====================================================== WARNING: possible circular locking dependency detected 5.10.0-rc7-next-20201210-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor247/12144 is trying to acquire lock: ffffffff8b69b620 (console_owner){....}-{0:0}, at: console_unlock+0x34e/0xc00 kernel/printk/printk.c:2537 but task is already holding lock: ffffffff90378c58 (&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+0x39/0x50 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+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x303/0x950 kernel/irq/handle.c:156 handle_irq_event_percpu+0x76/0x170 kernel/irq/handle.c:196 handle_irq_event+0xa1/0x130 kernel/irq/handle.c:213 handle_edge_irq+0x25f/0xd00 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+0x12f/0x220 arch/x86/kernel/irq.c:239 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:619 native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] acpi_safe_halt drivers/acpi/processor_idle.c:110 [inline] acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:516 acpi_idle_enter+0x361/0x500 drivers/acpi/processor_idle.c:647 cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237 cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351 call_cpuidle kernel/sched/idle.c:158 [inline] cpuidle_idle_call kernel/sched/idle.c:239 [inline] do_idle+0x3eb/0x590 kernel/sched/idle.c:299 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:396 start_kernel+0x49b/0x4bc init/main.c:1064 secondary_startup_64_no_verify+0xb0/0xbb -> #1 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159 serial8250_console_write+0x880/0xa90 drivers/tty/serial/8250/8250_port.c:3292 call_console_drivers kernel/printk/printk.c:1838 [inline] console_unlock+0x892/0xc00 kernel/printk/printk.c:2552 vprintk_emit+0x198/0x400 kernel/printk/printk.c:2074 vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2122 register_console kernel/printk/printk.c:2903 [inline] register_console+0x664/0x870 kernel/printk/printk.c:2783 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:690 console_init+0x41e/0x613 kernel/printk/printk.c:3003 start_kernel+0x32c/0x4bc init/main.c:992 secondary_startup_64_no_verify+0xb0/0xbb -> #0 (console_owner){....}-{0:0}: check_prev_add kernel/locking/lockdep.c:2868 [inline] check_prevs_add kernel/locking/lockdep.c:2993 [inline] validate_chain kernel/locking/lockdep.c:3608 [inline] __lock_acquire+0x2b39/0x54b0 kernel/locking/lockdep.c:4832 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x750 kernel/locking/lockdep.c:5402 console_lock_spinning_enable kernel/printk/printk.c:1690 [inline] console_unlock+0x3cb/0xc00 kernel/printk/printk.c:2549 vprintk_emit+0x198/0x400 kernel/printk/printk.c:2074 vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2122 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+0x45e/0x1210 drivers/tty/tty_io.c:1683 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 exit_task_work include/linux/task_work.h:30 [inline] do_exit+0xb89/0x2a00 kernel/exit.c:823 do_group_exit+0x125/0x310 kernel/exit.c:920 get_signal+0x3e9/0x2160 kernel/signal.c:2770 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 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-executor247/12144: #0: ffff8880197011c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19 #1: ffffffff90378c58 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567 #2: ffffffff8b77b9a0 (console_lock){+.+.}-{0:0}, at: vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:393 stack backtrace: CPU: 1 PID: 12144 Comm: syz-executor247 Not tainted 5.10.0-rc7-next-20201210-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+0x107/0x163 lib/dump_stack.c:120 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2117 check_prev_add kernel/locking/lockdep.c:2868 [inline] check_prevs_add kernel/locking/lockdep.c:2993 [inline] validate_chain kernel/locking/lockdep.c:3608 [inline] __lock_acquire+0x2b39/0x54b0 kernel/locking/lockdep.c:4832 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x750 kernel/locking/lockdep.c:5402 console_lock_spinning_enable kernel/printk/printk.c:1690 [inline] console_unlock+0x3cb/0xc00 kernel/printk/printk.c:2549 vprintk_emit+0x198/0x400 kernel/printk/printk.c:2074 vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:393 printk+0xba/0xed kernel/printk/printk.c:2122 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+0x45e/0x1210 drivers/tty/tty_io.c:1683 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 exit_task_work include/linux/task_work.h:30 [inline] do_exit+0xb89/0x2a00 kernel/exit.c:823 do_group_exit+0x125/0x310 kernel/exit.c:920 get_signal+0x3e9/0x2160 kernel/signal.c:2770 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x446e59 Code: Unable to access opcode bytes at RIP 0x446e2f. RSP: 002b:00007f972e10ecf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dcc38 RCX: 0000000000446e59 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dcc38 RBP: 00000000006dcc30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c R13: 00007ffd2984dc8f R14: 00007f972e10f9c0 R15: 20c49ba5e353f7cf