======================================================== WARNING: possible irq lock inversion dependency detected 6.6.0-rc3-syzkaller #0 Not tainted -------------------------------------------------------- kworker/u4:0/11 just changed the state of lock: ffffffff8db5d338 (disc_data_lock){.+..}-{2:2}, at: ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 but this lock was taken by another, HARDIRQ-safe lock in the past: (&port_lock_key){-.-.}-{2:2} and interrupts could create inverse lock ordering between them. 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 *** 4 locks held by kworker/u4:0/11: #0: ffff888012c71938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x787/0x15c0 kernel/workqueue.c:2605 #1: ffffc90000107d80 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x7e9/0x15c0 kernel/workqueue.c:2606 #2: ffff88801c840ce8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x31/0x780 drivers/tty/tty_buffer.c:467 #3: ffff88802e46f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 the shortest dependencies between 2nd lock and 1st lock: -> (&port_lock_key){-.-.}-{2:2} { IN-HARDIRQ-W at: lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 serial8250_handle_irq+0x91/0xbd0 drivers/tty/serial/8250/8250_port.c:1921 serial8250_default_handle_irq+0x94/0x210 drivers/tty/serial/8250/8250_port.c:1967 serial8250_interrupt+0xfc/0x200 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x22a/0x740 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+0x261/0xcf0 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:238 [inline] __common_interrupt+0xdb/0x240 arch/x86/kernel/irq.c:257 common_interrupt+0xa9/0xd0 arch/x86/kernel/irq.c:247 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636 orc_find arch/x86/kernel/unwind_orc.c:217 [inline] unwind_next_frame+0x27d/0x2390 arch/x86/kernel/unwind_orc.c:494 arch_stack_walk+0xfa/0x170 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x96/0xd0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 __kasan_slab_alloc+0x81/0x90 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook mm/slab.h:762 [inline] slab_alloc_node mm/slub.c:3478 [inline] slab_alloc mm/slub.c:3486 [inline] __kmem_cache_alloc_lru mm/slub.c:3493 [inline] kmem_cache_alloc+0x16c/0x3b0 mm/slub.c:3502 mm_alloc+0x1c/0xd0 kernel/fork.c:1333 bprm_mm_init fs/exec.c:373 [inline] alloc_bprm+0x191/0xaf0 fs/exec.c:1534 kernel_execve+0xaf/0x4e0 fs/exec.c:1989 call_usermodehelper_exec_async+0x256/0x4c0 kernel/umh.c:110 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 IN-SOFTIRQ-W at: lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 serial8250_handle_irq+0x91/0xbd0 drivers/tty/serial/8250/8250_port.c:1921 serial8250_default_handle_irq+0x94/0x210 drivers/tty/serial/8250/8250_port.c:1967 serial8250_interrupt+0xfc/0x200 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x22a/0x740 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+0x261/0xcf0 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline] handle_irq arch/x86/kernel/irq.c:238 [inline] __common_interrupt+0xdb/0x240 arch/x86/kernel/irq.c:257 common_interrupt+0x51/0xd0 arch/x86/kernel/irq.c:247 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636 unwind_next_frame+0xb1/0x2390 arch/x86/kernel/unwind_orc.c:470 arch_stack_walk+0xfa/0x170 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x96/0xd0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1800 [inline] slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826 slab_free mm/slub.c:3809 [inline] kmem_cache_free+0xf0/0x480 mm/slub.c:3831 rcu_do_batch kernel/rcu/tree.c:2139 [inline] rcu_core+0x805/0x1bb0 kernel/rcu/tree.c:2403 __do_softirq+0x218/0x965 kernel/softirq.c:553 invoke_softirq kernel/softirq.c:427 [inline] __irq_exit_rcu kernel/softirq.c:632 [inline] irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1074 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline] acpi_safe_halt+0x1b/0x20 drivers/acpi/processor_idle.c:112 acpi_idle_enter+0xc5/0x160 drivers/acpi/processor_idle.c:707 cpuidle_enter_state+0x82/0x500 drivers/cpuidle/cpuidle.c:267 cpuidle_enter+0x4e/0xa0 drivers/cpuidle/cpuidle.c:388 cpuidle_idle_call kernel/sched/idle.c:215 [inline] do_idle+0x315/0x3f0 kernel/sched/idle.c:282 cpu_startup_entry+0x50/0x60 kernel/sched/idle.c:380 rest_init+0x16f/0x2b0 init/main.c:726 arch_call_rest_init+0x13/0x30 init/main.c:823 start_kernel+0x39f/0x480 init/main.c:1068 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:556 x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:537 secondary_startup_64_no_verify+0x166/0x16b INITIAL USE at: lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 serial8250_do_set_termios+0x334/0x1240 drivers/tty/serial/8250/8250_port.c:2798 serial8250_set_termios+0x6b/0x80 drivers/tty/serial/8250/8250_port.c:2917 uart_set_options+0x316/0x5f0 drivers/tty/serial/serial_core.c:2278 serial8250_console_setup+0x18a/0x430 drivers/tty/serial/8250/8250_port.c:3512 univ8250_console_setup+0x168/0x210 drivers/tty/serial/8250/8250_core.c:632 try_enable_preferred_console+0x24d/0x470 kernel/printk/printk.c:3294 register_console+0x331/0x10d0 kernel/printk/printk.c:3467 univ8250_console_init+0x35/0x50 drivers/tty/serial/8250/8250_core.c:717 console_init+0xba/0x5c0 kernel/printk/printk.c:3667 start_kernel+0x25a/0x480 init/main.c:1004 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:556 x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:537 secondary_startup_64_no_verify+0x166/0x16b } ... key at: [] port_lock_key+0x0/0x40 ... acquired at: __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 ppp_asynctty_wakeup+0x18/0xb0 drivers/net/ppp/ppp_async.c:352 tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:523 tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x542/0xf60 drivers/tty/serial/8250/8250_port.c:1843 __start_tx drivers/tty/serial/8250/8250_port.c:1552 [inline] serial8250_start_tx+0x7a8/0x980 drivers/tty/serial/8250/8250_port.c:1661 serial_port_runtime_resume+0x29e/0x330 drivers/tty/serial/serial_port.c:40 __rpm_callback+0xc5/0x4c0 drivers/base/power/runtime.c:392 rpm_callback+0x1da/0x220 drivers/base/power/runtime.c:446 rpm_resume+0xdb5/0x1980 drivers/base/power/runtime.c:912 pm_runtime_work+0x12e/0x180 drivers/base/power/runtime.c:977 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 -> (disc_data_lock){.+..}-{2:2} { HARDIRQ-ON-R at: lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 ppp_asynctty_receive+0x2d/0x15a0 drivers/net/ppp/ppp_async.c:335 tty_ldisc_receive_buf+0x14c/0x180 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+0x261/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 INITIAL READ USE at: lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 ppp_asynctty_wakeup+0x18/0xb0 drivers/net/ppp/ppp_async.c:352 tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:523 tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69 serial8250_tx_chars+0x542/0xf60 drivers/tty/serial/8250/8250_port.c:1843 __start_tx drivers/tty/serial/8250/8250_port.c:1552 [inline] serial8250_start_tx+0x7a8/0x980 drivers/tty/serial/8250/8250_port.c:1661 serial_port_runtime_resume+0x29e/0x330 drivers/tty/serial/serial_port.c:40 __rpm_callback+0xc5/0x4c0 drivers/base/power/runtime.c:392 rpm_callback+0x1da/0x220 drivers/base/power/runtime.c:446 rpm_resume+0xdb5/0x1980 drivers/base/power/runtime.c:912 pm_runtime_work+0x12e/0x180 drivers/base/power/runtime.c:977 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 } ... key at: [] disc_data_lock+0x18/0x60 ... acquired at: mark_usage kernel/locking/lockdep.c:4578 [inline] __lock_acquire+0x13a5/0x5de0 kernel/locking/lockdep.c:5090 lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 ppp_asynctty_receive+0x2d/0x15a0 drivers/net/ppp/ppp_async.c:335 tty_ldisc_receive_buf+0x14c/0x180 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+0x261/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 stack backtrace: CPU: 0 PID: 11 Comm: kworker/u4:0 Not tainted 6.6.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 print_irq_inversion_bug.part.0+0x3e1/0x590 kernel/locking/lockdep.c:4079 print_irq_inversion_bug kernel/locking/lockdep.c:4032 [inline] check_usage_forwards kernel/locking/lockdep.c:4110 [inline] mark_lock_irq kernel/locking/lockdep.c:4242 [inline] mark_lock+0x920/0x1950 kernel/locking/lockdep.c:4677 mark_usage kernel/locking/lockdep.c:4578 [inline] __lock_acquire+0x13a5/0x5de0 kernel/locking/lockdep.c:5090 lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline] _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228 ap_get+0x18/0xf0 drivers/net/ppp/ppp_async.c:136 ppp_asynctty_receive+0x2d/0x15a0 drivers/net/ppp/ppp_async.c:335 tty_ldisc_receive_buf+0x14c/0x180 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+0x261/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304