====================================================== WARNING: possible circular locking dependency detected 5.7.0-rc1-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor853/10262 is trying to acquire lock: ffffffff892e6a30 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x2d/0x60 kernel/printk/printk.c:1679 but task is already holding lock: ffffffff8c07fb60 (&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+0x169/0x480 kernel/locking/lockdep.c:4934 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x9e/0xc0 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:1828 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1915 serial8250_default_handle_irq+0xac/0x190 drivers/tty/serial/8250/8250_port.c:1931 serial8250_interrupt+0x93/0x180 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x1b7/0x610 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:830 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] do_IRQ+0xf6/0x1d0 arch/x86/kernel/irq.c:250 ret_from_intr+0x0/0x2b arch_local_irq_restore arch/x86/include/asm/paravirt.h:759 [inline] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0xa5/0xd0 kernel/locking/spinlock.c:191 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] uart_write+0x7d3/0x9c0 drivers/tty/serial/serial_core.c:616 do_output_char+0x63b/0x940 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0xd5c/0x1170 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x593/0x940 drivers/tty/tty_io.c:1046 do_loop_readv_writev fs/read_write.c:718 [inline] do_iter_write+0x402/0x540 fs/read_write.c:1001 vfs_writev fs/read_write.c:1072 [inline] do_writev+0x23f/0x4a0 fs/read_write.c:1115 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #1 (&port->lock){-.-.}-{2:2}: lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159 serial8250_console_write+0x13e/0xd50 drivers/tty/serial/8250/8250_port.c:3240 call_console_drivers kernel/printk/printk.c:1814 [inline] console_unlock+0x90c/0xec0 kernel/printk/printk.c:2498 vprintk_emit+0x1f8/0x3c0 kernel/printk/printk.c:2021 printk+0x62/0x83 kernel/printk/printk.c:2081 register_console+0xb64/0xed0 kernel/printk/printk.c:2821 univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:690 console_init+0x52/0x97 kernel/printk/printk.c:2921 start_kernel+0x421/0x76f init/main.c:931 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 -> #0 (console_owner){-.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2c30 kernel/locking/lockdep.c:4355 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1682 console_unlock+0x73f/0xec0 kernel/printk/printk.c:2495 vprintk_emit+0x1f8/0x3c0 kernel/printk/printk.c:2021 printk+0x62/0x83 kernel/printk/printk.c:2081 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+0x40a/0x1100 drivers/tty/tty_io.c:1679 __fput+0x2ed/0x750 fs/file_table.c:280 task_work_run+0x147/0x1d0 kernel/task_work.c:123 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x5ef/0x1f80 kernel/exit.c:795 do_group_exit+0x15e/0x2c0 kernel/exit.c:893 get_signal+0x13cf/0x1d60 kernel/signal.c:2739 do_signal+0x33/0x610 arch/x86/kernel/signal.c:784 exit_to_usermode_loop arch/x86/entry/common.c:161 [inline] prepare_exit_to_usermode+0x32a/0x600 arch/x86/entry/common.c:196 entry_SYSCALL_64_after_hwframe+0x49/0xb3 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-executor853/10262: #0: ffff888092b081c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_release+0xb3/0x1100 drivers/tty/tty_io.c:1661 #1: ffffffff8c07fb60 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start+0x58/0x550 drivers/tty/tty_port.c:567 #2: ffffffff892e6910 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x1db/0x3c0 kernel/printk/printk.c:2020 stack backtrace: CPU: 0 PID: 10262 Comm: syz-executor853 Not tainted 5.7.0-rc1-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+0x1e9/0x30e lib/dump_stack.c:118 print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1722 check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1846 check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2c30 kernel/locking/lockdep.c:4355 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1682 console_unlock+0x73f/0xec0 kernel/printk/printk.c:2495 vprintk_emit+0x1f8/0x3c0 kernel/printk/printk.c:2021 printk+0x62/0x83 kernel/printk/printk.c:2081 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+0x40a/0x1100 drivers/tty/tty_io.c:1679 __fput+0x2ed/0x750 fs/file_table.c:280 task_work_run+0x147/0x1d0 kernel/task_work.c:123 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x5ef/0x1f80 kernel/exit.c:795 do_group_exit+0x15e/0x2c0 kernel/exit.c:893 get_signal+0x13cf/0x1d60 kernel/signal.c:2739 do_signal+0x33/0x610 arch/x86/kernel/signal.c:784 exit_to_usermode_loop arch/x86/entry/common.c:161 [inline] prepare_exit_to_usermode+0x32a/0x600 arch/x86/entry/common.c:196 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x446cf9 Code: Bad RIP value. RSP: 002b:00007fe7567aacf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dcc28 RCX: 0000000000446cf9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dcc28 RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc2c R13: 00007ffc933d653f R14: 00007fe7567ab9c0 R15: 20c49ba5e353f7cf