6 locks held by kworker/u8:5/1078: #0: ffff88801b481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 #1: ffffc90003e0fd18 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 #2: ffff888025558ca0 (&buf->lock){+.+.}-{4:4}, at: flush_to_ldisc+0x34/0x780 drivers/tty/tty_buffer.c:467 #3: ffff88805bc310a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 #4: ffffffff9ae25ff8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] #4: ffffffff9ae25ff8 (&port_lock_key){-.-.}-{3:3}, at: uart_write+0x13b/0xb30 drivers/tty/serial/serial_core.c:626 #5: ffff88805bc310a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 the dependencies between HARDIRQ-irq-safe lock and the holding lock: -> (&port_lock_key){-.-.}-{3:3} { IN-HARDIRQ-W at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921 serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970 serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline] handle_irq arch/x86/kernel/irq.c:254 [inline] call_irq_handler arch/x86/kernel/irq.c:266 [inline] __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:80 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:748 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x148 IN-SOFTIRQ-W at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921 serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970 serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline] handle_irq arch/x86/kernel/irq.c:254 [inline] call_irq_handler arch/x86/kernel/irq.c:266 [inline] __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0x61/0xe0 arch/x86/kernel/irq.c:285 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 instrument_atomic_read include/linux/instrumented.h:68 [inline] _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] blk_mq_sched_restart block/blk-mq-sched.h:27 [inline] __blk_mq_free_request+0x22e/0x530 block/blk-mq.c:782 blk_mq_free_request+0x1e9/0x340 block/blk-mq.c:799 __blk_mq_end_request+0x1b8/0x5b0 block/blk-mq.c:1136 scsi_end_request+0x445/0x9c0 drivers/scsi/scsi_lib.c:671 scsi_io_completion+0x17d/0x14c0 drivers/scsi/scsi_lib.c:1079 scsi_complete+0x124/0x250 drivers/scsi/scsi_lib.c:1544 blk_complete_reqs+0xae/0xf0 block/blk-mq.c:1220 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 common_interrupt+0xbf/0xe0 arch/x86/kernel/irq.c:285 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:80 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:748 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x148 INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:715 [inline] serial8250_do_set_termios+0x310/0x1710 drivers/tty/serial/8250/8250_port.c:2778 serial8250_set_termios+0x6e/0x80 drivers/tty/serial/8250/8250_port.c:2903 uart_set_options+0x31a/0x5f0 drivers/tty/serial/serial_core.c:2310 serial8250_console_setup+0x189/0x450 drivers/tty/serial/8250/8250_port.c:3519 univ8250_console_setup+0x1eb/0x2e0 drivers/tty/serial/8250/8250_core.c:428 console_call_setup kernel/printk/printk.c:3799 [inline] console_call_setup kernel/printk/printk.c:3790 [inline] try_enable_preferred_console+0x2fd/0x530 kernel/printk/printk.c:3843 register_console+0x3ab/0x11b0 kernel/printk/printk.c:4037 univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:513 console_init+0x14f/0x680 kernel/printk/printk.c:4323 start_kernel+0x29f/0x4d0 init/main.c:1034 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:513 x86_64_start_kernel+0xb0/0xc0 arch/x86/kernel/head64.c:494 common_startup_64+0x13e/0x148 } ... key at: [] port_lock_key+0x0/0x40 the dependencies between the lock to be acquired and HARDIRQ-irq-unsafe lock: -> (disc_data_lock#3){.+.+}-{3:3} { HARDIRQ-ON-R at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline] sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 SOFTIRQ-ON-R at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline] sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline] _raw_write_lock_irq+0x36/0x50 kernel/locking/spinlock.c:326 sixpack_close+0x1e/0x2f0 drivers/net/hamradio/6pack.c:641 tty_ldisc_close+0x111/0x1a0 drivers/tty/tty_ldisc.c:455 tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:613 tty_ldisc_release+0x109/0x2e0 drivers/tty/tty_ldisc.c:781 tty_release_struct+0x23/0xe0 drivers/tty/tty_io.c:1690 tty_release+0xe2d/0x1430 drivers/tty/tty_io.c:1861 __fput+0x3ff/0xb70 fs/file_table.c:465 task_work_run+0x14d/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f INITIAL READ USE at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline] sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 } ... key at: [] disc_data_lock+0x18/0xfe0 6pack.c:-1 ... acquired at: lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_write_wakeup+0x20/0x390 drivers/net/hamradio/6pack.c:391 tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:517 tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1842 __start_tx+0x3e9/0x4a0 drivers/tty/serial/8250/8250_port.c:1547 serial8250_start_tx+0x368/0x530 drivers/tty/serial/8250/8250_port.c:1657 __uart_start+0x292/0x4c0 drivers/tty/serial/serial_core.c:160 uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:635 decode_prio_command drivers/net/hamradio/6pack.c:868 [inline] sixpack_decode drivers/net/hamradio/6pack.c:943 [inline] sixpack_receive_buf drivers/net/hamradio/6pack.c:447 [inline] sixpack_receive_buf+0x3d0/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 stack backtrace: CPU: 1 UID: 0 PID: 1078 Comm: kworker/u8:5 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_bad_irq_dependency kernel/locking/lockdep.c:2652 [inline] check_irq_usage+0x7dc/0x920 kernel/locking/lockdep.c:2893 check_prev_add kernel/locking/lockdep.c:3170 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1189/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370 sixpack_write_wakeup+0x20/0x390 drivers/net/hamradio/6pack.c:391 tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:517 tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1842 __start_tx+0x3e9/0x4a0 drivers/tty/serial/8250/8250_port.c:1547 serial8250_start_tx+0x368/0x530 drivers/tty/serial/8250/8250_port.c:1657 __uart_start+0x292/0x4c0 drivers/tty/serial/serial_core.c:160 uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:635 decode_prio_command drivers/net/hamradio/6pack.c:868 [inline] sixpack_decode drivers/net/hamradio/6pack.c:943 [inline] sixpack_receive_buf drivers/net/hamradio/6pack.c:447 [inline] sixpack_receive_buf+0x3d0/0x1c90 drivers/net/hamradio/6pack.c:424 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245