syzbot

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
syzkaller #0 Tainted: G             L     
-----------------------------------------------------
syz.3.6441/22796 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffff88802928af30 (&new->fa_lock){....}-{3:3}, at: kill_fasync_rcu fs/fcntl.c:1135 [inline]
ffff88802928af30 (&new->fa_lock){....}-{3:3}, at: kill_fasync+0x199/0x4d0 fs/fcntl.c:1159

and this task is already holding:
ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: class_spinlock_irqsave_constructor include/linux/spinlock.h:585 [inline]
ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: start_tty drivers/tty/tty_io.c:793 [inline]
ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: tty_send_xchar+0x1c5/0x4d0 drivers/tty/tty_io.c:1153
which would create a new lock dependency:
 (&tty->flow.lock){....}-{3:3} -> (&new->fa_lock){....}-{3:3}

but this new dependency connects a SOFTIRQ-irq-safe lock:
 (kbd_event_lock){..-.}-{3:3}

... which became SOFTIRQ-irq-safe at:
  lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:351 [inline]
  class_spinlock_constructor include/linux/spinlock.h:565 [inline]
  kbd_event+0xd2/0x3fa0 drivers/tty/vt/keyboard.c:1510
  input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2541
  input_pass_values+0x288/0x890 drivers/input/input.c:128
  input_event_dispose+0x3e5/0x6b0 drivers/input/input.c:353
  input_event+0x89/0xe0 drivers/input/input.c:396
  hidinput_hid_event+0x145e/0x1e50 drivers/hid/hid-input.c:1747
  hid_process_event+0x4be/0x620 drivers/hid/hid-core.c:1565
  hid_process_report drivers/hid/hid-core.c:1713 [inline]
  hid_report_raw_event+0xe91/0x1720 drivers/hid/hid-core.c:2074
  __hid_input_report drivers/hid/hid-core.c:2144 [inline]
  hid_input_report+0x44b/0x580 drivers/hid/hid-core.c:2166
  hid_irq_in+0x47e/0x6d0 drivers/hid/usbhid/hid-core.c:286
  __usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1661
  dummy_timer+0x85f/0x45b0 drivers/usb/gadget/udc/dummy_hcd.c:1995
  __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
  __hrtimer_run_queues+0x51c/0xc30 kernel/time/hrtimer.c:1841
  hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1858
  handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622
  __do_softirq kernel/softirq.c:656 [inline]
  invoke_softirq kernel/softirq.c:496 [inline]
  __irq_exit_rcu+0x60/0x150 kernel/softirq.c:723
  irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
  native_irq_enable arch/x86/include/asm/irqflags.h:42 [inline]
  arch_local_irq_enable arch/x86/include/asm/irqflags.h:119 [inline]
  raw_spin_rq_unlock_irq kernel/sched/sched.h:1570 [inline]
  finish_lock_switch kernel/sched/core.c:4995 [inline]
  finish_task_switch+0x242/0x940 kernel/sched/core.c:5112
  context_switch kernel/sched/core.c:5259 [inline]
  __schedule+0x14a3/0x4fd0 kernel/sched/core.c:6863
  __schedule_loop kernel/sched/core.c:6945 [inline]
  schedule+0x165/0x360 kernel/sched/core.c:6960
  schedule_hrtimeout_range_clock+0x13c/0x2f0 kernel/time/sleep_timeout.c:216
  poll_schedule_timeout+0xd1/0x1b0 fs/select.c:241
  do_select+0xc47/0x17d0 fs/select.c:603
  core_sys_select+0x6e2/0xa20 fs/select.c:677
  do_pselect fs/select.c:759 [inline]
  __do_sys_pselect6 fs/select.c:798 [inline]
  __se_sys_pselect6+0x27a/0x300 fs/select.c:789
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

to a SOFTIRQ-irq-unsafe lock:
 (tasklist_lock){.+.+}-{3:3}

... which became SOFTIRQ-irq-unsafe at:
...
  lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
  __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
  _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
  __do_wait+0xde/0x740 kernel/exit.c:1672
  do_wait+0x1e8/0x4f0 kernel/exit.c:1716
  kernel_wait+0xab/0x170 kernel/exit.c:1892
  call_usermodehelper_exec_sync kernel/umh.c:136 [inline]
  call_usermodehelper_exec_work+0xbe/0x230 kernel/umh.c:163
  process_one_work kernel/workqueue.c:3257 [inline]
  process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
  worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
  kthread+0x711/0x8a0 kernel/kthread.c:463
  ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

other info that might help us debug this:

Chain exists of:
  kbd_event_lock --> &tty->flow.lock --> tasklist_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tasklist_lock);
                               local_irq_disable();
                               lock(kbd_event_lock);
                               lock(&tty->flow.lock);
  <Interrupt>
    lock(kbd_event_lock);

 *** DEADLOCK ***

6 locks held by syz.3.6441/22796:
 #0: ffff88807d0a60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffff88807d0a6130 (&tty->atomic_write_lock){+.+.}-{4:4}, at: tty_write_lock drivers/tty/tty_io.c:939 [inline]
 #1: ffff88807d0a6130 (&tty->atomic_write_lock){+.+.}-{4:4}, at: tty_send_xchar+0x170/0x4d0 drivers/tty/tty_io.c:1148
 #2: ffff88807d0a62e8 (&tty->termios_rwsem){++++}-{4:4}, at: tty_send_xchar+0x1af/0x4d0 drivers/tty/tty_io.c:1151
 #3: ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: class_spinlock_irqsave_constructor include/linux/spinlock.h:585 [inline]
 #3: ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: start_tty drivers/tty/tty_io.c:793 [inline]
 #3: ffff88807d0a6468 (&tty->flow.lock){....}-{3:3}, at: tty_send_xchar+0x1c5/0x4d0 drivers/tty/tty_io.c:1153
 #4: ffff88807d0a60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x90 drivers/tty/tty_ldisc.c:263
 #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #5: ffffffff8df41aa0 (rcu_read_lock){....}-{1:3}, at: kill_fasync+0x53/0x4d0 fs/fcntl.c:1158

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
 -> (kbd_event_lock){..-.}-{3:3} {
    IN-SOFTIRQ-W at:
                      lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                      __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
                      _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
                      spin_lock include/linux/spinlock.h:351 [inline]
                      class_spinlock_constructor include/linux/spinlock.h:565 [inline]
                      kbd_event+0xd2/0x3fa0 drivers/tty/vt/keyboard.c:1510
                      input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2541
                      input_pass_values+0x288/0x890 drivers/input/input.c:128
                      input_event_dispose+0x3e5/0x6b0 drivers/input/input.c:353
                      input_event+0x89/0xe0 drivers/input/input.c:396
                      hidinput_hid_event+0x145e/0x1e50 drivers/hid/hid-input.c:1747
                      hid_process_event+0x4be/0x620 drivers/hid/hid-core.c:1565
                      hid_process_report drivers/hid/hid-core.c:1713 [inline]
                      hid_report_raw_event+0xe91/0x1720 drivers/hid/hid-core.c:2074
                      __hid_input_report drivers/hid/hid-core.c:2144 [inline]
                      hid_input_report+0x44b/0x580 drivers/hid/hid-core.c:2166
                      hid_irq_in+0x47e/0x6d0 drivers/hid/usbhid/hid-core.c:286
                      __usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1661
                      dummy_timer+0x85f/0x45b0 drivers/usb/gadget/udc/dummy_hcd.c:1995
                      __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
                      __hrtimer_run_queues+0x51c/0xc30 kernel/time/hrtimer.c:1841
                      hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1858
                      handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622
                      __do_softirq kernel/softirq.c:656 [inline]
                      invoke_softirq kernel/softirq.c:496 [inline]
                      __irq_exit_rcu+0x60/0x150 kernel/softirq.c:723
                      irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
                      instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
                      sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
                      asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
                      native_irq_enable arch/x86/include/asm/irqflags.h:42 [inline]
                      arch_local_irq_enable arch/x86/include/asm/irqflags.h:119 [inline]
                      raw_spin_rq_unlock_irq kernel/sched/sched.h:1570 [inline]
                      finish_lock_switch kernel/sched/core.c:4995 [inline]
                      finish_task_switch+0x242/0x940 kernel/sched/core.c:5112
                      context_switch kernel/sched/core.c:5259 [inline]
                      __schedule+0x14a3/0x4fd0 kernel/sched/core.c:6863
                      __schedule_loop kernel/sched/core.c:6945 [inline]
                      schedule+0x165/0x360 kernel/sched/core.c:6960
                      schedule_hrtimeout_range_clock+0x13c/0x2f0 kernel/time/sleep_timeout.c:216
                      poll_schedule_timeout+0xd1/0x1b0 fs/select.c:241
                      do_select+0xc47/0x17d0 fs/select.c:603
                      core_sys_select+0x6e2/0xa20 fs/select.c:677
                      do_pselect fs/select.c:759 [inline]
                      __do_sys_pselect6 fs/select.c:798 [inline]
                      __se_sys_pselect6+0x27a/0x300 fs/select.c:789
                      do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                      do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                      entry_SYSCALL_64_after_hwframe+0x77/0x7f
    INITIAL USE at:
                     lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                     __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                     _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
                     class_spinlock_irqsave_constructor include/linux/spinlock.h:585 [inline]
                     vt_reset_unicode+0x2b/0x1a0 drivers/tty/vt/keyboard.c:2117
                     reset_vc+0x68/0x1b0 drivers/tty/vt/vt_ioctl.c:966
                     vc_init+0x70/0x4a0 drivers/tty/vt/vt.c:3728
                     con_init+0x385/0x9c0 drivers/tty/vt/vt.c:3793
                     console_init+0xfc/0x3f0 kernel/printk/printk.c:4369
                     start_kernel+0x227/0x3d0 init/main.c:1143
                     x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
                     x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
                     common_startup_64+0x13e/0x147
  }
  ... key      at: [<ffffffff8e783df8>] kbd_event_lock+0x18/0xa0 keyboard.c:-1
-> (&tty->flow.lock){....}-{3:3} {
   INITIAL USE at:
                   lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
                   class_spinlock_irqsave_constructor include/linux/spinlock.h:585 [inline]
                   start_tty+0x20/0x70 drivers/tty/tty_io.c:793
                   n_tty_set_termios+0xa7c/0x10c0 drivers/tty/n_tty.c:1848
                   tty_set_termios+0xda4/0x17e0 drivers/tty/tty_ioctl.c:348
                   set_termios+0x516/0x6c0 drivers/tty/tty_ioctl.c:516
                   tty_mode_ioctl+0x47e/0x740 drivers/tty/tty_ioctl.c:-1
                   tty_ioctl+0x9c6/0xde0 drivers/tty/tty_io.c:2801
                   vfs_ioctl fs/ioctl.c:51 [inline]
                   __do_sys_ioctl fs/ioctl.c:597 [inline]
                   __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
                   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
 }
 ... key      at: [<ffffffff99c0afc0>] alloc_tty_struct.__key.35+0x0/0x20
 ... acquired at:
   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
   _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
   class_spinlock_irqsave_constructor include/linux/spinlock.h:585 [inline]
   stop_tty+0x2f/0x150 drivers/tty/tty_io.c:765
   kbd_keycode drivers/tty/vt/keyboard.c:1497 [inline]
   kbd_event+0x2b9f/0x3fa0 drivers/tty/vt/keyboard.c:1515
   input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2541
   input_pass_values+0x288/0x890 drivers/input/input.c:128
   input_event_dispose+0x330/0x6b0 drivers/input/input.c:342
   input_inject_event+0x1dd/0x340 drivers/input/input.c:424
   evdev_write+0x2fc/0x480 drivers/input/evdev.c:528
   vfs_write+0x27e/0xb30 fs/read_write.c:684
   ksys_write+0x145/0x250 fs/read_write.c:738
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f


the dependencies between the lock to be acquired
 and SOFTIRQ-irq-unsafe lock:
  -> (tasklist_lock){.+.+}-{3:3} {
     HARDIRQ-ON-R at:
                        lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                        __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                        _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                        __do_wait+0xde/0x740 kernel/exit.c:1672
                        do_wait+0x1e8/0x4f0 kernel/exit.c:1716
                        kernel_wait+0xab/0x170 kernel/exit.c:1892
                        call_usermodehelper_exec_sync kernel/umh.c:136 [inline]
                        call_usermodehelper_exec_work+0xbe/0x230 kernel/umh.c:163
                        process_one_work kernel/workqueue.c:3257 [inline]
                        process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
                        worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
                        kthread+0x711/0x8a0 kernel/kthread.c:463
                        ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
                        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
     SOFTIRQ-ON-R at:
                        lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                        __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                        _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                        __do_wait+0xde/0x740 kernel/exit.c:1672
                        do_wait+0x1e8/0x4f0 kernel/exit.c:1716
                        kernel_wait+0xab/0x170 kernel/exit.c:1892
                        call_usermodehelper_exec_sync kernel/umh.c:136 [inline]
                        call_usermodehelper_exec_work+0xbe/0x230 kernel/umh.c:163
                        process_one_work kernel/workqueue.c:3257 [inline]
                        process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
                        worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
                        kthread+0x711/0x8a0 kernel/kthread.c:463
                        ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
                        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
     INITIAL USE at:
                       lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                       __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                       _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:326
                       copy_process+0x2185/0x3950 kernel/fork.c:2367
                       kernel_clone+0x21e/0x820 kernel/fork.c:2651
                       user_mode_thread+0xdd/0x140 kernel/fork.c:2727
                       rest_init+0x23/0x300 init/main.c:722
                       start_kernel+0x381/0x3d0 init/main.c:1206
                       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
                       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
                       common_startup_64+0x13e/0x147
     INITIAL READ USE at:
                            lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                            __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                            _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                            __do_wait+0xde/0x740 kernel/exit.c:1672
                            do_wait+0x1e8/0x4f0 kernel/exit.c:1716
                            kernel_wait+0xab/0x170 kernel/exit.c:1892
                            call_usermodehelper_exec_sync kernel/umh.c:136 [inline]
                            call_usermodehelper_exec_work+0xbe/0x230 kernel/umh.c:163
                            process_one_work kernel/workqueue.c:3257 [inline]
                            process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
                            worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
                            kthread+0x711/0x8a0 kernel/kthread.c:463
                            ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
                            ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
   }
   ... key      at: [<ffffffff8dc0c058>] tasklist_lock+0x18/0x40
   ... acquired at:
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
   send_sigurg+0x12b/0x420 fs/fcntl.c:978
   sk_send_sigurg+0x6c/0x2e0 net/core/sock.c:3669
   queue_oob+0x420/0x4f0 net/unix/af_unix.c:2357
   unix_stream_sendmsg+0xc32/0xde0 net/unix/af_unix.c:2491
   sock_sendmsg_nosec net/socket.c:727 [inline]
   __sock_sendmsg+0x21c/0x270 net/socket.c:742
   ____sys_sendmsg+0x52d/0x820 net/socket.c:2592
   ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
   __sys_sendmmsg+0x227/0x430 net/socket.c:2735
   __do_sys_sendmmsg net/socket.c:2762 [inline]
   __se_sys_sendmmsg net/socket.c:2759 [inline]
   __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2759
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

 -> (&f_owner->lock){....}-{3:3} {
    INITIAL USE at:
                     lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                     __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                     _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:326
                     __f_setown+0x67/0x370 fs/fcntl.c:136
                     generic_add_lease fs/locks.c:1898 [inline]
                     generic_setlease+0xb6c/0xea0 fs/locks.c:1974
                     do_fcntl_add_lease+0x34d/0x460 fs/locks.c:2077
                     fcntl_setlease+0x123/0x180 fs/locks.c:2102
                     do_fcntl+0x867/0x1a50 fs/fcntl.c:535
                     __do_sys_fcntl fs/fcntl.c:602 [inline]
                     __se_sys_fcntl+0xc8/0x150 fs/fcntl.c:587
                     do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                     do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                     entry_SYSCALL_64_after_hwframe+0x77/0x7f
    INITIAL READ USE at:
                          lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                          __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                          _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
                          send_sigurg+0x55/0x420 fs/fcntl.c:962
                          sk_send_sigurg+0x6c/0x2e0 net/core/sock.c:3669
                          queue_oob+0x420/0x4f0 net/unix/af_unix.c:2357
                          unix_stream_sendmsg+0xc32/0xde0 net/unix/af_unix.c:2491
                          sock_sendmsg_nosec net/socket.c:727 [inline]
                          __sock_sendmsg+0x21c/0x270 net/socket.c:742
                          ____sys_sendmsg+0x505/0x820 net/socket.c:2592
                          ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
                          __sys_sendmsg net/socket.c:2678 [inline]
                          __do_sys_sendmsg net/socket.c:2683 [inline]
                          __se_sys_sendmsg net/socket.c:2681 [inline]
                          __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
                          do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                          do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                          entry_SYSCALL_64_after_hwframe+0x77/0x7f
  }
  ... key      at: [<ffffffff9992cc60>] file_f_owner_allocate.__key+0x0/0x20
  ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
   send_sigio+0x38/0x370 fs/fcntl.c:918
   kill_fasync_rcu fs/fcntl.c:1144 [inline]
   kill_fasync+0x24d/0x4d0 fs/fcntl.c:1159
   lease_break_callback+0x26/0x30 fs/locks.c:567
   __break_lease+0x6e3/0x1490 fs/locks.c:1647
   break_deleg include/linux/filelock.h:497 [inline]
   try_break_deleg include/linux/filelock.h:516 [inline]
   vfs_mknod+0x443/0x580 fs/namei.c:4993
   unix_bind_bsd net/unix/af_unix.c:1381 [inline]
   unix_bind+0x543/0xe50 net/unix/af_unix.c:1474
   __sys_bind_socket net/socket.c:1874 [inline]
   __sys_bind+0x2c6/0x3e0 net/socket.c:1905
   __do_sys_bind net/socket.c:1910 [inline]
   __se_sys_bind net/socket.c:1908 [inline]
   __x64_sys_bind+0x7a/0x90 net/socket.c:1908
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> (&new->fa_lock){....}-{3:3} {
   INITIAL USE at:
                   lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                   __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                   _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:326
                   fasync_remove_entry+0xf1/0x1c0 fs/fcntl.c:1012
                   setfl fs/fcntl.c:76 [inline]
                   do_fcntl+0x11d2/0x1a50 fs/fcntl.c:477
                   __do_sys_fcntl fs/fcntl.c:602 [inline]
                   __se_sys_fcntl+0xc8/0x150 fs/fcntl.c:587
                   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL READ USE at:
                        lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
                        __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                        _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
                        kill_fasync_rcu fs/fcntl.c:1135 [inline]
                        kill_fasync+0x199/0x4d0 fs/fcntl.c:1159
                        wakeup_pipe_writers fs/splice.c:420 [inline]
                        splice_to_socket+0xe2a/0xf00 fs/splice.c:917
                        do_splice_from fs/splice.c:938 [inline]
                        do_splice+0xc79/0x1660 fs/splice.c:1351
                        __do_splice fs/splice.c:1433 [inline]
                        __do_sys_splice fs/splice.c:1636 [inline]
                        __se_sys_splice+0x2e1/0x460 fs/splice.c:1618
                        do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                        do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
                        entry_SYSCALL_64_after_hwframe+0x77/0x7f
 }
 ... key      at: [<ffffffff9992cc80>] fasync_insert_entry.__key+0x0/0x20
 ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
   kill_fasync_rcu fs/fcntl.c:1135 [inline]
   kill_fasync+0x199/0x4d0 fs/fcntl.c:1159
   tty_wakeup drivers/tty/tty_io.c:515 [inline]
   __start_tty+0x18c/0x220 drivers/tty/tty_io.c:777
   start_tty drivers/tty/tty_io.c:794 [inline]
   tty_send_xchar+0x1d2/0x4d0 drivers/tty/tty_io.c:1153
   tty_ioctl+0x9c6/0xde0 drivers/tty/tty_io.c:2801
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:597 [inline]
   __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f


stack backtrace:
CPU: 1 UID: 0 PID: 22796 Comm: syz.3.6441 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_bad_irq_dependency kernel/locking/lockdep.c:2616 [inline]
 check_irq_usage kernel/locking/lockdep.c:2857 [inline]
 check_prev_add kernel/locking/lockdep.c:3169 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x2a95/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
 __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
 _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
 kill_fasync_rcu fs/fcntl.c:1135 [inline]
 kill_fasync+0x199/0x4d0 fs/fcntl.c:1159
 tty_wakeup drivers/tty/tty_io.c:515 [inline]
 __start_tty+0x18c/0x220 drivers/tty/tty_io.c:777
 start_tty drivers/tty/tty_io.c:794 [inline]
 tty_send_xchar+0x1d2/0x4d0 drivers/tty/tty_io.c:1153
 tty_ioctl+0x9c6/0xde0 drivers/tty/tty_io.c:2801
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5addb8f749
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5adeae0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5addde5fa0 RCX: 00007f5addb8f749
RDX: 0000000000000002 RSI: 000000000000540a RDI: 0000000000000003
RBP: 00007f5addc13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5addde6038 R14: 00007f5addde5fa0 R15: 00007f5addf0fa28
 </TASK>