RDX: 0000000020000040 RSI: 0000000000005412 RDI: 0000000000000004 RBP: 0000000000000005 R08: 0000000000000001 R09: 00000000000000c2 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401f40 R13: 0000000000401fd0 R14: 0000000000000000 R15: 0000000000000000 ====================================================== WARNING: possible circular locking dependency detected 4.14.111 #1 Not tainted ------------------------------------------------------ syz-executor206/7038 is trying to acquire lock: (console_owner){-...}, at: [] console_trylock_spinning kernel/printk/printk.c:1652 [inline] (console_owner){-...}, at: [] vprintk_emit kernel/printk/printk.c:1916 [inline] (console_owner){-...}, at: [] vprintk_emit+0x2f1/0x600 kernel/printk/printk.c:1882 but task is already holding lock: (&(&port->lock)->rlock){-.-.}, at: [] pty_write+0xe0/0x1d0 drivers/tty/pty.c:119 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&(&port->lock)->rlock){-.-.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:160 tty_port_tty_get+0x22/0x80 drivers/tty/tty_port.c:287 tty_port_default_wakeup+0x16/0x40 drivers/tty/tty_port.c:46 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:389 uart_write_wakeup+0x46/0x70 drivers/tty/serial/serial_core.c:116 serial8250_tx_chars+0x41c/0xa30 drivers/tty/serial/8250/8250_port.c:1810 serial8250_handle_irq.part.0+0x198/0x220 drivers/tty/serial/8250/8250_port.c:1883 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1869 [inline] serial8250_default_handle_irq+0xa6/0x120 drivers/tty/serial/8250/8250_port.c:1899 serial8250_interrupt+0xef/0x1a0 drivers/tty/serial/8250/8250_core.c:129 __handle_irq_event_percpu+0x127/0x800 kernel/irq/handle.c:147 handle_irq_event_percpu+0x65/0x130 kernel/irq/handle.c:187 handle_irq_event+0xa7/0x134 kernel/irq/handle.c:204 handle_edge_irq+0x231/0x850 kernel/irq/chip.c:770 generic_handle_irq_desc include/linux/irqdesc.h:159 [inline] handle_irq+0x252/0x34c arch/x86/kernel/irq_64.c:78 do_IRQ+0x99/0x1e0 arch/x86/kernel/irq.c:230 ret_from_intr+0x0/0x1e native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:555 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x262/0x3d0 kernel/sched/idle.c:246 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:351 rest_init+0xf1/0xf6 init/main.c:435 start_kernel+0x6e2/0x700 init/main.c:709 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:380 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:361 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #1 (&port_lock_key){-.-.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:160 serial8250_console_write+0x72c/0x950 drivers/tty/serial/8250/8250_port.c:3232 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:597 call_console_drivers kernel/printk/printk.c:1719 [inline] console_unlock+0x9c1/0xed0 kernel/printk/printk.c:2391 vprintk_emit kernel/printk/printk.c:1917 [inline] vprintk_emit+0x1f9/0x600 kernel/printk/printk.c:1882 vprintk_default+0x28/0x30 kernel/printk/printk.c:1957 vprintk_func+0x5d/0x159 kernel/printk/printk_safe.c:401 printk+0x9e/0xbc kernel/printk/printk.c:1990 register_console+0x61c/0x9f0 kernel/printk/printk.c:2710 univ8250_console_init+0x33/0x3f drivers/tty/serial/8250/8250_core.c:692 console_init+0x54/0x60 kernel/printk/printk.c:2791 start_kernel+0x43f/0x700 init/main.c:635 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:380 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:361 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #0 (console_owner){-...}: check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 console_trylock_spinning kernel/printk/printk.c:1673 [inline] vprintk_emit kernel/printk/printk.c:1916 [inline] vprintk_emit+0x32e/0x600 kernel/printk/printk.c:1882 vprintk_default+0x28/0x30 kernel/printk/printk.c:1957 vprintk_func+0x5d/0x159 kernel/printk/printk_safe.c:401 printk+0x9e/0xbc kernel/printk/printk.c:1990 fail_dump lib/fault-inject.c:44 [inline] should_fail.cold+0xe4/0x159 lib/fault-inject.c:149 should_failslab+0xdb/0x130 mm/failslab.c:32 slab_pre_alloc_hook mm/slab.h:421 [inline] slab_alloc mm/slab.c:3376 [inline] __do_kmalloc mm/slab.c:3718 [inline] __kmalloc+0x71/0x7a0 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:169 [inline] __tty_buffer_request_room+0x1a4/0x500 drivers/tty/tty_buffer.c:267 tty_insert_flip_string_fixed_flag+0x8a/0x1c0 drivers/tty/tty_buffer.c:312 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x113/0x1d0 drivers/tty/pty.c:121 tty_put_char+0x113/0x140 drivers/tty/tty_io.c:2878 __process_echoes+0x2ce/0x8a0 drivers/tty/n_tty.c:708 flush_echoes drivers/tty/n_tty.c:829 [inline] __receive_buf drivers/tty/n_tty.c:1648 [inline] n_tty_receive_buf_common+0x998/0x2410 drivers/tty/n_tty.c:1742 n_tty_receive_buf+0x31/0x3b drivers/tty/n_tty.c:1771 tiocsti drivers/tty/tty_io.c:2184 [inline] tty_ioctl+0xe0e/0x1340 drivers/tty/tty_io.c:2570 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7b9/0x1070 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &(&port->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&port->lock)->rlock); lock(&port_lock_key); lock(&(&port->lock)->rlock); lock(console_owner); *** DEADLOCK *** 4 locks held by syz-executor206/7038: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&o_tty->termios_rwsem/1){++++}, at: [] n_tty_receive_buf_common+0x92/0x2410 drivers/tty/n_tty.c:1705 #2: (&ldata->output_lock){+.+.}, at: [] flush_echoes drivers/tty/n_tty.c:827 [inline] #2: (&ldata->output_lock){+.+.}, at: [] __receive_buf drivers/tty/n_tty.c:1648 [inline] #2: (&ldata->output_lock){+.+.}, at: [] n_tty_receive_buf_common+0x958/0x2410 drivers/tty/n_tty.c:1742 #3: (&(&port->lock)->rlock){-.-.}, at: [] pty_write+0xe0/0x1d0 drivers/tty/pty.c:119 stack backtrace: CPU: 1 PID: 7038 Comm: syz-executor206 Not tainted 4.14.111 #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x138/0x19c lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 console_trylock_spinning kernel/printk/printk.c:1673 [inline] vprintk_emit kernel/printk/printk.c:1916 [inline] vprintk_emit+0x32e/0x600 kernel/printk/printk.c:1882 vprintk_default+0x28/0x30 kernel/printk/printk.c:1957 vprintk_func+0x5d/0x159 kernel/printk/printk_safe.c:401 printk+0x9e/0xbc kernel/printk/printk.c:1990 fail_dump lib/fault-inject.c:44 [inline] should_fail.cold+0xe4/0x159 lib/fault-inject.c:149 should_failslab+0xdb/0x130 mm/failslab.c:32 slab_pre_alloc_hook mm/slab.h:421 [inline] slab_alloc mm/slab.c:3376 [inline] __do_kmalloc mm/slab.c:3718 [inline] __kmalloc+0x71/0x7a0 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:169 [inline] __tty_buffer_request_room+0x1a4/0x500 drivers/tty/tty_buffer.c:267 tty_insert_flip_string_fixed_flag+0x8a/0x1c0 drivers/tty/tty_buffer.c:312 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x113/0x1d0 drivers/tty/pty.c:121 tty_put_char+0x113/0x140 drivers/tty/tty_io.c:2878 __process_echoes+0x2ce/0x8a0 drivers/tty/n_tty.c:708 flush_echoes drivers/tty/n_tty.c:829 [inline] __receive_buf drivers/tty/n_tty.c:1648 [inline] n_tty_receive_buf_common+0x998/0x2410 drivers/tty/n_tty.c:1742 n_tty_receive_buf+0x31/0x3b drivers/tty/n_tty.c:1771 tiocsti drivers/tty/tty_io.c:2184 [inline] tty_ioctl+0xe0e/0x1340 drivers/tty/tty_io.c:2570 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7b9/0x1070 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x440679 RSP: 002b:00007ffdc3243ad8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010