===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected syzkaller #0 Not tainted ----------------------------------------------------- kworker/u8:3/18987 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff8f1127b8 (disc_data_lock){.+.+}-{3:3}, at: sp_get drivers/net/hamradio/6pack.c:370 [inline] ffffffff8f1127b8 (disc_data_lock){.+.+}-{3:3}, at: sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:391 and this task is already holding: ffffffff9a263db8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] ffffffff9a263db8 (&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:5868 __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:1798 serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846 serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x295/0xab0 kernel/irq/handle.c:203 handle_irq_event_percpu kernel/irq/handle.c:240 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:257 handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855 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:-1 [inline] __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:325 common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:318 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688 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:767 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:756 start_kernel+0x3a9/0x410 init/main.c:1109 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 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:5868 __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+0x23c/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:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 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/u8:3/18987: #0: ffff88801a889148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline] #0: ffff88801a889148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346 #1: ffffc9000b767ba0 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline] #1: ffffc9000b767ba0 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346 #2: ffff8880249f8ca0 (&buf->lock){+.+.}-{4:4}, at: flush_to_ldisc+0x38/0x6e0 drivers/tty/tty_buffer.c:467 #3: ffff888033b570a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x90 drivers/tty/tty_ldisc.c:263 #4: ffffffff9a263db8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] #4: ffffffff9a263db8 (&port_lock_key){-.-.}-{3:3}, at: uart_port_ref_lock+0xc4/0x3b0 drivers/tty/serial/serial_core.c:83 #5: ffff888033b570a0 (&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:5868 __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:1798 serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846 serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x295/0xab0 kernel/irq/handle.c:203 handle_irq_event_percpu kernel/irq/handle.c:240 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:257 handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855 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:-1 [inline] __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:325 common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:318 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688 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:767 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:756 start_kernel+0x3a9/0x410 init/main.c:1109 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 IN-SOFTIRQ-W at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __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:1798 serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846 serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:82 __handle_irq_event_percpu+0x295/0xab0 kernel/irq/handle.c:203 handle_irq_event_percpu kernel/irq/handle.c:240 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:257 handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855 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:-1 [inline] __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:325 common_interrupt+0x5e/0xe0 arch/x86/kernel/irq.c:318 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688 check_preemption_disabled+0x40/0x120 lib/smp_processor_id.c:53 rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:751 rcu_read_lock include/linux/rcupdate.h:842 [inline] class_rcu_constructor include/linux/rcupdate.h:1169 [inline] unwind_next_frame+0xd4/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2474 [inline] slab_free mm/slub.c:6181 [inline] kfree+0x199/0x6d0 mm/slub.c:6389 slab_free_after_rcu_debug+0x60/0x2a0 mm/slub.c:6227 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861 handle_softirqs+0x286/0x870 kernel/softirq.c:579 __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:1052 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 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:767 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:756 start_kernel+0x3a9/0x410 init/main.c:1109 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 INITIAL USE at: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __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] class_uart_port_lock_irqsave_constructor include/linux/serial_core.h:797 [inline] serial8250_do_set_termios+0x4d1/0x1c30 drivers/tty/serial/8250/8250_port.c:2760 uart_set_options+0x3c2/0x5b0 drivers/tty/serial/serial_core.c:2262 serial8250_console_setup+0x2f4/0x3c0 drivers/tty/serial/8250/8250_port.c:3405 univ8250_console_setup+0x43a/0x540 drivers/tty/serial/8250/8250_core.c:426 console_call_setup kernel/printk/printk.c:3773 [inline] try_enable_preferred_console+0x4e4/0x650 kernel/printk/printk.c:3817 register_console+0x551/0xf90 kernel/printk/printk.c:4011 univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:511 console_init+0x10e/0x430 kernel/printk/printk.c:4298 start_kernel+0x254/0x410 init/main.c:1047 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 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:5868 __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+0x23c/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:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 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:5868 __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+0x23c/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:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 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:5868 __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+0x1a4/0x200 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+0x44c/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/0x130 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [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/0xfa0 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:5868 __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+0x23c/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:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 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:5868 __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+0xfb/0x170 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1719 __start_tx+0x33b/0x480 drivers/tty/serial/8250/8250_port.c:1426 __uart_start+0x23f/0x460 drivers/tty/serial/serial_core.c:161 uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:633 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+0x119/0x160 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:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 stack backtrace: CPU: 0 UID: 0 PID: 18987 Comm: kworker/u8:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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:2616 [inline] check_irq_usage kernel/locking/lockdep.c:2857 [inline] check_prev_add kernel/locking/lockdep.c:3169 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0x1f05/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __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+0xfb/0x170 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1719 __start_tx+0x33b/0x480 drivers/tty/serial/8250/8250_port.c:1426 __uart_start+0x23f/0x460 drivers/tty/serial/serial_core.c:161 uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:633 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+0x119/0x160 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:3263 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245