syzbot

 sign-in | mailing list | source | docs
🐞 Open [1595]
≡ Subsystems
🐞 Fixed [6149]
🐞 Invalid [15385]
⬇ Missing Backports [172]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

possible deadlock in serial8250_handle_irq

Status: upstream: reported on 2023/07/22 01:33
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+5fd749c74105b0e1b302@syzkaller.appspotmail.com
First crash: 624d, last: 4d13h
▶ ▼ Discussions (6)
Title Replies (including bot) Last reply
[syzbot] Monthly hams report (Mar 2025) 0 (1) 2025/03/19 21:27
[syzbot] Monthly hams report (Feb 2025) 0 (1) 2025/02/16 21:54
[syzbot] Monthly hams report (Jan 2025) 0 (1) 2025/01/16 10:12
[syzbot] Monthly hams report (Dec 2024) 0 (1) 2024/12/16 09:45
[syzbot] Monthly hams report (Aug 2024) 0 (1) 2024/08/13 08:52
[syzbot] [ppp?] possible deadlock in serial8250_handle_irq 0 (1) 2023/07/22 01:33
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in serial8250_handle_irq 1 106d 106d 0/3 auto-obsoleted due to no activity on 2025/03/27 21:41

Sample crash report:
=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.14.0-syzkaller-07540-geff5f16bfd87 #0 Not tainted
-----------------------------------------------------
kworker/u8:2/36 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff8f568038 (disc_data_lock#3){.?.+}-{3:3}, at: sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370

and this task is already holding:
ffffffff9adc5138 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
ffffffff9adc5138 (&port_lock_key){-.-.}-{3:3}, at: uart_write+0x13b/0xb30 drivers/tty/serial/serial_core.c:626
which would create a new lock dependency:
 (&port_lock_key){-.-.}-{3:3} -> (disc_data_lock#3){.?.+}-{3:3}

but this new dependency connects a HARDIRQ-irq-safe lock:
 (&port_lock_key){-.-.}-{3:3}

... which became HARDIRQ-irq-safe at:
  lock_acquire kernel/locking/lockdep.c:5866 [inline]
  lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
  uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
  serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921
  serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970
  serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
  __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
  handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
  handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
  handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
  generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
  handle_irq arch/x86/kernel/irq.c:254 [inline]
  call_irq_handler arch/x86/kernel/irq.c:266 [inline]
  __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
  common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
  asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
  __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
  _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
  spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
  uart_port_unlock_irqrestore include/linux/serial_core.h:786 [inline]
  uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:636
  process_output_block drivers/tty/n_tty.c:574 [inline]
  n_tty_write+0x41f/0x1150 drivers/tty/n_tty.c:2389
  iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
  file_tty_write.constprop.0+0x512/0x9b0 drivers/tty/tty_io.c:1090
  tty_write drivers/tty/tty_io.c:1111 [inline]
  redirected_tty_write drivers/tty/tty_io.c:1134 [inline]
  redirected_tty_write+0xd4/0x150 drivers/tty/tty_io.c:1114
  new_sync_write fs/read_write.c:591 [inline]
  vfs_write+0x5ba/0x1180 fs/read_write.c:684
  ksys_write+0x12a/0x240 fs/read_write.c:736
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

to a HARDIRQ-irq-unsafe lock:
 (disc_data_lock#3){.?.+}-{3:3}

... which became HARDIRQ-irq-unsafe at:
...
  lock_acquire kernel/locking/lockdep.c:5866 [inline]
  lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
  __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
  _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
  sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
  sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline]
  sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424
  tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
  tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
  receive_buf drivers/tty/tty_buffer.c:445 [inline]
  flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
  process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
  process_scheduled_works kernel/workqueue.c:3319 [inline]
  worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
  kthread+0x3c2/0x780 kernel/kthread.c:464
  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(disc_data_lock#3);
                               local_irq_disable();
                               lock(&port_lock_key);
                               lock(disc_data_lock#3);
  <Interrupt>
    lock(&port_lock_key);

 *** DEADLOCK ***

6 locks held by kworker/u8:2/36:
 #0: ffff88801b481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc90000ad7d18 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffff8880258c0ca0 (&buf->lock){+.+.}-{4:4}, at: flush_to_ldisc+0x34/0x780 drivers/tty/tty_buffer.c:467
 #3: ffff888077cf00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263
 #4: ffffffff9adc5138 (&port_lock_key){-.-.}-{3:3}, at: uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
 #4: ffffffff9adc5138 (&port_lock_key){-.-.}-{3:3}, at: uart_write+0x13b/0xb30 drivers/tty/serial/serial_core.c:626
 #5: ffff888077cf00a0 (&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){-.-.}-{3:3} {
   IN-HARDIRQ-W at:
                    lock_acquire kernel/locking/lockdep.c:5866 [inline]
                    lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
                    uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
                    serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921
                    serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970
                    serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
                    __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
                    handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
                    handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
                    handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
                    generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
                    handle_irq arch/x86/kernel/irq.c:254 [inline]
                    call_irq_handler arch/x86/kernel/irq.c:266 [inline]
                    __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
                    common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
                    _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
                    spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
                    uart_port_unlock_irqrestore include/linux/serial_core.h:786 [inline]
                    uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:636
                    process_output_block drivers/tty/n_tty.c:574 [inline]
                    n_tty_write+0x41f/0x1150 drivers/tty/n_tty.c:2389
                    iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
                    file_tty_write.constprop.0+0x512/0x9b0 drivers/tty/tty_io.c:1090
                    tty_write drivers/tty/tty_io.c:1111 [inline]
                    redirected_tty_write drivers/tty/tty_io.c:1134 [inline]
                    redirected_tty_write+0xd4/0x150 drivers/tty/tty_io.c:1114
                    new_sync_write fs/read_write.c:591 [inline]
                    vfs_write+0x5ba/0x1180 fs/read_write.c:684
                    ksys_write+0x12a/0x240 fs/read_write.c:736
                    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                    do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
                    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   IN-SOFTIRQ-W at:
                    lock_acquire kernel/locking/lockdep.c:5866 [inline]
                    lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
                    uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
                    serial8250_handle_irq+0x95/0xcb0 drivers/tty/serial/8250/8250_port.c:1921
                    serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970
                    serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
                    __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
                    handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
                    handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
                    handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
                    generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
                    handle_irq arch/x86/kernel/irq.c:254 [inline]
                    call_irq_handler arch/x86/kernel/irq.c:266 [inline]
                    __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
                    common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __orc_find+0x65/0xf0 arch/x86/kernel/unwind_orc.c:100
                    orc_find arch/x86/kernel/unwind_orc.c:227 [inline]
                    unwind_next_frame+0x2be/0x1ff0 arch/x86/kernel/unwind_orc.c:494
                    __unwind_start+0x45f/0x7f0 arch/x86/kernel/unwind_orc.c:760
                    unwind_start arch/x86/include/asm/unwind.h:64 [inline]
                    arch_stack_walk+0x73/0x100 arch/x86/kernel/stacktrace.c:24
                    stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
                    kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
                    kasan_save_track+0x14/0x30 mm/kasan/common.c:68
                    kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
                    poison_slab_object mm/kasan/common.c:247 [inline]
                    __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
                    kasan_slab_free include/linux/kasan.h:233 [inline]
                    slab_free_hook mm/slub.c:2376 [inline]
                    slab_free mm/slub.c:4633 [inline]
                    kmem_cache_free+0x2d4/0x4d0 mm/slub.c:4735
                    rcu_do_batch kernel/rcu/tree.c:2568 [inline]
                    rcu_core+0x799/0x14e0 kernel/rcu/tree.c:2824
                    handle_softirqs+0x216/0x8e0 kernel/softirq.c:561
                    run_ksoftirqd kernel/softirq.c:950 [inline]
                    run_ksoftirqd+0x3a/0x60 kernel/softirq.c:942
                    smpboot_thread_fn+0x3f4/0xae0 kernel/smpboot.c:164
                    kthread+0x3c2/0x780 kernel/kthread.c:464
                    ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   INITIAL USE at:
                   lock_acquire kernel/locking/lockdep.c:5866 [inline]
                   lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
                   uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
                   serial8250_do_set_termios+0x310/0x1710 drivers/tty/serial/8250/8250_port.c:2780
                   serial8250_set_termios+0x6e/0x80 drivers/tty/serial/8250/8250_port.c:2905
                   uart_set_options+0x31a/0x5f0 drivers/tty/serial/serial_core.c:2311
                   serial8250_console_setup+0x189/0x450 drivers/tty/serial/8250/8250_port.c:3526
                   univ8250_console_setup+0x1eb/0x2e0 drivers/tty/serial/8250/8250_core.c:428
                   console_call_setup kernel/printk/printk.c:3799 [inline]
                   console_call_setup kernel/printk/printk.c:3790 [inline]
                   try_enable_preferred_console+0x2fd/0x530 kernel/printk/printk.c:3843
                   register_console+0x3ab/0x11b0 kernel/printk/printk.c:4037
                   univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:513
                   console_init+0x14f/0x680 kernel/printk/printk.c:4323
                   start_kernel+0x29f/0x4d0 init/main.c:1034
                   x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:513
                   x86_64_start_kernel+0xb0/0xc0 arch/x86/kernel/head64.c:494
                   common_startup_64+0x13e/0x148
 }
 ... key      at: [<ffffffff9adc43a0>] port_lock_key+0x0/0x40

the dependencies between the lock to be acquired
 and HARDIRQ-irq-unsafe lock:
-> (disc_data_lock#3){.?.+}-{3:3} {
   IN-HARDIRQ-R at:
                    lock_acquire kernel/locking/lockdep.c:5866 [inline]
                    lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                    _raw_read_lock+0x3a/0x70 kernel/locking/spinlock.c:228
                    sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
                    sixpack_write_wakeup+0x20/0x390 drivers/net/hamradio/6pack.c:391
                    tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:517
                    tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
                    serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1842
                    serial8250_handle_irq+0x761/0xcb0 drivers/tty/serial/8250/8250_port.c:1950
                    serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1970
                    serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
                    __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
                    handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
                    handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
                    handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
                    generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
                    handle_irq arch/x86/kernel/irq.c:254 [inline]
                    call_irq_handler arch/x86/kernel/irq.c:266 [inline]
                    __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
                    common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
                    asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
                    __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
                    _raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
                    spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
                    uart_port_unlock_irqrestore include/linux/serial_core.h:786 [inline]
                    uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:636
                    decode_prio_command drivers/net/hamradio/6pack.c:868 [inline]
                    sixpack_decode drivers/net/hamradio/6pack.c:943 [inline]
                    sixpack_receive_buf drivers/net/hamradio/6pack.c:447 [inline]
                    sixpack_receive_buf+0x3d0/0x1c90 drivers/net/hamradio/6pack.c:424
                    tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
                    tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
                    receive_buf drivers/tty/tty_buffer.c:445 [inline]
                    flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
                    process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
                    process_scheduled_works kernel/workqueue.c:3319 [inline]
                    worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
                    kthread+0x3c2/0x780 kernel/kthread.c:464
                    ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   HARDIRQ-ON-R at:
                    lock_acquire kernel/locking/lockdep.c:5866 [inline]
                    lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                    _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
                    sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
                    sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline]
                    sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424
                    tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
                    tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
                    receive_buf drivers/tty/tty_buffer.c:445 [inline]
                    flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
                    process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
                    process_scheduled_works kernel/workqueue.c:3319 [inline]
                    worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
                    kthread+0x3c2/0x780 kernel/kthread.c:464
                    ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   SOFTIRQ-ON-R at:
                    lock_acquire kernel/locking/lockdep.c:5866 [inline]
                    lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                    _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
                    sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
                    sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline]
                    sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424
                    tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
                    tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
                    receive_buf drivers/tty/tty_buffer.c:445 [inline]
                    flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
                    process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
                    process_scheduled_works kernel/workqueue.c:3319 [inline]
                    worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
                    kthread+0x3c2/0x780 kernel/kthread.c:464
                    ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
                    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
   INITIAL USE at:
                   lock_acquire kernel/locking/lockdep.c:5866 [inline]
                   lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                   __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                   _raw_write_lock_irq+0x36/0x50 kernel/locking/spinlock.c:326
                   sixpack_close+0x1e/0x2f0 drivers/net/hamradio/6pack.c:641
                   tty_ldisc_close+0x111/0x1a0 drivers/tty/tty_ldisc.c:455
                   tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:613
                   tty_ldisc_hangup+0x365/0x740 drivers/tty/tty_ldisc.c:729
                   __tty_hangup.part.0+0x3eb/0x890 drivers/tty/tty_io.c:624
                   __tty_hangup drivers/tty/tty_io.c:2725 [inline]
                   tty_vhangup drivers/tty/tty_io.c:694 [inline]
                   tty_vhangup drivers/tty/tty_io.c:691 [inline]
                   tty_ioctl+0xf4b/0x15f0 drivers/tty/tty_io.c:2742
                   vfs_ioctl fs/ioctl.c:51 [inline]
                   __do_sys_ioctl fs/ioctl.c:906 [inline]
                   __se_sys_ioctl fs/ioctl.c:892 [inline]
                   __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
                   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
                   do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
                   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   INITIAL READ USE at:
                        lock_acquire kernel/locking/lockdep.c:5866 [inline]
                        lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
                        __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                        _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
                        sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
                        sixpack_receive_buf drivers/net/hamradio/6pack.c:433 [inline]
                        sixpack_receive_buf+0x59/0x1c90 drivers/net/hamradio/6pack.c:424
                        tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
                        tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
                        receive_buf drivers/tty/tty_buffer.c:445 [inline]
                        flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
                        process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
                        process_scheduled_works kernel/workqueue.c:3319 [inline]
                        worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
                        kthread+0x3c2/0x780 kernel/kthread.c:464
                        ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
                        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 }
 ... key      at: [<ffffffff8f568038>] disc_data_lock+0x18/0xfe0 6pack.c:-1
 ... acquired at:
   lock_acquire kernel/locking/lockdep.c:5866 [inline]
   lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
   sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
   sixpack_write_wakeup+0x20/0x390 drivers/net/hamradio/6pack.c:391
   tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:517
   tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
   serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1842
   __start_tx+0x3e9/0x4a0 drivers/tty/serial/8250/8250_port.c:1547
   serial8250_start_tx+0x368/0x530 drivers/tty/serial/8250/8250_port.c:1657
   __uart_start+0x292/0x4c0 drivers/tty/serial/serial_core.c:160
   uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:635
   decode_prio_command drivers/net/hamradio/6pack.c:868 [inline]
   sixpack_decode drivers/net/hamradio/6pack.c:943 [inline]
   sixpack_receive_buf drivers/net/hamradio/6pack.c:447 [inline]
   sixpack_receive_buf+0x3d0/0x1c90 drivers/net/hamradio/6pack.c:424
   tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
   tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
   receive_buf drivers/tty/tty_buffer.c:445 [inline]
   flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
   process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
   process_scheduled_works kernel/workqueue.c:3319 [inline]
   worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
   kthread+0x3c2/0x780 kernel/kthread.c:464
   ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245


stack backtrace:
CPU: 1 UID: 0 PID: 36 Comm: kworker/u8:2 Not tainted 6.14.0-syzkaller-07540-geff5f16bfd87 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_bad_irq_dependency kernel/locking/lockdep.c:2652 [inline]
 check_irq_usage+0x7dc/0x920 kernel/locking/lockdep.c:2893
 check_prev_add kernel/locking/lockdep.c:3170 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain kernel/locking/lockdep.c:3909 [inline]
 __lock_acquire+0x1189/0x1ba0 kernel/locking/lockdep.c:5235
 lock_acquire kernel/locking/lockdep.c:5866 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
 __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
 _raw_read_lock+0x5f/0x70 kernel/locking/spinlock.c:228
 sp_get+0x18/0xf0 drivers/net/hamradio/6pack.c:370
 sixpack_write_wakeup+0x20/0x390 drivers/net/hamradio/6pack.c:391
 tty_wakeup+0xe5/0x120 drivers/tty/tty_io.c:517
 tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
 serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1842
 __start_tx+0x3e9/0x4a0 drivers/tty/serial/8250/8250_port.c:1547
 serial8250_start_tx+0x368/0x530 drivers/tty/serial/8250/8250_port.c:1657
 __uart_start+0x292/0x4c0 drivers/tty/serial/serial_core.c:160
 uart_write+0x218/0xb30 drivers/tty/serial/serial_core.c:635
 decode_prio_command drivers/net/hamradio/6pack.c:868 [inline]
 sixpack_decode drivers/net/hamradio/6pack.c:943 [inline]
 sixpack_receive_buf drivers/net/hamradio/6pack.c:447 [inline]
 sixpack_receive_buf+0x3d0/0x1c90 drivers/net/hamradio/6pack.c:424
 tty_ldisc_receive_buf+0x157/0x1a0 drivers/tty/tty_buffer.c:391
 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x268/0x780 drivers/tty/tty_buffer.c:495
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (76):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/29 09:59 upstream eff5f16bfd87 cf25e2c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/28 11:29 upstream acb4f33713b9 49900278 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/27 18:30 upstream 1a9239bb4253 6c09fb82 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2025/03/27 13:33 upstream 1e1ba8d23dae 20510e88 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/27 00:11 upstream 2df0c02dab82 89d30d73 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/26 14:36 upstream 2df0c02dab82 89d30d73 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/26 08:02 upstream 2df0c02dab82 89d30d73 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in serial8250_handle_irq
2025/03/20 19:01 upstream 5fc319360819 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/03/20 05:18 upstream a7f2e10ecd8f 3b7445cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2025/03/19 22:15 upstream a7f2e10ecd8f 3b7445cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2025/03/12 17:23 upstream 0fed89a961ea ee70e6db .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/24 18:11 upstream d082ecbc71e9 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/21 15:15 upstream 27eddbf34490 0808a665 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/20 07:33 upstream 87a132e73910 50668798 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/14 15:01 upstream 128c8f96eb86 d9a046cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/13 13:46 upstream 4dc1d1bec898 2afad16e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/11 14:24 upstream febbc555cf0f f2baddf5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2025/02/11 06:32 upstream febbc555cf0f 43f51a00 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto possible deadlock in serial8250_handle_irq
2025/02/09 15:01 upstream 9946eaf552b1 ef44b750 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/02/06 21:18 upstream 92514ef226f5 53657d1b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2025/01/25 09:11 upstream 0afd22092df4 9fbd772e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/01/18 22:12 upstream 595523945be0 f2cb035c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/01/16 23:34 upstream ce69b4019001 f9e07a6e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/01/10 09:16 upstream 2144da25584e 67d7ec0a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/01/10 06:16 upstream 643e2e259c2b 40f46913 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2025/01/09 08:43 upstream eea6e4b4dfb8 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/17 21:39 upstream 59dbb9d81adf c8c15bb2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/17 00:05 upstream 78d4f34e2115 f93b2b55 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/14 18:28 upstream a446e965a188 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/11 23:16 upstream f92f4749861b ff949d25 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/11 21:17 upstream f92f4749861b ff949d25 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/11 14:03 upstream f92f4749861b ff949d25 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/11 12:23 upstream f92f4749861b ff949d25 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/08 06:37 upstream 7503345ac5f5 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/12/02 22:12 upstream e70140ba0d2b bb326ffb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/11/26 03:41 upstream 9f16d5e6f220 a84878fc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/11/20 03:58 upstream a5c93bfec0be 7d02db5a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/11/17 16:35 upstream 4a5df3796467 cfe3a04a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/11/15 02:54 upstream cfaaa7d010d1 77f3eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in serial8250_handle_irq
2024/10/26 11:23 upstream 850925a8133c 65e8686b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2024/08/01 10:19 upstream 21b136cc63d2 1e9c4cf3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2024/07/11 15:20 upstream a19ea421490d c699c2eb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2024/04/21 06:07 upstream 977b1ef51866 af24b050 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2024/04/20 21:26 upstream 13a2e429f644 af24b050 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2024/03/28 03:24 upstream fe46a7dd189e 454571b6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in serial8250_handle_irq
2023/12/18 02:33 upstream 0e389834672c 3222d10c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in serial8250_handle_irq
2023/10/14 12:37 upstream 727fb8376504 6388bc36 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2023/10/10 09:01 upstream 94f6f0550c62 c9be5398 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce possible deadlock in serial8250_handle_irq
2023/09/21 23:49 upstream b5cbe7c00aa0 0b6a67ac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in serial8250_handle_irq
2023/09/19 00:22 upstream 2cf0f7156238 0b6a67ac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce possible deadlock in serial8250_handle_irq
2024/03/29 16:23 upstream fe46a7dd189e c52bcb23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2024/03/13 06:11 upstream 9187210eee7d db5b7ff0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/10/10 17:55 upstream 94f6f0550c62 83165b57 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/10/08 21:30 upstream 37faf07bf90a 5e837c76 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/09/28 05:45 upstream 633b47cb009d 2895a507 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/09/20 19:23 upstream 5d2f53532ecc 0b6a67ac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/07 04:51 upstream 52a93d39b17d 4ffcc9ef .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in serial8250_handle_irq
2023/08/04 19:17 upstream c1a515d3c027 4ffcc9ef .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce possible deadlock in serial8250_handle_irq
2023/07/19 08:20 upstream ccff6d117d8d 022df2bb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce possible deadlock in serial8250_handle_irq
2023/08/25 02:23 upstream b5cc3833f13a 49be837e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/24 12:52 upstream 93f5de5f648d 4d7ae7ab .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/21 18:36 upstream f7757129e3de 6b415825 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/21 01:21 upstream 706a74159504 d216d8a0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/17 18:29 upstream 16931859a650 74b106b6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/08 15:15 upstream 14f9643dc90a 3c27dfcd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/08/03 11:47 upstream ec351c8f2e62 39a91c18 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/07/23 08:40 upstream c2782531397f 27cbe77f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/07/21 16:06 upstream f7e3a1bafdea 28847498 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/07/21 02:38 upstream 57f1f9dd3abe 28847498 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2023/07/18 01:25 upstream fdf0eaf11452 20f8b3c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 possible deadlock in serial8250_handle_irq
2024/04/09 16:15 linux-next a053fd3ca5d1 56086b24 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in serial8250_handle_irq
2024/04/06 03:55 linux-next 8568bb2ccc27 18ea8213 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in serial8250_handle_irq
* Struck through repros no longer work on HEAD.