====================================================== WARNING: possible circular locking dependency detected 5.9.0-rc6-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor628/9065 is trying to acquire lock: ffffffff8a05ac20 (console_owner){-.-.}-{0:0}, at: log_next kernel/printk/printk.c:528 [inline] ffffffff8a05ac20 (console_owner){-.-.}-{0:0}, at: console_unlock+0x439/0xe60 kernel/printk/printk.c:2488 but task is already holding lock: ffffffff8df57538 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 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}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x94/0xce kernel/locking/spinlock.c:159 tty_port_tty_get+0x1f/0x100 drivers/tty/tty_port.c:288 tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x487/0xa80 drivers/tty/serial/8250/8250_port.c:1832 serial8250_handle_irq.part.0+0x328/0x3d0 drivers/tty/serial/8250/8250_port.c:1919 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1892 [inline] serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1935 serial8250_interrupt+0xe6/0x190 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x223/0xaa0 kernel/irq/handle.c:156 handle_irq_event_percpu kernel/irq/handle.c:196 [inline] handle_irq_event+0x102/0x285 kernel/irq/handle.c:213 handle_edge_irq+0x25f/0xd00 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+0x115/0x1f0 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 drivers/acpi/processor_idle.c:111 [inline] acpi_idle_do_entry+0x1e8/0x330 drivers/acpi/processor_idle.c:516 acpi_idle_enter+0x35a/0x550 drivers/acpi/processor_idle.c:647 cpuidle_enter_state+0x1ab/0xd20 drivers/cpuidle/cpuidle.c:247 cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:360 call_cpuidle kernel/sched/idle.c:132 [inline] cpuidle_idle_call kernel/sched/idle.c:213 [inline] do_idle+0x48e/0x730 kernel/sched/idle.c:273 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:369 start_kernel+0x490/0x4b1 init/main.c:1049 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x94/0xce kernel/locking/spinlock.c:159 serial8250_console_write+0x200/0xb30 drivers/tty/serial/8250/8250_port.c:3289 call_console_drivers kernel/printk/printk.c:1824 [inline] console_unlock+0xadb/0xe60 kernel/printk/printk.c:2501 vprintk_emit+0x2ff/0x740 kernel/printk/printk.c:2029 vprintk_func+0x8d/0x1d4 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2078 register_console kernel/printk/printk.c:2854 [inline] register_console+0x55f/0x830 kernel/printk/printk.c:2733 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:690 console_init+0x421/0x619 kernel/printk/printk.c:2954 start_kernel+0x31c/0x4b1 init/main.c:976 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 kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2a96/0x5780 kernel/locking/lockdep.c:4441 lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5029 console_lock_spinning_enable kernel/printk/printk.c:1690 [inline] console_unlock+0x4a1/0xe60 kernel/printk/printk.c:2498 vprintk_emit+0x2ff/0x740 kernel/printk/printk.c:2029 vprintk_func+0x8d/0x1d4 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2078 tty_port_close_start.part.0+0x503/0x550 drivers/tty/tty_port.c:569 tty_port_close_start drivers/tty/tty_port.c:641 [inline] tty_port_close+0x46/0x170 drivers/tty/tty_port.c:634 tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:165 [inline] exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:192 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:267 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &port->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&port->lock); lock(&port_lock_key); lock(&port->lock); lock(console_owner); *** DEADLOCK *** 3 locks held by syz-executor628/9065: #0: ffff8880913a51c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19 #1: ffffffff8df57538 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567 #2: ffffffff8a05aea0 (console_lock){+.+.}-{0:0}, at: vprintk_func+0x8d/0x1d4 kernel/printk/printk_safe.c:393 stack backtrace: CPU: 1 PID: 9065 Comm: syz-executor628 Not tainted 5.9.0-rc6-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+0x198/0x1fd lib/dump_stack.c:118 check_noncircular+0x324/0x3e0 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 kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2a96/0x5780 kernel/locking/lockdep.c:4441 lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5029 console_lock_spinning_enable kernel/printk/printk.c:1690 [inline] console_unlock+0x4a1/0xe60 kernel/printk/printk.c:2498 vprintk_emit+0x2ff/0x740 kernel/printk/printk.c:2029 vprintk_func+0x8d/0x1d4 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2078 tty_port_close_start.part.0+0x503/0x550 drivers/tty/tty_port.c:569 tty_port_close_start drivers/tty/tty_port.c:641 [inline] tty_port_close+0x46/0x170 drivers/tty/tty_port.c:634 tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:165 [inline] exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:192 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:267 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4066e1 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 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:00007ffe69617e80 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004066e1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000006e39f0 R08: 0000000000000000 R09: 0000000000000000 R10: 00007ffe69617eb0 R11: 0000000000000293 R12: 00000000006e39fc R13: 0000000000000001 R14: 000000000000002d R15: 20c49ba5e353f7cf