====================================================== WARNING: possible circular locking dependency detected 5.9.0-rc3-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor422/6821 is trying to acquire lock: ffffffff894fc9c0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x2d/0x60 kernel/printk/printk.c:1687 but task is already holding lock: ffffffff8c3267a0 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start+0x58/0x550 drivers/tty/tty_port.c:567 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&port->lock#2){-.-.}-{2:2}: lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xaa/0xd0 kernel/locking/spinlock.c:159 tty_port_tty_get+0x21/0xe0 drivers/tty/tty_port.c:288 tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x5ea/0x800 drivers/tty/serial/8250/8250_port.c:1832 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1919 serial8250_default_handle_irq+0xac/0x190 drivers/tty/serial/8250/8250_port.c:1935 serial8250_interrupt+0x93/0x180 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x1f1/0x6e0 kernel/irq/handle.c:156 handle_irq_event_percpu kernel/irq/handle.c:196 [inline] handle_irq_event+0xbd/0x280 kernel/irq/handle.c:213 handle_edge_irq+0x245/0xbf0 kernel/irq/chip.c:819 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] handle_irq arch/x86/kernel/irq.c:230 [inline] __common_interrupt arch/x86/kernel/irq.c:249 [inline] common_interrupt+0x13c/0x230 arch/x86/kernel/irq.c:239 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:572 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_safe_halt arch/x86/include/asm/paravirt.h:150 [inline] acpi_safe_halt+0x8f/0x140 drivers/acpi/processor_idle.c:111 acpi_idle_do_entry drivers/acpi/processor_idle.c:524 [inline] acpi_idle_enter+0x3ef/0xac0 drivers/acpi/processor_idle.c:650 cpuidle_enter_state+0x38d/0x950 drivers/cpuidle/cpuidle.c:243 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:355 call_cpuidle kernel/sched/idle.c:132 [inline] cpuidle_idle_call kernel/sched/idle.c:213 [inline] do_idle+0x4a7/0x650 kernel/sched/idle.c:273 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:369 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port->lock){-.-.}-{2:2}: lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xaa/0xd0 kernel/locking/spinlock.c:159 serial8250_console_write+0x145/0xd10 drivers/tty/serial/8250/8250_port.c:3289 call_console_drivers kernel/printk/printk.c:1822 [inline] console_unlock+0x94c/0xe20 kernel/printk/printk.c:2501 vprintk_emit+0x205/0x370 kernel/printk/printk.c:2029 printk+0x62/0x83 kernel/printk/printk.c:2078 register_console+0x7a6/0xab0 kernel/printk/printk.c:2854 univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:690 console_init+0x52/0x97 kernel/printk/printk.c:2954 start_kernel+0x319/0x57c init/main.c:975 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain+0x1b0c/0x88a0 kernel/locking/lockdep.c:3218 __lock_acquire+0x110b/0x2ae0 kernel/locking/lockdep.c:4426 lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1690 console_unlock+0x77f/0xe20 kernel/printk/printk.c:2498 vprintk_emit+0x205/0x370 kernel/printk/printk.c:2029 printk+0x62/0x83 kernel/printk/printk.c:2078 tty_port_close_start+0x3c8/0x550 drivers/tty/tty_port.c:569 tty_port_close+0x25/0x140 drivers/tty/tty_port.c:634 tty_release+0x378/0xf90 drivers/tty/tty_io.c:1679 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:140 [inline] exit_to_user_mode_prepare+0x11a/0x1e0 kernel/entry/common.c:167 syscall_exit_to_user_mode+0x82/0x1d0 kernel/entry/common.c:242 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Chain exists of: console_owner --> &port->lock --> &port->lock#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&port->lock#2); lock(&port->lock); lock(&port->lock#2); lock(console_owner); *** DEADLOCK *** 3 locks held by syz-executor422/6821: #0: ffff8880a1ae31c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_release+0xa5/0xf90 drivers/tty/tty_io.c:1661 #1: ffffffff8c3267a0 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start+0x58/0x550 drivers/tty/tty_port.c:567 #2: ffffffff894fc8a0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x1e8/0x370 kernel/printk/printk.c:2028 stack backtrace: CPU: 1 PID: 6821 Comm: syz-executor422 Not tainted 5.9.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d6/0x29e lib/dump_stack.c:118 print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1703 check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1827 check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain+0x1b0c/0x88a0 kernel/locking/lockdep.c:3218 __lock_acquire+0x110b/0x2ae0 kernel/locking/lockdep.c:4426 lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1690 console_unlock+0x77f/0xe20 kernel/printk/printk.c:2498 vprintk_emit+0x205/0x370 kernel/printk/printk.c:2029 printk+0x62/0x83 kernel/printk/printk.c:2078 tty_port_close_start+0x3c8/0x550 drivers/tty/tty_port.c:569 tty_port_close+0x25/0x140 drivers/tty/tty_port.c:634 tty_release+0x378/0xf90 drivers/tty/tty_io.c:1679 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:140 [inline] exit_to_user_mode_prepare+0x11a/0x1e0 kernel/entry/common.c:167 syscall_exit_to_user_mode+0x82/0x1d0 kernel/entry/common.c:242 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4081c1 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 24 1a 00 00 c3 48 83 ec 08 e8 6a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 b3 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffe7bc42860 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007ffe7bc42890 RCX: 00000000004081c1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007ffe7bc428f0 R08: 0000006e0000005b R09: 0000006e0000005b R10: 00007ffe7bc42890 R11: 0000000000000293 R12: 0000000000000004 R13: 0000000000000064 R14: 0000000000000000 R15: 00000000006dfc3c