INFO: task syz.4.4080:25449 blocked for more than 145 seconds.
Tainted: G U W L XTNJ syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.4080 state:D stack:28744 pid:25449 tgid:25444 ppid:22935 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x6020 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7004
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
__tty_hangup.part.0+0xd9/0x7f0 drivers/tty/tty_io.c:581
__tty_hangup drivers/tty/tty_io.c:688 [inline]
tty_vhangup drivers/tty/tty_io.c:691 [inline]
tty_vhangup drivers/tty/tty_io.c:688 [inline]
tty_ioctl+0xa12/0x1690 drivers/tty/tty_io.c:2732
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3e879bf79
RSP: 002b:00007fe3e96fa028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe3e8a16090 RCX: 00007fe3e879bf79
RDX: 0000000000000000 RSI: 0000000000005437 RDI: 000000000000000a
RBP: 00007fe3e88327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe3e8a16128 R14: 00007fe3e8a16090 R15: 00007ffe6c6cfa38
</TASK>
INFO: task syz.4.4080:25453 blocked for more than 145 seconds.
Tainted: G U W L XTNJ syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.4080 state:D stack:28792 pid:25453 tgid:25444 ppid:22935 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x6020 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7004
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
rwsem_down_write_slowpath+0x530/0x1280 kernel/locking/rwsem.c:1185
__down_write_common kernel/locking/rwsem.c:1317 [inline]
__down_write kernel/locking/rwsem.c:1326 [inline]
down_write+0x1c7/0x1f0 kernel/locking/rwsem.c:1591
class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
n_tty_flush_buffer+0x1f/0x140 drivers/tty/n_tty.c:349
tty_ldisc_hangup+0xdb/0x6e0 drivers/tty/tty_ldisc.c:699
__tty_hangup.part.0+0x3e4/0x7f0 drivers/tty/tty_io.c:621
__tty_hangup drivers/tty/tty_io.c:688 [inline]
tty_vhangup drivers/tty/tty_io.c:691 [inline]
tty_vhangup drivers/tty/tty_io.c:688 [inline]
tty_ioctl+0xa12/0x1690 drivers/tty/tty_io.c:2732
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3e879bf79
RSP: 002b:00007fe3e96b8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe3e8a16270 RCX: 00007fe3e879bf79
RDX: 0000000000000000 RSI: 0000000000005437 RDI: 000000000000000a
RBP: 00007fe3e88327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe3e8a16308 R14: 00007fe3e8a16270 R15: 00007ffe6c6cfa38
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
1 lock held by kswapd0/85:
2 locks held by kworker/0:2/104:
3 locks held by udevd/5188:
1 lock held by dhcpcd/5482:
1 lock held by crond/5560:
3 locks held by syz-executor/5804:
4 locks held by kworker/u8:26/9062:
4 locks held by kworker/u8:28/9064:
3 locks held by kworker/u8:30/9066:
3 locks held by kworker/u8:36/9072:
2 locks held by kworker/u8:38/9074:
4 locks held by kworker/u8:41/9077:
2 locks held by kworker/u8:42/9078:
3 locks held by kworker/u8:43/9079:
3 locks held by kworker/u8:48/9084:
4 locks held by kworker/u8:50/9086:
3 locks held by kworker/u8:51/9087:
5 locks held by kworker/u8:52/9088:
3 locks held by kworker/u8:53/9090:
3 locks held by kworker/u8:56/9093:
3 locks held by kworker/u8:57/9094:
3 locks held by kworker/u8:58/9095:
3 locks held by kworker/u8:59/9096:
3 locks held by kworker/u8:61/9098:
3 locks held by kworker/u8:63/9100:
3 locks held by kworker/u8:64/9101:
3 locks held by kworker/u8:0/16137:
2 locks held by kworker/u8:2/20777:
2 locks held by getty/22116:
#0: ffff8880335780a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc90002f642f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/23937:
6 locks held by syz.7.4076/25425:
1 lock held by syz.4.4080/25449:
#0: ffff88806b23f1c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: __tty_hangup.part.0+0xd9/0x7f0 drivers/tty/tty_io.c:581
3 locks held by syz.4.4080/25453:
#0: ffff88806b23f1c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: __tty_hangup.part.0+0xd9/0x7f0 drivers/tty/tty_io.c:581
#1: ffff88806b23f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline]
#1: ffff88806b23f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_hangup+0x3d/0x6e0 drivers/tty/tty_ldisc.c:696
#2: ffff88806b23f2e8 (&tty->termios_rwsem){++++}-{4:4}, at: class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
#2: ffff88806b23f2e8 (&tty->termios_rwsem){++++}-{4:4}, at: n_tty_flush_buffer+0x1f/0x140 drivers/tty/n_tty.c:349
3 locks held by syz.4.4080/25456:
2 locks held by syz.0.4082/25457:
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U W L XTNJ syzkaller #0 PREEMPT(full)
Tainted: [U]=USER, [W]=WARN, [L]=SOFTLOCKUP, [X]=AUX, [T]=RANDSTRUCT, [N]=TEST, [J]=FWCTL
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
watchdog+0xcc3/0xfe0 kernel/hung_task.c:515
kthread+0x370/0x450 kernel/kthread.c:467
ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>