====================================================== WARNING: possible circular locking dependency detected 5.12.0-rc8-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor397/11955 is trying to acquire lock: ffffffff8cd04c60 (console_owner){....}-{0:0}, at: console_lock_spinning_enable+0x2d/0x60 kernel/printk/printk.c:1711 but task is already holding lock: ffffffff906ca918 (&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+0x17f/0x720 kernel/locking/lockdep.c:5511 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb3/0x100 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+0xaf/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+0x20a/0x6d0 kernel/irq/handle.c:156 handle_irq_event_percpu kernel/irq/handle.c:196 [inline] handle_irq_event+0x10a/0x2f0 kernel/irq/handle.c:213 handle_edge_irq+0x245/0xbe0 kernel/irq/chip.c:819 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0xce/0x1e0 arch/x86/kernel/irq.c:250 common_interrupt+0x9c/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:623 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:191 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline] uart_write+0x6a1/0x8f0 drivers/tty/serial/serial_core.c:615 do_output_char+0x638/0x940 drivers/tty/n_tty.c:443 process_output drivers/tty/n_tty.c:510 [inline] n_tty_write+0xe33/0x1310 drivers/tty/n_tty.c:2365 do_tty_write drivers/tty/tty_io.c:1043 [inline] file_tty_write+0x5c5/0x9a0 drivers/tty/tty_io.c:1133 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:1971 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 vfs_writev fs/read_write.c:939 [inline] do_writev+0x240/0x440 fs/read_write.c:982 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&port_lock_key){-.-.}-{2:2}: lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5511 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb3/0x100 kernel/locking/spinlock.c:159 serial8250_console_write+0x177/0xe40 drivers/tty/serial/8250/8250_port.c:3292 call_console_drivers kernel/printk/printk.c:1862 [inline] console_unlock+0x9ca/0xf00 kernel/printk/printk.c:2576 vprintk_emit+0x21a/0x2f0 kernel/printk/printk.c:2098 printk+0xc0/0x103 kernel/printk/printk.c:2146 register_console+0x8dc/0xbc0 kernel/printk/printk.c:2927 univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:690 console_init+0x52/0x97 kernel/printk/printk.c:3027 start_kernel+0x30c/0x544 init/main.c:993 secondary_startup_64_no_verify+0xb0/0xbb -> #0 (console_owner){....}-{0:0}: check_prev_add kernel/locking/lockdep.c:2937 [inline] check_prevs_add+0x4d6/0x5a90 kernel/locking/lockdep.c:3060 validate_chain kernel/locking/lockdep.c:3675 [inline] __lock_acquire+0x4307/0x6040 kernel/locking/lockdep.c:4901 lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5511 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1714 console_unlock+0x711/0xf00 kernel/printk/printk.c:2573 vprintk_emit+0x21a/0x2f0 kernel/printk/printk.c:2098 printk+0xc0/0x103 kernel/printk/printk.c:2146 tty_port_close_start+0x3c8/0x550 drivers/tty/tty_port.c:569 tty_port_close+0x26/0x140 drivers/tty/tty_port.c:634 tty_release+0x30c/0xef0 drivers/tty/tty_io.c:1779 __fput+0x352/0x7b0 fs/file_table.c:280 task_work_run+0x146/0x1c0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x10b/0x1e0 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x26/0x70 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae 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-executor397/11955: #0: ffff888034da31c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_release+0xac/0xef0 drivers/tty/tty_io.c:1761 #1: ffffffff906ca918 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start+0x58/0x550 drivers/tty/tty_port.c:567 #2: ffffffff8cbec980 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x201/0x2f0 kernel/printk/printk.c:2097 stack backtrace: CPU: 1 PID: 11955 Comm: syz-executor397 Not tainted 5.12.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x202/0x31e lib/dump_stack.c:120 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2006 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2128 check_prev_add kernel/locking/lockdep.c:2937 [inline] check_prevs_add+0x4d6/0x5a90 kernel/locking/lockdep.c:3060 validate_chain kernel/locking/lockdep.c:3675 [inline] __lock_acquire+0x4307/0x6040 kernel/locking/lockdep.c:4901 lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5511 console_lock_spinning_enable+0x52/0x60 kernel/printk/printk.c:1714 console_unlock+0x711/0xf00 kernel/printk/printk.c:2573 vprintk_emit+0x21a/0x2f0 kernel/printk/printk.c:2098 printk+0xc0/0x103 kernel/printk/printk.c:2146 tty_port_close_start+0x3c8/0x550 drivers/tty/tty_port.c:569 tty_port_close+0x26/0x140 drivers/tty/tty_port.c:634 tty_release+0x30c/0xef0 drivers/tty/tty_io.c:1779 __fput+0x352/0x7b0 fs/file_table.c:280 task_work_run+0x146/0x1c0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x10b/0x1e0 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x26/0x70 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x409deb Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffd3a2fb330 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000409deb RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffd0000000a R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000011f73 R13: 00000000004cf4dc R14: 00007ffd3a2fb3d0 R15: 00000000004cf4c0