===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.16.0-rc6-next-20250718-syzkaller #0 Not tainted ----------------------------------------------------- kworker/u8:11/9706 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff8f10e598 (disc_data_lock){.+.+}-{3:3}, at: sp_get drivers/net/hamradio/6pack.c:370 [inline] ffffffff8f10e598 (disc_data_lock){.+.+}-{3:3}, at: sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:391 and this task is already holding: ffffffff9a2700d8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] ffffffff9a2700d8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_ref_lock+0xc4/0x3b0 drivers/tty/serial/serial_core.c:83 which would create a new lock dependency: (&port_lock_key){-.-.}-{3:3} -> (disc_data_lock){.+.+}-{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+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] serial8250_handle_irq+0x6b/0xbb0 drivers/tty/serial/8250/8250_port.c:1807 serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1856 serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x28c/0x980 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x267/0x9e0 kernel/irq/chip.c:797 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+0x143/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0xb6/0xe0 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+0x13/0x20 arch/x86/kernel/paravirt.c:81 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1e8/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428 rest_init+0x2de/0x300 init/main.c:744 start_kernel+0x47d/0x500 init/main.c:1097 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x147 to a HARDIRQ-irq-unsafe lock: (disc_data_lock){.+.+}-{3:3} ... which became HARDIRQ-irq-unsafe at: ... lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_receive_buf+0x5c/0x1450 drivers/net/hamradio/6pack.c:433 tiocsti+0x239/0x2c0 drivers/tty/tty_io.c:2290 tty_ioctl+0x626/0xde0 drivers/tty/tty_io.c:2706 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(disc_data_lock); local_irq_disable(); lock(&port_lock_key); lock(disc_data_lock); lock(&port_lock_key); *** DEADLOCK *** 6 locks held by kworker/u8:11/9706: #0: ffff88801a889148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] #0: ffff88801a889148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319 #1: ffffc90002fa7bc0 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] #1: ffffc90002fa7bc0 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319 #2: ffff888142378ca0 (&buf->lock){+.+.}-{4:4}, at: flush_to_ldisc+0x38/0x6e0 drivers/tty/tty_buffer.c:467 #3: ffff88807df880a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x90 drivers/tty/tty_ldisc.c:263 #4: ffffffff9a2700d8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] #4: ffffffff9a2700d8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_ref_lock+0xc4/0x3b0 drivers/tty/serial/serial_core.c:83 #5: ffff88807df880a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x90 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+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] serial8250_handle_irq+0x6b/0xbb0 drivers/tty/serial/8250/8250_port.c:1807 serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1856 serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x28c/0x980 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x267/0x9e0 kernel/irq/chip.c:797 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+0x143/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0xb6/0xe0 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+0x13/0x20 arch/x86/kernel/paravirt.c:81 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:757 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1e8/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428 rest_init+0x2de/0x300 init/main.c:744 start_kernel+0x47d/0x500 init/main.c:1097 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x147 IN-SOFTIRQ-W at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] serial8250_handle_irq+0x6b/0xbb0 drivers/tty/serial/8250/8250_port.c:1807 serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1856 serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x28c/0x980 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x267/0x9e0 kernel/irq/chip.c:797 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+0x143/0x250 arch/x86/kernel/irq.c:292 common_interrupt+0x5e/0xe0 arch/x86/kernel/irq.c:285 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 native_irq_enable arch/x86/include/asm/irqflags.h:-1 [inline] arch_local_irq_enable arch/x86/include/asm/irqflags.h:119 [inline] handle_softirqs+0x1b0/0x870 kernel/softirq.c:563 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline] uart_port_unlock_deref+0x111/0x2f0 drivers/tty/serial/serial_core.c:91 uart_write+0xe8/0x130 drivers/tty/serial/serial_core.c:637 process_output_block drivers/tty/n_tty.c:561 [inline] n_tty_write+0xd29/0x1200 drivers/tty/n_tty.c:2377 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write+0x551/0xa20 drivers/tty/tty_io.c:1081 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x54b/0xa90 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f INITIAL USE at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] serial8250_do_set_termios+0x4b1/0x1c10 drivers/tty/serial/8250/8250_port.c:2810 uart_set_options+0x3c2/0x5b0 drivers/tty/serial/serial_core.c:2282 serial8250_console_setup+0x2f4/0x3c0 drivers/tty/serial/8250/8250_port.c:3459 univ8250_console_setup+0x43a/0x540 drivers/tty/serial/8250/8250_core.c:431 console_call_setup kernel/printk/printk.c:3800 [inline] try_enable_preferred_console+0x4e4/0x650 kernel/printk/printk.c:3844 register_console+0x551/0xf90 kernel/printk/printk.c:4038 univ8250_console_init+0x52/0x90 drivers/tty/serial/8250/8250_core.c:516 console_init+0x1a1/0x670 kernel/printk/printk.c:4325 start_kernel+0x2cc/0x500 init/main.c:1035 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x147 } ... key at: [] port_lock_key+0x0/0x20 the dependencies between the lock to be acquired and HARDIRQ-irq-unsafe lock: -> (disc_data_lock){.+.+}-{3:3} { HARDIRQ-ON-R at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_receive_buf+0x5c/0x1450 drivers/net/hamradio/6pack.c:433 tiocsti+0x239/0x2c0 drivers/tty/tty_io.c:2290 tty_ioctl+0x626/0xde0 drivers/tty/tty_io.c:2706 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f SOFTIRQ-ON-R at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_receive_buf+0x5c/0x1450 drivers/net/hamradio/6pack.c:433 tiocsti+0x239/0x2c0 drivers/tty/tty_io.c:2290 tty_ioctl+0x626/0xde0 drivers/tty/tty_io.c:2706 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f INITIAL USE at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline] _raw_write_lock_irq+0xa2/0xf0 kernel/locking/spinlock.c:326 sixpack_close+0x2c/0x280 drivers/net/hamradio/6pack.c:641 tty_ldisc_kill+0xa3/0x1a0 drivers/tty/tty_ldisc.c:613 tty_ldisc_release+0x174/0x200 drivers/tty/tty_ldisc.c:781 tty_release_struct+0x2a/0xd0 drivers/tty/tty_io.c:1681 tty_release+0xcb0/0x1640 drivers/tty/tty_io.c:1852 __fput+0x449/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:208 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f INITIAL READ USE at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_receive_buf+0x5c/0x1450 drivers/net/hamradio/6pack.c:433 tiocsti+0x239/0x2c0 drivers/tty/tty_io.c:2290 tty_ioctl+0x626/0xde0 drivers/tty/tty_io.c:2706 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f } ... key at: [] disc_data_lock+0x18/0x100 6pack.c:-1 ... acquired at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:391 tty_wakeup+0xbe/0x100 drivers/tty/tty_io.c:515 tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1728 __start_tx+0x33b/0x480 drivers/tty/serial/8250/8250_port.c:1433 __uart_start+0x23c/0x460 drivers/tty/serial/serial_core.c:161 uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:636 decode_prio_command drivers/net/hamradio/6pack.c:868 [inline] sixpack_decode drivers/net/hamradio/6pack.c:943 [inline] sixpack_receive_buf+0x447/0x1450 drivers/net/hamradio/6pack.c:447 tty_ldisc_receive_buf+0x116/0x160 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x24a/0x6e0 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 stack backtrace: CPU: 1 UID: 0 PID: 9706 Comm: kworker/u8:11 Not tainted 6.16.0-rc6-next-20250718-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: events_unbound flush_to_ldisc Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_bad_irq_dependency kernel/locking/lockdep.c:2619 [inline] check_irq_usage kernel/locking/lockdep.c:2860 [inline] check_prev_add kernel/locking/lockdep.c:3172 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0x1f05/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228 sp_get drivers/net/hamradio/6pack.c:370 [inline] sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:391 tty_wakeup+0xbe/0x100 drivers/tty/tty_io.c:515 tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1728 __start_tx+0x33b/0x480 drivers/tty/serial/8250/8250_port.c:1433 __uart_start+0x23c/0x460 drivers/tty/serial/serial_core.c:161 uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:636 decode_prio_command drivers/net/hamradio/6pack.c:868 [inline] sixpack_decode drivers/net/hamradio/6pack.c:943 [inline] sixpack_receive_buf+0x447/0x1450 drivers/net/hamradio/6pack.c:447 tty_ldisc_receive_buf+0x116/0x160 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x24a/0x6e0 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245