INFO: task syz.0.452:7695 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.452 state:D stack:28120 pid:7695 tgid:7689 ppid:5629 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7339
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7f7/0x1550 kernel/locking/mutex.c:820
comedi_open+0xc0/0x5e0 drivers/comedi/comedi_fops.c:2982
chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
do_dentry_open+0x785/0x14e0 fs/open.c:947
vfs_open+0x3b/0x340 fs/open.c:1079
do_open fs/namei.c:4699 [inline]
path_openat+0x2e08/0x3860 fs/namei.c:4858
do_file_open+0x23e/0x4a0 fs/namei.c:4887
do_sys_openat2+0x113/0x200 fs/open.c:1364
do_sys_open fs/open.c:1370 [inline]
__do_sys_openat fs/open.c:1386 [inline]
__se_sys_openat fs/open.c:1381 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1381
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f178799cdd9
RSP: 002b:00007f178880e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f1787c16090 RCX: 00007f178799cdd9
RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f1787a32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1787c16128 R14: 00007f1787c16090 R15: 00007ffef5f87ca8
Showing all locks held in the system:
1 lock held by kworker/0:1/10:
#0: ffff8880b863aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb6/0x150 kernel/sched/core.c:660
1 lock held by khungtaskd/31:
#0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5373:
#0: ffff8880372920a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
1 lock held by syz.3.332/7196:
1 lock held by syz-executor/7338:
#0: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
#0: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770 kernel/rcu/tree_exp.h:961
1 lock held by syz.0.452/7695:
#0: ffff888031f668f0 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x5e0 drivers/comedi/comedi_fops.c:2982
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd3/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7196 Comm: syz.3.332 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:c6xdigio_chk_status drivers/comedi/drivers/c6xdigio.c:54 [inline]
RIP: 0010:c6xdigio_write_data drivers/comedi/drivers/c6xdigio.c:66 [inline]
RIP: 0010:c6xdigio_encoder_read drivers/comedi/drivers/c6xdigio.c:143 [inline]
RIP: 0010:c6xdigio_encoder_insn_read+0x705/0xa00 drivers/comedi/drivers/c6xdigio.c:201
Code: 71 e9 bc f8 e8 ec ef 62 f8 eb 05 e8 65 e9 bc f8 bd 01 00 00 00 43 80 3c 2c 00 74 08 4c 89 ff e8 c1 24 28 f9 41 8b 17 ff c2 ec <44> 0f b6 e8 bf ff 00 00 00 44 89 ee e8 3a ec bc f8 bf 14 00 00 00
RSP: 0018:ffffc9000ea4f8a8 EFLAGS: 00000206
RAX: ffffffff8908c3ff RBX: dffffc0000000000 RCX: 0000000000080000
RDX: 00000000000003c5 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000012 R08: ffff88802dd00000 R09: 0000000000000004
R10: 000000000c000003 R11: ffffffff8908bbd0 R12: 1ffff110063ecd38
R13: dffffc0000000000 R14: 000000008908c1ff R15: ffff888031f669c0
FS: 00007fafc87136c0(0000) GS:ffff888125290000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fda293e8158 CR3: 000000007945b000 CR4: 0000000000350ef0
Call Trace:
parse_insn+0xa3e/0x1b20 drivers/comedi/comedi_fops.c:1565
do_insn_ioctl+0x174/0x5a0 drivers/comedi/comedi_fops.c:1790
comedi_unlocked_ioctl+0xe06/0x1af0 drivers/comedi/comedi_fops.c:2422
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fafc779cdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fafc8713028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fafc7a15fa0 RCX: 00007fafc779cdd9
RDX: 0000200000000000 RSI: 000000008028640c RDI: 0000000000000003
RBP: 00007fafc7832d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fafc7a16038 R14: 00007fafc7a15fa0 R15: 00007ffc0f2e9a08