syzbot

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
syzkaller #0 Tainted: G             L     
-----------------------------------------------------
syz.1.6834/745 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff8e60a058 (tasklist_lock){.+.+}-{3:3}, at: send_sigurg+0x12b/0x420 fs/fcntl.c:978

and this task is already holding:
ffff888034a070a0 (&f_owner->lock){....}-{3:3}, at: send_sigurg+0x55/0x420 fs/fcntl.c:962
which would create a new lock dependency:
 (&f_owner->lock){....}-{3:3} -> (tasklist_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+0x106/0x350 kernel/locking/lockdep.c:5868
  __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
  spin_lock include/linux/spinlock.h:342 [inline]
  class_spinlock_constructor include/linux/spinlock.h:587 [inline]
  kbd_event+0xd7/0x42f0 drivers/tty/vt/keyboard.c:1578
  input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2558
  input_pass_values+0x288/0x890 drivers/input/input.c:128
  input_event_dispose+0x3e5/0x6b0 drivers/input/input.c:353
  input_event+0x84/0xc0 drivers/input/input.c:396
  hidinput_hid_event+0x13df/0x1ec0 drivers/hid/hid-input.c:1760
  hid_process_event+0x4be/0x620 drivers/hid/hid-core.c:1576
  hid_process_report drivers/hid/hid-core.c:1724 [inline]
  hid_report_raw_event+0xed6/0x1850 drivers/hid/hid-core.c:2095
  __hid_input_report+0x45c/0x590 drivers/hid/hid-core.c:2166
  hid_irq_in+0x495/0x710 drivers/hid/usbhid/hid-core.c:286
  __usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1655
  dummy_timer+0xbc0/0x4650 drivers/usb/gadget/udc/dummy_hcd.c:2005
  __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
  __hrtimer_run_queues+0x3c0/0xa20 kernel/time/hrtimer.c:1994
  hrtimer_run_softirq+0x17a/0x240 kernel/time/hrtimer.c:2011
  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
  __do_softirq kernel/softirq.c:656 [inline]
  invoke_softirq kernel/softirq.c:496 [inline]
  __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
  irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
  rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
  rcu_is_watching+0x3a/0xb0 kernel/rcu/tree.c:752
  trace_lock_release include/trace/events/lock.h:69 [inline]
  lock_release+0x4b/0x3c0 kernel/locking/lockdep.c:5879
  rcu_lock_release include/linux/rcupdate.h:310 [inline]
  rcu_read_unlock include/linux/rcupdate.h:869 [inline]
  class_rcu_destructor include/linux/rcupdate.h:1181 [inline]
  unwind_next_frame+0x1bba/0x2550 arch/x86/kernel/unwind_orc.c:709
  arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
  stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
  save_stack+0x122/0x230 mm/page_owner.c:165
  __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
  set_page_owner include/linux/page_owner.h:32 [inline]
  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
  prep_new_page mm/page_alloc.c:1861 [inline]
  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
  alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
  folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2509
  vma_alloc_folio_noprof+0xe1/0x1e0 mm/mempolicy.c:2544
  folio_prealloc mm/memory.c:-1 [inline]
  alloc_anon_folio mm/memory.c:5298 [inline]
  do_anonymous_page mm/memory.c:5392 [inline]
  do_pte_missing+0x159d/0x33f0 mm/memory.c:4564
  handle_pte_fault mm/memory.c:6427 [inline]
  __handle_mm_fault mm/memory.c:6565 [inline]
  handle_mm_fault+0x1bf2/0x3170 mm/memory.c:6734
  do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
  handle_page_fault arch/x86/mm/fault.c:1474 [inline]
  exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
  asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

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

... which became SOFTIRQ-irq-unsafe at:
...
  lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
  __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
  _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
  __do_wait+0xde/0x740 kernel/exit.c:1679
  do_wait+0x1e7/0x510 kernel/exit.c:1723
  kernel_wait+0xd6/0x1c0 kernel/exit.c:1899
  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:3314 [inline]
  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
  kthread+0x389/0x470 kernel/kthread.c:436
  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  kbd_event_lock --> &f_owner->lock --> tasklist_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tasklist_lock);
                               local_irq_disable();
                               lock(kbd_event_lock);
                               lock(&f_owner->lock);
  <Interrupt>
    lock(kbd_event_lock);

 *** DEADLOCK ***

2 locks held by syz.1.6834/745:
 #0: ffff88807a6bd350 (&u->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
 #0: ffff88807a6bd350 (&u->lock){+.+.}-{3:3}, at: queue_oob+0x1b6/0x4f0 net/unix/af_unix.c:2347
 #1: ffff888034a070a0 (&f_owner->lock){....}-{3:3}, at: send_sigurg+0x55/0x420 fs/fcntl.c:962

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
   -> (kbd_event_lock){..-.}-{3:3} {
      IN-SOFTIRQ-W at:
                          lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                          __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
                          _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
                          spin_lock include/linux/spinlock.h:342 [inline]
                          class_spinlock_constructor include/linux/spinlock.h:587 [inline]
                          kbd_event+0xd7/0x42f0 drivers/tty/vt/keyboard.c:1578
                          input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2558
                          input_pass_values+0x288/0x890 drivers/input/input.c:128
                          input_event_dispose+0x3e5/0x6b0 drivers/input/input.c:353
                          input_event+0x84/0xc0 drivers/input/input.c:396
                          hidinput_hid_event+0x13df/0x1ec0 drivers/hid/hid-input.c:1760
                          hid_process_event+0x4be/0x620 drivers/hid/hid-core.c:1576
                          hid_process_report drivers/hid/hid-core.c:1724 [inline]
                          hid_report_raw_event+0xed6/0x1850 drivers/hid/hid-core.c:2095
                          __hid_input_report+0x45c/0x590 drivers/hid/hid-core.c:2166
                          hid_irq_in+0x495/0x710 drivers/hid/usbhid/hid-core.c:286
                          __usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1655
                          dummy_timer+0xbc0/0x4650 drivers/usb/gadget/udc/dummy_hcd.c:2005
                          __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
                          __hrtimer_run_queues+0x3c0/0xa20 kernel/time/hrtimer.c:1994
                          hrtimer_run_softirq+0x17a/0x240 kernel/time/hrtimer.c:2011
                          handle_softirqs+0x22a/0x840 kernel/softirq.c:622
                          __do_softirq kernel/softirq.c:656 [inline]
                          invoke_softirq kernel/softirq.c:496 [inline]
                          __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
                          irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
                          instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
                          sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
                          asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
                          rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
                          rcu_is_watching+0x3a/0xb0 kernel/rcu/tree.c:752
                          trace_lock_release include/trace/events/lock.h:69 [inline]
                          lock_release+0x4b/0x3c0 kernel/locking/lockdep.c:5879
                          rcu_lock_release include/linux/rcupdate.h:310 [inline]
                          rcu_read_unlock include/linux/rcupdate.h:869 [inline]
                          class_rcu_destructor include/linux/rcupdate.h:1181 [inline]
                          unwind_next_frame+0x1bba/0x2550 arch/x86/kernel/unwind_orc.c:709
                          arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
                          stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
                          save_stack+0x122/0x230 mm/page_owner.c:165
                          __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
                          set_page_owner include/linux/page_owner.h:32 [inline]
                          post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
                          prep_new_page mm/page_alloc.c:1861 [inline]
                          get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
                          __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
                          alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
                          folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2509
                          vma_alloc_folio_noprof+0xe1/0x1e0 mm/mempolicy.c:2544
                          folio_prealloc mm/memory.c:-1 [inline]
                          alloc_anon_folio mm/memory.c:5298 [inline]
                          do_anonymous_page mm/memory.c:5392 [inline]
                          do_pte_missing+0x159d/0x33f0 mm/memory.c:4564
                          handle_pte_fault mm/memory.c:6427 [inline]
                          __handle_mm_fault mm/memory.c:6565 [inline]
                          handle_mm_fault+0x1bf2/0x3170 mm/memory.c:6734
                          do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
                          handle_page_fault arch/x86/mm/fault.c:1474 [inline]
                          exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
                          asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
      INITIAL USE at:
                         lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                         __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
                         _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
                         class_spinlock_irqsave_constructor include/linux/spinlock.h:619 [inline]
                         vt_reset_unicode+0x2b/0x160 drivers/tty/vt/keyboard.c:2194
                         reset_vc+0x68/0x1b0 drivers/tty/vt/vt_ioctl.c:966
                         vc_init+0x70/0x4a0 drivers/tty/vt/vt.c:3823
                         con_init+0x377/0x6a0 drivers/tty/vt/vt.c:3889
                         console_init+0x10b/0x4a0 kernel/printk/printk.c:4407
                         start_kernel+0x230/0x3e0 init/main.c:1157
                         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: [<ffffffff8f20d658>] kbd_event_lock+0x18/0xa0 keyboard.c:-1
  -> (&tty->flow.lock){....}-{3:3} {
     INITIAL USE at:
                       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
                       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
                       class_spinlock_irqsave_constructor include/linux/spinlock.h:619 [inline]
                       start_tty+0x1b/0x50 drivers/tty/tty_io.c:793
                       n_tty_set_termios+0xa7c/0x10a0 drivers/tty/n_tty.c:1848
                       tty_set_termios+0xdb3/0x1800 drivers/tty/tty_ioctl.c:348
                       set_termios+0x566/0x710 drivers/tty/tty_ioctl.c:516
                       tty_mode_ioctl+0x4a6/0x7d0 drivers/tty/tty_ioctl.c:-1
                       tty_ioctl+0x9c5/0xde0 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+0x174/0x580 arch/x86/entry/syscall_64.c:94
                       entry_SYSCALL_64_after_hwframe+0x77/0x7f
   }
   ... key      at: [<ffffffff9a78d860>] alloc_tty_struct.__key.35+0x0/0x20
   ... acquired at:
   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
   _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
   class_spinlock_irqsave_constructor include/linux/spinlock.h:619 [inline]
   stop_tty+0x2f/0x140 drivers/tty/tty_io.c:765
   kbd_keycode drivers/tty/vt/keyboard.c:1565 [inline]
   kbd_event+0x2f91/0x42f0 drivers/tty/vt/keyboard.c:1583
   input_handle_events_default+0xd4/0x1a0 drivers/input/input.c:2558
   input_pass_values+0x288/0x890 drivers/input/input.c:128
   input_event_dispose+0x330/0x6b0 drivers/input/input.c:342
   input_inject_event+0x1dc/0x330 drivers/input/input.c:424
   evdev_write+0x325/0x4c0 drivers/input/evdev.c:528
   vfs_write+0x29a/0xb90 fs/read_write.c:686
   ksys_write+0x150/0x270 fs/read_write.c:740
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

 -> (&new->fa_lock){....}-{3:3} {
    INITIAL USE at:
                     lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                     __raw_write_lock_irq include/linux/rwlock_api_smp.h:213 [inline]
                     _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:330
                     fasync_remove_entry+0xf1/0x1c0 fs/fcntl.c:1012
                     lease_modify+0x4f7/0x6c0 fs/locks.c:1514
                     locks_remove_lease fs/locks.c:2773 [inline]
                     locks_remove_file+0x5f0/0xf70 fs/locks.c:2798
                     __fput+0x3ae/0xa60 fs/file_table.c:502
                     task_work_run+0x1d9/0x270 kernel/task_work.c:233
                     get_signal+0x11eb/0x1330 kernel/signal.c:2809
                     arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
                     __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
                     exit_to_user_mode_loop+0xa9/0x680 kernel/entry/common.c:98
                     __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
                     syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
                     syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
                     do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
                     entry_SYSCALL_64_after_hwframe+0x77/0x7f
    INITIAL READ USE at:
                          lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                          __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:174 [inline]
                          _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:240
                          kill_fasync_rcu fs/fcntl.c:1135 [inline]
                          kill_fasync+0x199/0x4d0 fs/fcntl.c:1159
                          lease_break_callback+0x26/0x30 fs/locks.c:577
                          __break_lease+0x81f/0x1ea0 fs/locks.c:1669
                          break_deleg include/linux/filelock.h:505 [inline]
                          try_break_deleg+0xfc/0x180 include/linux/filelock.h:524
                          notify_change+0xb5a/0xf40 fs/attr.c:550
                          chmod_common+0x273/0x4a0 fs/open.c:637
                          do_fchmodat+0x12d/0x230 fs/open.c:682
                          __do_sys_chmod fs/open.c:706 [inline]
                          __se_sys_chmod fs/open.c:704 [inline]
                          __x64_sys_chmod+0x62/0x70 fs/open.c:704
                          do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                          do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
                          entry_SYSCALL_64_after_hwframe+0x77/0x7f
  }
  ... key      at: [<ffffffff9a4b08a0>] fasync_insert_entry.__key+0x0/0x20
  ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:174 [inline]
   _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:240
   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+0x1cf/0x4b0 drivers/tty/tty_io.c:1153
   tty_ioctl+0x9c5/0xde0 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+0x174/0x580 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> (&f_owner->lock){....}-{3:3} {
   INITIAL USE at:
                   lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                   __raw_write_lock_irq include/linux/rwlock_api_smp.h:213 [inline]
                   _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:330
                   __f_setown+0x67/0x370 fs/fcntl.c:136
                   generic_add_lease fs/locks.c:1924 [inline]
                   generic_setlease+0xacf/0xfd0 fs/locks.c:2000
                   do_fcntl_add_lease+0x35e/0x470 fs/locks.c:2102
                   fcntl_setdeleg+0x14c/0x1e0 fs/locks.c:2148
                   do_fcntl+0xe6d/0x1a20 fs/fcntl.c:564
                   __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+0x174/0x580 arch/x86/entry/syscall_64.c:94
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL READ USE at:
                        lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                        __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:174 [inline]
                        _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:240
                        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:577
                        __break_lease+0x81f/0x1ea0 fs/locks.c:1669
                        break_deleg include/linux/filelock.h:505 [inline]
                        try_break_deleg+0xfc/0x180 include/linux/filelock.h:524
                        notify_change+0xb5a/0xf40 fs/attr.c:550
                        chmod_common+0x273/0x4a0 fs/open.c:637
                        do_fchmodat+0x12d/0x230 fs/open.c:682
                        __do_sys_chmod fs/open.c:706 [inline]
                        __se_sys_chmod fs/open.c:704 [inline]
                        __x64_sys_chmod+0x62/0x70 fs/open.c:704
                        do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                        do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
                        entry_SYSCALL_64_after_hwframe+0x77/0x7f
 }
 ... key      at: [<ffffffff9a4b0880>] file_f_owner_allocate.__key+0x0/0x20
 ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:174 [inline]
   _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:240
   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:577
   __break_lease+0x81f/0x1ea0 fs/locks.c:1669
   break_deleg include/linux/filelock.h:505 [inline]
   try_break_deleg+0xfc/0x180 include/linux/filelock.h:524
   notify_change+0xb5a/0xf40 fs/attr.c:550
   chmod_common+0x273/0x4a0 fs/open.c:637
   do_fchmodat+0x12d/0x230 fs/open.c:682
   __do_sys_chmod fs/open.c:706 [inline]
   __se_sys_chmod fs/open.c:704 [inline]
   __x64_sys_chmod+0x62/0x70 fs/open.c:704
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x174/0x580 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+0x106/0x350 kernel/locking/lockdep.c:5868
                    __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
                    _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
                    __do_wait+0xde/0x740 kernel/exit.c:1679
                    do_wait+0x1e7/0x510 kernel/exit.c:1723
                    kernel_wait+0xd6/0x1c0 kernel/exit.c:1899
                    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:3314 [inline]
                    process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
                    worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
                    kthread+0x389/0x470 kernel/kthread.c:436
                    ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   SOFTIRQ-ON-R at:
                    lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                    __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
                    _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
                    __do_wait+0xde/0x740 kernel/exit.c:1679
                    do_wait+0x1e7/0x510 kernel/exit.c:1723
                    kernel_wait+0xd6/0x1c0 kernel/exit.c:1899
                    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:3314 [inline]
                    process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
                    worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
                    kthread+0x389/0x470 kernel/kthread.c:436
                    ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   INITIAL USE at:
                   lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
                   __raw_write_lock_irq include/linux/rwlock_api_smp.h:213 [inline]
                   _raw_write_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:330
                   copy_process+0x2b4c/0x4440 kernel/fork.c:2411
                   kernel_clone+0x2d7/0x940 kernel/fork.c:2722
                   user_mode_thread+0x110/0x180 kernel/fork.c:2798
                   rest_init+0x23/0x300 init/main.c:727
                   start_kernel+0x38a/0x3e0 init/main.c:1220
                   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+0x106/0x350 kernel/locking/lockdep.c:5868
                        __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
                        _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
                        __do_wait+0xde/0x740 kernel/exit.c:1679
                        do_wait+0x1e7/0x510 kernel/exit.c:1723
                        kernel_wait+0xd6/0x1c0 kernel/exit.c:1899
                        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:3314 [inline]
                        process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
                        worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
                        kthread+0x389/0x470 kernel/kthread.c:436
                        ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
                        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 }
 ... key      at: [<ffffffff8e60a058>] tasklist_lock+0x18/0x40
 ... acquired at:
   __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
   _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
   send_sigurg+0x12b/0x420 fs/fcntl.c:978
   sk_send_sigurg+0x6c/0x2e0 net/core/sock.c:3672
   queue_oob+0x42c/0x4f0 net/unix/af_unix.c:2368
   unix_stream_sendmsg+0xcb1/0xe80 net/unix/af_unix.c:2502
   sock_sendmsg_nosec net/socket.c:787 [inline]
   __sock_sendmsg net/socket.c:802 [inline]
   ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
   ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
   __sys_sendmmsg+0x27c/0x4e0 net/socket.c:2841
   __do_sys_sendmmsg net/socket.c:2868 [inline]
   __se_sys_sendmmsg net/socket.c:2865 [inline]
   __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2865
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f


stack backtrace:
CPU: 1 UID: 0 PID: 745 Comm: syz.1.6834 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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+0x2a94/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
 _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:232
 send_sigurg+0x12b/0x420 fs/fcntl.c:978
 sk_send_sigurg+0x6c/0x2e0 net/core/sock.c:3672
 queue_oob+0x42c/0x4f0 net/unix/af_unix.c:2368
 unix_stream_sendmsg+0xcb1/0xe80 net/unix/af_unix.c:2502
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
 __sys_sendmmsg+0x27c/0x4e0 net/socket.c:2841
 __do_sys_sendmmsg net/socket.c:2868 [inline]
 __se_sys_sendmmsg net/socket.c:2865 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2865
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbdd1d9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbdd2c09028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fbdd2015fa0 RCX: 00007fbdd1d9ce59
RDX: 0000000000000001 RSI: 0000200000006c40 RDI: 0000000000000004
RBP: 00007fbdd1e32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000040015 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbdd2016038 R14: 00007fbdd2015fa0 R15: 00007fbdd213fa48
 </TASK>