INFO: task syz.0.278:7003 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.278 state:D stack:27624 pid:7003 tgid:7001 ppid:5805 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
comedi_open+0xe0/0x5a0 drivers/comedi/comedi_fops.c:2868
chrdev_open+0x234/0x6a0 fs/char_dev.c:414
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4134
do_filp_open+0x20b/0x470 fs/namei.c:4161
do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f76e158f6c9
RSP: 002b:00007f76e23b6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f76e17e6090 RCX: 00007f76e158f6c9
RDX: 0000000000002000 RSI: 0000200000000040 RDI: 00000000ffffff9c
RBP: 00007f76e1611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f76e17e6128 R14: 00007f76e17e6090 R15: 00007fff3efd6a78
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e3c4720 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
1 lock held by udevd/5182:
#0: ffff8880b843a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:646 [inline]
#0: ffff8880b843a398 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:631
2 locks held by getty/5569:
#0: ffff88814cde20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by kworker/u8:7/5906:
#0: ffff88801ef4c148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc90003b77d00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
1 lock held by syz.3.276/6991:
1 lock held by syz.0.278/7003:
#0: ffff88814c8f30f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xe0/0x5a0 drivers/comedi/comedi_fops.c:2868
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf3f/0x1170 kernel/hung_task.c:495
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6991 Comm: syz.3.276 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:c6xdigio_chk_status drivers/comedi/drivers/c6xdigio.c:54 [inline]
RIP: 0010:c6xdigio_write_data.isra.0+0xbb/0x110 drivers/comedi/drivers/c6xdigio.c:66
Code: 31 ed 41 83 c5 01 eb 19 e8 52 c2 f5 f8 83 c5 01 bf 14 00 00 00 89 ee e8 83 bd f5 f8 83 fd 14 74 20 e8 39 c2 f5 f8 44 89 ea ec <89> c3 44 89 e6 81 e3 80 00 00 00 89 df e8 a3 bc f5 f8 44 39 e3 74
RSP: 0018:ffffc900033b7a80 EFLAGS: 00000246
RAX: 00000000000800e9 RBX: 0000000000000080 RCX: ffffc9000c979000
RDX: 0000000000000402 RSI: ffffffff88c72697 RDI: 0000000000000005
RBP: 000000000000000d R08: 0000000000000005 R09: 0000000000000014
R10: 000000000000000d R11: 0000000000000000 R12: 0000000000000080
R13: 0000000000000402 R14: 0000000000000050 R15: 000000000000a497
FS: 00007f4cbc6f26c0(0000) GS:ffff888124b08000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb9f15b4198 CR3: 000000007dc2b000 CR4: 00000000003526f0
Call Trace:
c6xdigio_get_encoder_bits drivers/comedi/drivers/c6xdigio.c:82 [inline]
c6xdigio_encoder_read drivers/comedi/drivers/c6xdigio.c:137 [inline]
c6xdigio_encoder_insn_read+0x289/0x470 drivers/comedi/drivers/c6xdigio.c:201
parse_insn+0xf4c/0x1970 drivers/comedi/comedi_fops.c:1454
do_insn_ioctl+0x152/0x4e0 drivers/comedi/comedi_fops.c:1679
comedi_unlocked_ioctl+0x1618/0x2f00 drivers/comedi/comedi_fops.c:2308
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+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4cbb78f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4cbc6f2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4cbb9e5fa0 RCX: 00007f4cbb78f6c9
RDX: 0000200000000000 RSI: 000000008028640c RDI: 0000000000000004
RBP: 00007f4cbb811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4cbb9e6038 R14: 00007f4cbb9e5fa0 R15: 00007ffdfd70c7e8