====================================================== WARNING: possible circular locking dependency detected 5.10.0-rc4-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.5/28128 is trying to acquire lock: ffffffff8badba20 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning+0x114/0x260 kernel/printk/printk.c:1811 but task is already holding lock: ffffffff8fe55a38 (&port->lock){-.-.}-{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}: lock_acquire+0x114/0x5e0 kernel/locking/lockdep.c:5435 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x73/0xa0 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+0xa3/0x1e0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x1b7/0x620 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+0x245/0xbe0 kernel/irq/chip.c:819 asm_call_irq_on_stack+0xf/0x20 __run_irq_on_irqstack arch/x86/include/asm/irq_stack.h:48 [inline] run_irq_on_irqstack_cond arch/x86/include/asm/irq_stack.h:101 [inline] handle_irq arch/x86/kernel/irq.c:230 [inline] __common_interrupt arch/x86/kernel/irq.c:249 [inline] common_interrupt+0x147/0x230 arch/x86/kernel/irq.c:239 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:622 native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline] arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x36/0x60 kernel/locking/spinlock.c:191 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline] uart_write+0x686/0x8d0 drivers/tty/serial/serial_core.c:615 do_output_char+0x638/0x940 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0xd59/0x1160 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x585/0x8f0 drivers/tty/tty_io.c:1046 do_loop_readv_writev fs/read_write.c:764 [inline] do_iter_write+0x415/0x5f0 fs/read_write.c:868 vfs_writev fs/read_write.c:939 [inline] do_writev+0x19a/0x350 fs/read_write.c:982 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&port_lock_key){-.-.}-{2:2}: lock_acquire+0x114/0x5e0 kernel/locking/lockdep.c:5435 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x73/0xa0 kernel/locking/spinlock.c:159 serial8250_console_write+0x108/0xcc0 drivers/tty/serial/8250/8250_port.c:3292 call_console_drivers kernel/printk/printk.c:1881 [inline] console_unlock+0xbe3/0xff0 kernel/printk/printk.c:2499 vprintk_emit+0x176/0x210 kernel/printk/printk.c:2028 printk+0x62/0x83 kernel/printk/printk.c:2076 register_console+0x782/0xa60 kernel/printk/printk.c:2850 univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:690 console_init+0x52/0x97 kernel/printk/printk.c:2950 start_kernel+0x302/0x53f init/main.c:988 secondary_startup_64_no_verify+0xb0/0xbb -> #0 (console_owner){-.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:2866 [inline] check_prevs_add+0x341/0x52b0 kernel/locking/lockdep.c:2991 validate_chain kernel/locking/lockdep.c:3606 [inline] __lock_acquire+0x43cb/0x6210 kernel/locking/lockdep.c:4830 lock_acquire+0x114/0x5e0 kernel/locking/lockdep.c:5435 console_trylock_spinning+0x134/0x260 kernel/printk/printk.c:1828 vprintk_emit+0x15d/0x210 kernel/printk/printk.c:2027 printk+0x62/0x83 kernel/printk/printk.c:2076 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+0x30c/0xef0 drivers/tty/tty_io.c:1681 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:151 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:164 [inline] exit_to_user_mode_prepare+0xe4/0x170 kernel/entry/common.c:191 syscall_exit_to_user_mode+0x4a/0x170 kernel/entry/common.c:266 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 *** 2 locks held by syz-executor.5/28128: #0: ffff888071fcc1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_release+0xac/0xef0 drivers/tty/tty_io.c:1663 #1: ffffffff8fe55a38 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start+0x58/0x550 drivers/tty/tty_port.c:567 stack backtrace: CPU: 1 PID: 28128 Comm: syz-executor.5 Not tainted 5.10.0-rc4-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+0x137/0x1be lib/dump_stack.c:118 print_circular_bug+0xb10/0xdb0 kernel/locking/lockdep.c:1994 check_noncircular+0x221/0x2d0 kernel/locking/lockdep.c:2115 check_prev_add kernel/locking/lockdep.c:2866 [inline] check_prevs_add+0x341/0x52b0 kernel/locking/lockdep.c:2991 validate_chain kernel/locking/lockdep.c:3606 [inline] __lock_acquire+0x43cb/0x6210 kernel/locking/lockdep.c:4830 lock_acquire+0x114/0x5e0 kernel/locking/lockdep.c:5435 console_trylock_spinning+0x134/0x260 kernel/printk/printk.c:1828 vprintk_emit+0x15d/0x210 kernel/printk/printk.c:2027 printk+0x62/0x83 kernel/printk/printk.c:2076 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+0x30c/0xef0 drivers/tty/tty_io.c:1681 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:151 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:164 [inline] exit_to_user_mode_prepare+0xe4/0x170 kernel/entry/common.c:191 syscall_exit_to_user_mode+0x4a/0x170 kernel/entry/common.c:266 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x417811 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffd9316c1b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417811 RDX: 0000001b2ee20000 RSI: 000000000000026b RDI: 0000000000000003 RBP: 0000000000000001 R08: 00000000c143a26b R09: 00000000c143a26f R10: 00007ffd9316c290 R11: 0000000000000293 R12: 000000000118c9a0 R13: 000000000118c9a0 R14: 00000000000003e8 R15: 000000000118c07c