RDX: 0000000000000006 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007f54979241d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff8bdf508f R14: 00007f5497924300 R15: 0000000000022000
======================================================
WARNING: possible circular locking dependency detected
4.14.291-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/15839 is trying to acquire lock:
 (console_owner){....}, at: [<ffffffff8143f7c7>] log_next kernel/printk/printk.c:495 [inline]
 (console_owner){....}, at: [<ffffffff8143f7c7>] console_unlock+0x307/0xf20 kernel/printk/printk.c:2396

but task is already holding lock:
 (&(&port->lock)->rlock){-.-.}, at: [<ffffffff8355a6cb>] tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:569

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&(&port->lock)->rlock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160
       tty_port_tty_get+0x1d/0x80 drivers/tty/tty_port.c:288
       tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:46
       serial8250_tx_chars+0x3fe/0xc70 drivers/tty/serial/8250/8250_port.c:1828
       serial8250_handle_irq.part.0+0x28d/0x330 drivers/tty/serial/8250/8250_port.c:1915
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1888 [inline]
       serial8250_default_handle_irq+0x8a/0x1f0 drivers/tty/serial/8250/8250_port.c:1931
       serial8250_interrupt+0xf3/0x210 drivers/tty/serial/8250/8250_core.c:129
       __handle_irq_event_percpu+0xee/0x7f0 kernel/irq/handle.c:147
       handle_irq_event_percpu kernel/irq/handle.c:187 [inline]
       handle_irq_event+0xed/0x240 kernel/irq/handle.c:204
       handle_edge_irq+0x224/0xc40 kernel/irq/chip.c:770
       generic_handle_irq_desc include/linux/irqdesc.h:159 [inline]
       handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87
       do_IRQ+0x93/0x1d0 arch/x86/kernel/irq.c:230
       ret_from_intr+0x0/0x1e
       native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
       arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
       default_idle+0x47/0x370 arch/x86/kernel/process.c:558
       cpuidle_idle_call kernel/sched/idle.c:156 [inline]
       do_idle+0x250/0x3c0 kernel/sched/idle.c:246
       cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:351
       start_kernel+0x743/0x763 init/main.c:712
       secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

-> #1 (&port_lock_key){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160
       serial8250_console_write+0x7d5/0xa10 drivers/tty/serial/8250/8250_port.c:3273
       call_console_drivers kernel/printk/printk.c:1727 [inline]
       console_unlock+0x99d/0xf20 kernel/printk/printk.c:2409
       vprintk_emit+0x224/0x620 kernel/printk/printk.c:1925
       vprintk_func+0x58/0x160 kernel/printk/printk_safe.c:409
       printk+0x9e/0xbc kernel/printk/printk.c:1998
       register_console+0x6f4/0xad0 kernel/printk/printk.c:2728
       univ8250_console_init+0x2f/0x3a drivers/tty/serial/8250/8250_core.c:691
       console_init+0x46/0x53 kernel/printk/printk.c:2809
       start_kernel+0x521/0x763 init/main.c:638
       secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

-> #0 (console_owner){....}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       console_lock_spinning_enable kernel/printk/printk.c:1590 [inline]
       console_unlock+0x36f/0xf20 kernel/printk/printk.c:2406
       vprintk_emit+0x224/0x620 kernel/printk/printk.c:1925
       vprintk_func+0x58/0x160 kernel/printk/printk_safe.c:409
       printk+0x9e/0xbc kernel/printk/printk.c:1998
       fail_dump lib/fault-inject.c:44 [inline]
       should_fail.cold+0xdf/0x149 lib/fault-inject.c:149
       should_failslab+0xd6/0x130 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+0x6d/0x400 mm/slab.c:3729
       kmalloc include/linux/slab.h:493 [inline]
       tty_buffer_alloc+0xc0/0x270 drivers/tty/tty_buffer.c:169
       __tty_buffer_request_room+0x12c/0x290 drivers/tty/tty_buffer.c:268
       tty_insert_flip_string_fixed_flag+0x8b/0x210 drivers/tty/tty_buffer.c:313
       tty_insert_flip_string include/linux/tty_flip.h:36 [inline]
       tty_insert_flip_string_and_push_buffer+0x3e/0x160 drivers/tty/tty_buffer.c:570
       pty_write+0xc3/0xf0 drivers/tty/pty.c:118
       n_tty_write+0x85e/0xda0 drivers/tty/n_tty.c:2356
       do_tty_write drivers/tty/tty_io.c:959 [inline]
       tty_write+0x410/0x740 drivers/tty/tty_io.c:1043
       __vfs_write+0xe4/0x630 fs/read_write.c:480
       vfs_write+0x17f/0x4d0 fs/read_write.c:544
       SYSC_write fs/read_write.c:590 [inline]
       SyS_write+0xf2/0x210 fs/read_write.c:582
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

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 ***

6 locks held by syz-executor.0/15839:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff83556b42>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&tty->atomic_write_lock){+.+.}, at: [<ffffffff8353f7bd>] tty_write_lock drivers/tty/tty_io.c:885 [inline]
 #1:  (&tty->atomic_write_lock){+.+.}, at: [<ffffffff8353f7bd>] do_tty_write drivers/tty/tty_io.c:908 [inline]
 #1:  (&tty->atomic_write_lock){+.+.}, at: [<ffffffff8353f7bd>] tty_write+0x22d/0x740 drivers/tty/tty_io.c:1043
CPU: 0 PID: 15846 Comm: syz-executor.5 Not tainted 4.14.291-syzkaller #0
 #2:  (&tty->termios_rwsem){++++}, at: [<ffffffff8354a9fa>] n_tty_write+0x18a/0xda0 drivers/tty/n_tty.c:2316
 #3:  (&ldata->output_lock){+.+.}, at: [<ffffffff8354b09b>] n_tty_write+0x82b/0xda0 drivers/tty/n_tty.c:2355
 #4:  (&(&port->lock)->rlock){-.-.}, at: [<ffffffff8355a6cb>] tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:569
 #5:  (console_lock){+.+.}, at: [<ffffffff81443128>] vprintk_func+0x58/0x160 kernel/printk/printk_safe.c:409

stack backtrace:
CPU: 1 PID: 15839 Comm: syz-executor.0 Not tainted 4.14.291-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 console_lock_spinning_enable kernel/printk/printk.c:1590 [inline]
 console_unlock+0x36f/0xf20 kernel/printk/printk.c:2406
 vprintk_emit+0x224/0x620 kernel/printk/printk.c:1925
 vprintk_func+0x58/0x160 kernel/printk/printk_safe.c:409
 printk+0x9e/0xbc kernel/printk/printk.c:1998
 fail_dump lib/fault-inject.c:44 [inline]
 should_fail.cold+0xdf/0x149 lib/fault-inject.c:149
 should_failslab+0xd6/0x130 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+0x6d/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 tty_buffer_alloc+0xc0/0x270 drivers/tty/tty_buffer.c:169
 __tty_buffer_request_room+0x12c/0x290 drivers/tty/tty_buffer.c:268
 tty_insert_flip_string_fixed_flag+0x8b/0x210 drivers/tty/tty_buffer.c:313
 tty_insert_flip_string include/linux/tty_flip.h:36 [inline]
 tty_insert_flip_string_and_push_buffer+0x3e/0x160 drivers/tty/tty_buffer.c:570
 pty_write+0xc3/0xf0 drivers/tty/pty.c:118
 n_tty_write+0x85e/0xda0 drivers/tty/n_tty.c:2356
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x410/0x740 drivers/tty/tty_io.c:1043
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f5498faf279
RSP: 002b:00007f5497924168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f54990c1f80 RCX: 00007f5498faf279
RDX: 0000000000000006 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007f54979241d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff8bdf508f R14: 00007f5497924300 R15: 0000000000022000
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x149 lib/fault-inject.c:149
 should_failslab+0xd6/0x130 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+0x2c1/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 n_hdlc_alloc drivers/tty/n_hdlc.c:857 [inline]
 n_hdlc_tty_open+0x25b/0x4d0 drivers/tty/n_hdlc.c:342
 tty_ldisc_open+0x6c/0xb0 drivers/tty/tty_ldisc.c:481
 tty_set_ldisc+0x287/0x5d0 drivers/tty/tty_ldisc.c:606
 tiocsetd drivers/tty/tty_io.c:2351 [inline]
 tty_ioctl+0xa2a/0x1430 drivers/tty/tty_io.c:2595
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fa663077279
RSP: 002b:00007fa6619ec168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa663189f80 RCX: 00007fa663077279
RDX: 0000000020000040 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fa6619ec1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcdd69f1ff R14: 00007fa6619ec300 R15: 0000000000022000
Bluetooth: hci2 command 0x0401 tx timeout
Bluetooth: hci2 command 0x0401 tx timeout
Bluetooth: hci2 command 0x0401 tx timeout