INFO: task syz.4.5119:32164 blocked for more than 143 seconds.
Not tainted 6.16.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.5119 state:D stack:27496 pid:32164 tgid:32160 ppid:5864 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5397 [inline]
__schedule+0x16fd/0x4cf0 kernel/sched/core.c:6786
__schedule_loop kernel/sched/core.c:6864 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6879
schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:95 [inline]
__wait_for_common kernel/sched/completion.c:116 [inline]
wait_for_common kernel/sched/completion.c:127 [inline]
wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:148
__flush_work+0x9b9/0xbc0 kernel/workqueue.c:4246
n_tty_poll+0x2db/0x740 drivers/tty/n_tty.c:2455
tty_poll+0xbb/0x160 drivers/tty/tty_io.c:2199
vfs_poll include/linux/poll.h:82 [inline]
select_poll_one fs/select.c:480 [inline]
do_select+0x105e/0x17e0 fs/select.c:536
core_sys_select+0x6dd/0xa20 fs/select.c:677
do_pselect fs/select.c:759 [inline]
__do_sys_pselect6 fs/select.c:802 [inline]
__se_sys_pselect6+0x27a/0x300 fs/select.c:793
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a01f8e9a9
RSP: 002b:00007f2a02d6c038 EFLAGS: 00000246 ORIG_RAX: 000000000000010e
RAX: ffffffffffffffda RBX: 00007f2a021b6080 RCX: 00007f2a01f8e9a9
RDX: 0000000000000000 RSI: 0000200000000600 RDI: 0000000000000040
RBP: 00007f2a02010d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000400 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f2a021b6080 R15: 00007f2a022dfa28
</TASK>
INFO: task syz.4.5119:32166 blocked for more than 146 seconds.
Not tainted 6.16.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.5119 state:D stack:27400 pid:32166 tgid:32160 ppid:5864 task_flags:0x400040 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5397 [inline]
__schedule+0x16fd/0x4cf0 kernel/sched/core.c:6786
__schedule_loop kernel/sched/core.c:6864 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6879
schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:95 [inline]
__wait_for_common kernel/sched/completion.c:116 [inline]
wait_for_common kernel/sched/completion.c:127 [inline]
wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:148
__flush_work+0x9b9/0xbc0 kernel/workqueue.c:4246
n_tty_poll+0x2db/0x740 drivers/tty/n_tty.c:2455
tty_poll+0xbb/0x160 drivers/tty/tty_io.c:2199
vfs_poll include/linux/poll.h:82 [inline]
select_poll_one fs/select.c:480 [inline]
do_select+0x105e/0x17e0 fs/select.c:536
core_sys_select+0x6dd/0xa20 fs/select.c:677
do_pselect fs/select.c:759 [inline]
__do_sys_pselect6 fs/select.c:802 [inline]
__se_sys_pselect6+0x27a/0x300 fs/select.c:793
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2a01f8e9a9
RSP: 002b:00007f2a02d4b038 EFLAGS: 00000246 ORIG_RAX: 000000000000010e
RAX: ffffffffffffffda RBX: 00007f2a021b6160 RCX: 00007f2a01f8e9a9
RDX: 0000000000000000 RSI: 0000200000000600 RDI: 0000000000000040
RBP: 00007f2a02010d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000680 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f2a021b6160 R15: 00007f2a022dfa28
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8e13f0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
2 locks held by getty/5609:
#0: ffff88814d7380a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000333b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
6 locks held by kworker/u8:8/6105:
2 locks held by kworker/u8:1/28571:
1 lock held by syz.0.5051/31807:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.0.5051/31808:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.4.5119/32164:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.4.5119/32166:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.2.5131/32230:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.2.5131/32231:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.3.5178/32512:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.3.5178/32513:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.5.5196/32608:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
1 lock held by syz.5.5196/32609:
#0: ffff88803507f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
4 locks held by dhcpcd-run-hook/571:
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
watchdog+0xfee/0x1030 kernel/hung_task.c:470
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6105 Comm: kworker/u8:8 Not tainted 6.16.0-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound flush_to_ldisc
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 1e f8 79 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ff 09 dc fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc90000007c78 EFLAGS: 00000006
RAX: 1ffffffff33bed00 RBX: 00000000000002e8 RCX: 0000000000000000
RDX: 00000000000002e8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffffff99df6e50 R08: ffff888025880000 R09: 0000000000000004
R10: 0000000000000003 R11: ffffffff85462e70 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff99df6e40 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125c23000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f06e9f7c260 CR3: 000000000df38000 CR4: 00000000003526f0
Call Trace:
<IRQ>
serial_in drivers/tty/serial/8250/8250.h:137 [inline]
serial8250_read_char+0x65/0x380 drivers/tty/serial/8250/8250_port.c:1709
serial8250_rx_chars drivers/tty/serial/8250/8250_port.c:1777 [inline]
serial8250_handle_irq+0x4fb/0xbb0 drivers/tty/serial/8250/8250_port.c:1941
serial8250_default_handle_irq+0xbf/0x1b0 drivers/tty/serial/8250/8250_port.c:1966
serial8250_interrupt+0xa2/0x1d0 drivers/tty/serial/8250/8250_core.c:86
__handle_irq_event_percpu+0x28c/0x980 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x267/0x9c0 kernel/irq/chip.c:797
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+0x140/0x250 arch/x86/kernel/irq.c:292
common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:285
</IRQ>
<TASK>
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:lock_is_held_type+0x137/0x190 kernel/locking/lockdep.c:5948
Code: 01 75 44 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 4c 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 05 f9 22 32 07 <48> 3b 44 24 08 75 43 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc9000b8a7558 EFLAGS: 00000206
RAX: ef961a40b26a4900 RBX: 0000000000000000 RCX: ef961a40b26a4900
RDX: 0000000000000000 RSI: ffffffff8db8419f RDI: ffffffff8be28d80
RBP: 00000000ffffffff R08: ffffc9000b8a77c7 R09: 0000000000000000
R10: ffffc9000b8a77a0 R11: fffff52001714ef9 R12: 0000000000000246
R13: ffff888025880000 R14: ffffffff8e13f1a0 R15: 0000000000000005
lock_is_held include/linux/lockdep.h:249 [inline]
__might_resched+0xf5/0x610 kernel/sched/core.c:8762
__mutex_lock_common kernel/locking/mutex.c:579 [inline]
__mutex_lock+0x106/0xe80 kernel/locking/mutex.c:747
flush_echoes drivers/tty/n_tty.c:789 [inline]
__receive_buf drivers/tty/n_tty.c:1626 [inline]
n_tty_receive_buf_common+0xbe3/0x12f0 drivers/tty/n_tty.c:1723
tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:445 [inline]
flush_to_ldisc+0x24a/0x720 drivers/tty/tty_buffer.c:495
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>