=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.1.145-syzkaller #0 Not tainted
-----------------------------------------------------
kworker/u4:10/9904 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffffffff8d592eb8 (disc_data_lock#2){.+.+}-{2:2}, at: sp_get drivers/net/hamradio/6pack.c:376 [inline]
ffffffff8d592eb8 (disc_data_lock#2){.+.+}-{2:2}, at: sixpack_write_wakeup+0x2c/0x460 drivers/net/hamradio/6pack.c:397
and this task is already holding:
ffffffff96f71308 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x113/0x910 drivers/tty/serial/serial_core.c:581
which would create a new lock dependency:
(&port_lock_key){-.-.}-{2:2} -> (disc_data_lock#2){.+.+}-{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+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
serial8250_handle_irq+0x7a/0x6d0 drivers/tty/serial/8250/8250_port.c:1932
serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1981
serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x298/0xa30 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0x87/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x243/0xb20 kernel/irq/chip.c:819
generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
handle_irq arch/x86/kernel/irq.c:233 [inline]
__common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:682
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
uart_write+0x68a/0x910 drivers/tty/serial/serial_core.c:602
process_output_block drivers/tty/n_tty.c:586 [inline]
n_tty_write+0xd1a/0x11c0 drivers/tty/n_tty.c:2377
do_tty_write drivers/tty/tty_io.c:1018 [inline]
file_tty_write+0x4dd/0x860 drivers/tty/tty_io.c:1089
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x44c/0x960 fs/read_write.c:584
ksys_write+0x143/0x240 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
to a HARDIRQ-irq-unsafe lock:
(disc_data_lock#2){.+.+}-{2:2}
... which became HARDIRQ-irq-unsafe at:
...
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_receive_buf+0x50/0x1430 drivers/net/hamradio/6pack.c:439
tty_ldisc_receive_buf+0x113/0x150 drivers/tty/tty_buffer.c:461
tty_port_default_receive_buf+0x69/0x90 drivers/tty/tty_port.c:39
receive_buf drivers/tty/tty_buffer.c:515 [inline]
flush_to_ldisc+0x2f7/0x860 drivers/tty/tty_buffer.c:565
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(disc_data_lock#2);
local_irq_disable();
lock(&port_lock_key);
lock(disc_data_lock#2);
<Interrupt>
lock(&port_lock_key);
*** DEADLOCK ***
6 locks held by kworker/u4:10/9904:
#0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc900034cfd00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff888024510ce8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x34/0x860 drivers/tty/tty_buffer.c:537
#3: ffff88805399f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:264
#4: ffffffff96f71308 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x113/0x910 drivers/tty/serial/serial_core.c:581
#5: ffff88805399f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:264
the dependencies between HARDIRQ-irq-safe lock and the holding lock:
-> (&port_lock_key){-.-.}-{2:2} {
IN-HARDIRQ-W at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
serial8250_handle_irq+0x7a/0x6d0 drivers/tty/serial/8250/8250_port.c:1932
serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1981
serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x298/0xa30 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0x87/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x243/0xb20 kernel/irq/chip.c:819
generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
handle_irq arch/x86/kernel/irq.c:233 [inline]
__common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:682
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
uart_write+0x68a/0x910 drivers/tty/serial/serial_core.c:602
process_output_block drivers/tty/n_tty.c:586 [inline]
n_tty_write+0xd1a/0x11c0 drivers/tty/n_tty.c:2377
do_tty_write drivers/tty/tty_io.c:1018 [inline]
file_tty_write+0x4dd/0x860 drivers/tty/tty_io.c:1089
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x44c/0x960 fs/read_write.c:584
ksys_write+0x143/0x240 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
IN-SOFTIRQ-W at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
serial8250_console_write+0x169/0x17a0 drivers/tty/serial/8250/8250_port.c:3433
call_console_driver kernel/printk/printk.c:1977 [inline]
console_emit_next_record+0x947/0xc90 kernel/printk/printk.c:2777
console_flush_all kernel/printk/printk.c:-1 [inline]
console_unlock+0x223/0x630 kernel/printk/printk.c:2906
vprintk_emit+0x489/0x680 kernel/printk/printk.c:2303
dev_vprintk_emit+0x32d/0x3d3 drivers/base/core.c:4933
dev_printk_emit+0xdd/0x11d drivers/base/core.c:4944
_dev_warn+0x107/0x14e drivers/base/core.c:5000
qt2_process_read_urb drivers/usb/serial/quatech2.c:537 [inline]
qt2_read_bulk_callback+0x9a9/0xee0 drivers/usb/serial/quatech2.c:582
__usb_hcd_giveback_urb+0x35f/0x520 drivers/usb/core/hcd.c:1675
dummy_timer+0x888/0x31b0 drivers/usb/gadget/udc/dummy_hcd.c:1994
__run_hrtimer kernel/time/hrtimer.c:1752 [inline]
__hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1816
hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1833
handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
hrtimer_start_expires include/linux/hrtimer.h:435 [inline]
hrtimer_sleeper_start_expires kernel/time/hrtimer.c:2032 [inline]
do_nanosleep+0x17b/0x5f0 kernel/time/hrtimer.c:2108
hrtimer_nanosleep+0x15b/0x340 kernel/time/hrtimer.c:2159
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1314 [inline]
__se_sys_clock_nanosleep+0x2e6/0x370 kernel/time/posix-timers.c:1291
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
INITIAL USE at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
serial8250_do_set_termios+0x544/0x17d0 drivers/tty/serial/8250/8250_port.c:2795
uart_set_options+0x3c2/0x5d0 drivers/tty/serial/serial_core.c:2283
serial8250_console_setup+0x2ce/0x3a0 drivers/tty/serial/8250/8250_port.c:3537
univ8250_console_setup+0xe9/0x180 drivers/tty/serial/8250/8250_core.c:602
console_call_setup kernel/printk/printk.c:3063 [inline]
try_enable_preferred_console+0x48a/0x600 kernel/printk/printk.c:3104
register_console+0x1b0/0x9c0 kernel/printk/printk.c:3211
univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:687
console_init+0x1bc/0x78e kernel/printk/printk.c:3359
start_kernel+0x303/0x539 init/main.c:1076
secondary_startup_64_no_verify+0xcf/0xdb
}
... key at: [<ffffffff96f707a0>] port_lock_key+0x0/0x20
the dependencies between the lock to be acquired
and HARDIRQ-irq-unsafe lock:
-> (disc_data_lock#2){.+.+}-{2:2} {
HARDIRQ-ON-R at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_receive_buf+0x50/0x1430 drivers/net/hamradio/6pack.c:439
tty_ldisc_receive_buf+0x113/0x150 drivers/tty/tty_buffer.c:461
tty_port_default_receive_buf+0x69/0x90 drivers/tty/tty_port.c:39
receive_buf drivers/tty/tty_buffer.c:515 [inline]
flush_to_ldisc+0x2f7/0x860 drivers/tty/tty_buffer.c:565
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
SOFTIRQ-ON-R at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_write_wakeup+0x2c/0x460 drivers/net/hamradio/6pack.c:397
tty_ldisc_hangup+0x16a/0x4a0 drivers/tty/tty_ldisc.c:704
__tty_hangup+0x3e5/0x620 drivers/tty/tty_io.c:631
tty_vhangup drivers/tty/tty_io.c:701 [inline]
tty_ioctl+0x430/0xba0 drivers/tty/tty_io.c:2716
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
INITIAL USE at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
_raw_write_lock_irq+0x9f/0xe0 kernel/locking/spinlock.c:326
sixpack_close+0x28/0x290 drivers/net/hamradio/6pack.c:653
tty_ldisc_kill+0xa6/0x1a0 drivers/tty/tty_ldisc.c:614
tty_ldisc_hangup+0x392/0x4a0 drivers/tty/tty_ldisc.c:730
__tty_hangup+0x3e5/0x620 drivers/tty/tty_io.c:631
tty_vhangup drivers/tty/tty_io.c:701 [inline]
tty_ioctl+0x430/0xba0 drivers/tty/tty_io.c:2716
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
INITIAL READ USE at:
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_write_wakeup+0x2c/0x460 drivers/net/hamradio/6pack.c:397
tty_ldisc_hangup+0x16a/0x4a0 drivers/tty/tty_ldisc.c:704
__tty_hangup+0x3e5/0x620 drivers/tty/tty_io.c:631
tty_vhangup drivers/tty/tty_io.c:701 [inline]
tty_ioctl+0x430/0xba0 drivers/tty/tty_io.c:2716
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
}
... key at: [<ffffffff8d592eb8>] disc_data_lock+0x18/0x100
... acquired at:
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_write_wakeup+0x2c/0x460 drivers/net/hamradio/6pack.c:397
tty_wakeup+0xb4/0xf0 drivers/tty/tty_io.c:524
tty_port_default_wakeup+0x9e/0xf0 drivers/tty/tty_port.c:71
serial8250_tx_chars+0x629/0x830 drivers/tty/serial/8250/8250_port.c:1854
__start_tx drivers/tty/serial/8250/8250_port.c:1570 [inline]
serial8250_start_tx+0x6a9/0x8a0 drivers/tty/serial/8250/8250_port.c:1676
__uart_start drivers/tty/serial/serial_core.c:139 [inline]
uart_write+0x67d/0x910 drivers/tty/serial/serial_core.c:601
decode_prio_command drivers/net/hamradio/6pack.c:888 [inline]
sixpack_decode drivers/net/hamradio/6pack.c:963 [inline]
sixpack_receive_buf+0x438/0x1430 drivers/net/hamradio/6pack.c:453
tty_ldisc_receive_buf+0x113/0x150 drivers/tty/tty_buffer.c:461
tty_port_default_receive_buf+0x69/0x90 drivers/tty/tty_port.c:39
receive_buf drivers/tty/tty_buffer.c:515 [inline]
flush_to_ldisc+0x2f7/0x860 drivers/tty/tty_buffer.c:565
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
stack backtrace:
CPU: 1 PID: 9904 Comm: kworker/u4:10 Not tainted 6.1.145-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound flush_to_ldisc
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
print_bad_irq_dependency kernel/locking/lockdep.c:2604 [inline]
check_irq_usage kernel/locking/lockdep.c:2843 [inline]
check_prev_add kernel/locking/lockdep.c:3094 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain kernel/locking/lockdep.c:3825 [inline]
__lock_acquire+0x660b/0x7c50 kernel/locking/lockdep.c:5049
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
sp_get drivers/net/hamradio/6pack.c:376 [inline]
sixpack_write_wakeup+0x2c/0x460 drivers/net/hamradio/6pack.c:397
tty_wakeup+0xb4/0xf0 drivers/tty/tty_io.c:524
tty_port_default_wakeup+0x9e/0xf0 drivers/tty/tty_port.c:71
serial8250_tx_chars+0x629/0x830 drivers/tty/serial/8250/8250_port.c:1854
__start_tx drivers/tty/serial/8250/8250_port.c:1570 [inline]
serial8250_start_tx+0x6a9/0x8a0 drivers/tty/serial/8250/8250_port.c:1676
__uart_start drivers/tty/serial/serial_core.c:139 [inline]
uart_write+0x67d/0x910 drivers/tty/serial/serial_core.c:601
decode_prio_command drivers/net/hamradio/6pack.c:888 [inline]
sixpack_decode drivers/net/hamradio/6pack.c:963 [inline]
sixpack_receive_buf+0x438/0x1430 drivers/net/hamradio/6pack.c:453
tty_ldisc_receive_buf+0x113/0x150 drivers/tty/tty_buffer.c:461
tty_port_default_receive_buf+0x69/0x90 drivers/tty/tty_port.c:39
receive_buf drivers/tty/tty_buffer.c:515 [inline]
flush_to_ldisc+0x2f7/0x860 drivers/tty/tty_buffer.c:565
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>