RBP: 00007fee6a1f11d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcb8dc909f R14: 00007fee6a1f1300 R15: 0000000000022000
======================================================
WARNING: possible circular locking dependency detected
5.10.223 #1 Not tainted
------------------------------------------------------
syz-executor.2/6120 is trying to acquire lock:
ffffffff84f0ce80 (console_owner){-.-.}-{0:0}, at: console_unlock+0x2e1/0xb40 kernel/printk/printk.c:2513

but task is already holding lock:
ffff88800efdb958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:575

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+0x36/0x60 kernel/locking/spinlock.c:159
       tty_port_tty_get+0x1f/0x100 drivers/tty/tty_port.c:289
       tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:48
       serial8250_tx_chars+0x51f/0xb00 drivers/tty/serial/8250/8250_port.c:1826
       serial8250_handle_irq+0x4e4/0x660 drivers/tty/serial/8250/8250_port.c:1922
       serial8250_default_handle_irq+0x96/0x210 drivers/tty/serial/8250/8250_port.c:1938
       serial8250_interrupt+0xf4/0x1b0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x2ef/0x6d0 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xff/0x280 kernel/irq/handle.c:213
       handle_edge_irq+0x249/0xd00 kernel/irq/chip.c:822
       asm_call_irq_on_stack+0x12/0x20
       __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+0xdd/0x1a0 arch/x86/kernel/irq.c:239
       asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:626
       native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
       arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
       _raw_spin_unlock_irqrestore+0x25/0x40 kernel/locking/spinlock.c:191
       spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
       uart_write+0x304/0x580 drivers/tty/serial/serial_core.c:614
       do_output_char+0x5e8/0x870 drivers/tty/n_tty.c:443
       process_output drivers/tty/n_tty.c:510 [inline]
       n_tty_write+0x4c9/0xfe0 drivers/tty/n_tty.c:2396
       do_tty_write drivers/tty/tty_io.c:1029 [inline]
       file_tty_write.constprop.0+0x529/0x910 drivers/tty/tty_io.c:1119
       redirected_tty_write+0xa5/0xd0 drivers/tty/tty_io.c:1126
       call_write_iter include/linux/fs.h:2002 [inline]
       do_iter_readv_writev+0x476/0x750 fs/read_write.c:740
       do_iter_write+0x191/0x700 fs/read_write.c:866
       vfs_writev+0x1ae/0x620 fs/read_write.c:939
       do_writev+0x139/0x300 fs/read_write.c:982
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x67/0xd1

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x36/0x60 kernel/locking/spinlock.c:159
       serial8250_console_write+0x9f5/0xc60 drivers/tty/serial/8250/8250_port.c:3325
       call_console_drivers kernel/printk/printk.c:1917 [inline]
       console_unlock+0x82a/0xb40 kernel/printk/printk.c:2538
       register_console kernel/printk/printk.c:2902 [inline]
       register_console+0x40c/0x850 kernel/printk/printk.c:2802
       univ8250_console_init+0x3a/0x4a drivers/tty/serial/8250/8250_core.c:700
       console_init+0x24c/0x356 kernel/printk/printk.c:3012
       start_kernel+0x2e6/0x489 init/main.c:981
       secondary_startup_64_no_verify+0xbe/0xcb

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:2988 [inline]
       check_prevs_add kernel/locking/lockdep.c:3113 [inline]
       validate_chain kernel/locking/lockdep.c:3729 [inline]
       __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4955
       lock_acquire kernel/locking/lockdep.c:5566 [inline]
       lock_acquire+0x197/0x470 kernel/locking/lockdep.c:5531
       console_lock_spinning_enable kernel/printk/printk.c:1763 [inline]
       console_unlock+0x360/0xb40 kernel/printk/printk.c:2535
       vprintk_emit+0x1de/0x4e0 kernel/printk/printk.c:2060
       vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401
       printk+0xba/0xf1 kernel/printk/printk.c:2108
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x47a/0x5a0 lib/fault-inject.c:146
       should_failslab+0x5/0x20 mm/slab_common.c:1193
       slab_pre_alloc_hook mm/slab.h:515 [inline]
       slab_alloc_node mm/slub.c:2821 [inline]
       slab_alloc mm/slub.c:2904 [inline]
       __kmalloc+0x72/0x390 mm/slub.c:3967
       kmalloc include/linux/slab.h:557 [inline]
       tty_buffer_alloc+0x243/0x2b0 drivers/tty/tty_buffer.c:175
       __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
       tty_insert_flip_string_fixed_flag+0x91/0x250 drivers/tty/tty_buffer.c:319
       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:576
       pty_write+0xe6/0x110 drivers/tty/pty.c:119
       tty_send_xchar+0x29b/0x3c0 drivers/tty/tty_io.c:1176
       n_tty_ioctl_helper+0x191/0x3a0 drivers/tty/tty_ioctl.c:892
       n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2517
       tty_ioctl+0x912/0x18b0 drivers/tty/tty_io.c:2757
       vfs_ioctl fs/ioctl.c:48 [inline]
       __do_sys_ioctl fs/ioctl.c:753 [inline]
       __se_sys_ioctl fs/ioctl.c:739 [inline]
       __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x67/0xd1

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.2/6120:
 #0: ffff88801b4f8098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x90 drivers/tty/tty_ldisc.c:267
 #1: ffff88801b4f8130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:953 [inline]
 #1: ffff88801b4f8130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_send_xchar+0x1e2/0x3c0 drivers/tty/tty_io.c:1170
 #2: ffff88801b4f82e8 (&tty->termios_rwsem){++++}-{3:3}, at: tty_send_xchar+0x22f/0x3c0 drivers/tty/tty_io.c:1173
 #3: ffff88800efdb958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x2b/0x160 drivers/tty/tty_buffer.c:575
 #4: ffffffff84fed200 (console_lock){+.+.}-{0:0}, at: vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401

stack backtrace:
CPU: 1 PID: 6120 Comm: syz-executor.2 Not tainted 5.10.223 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 check_noncircular+0x263/0x2e0 kernel/locking/lockdep.c:2123
 check_prev_add kernel/locking/lockdep.c:2988 [inline]
 check_prevs_add kernel/locking/lockdep.c:3113 [inline]
 validate_chain kernel/locking/lockdep.c:3729 [inline]
 __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4955
 lock_acquire kernel/locking/lockdep.c:5566 [inline]
 lock_acquire+0x197/0x470 kernel/locking/lockdep.c:5531
 console_lock_spinning_enable kernel/printk/printk.c:1763 [inline]
 console_unlock+0x360/0xb40 kernel/printk/printk.c:2535
 vprintk_emit+0x1de/0x4e0 kernel/printk/printk.c:2060
 vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401
 printk+0xba/0xf1 kernel/printk/printk.c:2108
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x47a/0x5a0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 __kmalloc+0x72/0x390 mm/slub.c:3967
 kmalloc include/linux/slab.h:557 [inline]
 tty_buffer_alloc+0x243/0x2b0 drivers/tty/tty_buffer.c:175
 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
 tty_insert_flip_string_fixed_flag+0x91/0x250 drivers/tty/tty_buffer.c:319
 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:576
 pty_write+0xe6/0x110 drivers/tty/pty.c:119
 tty_send_xchar+0x29b/0x3c0 drivers/tty/tty_io.c:1176
 n_tty_ioctl_helper+0x191/0x3a0 drivers/tty/tty_ioctl.c:892
 n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2517
 tty_ioctl+0x912/0x18b0 drivers/tty/tty_io.c:2757
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x7fee6cc7bb19
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:00007fee6a1f1188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fee6cd8ef60 RCX: 00007fee6cc7bb19
RDX: 0000000000000002 RSI: 000000000000540a RDI: 0000000000000004
RBP: 00007fee6a1f11d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcb8dc909f R14: 00007fee6a1f1300 R15: 0000000000022000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 6125 Comm: syz-executor.4 Not tainted 5.10.223 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 kmem_cache_alloc+0x5b/0x310 mm/slub.c:2909
 mem_pool_alloc mm/kmemleak.c:423 [inline]
 create_object.isra.0+0x3a/0xa20 mm/kmemleak.c:578
 kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
 slab_post_alloc_hook mm/slab.h:534 [inline]
 slab_alloc_node mm/slub.c:2896 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 kmem_cache_alloc+0x159/0x310 mm/slub.c:2909
 __d_alloc+0x2a/0x990 fs/dcache.c:1714
 d_alloc fs/dcache.c:1793 [inline]
 d_alloc_parallel+0x111/0x1bc0 fs/dcache.c:2547
 proc_fill_cache+0x2f6/0x4a0 fs/proc/base.c:2070
 proc_pid_readdir+0x3d3/0x830 fs/proc/base.c:3493
 proc_root_readdir+0xa0/0xd0 fs/proc/root.c:336
 iterate_dir+0x584/0x710 fs/readdir.c:65
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64 fs/readdir.c:354 [inline]
 __x64_sys_getdents64+0x13a/0x2c0 fs/readdir.c:354
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x7f7cf9c49b19
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:00007f7cf71bf188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f7cf9d5cf60 RCX: 00007f7cf9c49b19
RDX: 0000000000001000 RSI: 0000000020000880 RDI: 0000000000000004
RBP: 00007f7cf71bf1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe06d95f4f R14: 00007f7cf71bf300 R15: 0000000000022000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 0 PID: 6134 Comm: syz-executor.0 Not tainted 5.10.223 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 __kmalloc+0x72/0x390 mm/slub.c:3967
 kmalloc include/linux/slab.h:557 [inline]
 tty_buffer_alloc+0x243/0x2b0 drivers/tty/tty_buffer.c:175
 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
 tty_insert_flip_string_fixed_flag+0x91/0x250 drivers/tty/tty_buffer.c:319
 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:576
 pty_write+0xe6/0x110 drivers/tty/pty.c:119
 tty_send_xchar+0x29b/0x3c0 drivers/tty/tty_io.c:1176
 n_tty_ioctl_helper+0x191/0x3a0 drivers/tty/tty_ioctl.c:892
 n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2517
 tty_ioctl+0x912/0x18b0 drivers/tty/tty_io.c:2757
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x7ff9738d4b19
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:00007ff970e4a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff9739e7f60 RCX: 00007ff9738d4b19
RDX: 0000000000000002 RSI: 000000000000540a RDI: 0000000000000004
RBP: 00007ff970e4a1d0 R08: 0000000000000000 R09: 0000000000000000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc3b151fbf R14: 00007ff970e4a300 R15: 0000000000022000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 6136 Comm: syz-executor.4 Not tainted 5.10.223 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 kmem_cache_alloc+0x5b/0x310 mm/slub.c:2909
 proc_alloc_inode+0x18/0x200 fs/proc/inode.c:69
 alloc_inode+0x63/0x240 fs/inode.c:233
 new_inode_pseudo fs/inode.c:929 [inline]
 new_inode+0x23/0x250 fs/inode.c:958
 proc_pid_make_inode+0x22/0x220 fs/proc/base.c:1893
 proc_pid_make_base_inode.constprop.0+0x25/0x180 fs/proc/base.c:1944
 proc_pid_instantiate+0x50/0x1e0 fs/proc/base.c:3372
 proc_fill_cache+0x373/0x4a0 fs/proc/base.c:2075
 proc_pid_readdir+0x3d3/0x830 fs/proc/base.c:3493
 proc_root_readdir+0xa0/0xd0 fs/proc/root.c:336
 iterate_dir+0x584/0x710 fs/readdir.c:65
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64 fs/readdir.c:354 [inline]
 __x64_sys_getdents64+0x13a/0x2c0 fs/readdir.c:354
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x7f7cf9c49b19
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:00007f7cf71bf188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f7cf9d5cf60 RCX: 00007f7cf9c49b19
RDX: 0000000000001000 RSI: 0000000020000880 RDI: 0000000000000004
RBP: 00007f7cf71bf1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe06d95f4f R14: 00007f7cf71bf300 R15: 0000000000022000
CPU: 0 PID: 6132 Comm: syz-executor.2 Not tainted 5.10.223 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x167 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail.cold+0x5/0xa lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 kmem_cache_alloc+0x5b/0x310 mm/slub.c:2909
 mem_pool_alloc mm/kmemleak.c:423 [inline]
 create_object.isra.0+0x3a/0xa20 mm/kmemleak.c:578
 kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
 slab_post_alloc_hook mm/slab.h:534 [inline]
 slab_alloc_node mm/slub.c:2896 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 __kmalloc+0x16e/0x390 mm/slub.c:3967
 kmalloc include/linux/slab.h:557 [inline]
 tty_buffer_alloc+0x243/0x2b0 drivers/tty/tty_buffer.c:175
 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:274
 tty_insert_flip_string_fixed_flag+0x91/0x250 drivers/tty/tty_buffer.c:319
 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:576
 pty_write+0xe6/0x110 drivers/tty/pty.c:119
 tty_send_xchar+0x29b/0x3c0 drivers/tty/tty_io.c:1176
 n_tty_ioctl_helper+0x191/0x3a0 drivers/tty/tty_ioctl.c:892
 n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2517
 tty_ioctl+0x912/0x18b0 drivers/tty/tty_io.c:2757
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x7fee6cc7bb19
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:00007fee6a1f1188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fee6cd8ef60 RCX: 00007fee6cc7bb19
RDX: 0000000000000002 RSI: 000000000000540a RDI: 0000000000000004
RBP: 00007fee6a1f11d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcb8dc909f R14: 00007fee6a1f1300 R15: 0000000000022000