===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 6.6.95-syzkaller #0 Not tainted ----------------------------------------------------- kworker/u4:7/1132 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff8d7d9338 (disc_data_lock#2){.+.+}-{2:2}, at: sp_get drivers/net/hamradio/6pack.c:376 [inline] ffffffff8d7d9338 (disc_data_lock#2){.+.+}-{2:2}, at: sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:397 and this task is already holding: ffffffff971d60b8 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0xfb/0x5d0 drivers/tty/serial/serial_core.c:613 which would create a new lock dependency: (&port_lock_key){-.-.}-{2:2} -> (disc_data_lock#2){.+.+}-{2:2} but this new dependency connects a HARDIRQ-irq-safe lock: (&port_lock_key){-.-.}-{2:2} ... which became HARDIRQ-irq-safe at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162 serial8250_handle_irq+0x7a/0x6e0 drivers/tty/serial/8250/8250_port.c:1915 serial8250_default_handle_irq+0xb8/0x1a0 drivers/tty/serial/8250/8250_port.c:1964 serial8250_interrupt+0x9f/0x1c0 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x276/0x930 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+0x247/0xb30 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:240 [inline] __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259 common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:147 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b to a HARDIRQ-irq-unsafe lock: (disc_data_lock#2){.+.+}-{2:2} ... which became HARDIRQ-irq-unsafe at: ... lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:376 [inline] sixpack_receive_buf+0x59/0x1360 drivers/net/hamradio/6pack.c:439 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(disc_data_lock#2); local_irq_disable(); lock(&port_lock_key); lock(disc_data_lock#2); lock(&port_lock_key); *** DEADLOCK *** 6 locks held by kworker/u4:7/1132: #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #1: ffffc900045ffd00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc900045ffd00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffff888020c30ce8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x38/0x830 drivers/tty/tty_buffer.c:467 #3: ffff88802a3b50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 #4: ffffffff971d60b8 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0xfb/0x5d0 drivers/tty/serial/serial_core.c:613 #5: ffff88802a3b50a0 (&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){-.-.}-{2:2} { IN-HARDIRQ-W at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162 serial8250_handle_irq+0x7a/0x6e0 drivers/tty/serial/8250/8250_port.c:1915 serial8250_default_handle_irq+0xb8/0x1a0 drivers/tty/serial/8250/8250_port.c:1964 serial8250_interrupt+0x9f/0x1c0 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x276/0x930 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+0x247/0xb30 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:240 [inline] __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259 common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:147 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b IN-SOFTIRQ-W at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162 serial8250_handle_irq+0x7a/0x6e0 drivers/tty/serial/8250/8250_port.c:1915 serial8250_default_handle_irq+0xb8/0x1a0 drivers/tty/serial/8250/8250_port.c:1964 serial8250_interrupt+0x9f/0x1c0 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x276/0x930 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+0x247/0xb30 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:240 [inline] __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259 common_interrupt+0x5d/0xd0 arch/x86/kernel/irq.c:249 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678 native_irq_enable arch/x86/include/asm/irqflags.h:-1 [inline] arch_local_irq_enable arch/x86/include/asm/irqflags.h:99 [inline] handle_softirqs+0x1b0/0x820 kernel/softirq.c:562 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:147 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:753 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b INITIAL USE at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162 serial8250_do_set_termios+0x548/0x17e0 drivers/tty/serial/8250/8250_port.c:2804 uart_set_options+0x3bc/0x5b0 drivers/tty/serial/serial_core.c:2339 serial8250_console_setup+0x2d2/0x3a0 drivers/tty/serial/8250/8250_port.c:3538 univ8250_console_setup+0x3c4/0x480 drivers/tty/serial/8250/8250_core.c:632 console_call_setup kernel/printk/printk.c:3311 [inline] try_enable_preferred_console+0x48a/0x600 kernel/printk/printk.c:3352 register_console+0x3be/0xe60 kernel/printk/printk.c:3526 univ8250_console_init+0x45/0x50 drivers/tty/serial/8250/8250_core.c:717 console_init+0x17b/0x5e0 kernel/printk/printk.c:3726 start_kernel+0x2c0/0x4e0 init/main.c:1010 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b } ... key at: [] port_lock_key+0x0/0x20 the dependencies between the lock to be acquired and HARDIRQ-irq-unsafe lock: -> (disc_data_lock#2){.+.+}-{2:2} { HARDIRQ-ON-R at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:376 [inline] sixpack_receive_buf+0x59/0x1360 drivers/net/hamradio/6pack.c:439 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 SOFTIRQ-ON-R at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:376 [inline] sixpack_receive_buf+0x59/0x1360 drivers/net/hamradio/6pack.c:439 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 INITIAL READ USE at: lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:376 [inline] sixpack_receive_buf+0x59/0x1360 drivers/net/hamradio/6pack.c:439 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 } ... key at: [] disc_data_lock+0x18/0x100 ... acquired at: __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:376 [inline] sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:397 tty_wakeup+0xb8/0x100 drivers/tty/tty_io.c:523 tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x6bd/0x8a0 drivers/tty/serial/8250/8250_port.c:1837 __start_tx+0x313/0x450 drivers/tty/serial/8250/8250_port.c:1546 __uart_start+0x23a/0x3e0 drivers/tty/serial/serial_core.c:160 uart_write+0x449/0x5d0 drivers/tty/serial/serial_core.c:633 decode_prio_command drivers/net/hamradio/6pack.c:888 [inline] sixpack_decode drivers/net/hamradio/6pack.c:963 [inline] sixpack_receive_buf+0x424/0x1360 drivers/net/hamradio/6pack.c:453 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 stack backtrace: CPU: 1 PID: 1132 Comm: kworker/u4:7 Not tainted 6.6.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: events_unbound flush_to_ldisc Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 print_bad_irq_dependency kernel/locking/lockdep.c:2626 [inline] check_irq_usage kernel/locking/lockdep.c:2865 [inline] check_prev_add kernel/locking/lockdep.c:3138 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x678f/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __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:376 [inline] sixpack_write_wakeup+0x30/0x480 drivers/net/hamradio/6pack.c:397 tty_wakeup+0xb8/0x100 drivers/tty/tty_io.c:523 tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x6bd/0x8a0 drivers/tty/serial/8250/8250_port.c:1837 __start_tx+0x313/0x450 drivers/tty/serial/8250/8250_port.c:1546 __uart_start+0x23a/0x3e0 drivers/tty/serial/serial_core.c:160 uart_write+0x449/0x5d0 drivers/tty/serial/serial_core.c:633 decode_prio_command drivers/net/hamradio/6pack.c:888 [inline] sixpack_decode drivers/net/hamradio/6pack.c:963 [inline] sixpack_receive_buf+0x424/0x1360 drivers/net/hamradio/6pack.c:453 tty_ldisc_receive_buf+0x117/0x160 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+0x2f2/0x830 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293