FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
5.17.0-rc4-next-20220217 #1 Not tainted
------------------------------------------------------
syz-executor.5/14581 is trying to acquire lock:
ffffffff85114880 (console_owner){-.-.}-{0:0}, at: console_unlock+0x34e/0xd40

but task is already holding lock:
ffff888019a83158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xea/0x1e0

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+0x39/0x50
       tty_port_tty_get+0x1f/0x100
       tty_port_default_wakeup+0x11/0x40
       serial8250_tx_chars+0x50b/0xb00
       serial8250_start_tx+0x661/0x9f0
       __uart_start.isra.0+0x168/0x1b0
       uart_write+0x2f2/0x580
       do_output_char+0x5e4/0x860
       n_tty_write+0x4c9/0xfe0
       file_tty_write.constprop.0+0x529/0x910
       redirected_tty_write+0xa1/0xc0
       do_iter_readv_writev+0x481/0x760
       do_iter_write+0x18d/0x700
       vfs_writev+0x1aa/0x630
       do_writev+0x139/0x300
       do_syscall_64+0x3b/0x90
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #1 (&port_lock_key){-.-.}-{2:2}:
       _raw_spin_lock_irqsave+0x39/0x50
       serial8250_console_write+0x90e/0xb20
       console_unlock+0x8c7/0xd40
       register_console+0x378/0x7d0
       univ8250_console_init+0x3a/0x46
       console_init+0x3c1/0x58d
       start_kernel+0x301/0x4aa
       secondary_startup_64_no_verify+0xd5/0xdb

-> #0 (console_owner){-.-.}-{0:0}:
       __lock_acquire+0x2c2f/0x6120
       lock_acquire+0x1a2/0x4d0
       console_unlock+0x3a1/0xd40
       vprintk_emit+0x1b4/0x550
       vprintk+0x80/0x90
       _printk+0xba/0xed
       should_fail+0x472/0x5a0
       should_failslab+0x5/0x10
       __kmalloc+0x72/0x440
       tty_buffer_alloc+0x23f/0x2a0
       __tty_buffer_request_room+0x156/0x2a0
       tty_insert_flip_string_fixed_flag+0x91/0x240
       pty_write+0x11c/0x1e0
       n_tty_write+0x416/0xfe0
       file_tty_write.constprop.0+0x529/0x910
       new_sync_write+0x437/0x660
       vfs_write+0x7d1/0xae0
       ksys_write+0x12d/0x250
       do_syscall_64+0x3b/0x90
       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 ***

6 locks held by syz-executor.5/14581:
 #0: ffff88801d71d098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80
 #1: ffff88801d71d130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write.constprop.0+0x29f/0x910
 #2: ffff88801d71d2e8 (&o_tty->termios_rwsem/1){++++}-{3:3}, at: n_tty_write+0x1bf/0xfe0
 #3: ffffc9000108b378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x542/0xfe0
 #4: ffff888019a83158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xea/0x1e0
 #5: ffffffff851f4cc0 (console_lock){+.+.}-{0:0}, at: vprintk+0x80/0x90

stack backtrace:
CPU: 1 PID: 14581 Comm: syz-executor.5 Not tainted 5.17.0-rc4-next-20220217 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8b/0xb3
 check_noncircular+0x25f/0x2e0
 __lock_acquire+0x2c2f/0x6120
 lock_acquire+0x1a2/0x4d0
 console_unlock+0x3a1/0xd40
 vprintk_emit+0x1b4/0x550
 vprintk+0x80/0x90
 _printk+0xba/0xed
 should_fail+0x472/0x5a0
 should_failslab+0x5/0x10
 __kmalloc+0x72/0x440
 tty_buffer_alloc+0x23f/0x2a0
 __tty_buffer_request_room+0x156/0x2a0
 tty_insert_flip_string_fixed_flag+0x91/0x240
 pty_write+0x11c/0x1e0
 n_tty_write+0x416/0xfe0
 file_tty_write.constprop.0+0x529/0x910
 new_sync_write+0x437/0x660
 vfs_write+0x7d1/0xae0
 ksys_write+0x12d/0x250
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f3db00c2b19
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:00007f3dad638188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3db01d5f60 RCX: 00007f3db00c2b19
RDX: 00000000fffffecb RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f3dad6381d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffff5599cbf R14: 00007f3dad638300 R15: 0000000000022000
 </TASK>
CPU: 1 PID: 14581 Comm: syz-executor.5 Not tainted 5.17.0-rc4-next-20220217 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8b/0xb3
 should_fail.cold+0x5/0xa
 should_failslab+0x5/0x10
 __kmalloc+0x72/0x440
 tty_buffer_alloc+0x23f/0x2a0
 __tty_buffer_request_room+0x156/0x2a0
 tty_insert_flip_string_fixed_flag+0x91/0x240
 pty_write+0x11c/0x1e0
 n_tty_write+0x416/0xfe0
 file_tty_write.constprop.0+0x529/0x910
 new_sync_write+0x437/0x660
 vfs_write+0x7d1/0xae0
 ksys_write+0x12d/0x250
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f3db00c2b19
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:00007f3dad638188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3db01d5f60 RCX: 00007f3db00c2b19
RDX: 00000000fffffecb RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f3dad6381d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffff5599cbf R14: 00007f3dad638300 R15: 0000000000022000
 </TASK>