====================================================== WARNING: possible circular locking dependency detected 5.8.0-rc7-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/25653 is trying to acquire lock: ffffffff89bb5a80 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] ffffffff89bb5a80 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x467/0x770 kernel/printk/printk.c:2020 but task is already holding lock: ffffffff8d42dd78 (&port->lock#2){-.-.}-{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){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 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:1831 serial8250_handle_irq.part.0+0x328/0x3d0 drivers/tty/serial/8250/8250_port.c:1918 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1891 [inline] serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1934 serial8250_interrupt+0xe6/0x190 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x223/0xa30 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:830 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 __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+0x141/0x220 arch/x86/kernel/irq.c:239 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:576 arch_local_irq_restore arch/x86/include/asm/paravirt.h:770 [inline] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x8c/0xe0 kernel/locking/spinlock.c:191 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] uart_write+0x30d/0x56a drivers/tty/serial/serial_core.c:614 do_output_char+0x5de/0x850 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0x481/0xf80 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046 redirected_tty_write+0xaa/0xb0 drivers/tty/tty_io.c:1067 do_loop_readv_writev fs/read_write.c:737 [inline] do_loop_readv_writev fs/read_write.c:721 [inline] do_iter_write+0x48b/0x5f0 fs/read_write.c:1020 vfs_writev+0x1aa/0x2e0 fs/read_write.c:1091 do_writev+0x139/0x300 fs/read_write.c:1134 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&port->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:159 serial8250_console_write+0x211/0xb70 drivers/tty/serial/8250/8250_port.c:3245 call_console_drivers kernel/printk/printk.c:1816 [inline] console_unlock+0xaf0/0xf30 kernel/printk/printk.c:2493 vprintk_emit+0x2fd/0x770 kernel/printk/printk.c:2021 vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2070 register_console kernel/printk/printk.c:2846 [inline] register_console+0x55f/0x7e0 kernel/printk/printk.c:2725 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:690 console_init+0x421/0x619 kernel/printk/printk.c:2946 start_kernel+0x77b/0xa06 init/main.c:970 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+0x2acb/0x56e0 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 console_trylock_spinning kernel/printk/printk.c:1773 [inline] vprintk_emit+0x4a4/0x770 kernel/printk/printk.c:2020 vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2070 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+0x33c/0x880 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:135 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:239 [inline] __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:269 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393 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 *** 2 locks held by syz-executor.4/25653: #0: ffff8880918061c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19 #1: ffffffff8d42dd78 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567 stack backtrace: CPU: 0 PID: 25653 Comm: syz-executor.4 Not tainted 5.8.0-rc7-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+0x18f/0x20d 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+0x2acb/0x56e0 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 console_trylock_spinning kernel/printk/printk.c:1773 [inline] vprintk_emit+0x4a4/0x770 kernel/printk/printk.c:2020 vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2070 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+0x33c/0x880 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:135 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:239 [inline] __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:269 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x415ee1 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 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:00007ffe0ce69d40 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000415ee1 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000790250 R09: 0000000000000000 R10: 00007ffe0ce69e20 R11: 0000000000000293 R12: 0000000000790258 R13: 0000000000000000 R14: ffffffffffffffff R15: 000000000078bf0c