FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
5.16.0-next-20220113-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/17663 is trying to acquire lock:
ffffffff8ba91a80 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1854 [inline]
ffffffff8ba91a80 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x29b/0x4f0 kernel/printk/printk.c:2247

but task is already holding lock:
ffff888091e5b958 (&port->lock){-.-.}-{2:2}, at: pty_write+0xea/0x1e0 drivers/tty/pty.c:120

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:162
       tty_port_tty_get+0x1f/0x100 drivers/tty/tty_port.c:305
       tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:48
       serial8250_tx_chars+0x4f3/0xad0 drivers/tty/serial/8250/8250_port.c:1845
       serial8250_handle_irq.part.0+0x328/0x3d0 drivers/tty/serial/8250/8250_port.c:1932
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1905 [inline]
       serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1949
       serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126
       __handle_irq_event_percpu+0x22b/0x880 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0xa7/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:820
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:231 [inline]
       __common_interrupt+0x9d/0x210 arch/x86/kernel/irq.c:250
       common_interrupt+0xa4/0xc0 arch/x86/kernel/irq.c:240
       asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:629
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
       _raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
       uart_write+0x30d/0x570 drivers/tty/serial/serial_core.c:598
       process_output_block drivers/tty/n_tty.c:581 [inline]
       n_tty_write+0x410/0xfd0 drivers/tty/n_tty.c:2250
       do_tty_write drivers/tty/tty_io.c:1024 [inline]
       file_tty_write.constprop.0+0x526/0x910 drivers/tty/tty_io.c:1095
       redirected_tty_write+0xa1/0xc0 drivers/tty/tty_io.c:1116
       call_write_iter include/linux/fs.h:2074 [inline]
       new_sync_write+0x431/0x660 fs/read_write.c:503
       vfs_write+0x7cd/0xae0 fs/read_write.c:590
       ksys_write+0x12d/0x250 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #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:162
       serial8250_console_write+0xb11/0xe90 drivers/tty/serial/8250/8250_port.c:3387
       call_console_drivers kernel/printk/printk.c:1932 [inline]
       console_unlock+0x7a9/0xb70 kernel/printk/printk.c:2714
       vprintk_emit+0x198/0x4f0 kernel/printk/printk.c:2248
       vprintk+0x80/0x90 kernel/printk/printk_safe.c:50
       _printk+0xba/0xed kernel/printk/printk.c:2269
       register_console kernel/printk/printk.c:3067 [inline]
       register_console+0x410/0x7c0 kernel/printk/printk.c:2948
       univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:679
       console_init+0x3c1/0x58d kernel/printk/printk.c:3167
       start_kernel+0x30b/0x49b init/main.c:1070
       secondary_startup_64_no_verify+0xc3/0xcb

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3063 [inline]
       check_prevs_add kernel/locking/lockdep.c:3186 [inline]
       validate_chain kernel/locking/lockdep.c:3801 [inline]
       __lock_acquire+0x2a2c/0x5470 kernel/locking/lockdep.c:5027
       lock_acquire kernel/locking/lockdep.c:5639 [inline]
       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
       console_trylock_spinning kernel/printk/printk.c:1875 [inline]
       vprintk_emit+0x2d8/0x4f0 kernel/printk/printk.c:2247
       vprintk+0x80/0x90 kernel/printk/printk_safe.c:50
       _printk+0xba/0xed kernel/printk/printk.c:2269
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x472/0x5a0 lib/fault-inject.c:146
       should_failslab+0x5/0x10 mm/slab_common.c:1304
       slab_pre_alloc_hook mm/slab.h:707 [inline]
       slab_alloc_node mm/slub.c:3144 [inline]
       slab_alloc mm/slub.c:3238 [inline]
       __kmalloc+0x72/0x340 mm/slub.c:4420
       kmalloc include/linux/slab.h:586 [inline]
       tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:178
       __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
       tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:321
       tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
       pty_write+0x11c/0x1e0 drivers/tty/pty.c:122
       tty_put_char+0x122/0x150 drivers/tty/tty_io.c:3144
       __process_echoes+0x577/0x9f0 drivers/tty/n_tty.c:711
       flush_echoes drivers/tty/n_tty.c:812 [inline]
       __receive_buf drivers/tty/n_tty.c:1551 [inline]
       n_tty_receive_buf_common+0x1699/0x4780 drivers/tty/n_tty.c:1645
       tiocsti drivers/tty/tty_io.c:2293 [inline]
       tty_ioctl+0x909/0x1660 drivers/tty/tty_io.c:2692
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       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 ***

5 locks held by syz-executor.4/17663:
 #0: ffff8880823b4098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffff888091e5a0b8 (&port->buf.lock/1){+.+.}-{3:3}, at: tiocsti drivers/tty/tty_io.c:2291 [inline]
 #1: ffff888091e5a0b8 (&port->buf.lock/1){+.+.}-{3:3}, at: tty_ioctl+0x89f/0x1660 drivers/tty/tty_io.c:2692
 #2: ffff8880823b42e8 (&o_tty->termios_rwsem/1){++++}-{3:3}, at: n_tty_receive_buf_common+0x84/0x4780 drivers/tty/n_tty.c:1608
 #3: ffffc90006c3b378 (&ldata->output_lock){+.+.}-{3:3}, at: flush_echoes drivers/tty/n_tty.c:810 [inline]
 #3: ffffc90006c3b378 (&ldata->output_lock){+.+.}-{3:3}, at: __receive_buf drivers/tty/n_tty.c:1551 [inline]
 #3: ffffc90006c3b378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_receive_buf_common+0x1663/0x4780 drivers/tty/n_tty.c:1645
 #4: ffff888091e5b958 (&port->lock){-.-.}-{2:2}, at: pty_write+0xea/0x1e0 drivers/tty/pty.c:120

stack backtrace:
CPU: 1 PID: 17663 Comm: syz-executor.4 Not tainted 5.16.0-next-20220113-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2143
 check_prev_add kernel/locking/lockdep.c:3063 [inline]
 check_prevs_add kernel/locking/lockdep.c:3186 [inline]
 validate_chain kernel/locking/lockdep.c:3801 [inline]
 __lock_acquire+0x2a2c/0x5470 kernel/locking/lockdep.c:5027
 lock_acquire kernel/locking/lockdep.c:5639 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
 console_trylock_spinning kernel/printk/printk.c:1875 [inline]
 vprintk_emit+0x2d8/0x4f0 kernel/printk/printk.c:2247
 vprintk+0x80/0x90 kernel/printk/printk_safe.c:50
 _printk+0xba/0xed kernel/printk/printk.c:2269
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x472/0x5a0 lib/fault-inject.c:146
 should_failslab+0x5/0x10 mm/slab_common.c:1304
 slab_pre_alloc_hook mm/slab.h:707 [inline]
 slab_alloc_node mm/slub.c:3144 [inline]
 slab_alloc mm/slub.c:3238 [inline]
 __kmalloc+0x72/0x340 mm/slub.c:4420
 kmalloc include/linux/slab.h:586 [inline]
 tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:178
 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
 tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:321
 tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
 pty_write+0x11c/0x1e0 drivers/tty/pty.c:122
 tty_put_char+0x122/0x150 drivers/tty/tty_io.c:3144
 __process_echoes+0x577/0x9f0 drivers/tty/n_tty.c:711
 flush_echoes drivers/tty/n_tty.c:812 [inline]
 __receive_buf drivers/tty/n_tty.c:1551 [inline]
 n_tty_receive_buf_common+0x1699/0x4780 drivers/tty/n_tty.c:1645
 tiocsti drivers/tty/tty_io.c:2293 [inline]
 tty_ioctl+0x909/0x1660 drivers/tty/tty_io.c:2692
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2bf1361eb9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2befcd7168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2bf1474f60 RCX: 00007f2bf1361eb9
RDX: 0000000020000380 RSI: 0000000000005412 RDI: 0000000000000004
RBP: 00007f2befcd71d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe1cd25caf R14: 00007f2befcd7300 R15: 0000000000022000
 </TASK>
CPU: 1 PID: 17663 Comm: syz-executor.4 Not tainted 5.16.0-next-20220113-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x10 mm/slab_common.c:1304
 slab_pre_alloc_hook mm/slab.h:707 [inline]
 slab_alloc_node mm/slub.c:3144 [inline]
 slab_alloc mm/slub.c:3238 [inline]
 __kmalloc+0x72/0x340 mm/slub.c:4420
 kmalloc include/linux/slab.h:586 [inline]
 tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:178
 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
 tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:321
 tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
 pty_write+0x11c/0x1e0 drivers/tty/pty.c:122
 tty_put_char+0x122/0x150 drivers/tty/tty_io.c:3144
 __process_echoes+0x577/0x9f0 drivers/tty/n_tty.c:711
 flush_echoes drivers/tty/n_tty.c:812 [inline]
 __receive_buf drivers/tty/n_tty.c:1551 [inline]
 n_tty_receive_buf_common+0x1699/0x4780 drivers/tty/n_tty.c:1645
 tiocsti drivers/tty/tty_io.c:2293 [inline]
 tty_ioctl+0x909/0x1660 drivers/tty/tty_io.c:2692
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2bf1361eb9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2befcd7168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2bf1474f60 RCX: 00007f2bf1361eb9
RDX: 0000000020000380 RSI: 0000000000005412 RDI: 0000000000000004
RBP: 00007f2befcd71d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe1cd25caf R14: 00007f2befcd7300 R15: 0000000000022000
 </TASK>