syzbot

=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0 Not tainted
-----------------------------------------------------
kworker/1:11/8130 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff8ee20218 (disc_data_lock){.+.+}-{2:2}, at: ap_get drivers/net/ppp/ppp_async.c:137 [inline]
ffffffff8ee20218 (disc_data_lock){.+.+}-{2:2}, at: ppp_asynctty_wakeup+0x20/0x210 drivers/net/ppp/ppp_async.c:353

and this task is already holding:
ffffffff94a21278 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
ffffffff94a21278 (&port_lock_key){-.-.}-{2:2}, at: serial_port_runtime_resume+0x85/0x2b0 drivers/tty/serial/serial_port.c:41
which would create a new lock dependency:
 (&port_lock_key){-.-.}-{2:2} -> (disc_data_lock){.+.+}-{2:2}

but this new dependency connects a HARDIRQ-irq-safe lock:
 (&port_lock_key){-.-.}-{2:2}

... which became HARDIRQ-irq-safe at:
  lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
  uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
  serial8250_handle_irq+0x81/0x710 drivers/tty/serial/8250/8250_port.c:1903
  serial8250_default_handle_irq+0xd1/0x1f0 drivers/tty/serial/8250/8250_port.c:1952
  serial8250_interrupt+0xa9/0x1f0 drivers/tty/serial/8250/8250_core.c:127
  __handle_irq_event_percpu+0x29a/0xa80 kernel/irq/handle.c:158
  handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
  handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210
  handle_edge_irq+0x25f/0xc20 kernel/irq/chip.c:831
  generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
  handle_irq arch/x86/kernel/irq.c:238 [inline]
  __common_interrupt+0x138/0x230 arch/x86/kernel/irq.c:257
  common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247
  asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
  __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
  _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
  spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
  uart_port_unlock_irqrestore include/linux/serial_core.h:670 [inline]
  serial_port_runtime_resume+0x204/0x2b0 drivers/tty/serial/serial_port.c:44
  __rpm_callback+0x2df/0x790 drivers/base/power/runtime.c:394
  rpm_callback drivers/base/power/runtime.c:448 [inline]
  rpm_resume+0xfca/0x1670 drivers/base/power/runtime.c:914
  pm_runtime_work+0x147/0x210 drivers/base/power/runtime.c:979
  process_one_work kernel/workqueue.c:3254 [inline]
  process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
  worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
  kthread+0x2f0/0x390 kernel/kthread.c:388
  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

to a HARDIRQ-irq-unsafe lock:
 (disc_data_lock){.+.+}-{2:2}

... which became HARDIRQ-irq-unsafe at:
...
  lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
  __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
  _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
  ap_get drivers/net/ppp/ppp_async.c:137 [inline]
  ppp_asynctty_receive+0x40/0x2000 drivers/net/ppp/ppp_async.c:336
  tiocsti+0x24d/0x300 drivers/tty/tty_io.c:2299
  tty_ioctl+0x51e/0xdc0 drivers/tty/tty_io.c:2717
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:904 [inline]
  __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:890
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(disc_data_lock);
                               local_irq_disable();
                               lock(&port_lock_key);
                               lock(disc_data_lock);
  <Interrupt>
    lock(&port_lock_key);

 *** DEADLOCK ***

4 locks held by kworker/1:11/8130:
 #0: ffff888016281548 ((wq_completion)pm){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline]
 #0: ffff888016281548 ((wq_completion)pm){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x17c0 kernel/workqueue.c:3335
 #1: ffffc90004957d00 ((work_completion)(&dev->power.work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline]
 #1: ffffc90004957d00 ((work_completion)(&dev->power.work)){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x17c0 kernel/workqueue.c:3335
 #2: ffffffff94a21278 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
 #2: ffffffff94a21278 (&port_lock_key){-.-.}-{2:2}, at: serial_port_runtime_resume+0x85/0x2b0 drivers/tty/serial/serial_port.c:41
 #3: ffff88805e4170a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263

the dependencies between HARDIRQ-irq-safe lock and the holding lock:
-> (&port_lock_key){-.-.}-{2:2} {
   IN-HARDIRQ-W at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
                    uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
                    serial8250_handle_irq+0x81/0x710 drivers/tty/serial/8250/8250_port.c:1903
                    serial8250_default_handle_irq+0xd1/0x1f0 drivers/tty/serial/8250/8250_port.c:1952
                    serial8250_interrupt+0xa9/0x1f0 drivers/tty/serial/8250/8250_core.c:127
                    __handle_irq_event_percpu+0x29a/0xa80 kernel/irq/handle.c:158
                    handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
                    handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210
                    handle_edge_irq+0x25f/0xc20 kernel/irq/chip.c:831
                    generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
                    handle_irq arch/x86/kernel/irq.c:238 [inline]
                    __common_interrupt+0x138/0x230 arch/x86/kernel/irq.c:257
                    common_interrupt+0xa5/0xd0 arch/x86/kernel/irq.c:247
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
                    _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
                    spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
                    uart_port_unlock_irqrestore include/linux/serial_core.h:670 [inline]
                    serial_port_runtime_resume+0x204/0x2b0 drivers/tty/serial/serial_port.c:44
                    __rpm_callback+0x2df/0x790 drivers/base/power/runtime.c:394
                    rpm_callback drivers/base/power/runtime.c:448 [inline]
                    rpm_resume+0xfca/0x1670 drivers/base/power/runtime.c:914
                    pm_runtime_work+0x147/0x210 drivers/base/power/runtime.c:979
                    process_one_work kernel/workqueue.c:3254 [inline]
                    process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
                    worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
                    kthread+0x2f0/0x390 kernel/kthread.c:388
                    ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
   IN-SOFTIRQ-W at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
                    uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
                    serial8250_handle_irq+0x81/0x710 drivers/tty/serial/8250/8250_port.c:1903
                    serial8250_default_handle_irq+0xd1/0x1f0 drivers/tty/serial/8250/8250_port.c:1952
                    serial8250_interrupt+0xa9/0x1f0 drivers/tty/serial/8250/8250_core.c:127
                    __handle_irq_event_percpu+0x29a/0xa80 kernel/irq/handle.c:158
                    handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
                    handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210
                    handle_edge_irq+0x25f/0xc20 kernel/irq/chip.c:831
                    generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
                    handle_irq arch/x86/kernel/irq.c:238 [inline]
                    __common_interrupt+0x138/0x230 arch/x86/kernel/irq.c:257
                    common_interrupt+0x4f/0xd0 arch/x86/kernel/irq.c:247
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
                    _raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
                    debug_object_deactivate+0x2d5/0x390 lib/debugobjects.c:778
                    debug_rcu_head_unqueue kernel/rcu/rcu.h:239 [inline]
                    rcu_do_batch kernel/rcu/tree.c:2188 [inline]
                    rcu_core+0xa7f/0x1830 kernel/rcu/tree.c:2471
                    __do_softirq+0x2c6/0x980 kernel/softirq.c:554
                    invoke_softirq kernel/softirq.c:428 [inline]
                    __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
                    irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
                    instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
                    sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
                    asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
                    preempt_count arch/x86/include/asm/preempt.h:26 [inline]
                    check_kcov_mode kernel/kcov.c:173 [inline]
                    __sanitizer_cov_trace_pc+0x18/0x70 kernel/kcov.c:207
                    unwind_next_frame+0x1e5b/0x2a00 arch/x86/kernel/unwind_orc.c:665
                    arch_stack_walk+0x151/0x1b0 arch/x86/kernel/stacktrace.c:25
                    stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
                    save_stack+0xfb/0x1f0 mm/page_owner.c:156
                    __set_page_owner+0x8d/0x810 mm/page_owner.c:325
                    set_page_owner include/linux/page_owner.h:32 [inline]
                    post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
                    prep_new_page mm/page_alloc.c:1541 [inline]
                    get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
                    __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
                    __alloc_pages_node include/linux/gfp.h:238 [inline]
                    alloc_pages_node include/linux/gfp.h:261 [inline]
                    alloc_slab_page+0x5f/0x160 mm/slub.c:2175
                    allocate_slab mm/slub.c:2338 [inline]
                    new_slab+0x84/0x2f0 mm/slub.c:2391
                    ___slab_alloc+0xc73/0x1260 mm/slub.c:3525
                    __slab_alloc mm/slub.c:3610 [inline]
                    __slab_alloc_node mm/slub.c:3663 [inline]
                    slab_alloc_node mm/slub.c:3835 [inline]
                    kmem_cache_alloc_lru+0x253/0x350 mm/slub.c:3864
                    alloc_inode_sb include/linux/fs.h:3091 [inline]
                    ext4_alloc_inode+0x2e/0x580 fs/ext4/super.c:1408
                    alloc_inode fs/inode.c:261 [inline]
                    iget_locked+0x1ad/0x850 fs/inode.c:1280
                    __ext4_iget+0x264/0x3ff0 fs/ext4/inode.c:4689
                    ext4_lookup+0x3e3/0x750 fs/ext4/namei.c:1854
                    __lookup_slow+0x28c/0x3f0 fs/namei.c:1692
                    lookup_slow+0x53/0x70 fs/namei.c:1709
                    walk_component+0x2e1/0x410 fs/namei.c:2004
                    lookup_last fs/namei.c:2461 [inline]
                    path_lookupat+0x16f/0x450 fs/namei.c:2485
                    filename_lookup+0x256/0x610 fs/namei.c:2514
                    vfs_statx+0x105/0x4e0 fs/stat.c:244
                    vfs_fstatat+0x135/0x190 fs/stat.c:304
                    __do_sys_newfstatat fs/stat.c:468 [inline]
                    __se_sys_newfstatat fs/stat.c:462 [inline]
                    __x64_sys_newfstatat+0x117/0x190 fs/stat.c:462
                    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                    do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL USE at:
                   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
                   uart_port_lock_irqsave include/linux/serial_core.h:619 [inline]
                   serial8250_do_set_termios+0x4c2/0x1720 drivers/tty/serial/8250/8250_port.c:2745
                   uart_set_options+0x3eb/0x730 drivers/tty/serial/serial_core.c:2320
                   serial8250_console_setup+0x3db/0x670 drivers/tty/serial/8250/8250_port.c:3459
                   univ8250_console_setup+0x3ac/0x470 drivers/tty/serial/8250/8250_core.c:632
                   console_call_setup kernel/printk/printk.c:3287 [inline]
                   try_enable_preferred_console+0x409/0x560 kernel/printk/printk.c:3328
                   register_console+0x261/0xcf0 kernel/printk/printk.c:3506
                   univ8250_console_init+0x49/0x50 drivers/tty/serial/8250/8250_core.c:717
                   console_init+0x1b8/0x6f0 kernel/printk/printk.c:3715
                   start_kernel+0x2d3/0x500 init/main.c:1016
                   x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
                   x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:488
                   common_startup_64+0x13e/0x147
 }
 ... key      at: [<ffffffff94a20660>] port_lock_key+0x0/0x20

the dependencies between the lock to be acquired
 and HARDIRQ-irq-unsafe lock:
-> (disc_data_lock){.+.+}-{2:2} {
   HARDIRQ-ON-R at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                    _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                    ap_get drivers/net/ppp/ppp_async.c:137 [inline]
                    ppp_asynctty_receive+0x40/0x2000 drivers/net/ppp/ppp_async.c:336
                    tiocsti+0x24d/0x300 drivers/tty/tty_io.c:2299
                    tty_ioctl+0x51e/0xdc0 drivers/tty/tty_io.c:2717
                    vfs_ioctl fs/ioctl.c:51 [inline]
                    __do_sys_ioctl fs/ioctl.c:904 [inline]
                    __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:890
                    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                    do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   SOFTIRQ-ON-R at:
                    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                    _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                    ap_get drivers/net/ppp/ppp_async.c:137 [inline]
                    ppp_asynctty_receive+0x40/0x2000 drivers/net/ppp/ppp_async.c:336
                    tiocsti+0x24d/0x300 drivers/tty/tty_io.c:2299
                    tty_ioctl+0x51e/0xdc0 drivers/tty/tty_io.c:2717
                    vfs_ioctl fs/ioctl.c:51 [inline]
                    __do_sys_ioctl fs/ioctl.c:904 [inline]
                    __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:890
                    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                    do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL USE at:
                   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                   __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                   _raw_write_lock_irq+0xd3/0x120 kernel/locking/spinlock.c:326
                   ppp_asynctty_close+0x29/0x190 drivers/net/ppp/ppp_async.c:220
                   tty_ldisc_kill+0xa3/0x1a0 drivers/tty/tty_ldisc.c:607
                   tty_ldisc_release+0x1a1/0x200 drivers/tty/tty_ldisc.c:775
                   tty_release_struct+0x2b/0xe0 drivers/tty/tty_io.c:1696
                   tty_release+0xd0c/0x12c0 drivers/tty/tty_io.c:1867
                   __fput+0x429/0x8a0 fs/file_table.c:422
                   __do_sys_close fs/open.c:1556 [inline]
                   __se_sys_close fs/open.c:1541 [inline]
                   __x64_sys_close+0x7f/0x110 fs/open.c:1541
                   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                   do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL READ USE at:
                        lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
                        __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                        _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
                        ap_get drivers/net/ppp/ppp_async.c:137 [inline]
                        ppp_asynctty_receive+0x40/0x2000 drivers/net/ppp/ppp_async.c:336
                        tiocsti+0x24d/0x300 drivers/tty/tty_io.c:2299
                        tty_ioctl+0x51e/0xdc0 drivers/tty/tty_io.c:2717
                        vfs_ioctl fs/ioctl.c:51 [inline]
                        __do_sys_ioctl fs/ioctl.c:904 [inline]
                        __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:890
                        do_syscall_x64 arch/x86/entry/common.c:52 [inline]
                        do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
                        entry_SYSCALL_64_after_hwframe+0x77/0x7f
 }
 ... key      at: [<ffffffff8ee20218>] disc_data_lock+0x18/0x60
 ... acquired at:
   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
   ap_get drivers/net/ppp/ppp_async.c:137 [inline]
   ppp_asynctty_wakeup+0x20/0x210 drivers/net/ppp/ppp_async.c:353
   tty_wakeup+0xbb/0x100 drivers/tty/tty_io.c:523
   tty_port_default_wakeup+0xa6/0xf0 drivers/tty/tty_port.c:69
   serial8250_tx_chars+0x6ad/0x8a0 drivers/tty/serial/8250/8250_port.c:1825
   __start_tx+0x32e/0x470 drivers/tty/serial/8250/8250_port.c:1534
   serial_port_runtime_resume+0x1f0/0x2b0 drivers/tty/serial/serial_port.c:43
   __rpm_callback+0x2df/0x790 drivers/base/power/runtime.c:394
   rpm_callback drivers/base/power/runtime.c:448 [inline]
   rpm_resume+0xfca/0x1670 drivers/base/power/runtime.c:914
   pm_runtime_work+0x147/0x210 drivers/base/power/runtime.c:979
   process_one_work kernel/workqueue.c:3254 [inline]
   process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
   worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
   kthread+0x2f0/0x390 kernel/kthread.c:388
   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244


stack backtrace:
CPU: 1 PID: 8130 Comm: kworker/1:11 Not tainted 6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: pm pm_runtime_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_bad_irq_dependency kernel/locking/lockdep.c:2626 [inline]
 check_irq_usage kernel/locking/lockdep.c:2865 [inline]
 check_prev_add kernel/locking/lockdep.c:3138 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x4dc7/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
 _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
 ap_get drivers/net/ppp/ppp_async.c:137 [inline]
 ppp_asynctty_wakeup+0x20/0x210 drivers/net/ppp/ppp_async.c:353
 tty_wakeup+0xbb/0x100 drivers/tty/tty_io.c:523
 tty_port_default_wakeup+0xa6/0xf0 drivers/tty/tty_port.c:69
 serial8250_tx_chars+0x6ad/0x8a0 drivers/tty/serial/8250/8250_port.c:1825
 __start_tx+0x32e/0x470 drivers/tty/serial/8250/8250_port.c:1534
 serial_port_runtime_resume+0x1f0/0x2b0 drivers/tty/serial/serial_port.c:43
 __rpm_callback+0x2df/0x790 drivers/base/power/runtime.c:394
 rpm_callback drivers/base/power/runtime.c:448 [inline]
 rpm_resume+0xfca/0x1670 drivers/base/power/runtime.c:914
 pm_runtime_work+0x147/0x210 drivers/base/power/runtime.c:979
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
 kthread+0x2f0/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>