INFO: task syz.6.2922:17583 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.2922      state:D stack:28776 pid:17583 tgid:17581 ppid:16793  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 comedi_open+0xe0/0x5e0 drivers/comedi/comedi_fops.c:2982
 chrdev_open+0x234/0x6a0 fs/char_dev.c:411
 do_dentry_open+0x6ab/0x14d0 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1052
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2873/0x4280 fs/namei.c:4863
 do_file_open+0x20e/0x430 fs/namei.c:4892
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1385
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff7c839de59
RSP: 002b:00007ff7c9185028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ff7c8625fa0 RCX: 00007ff7c839de59
RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007ff7c8433e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff7c8626038 R14: 00007ff7c8625fa0 R15: 00007fffffe69d18
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8ebe6100 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8ebe6100 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8ebe6100 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:5/138:
 #0: ffff88801bc44140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc90002e17d08 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffffffff90a9b400 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:313
2 locks held by getty/5367:
 #0: ffff8880382560a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
2 locks held by kworker/1:7/5721:
 #0: ffff88801bc0b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
 #1: ffffc9000206fd08 ((work_completion)(&m->mpeg_thread)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
4 locks held by kworker/u8:11/7197:
 #0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
 #0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659
 #1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:218 [inline]
 #1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2e8e/0x6730 kernel/sched/core.c:7228
 #2: ffff8880b8526298 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x6e7/0xca0 kernel/time/timer.c:1117
 #3: ffffffff9b9444b8 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x144/0x4b0 lib/debugobjects.c:873
1 lock held by syz.0.2803/16845:
1 lock held by syz.6.2922/17583:
 #0: ffff888032c258f0 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xe0/0x5e0 drivers/comedi/comedi_fops.c:2982
1 lock held by syz.5.3254/19184:
 #0: ffff888032c258f0 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xe0/0x5e0 drivers/comedi/comedi_fops.c:2982
1 lock held by syz.8.3380/19767:
 #0: ffff888032c258f0 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xe0/0x5e0 drivers/comedi/comedi_fops.c:2982
2 locks held by syz.4.3385/19798:
 #0: ffffffff90a9b400 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
 #0: ffffffff90a9b400 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3506
 #1: ffffffff8ebf1ba8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311
3 locks held by sed/19835:
 #0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
 #0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659
 #1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:218 [inline]
 #1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2e8e/0x6730 kernel/sched/core.c:7228
 #2: ffffffff9b72f148 (&____s->seqcount#2){----}-{0:0}, at: clockevents_program_event+0x23e/0x820 kernel/time/clockevents.c:363

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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:122
 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [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:353 [inline]
 watchdog+0xcb1/0x1030 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 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: 16845 Comm: syz.0.2803 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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_get_encoder_bits drivers/comedi/drivers/c6xdigio.c:82 [inline]
RIP: 0010:c6xdigio_encoder_read drivers/comedi/drivers/c6xdigio.c:131 [inline]
RIP: 0010:c6xdigio_encoder_insn_read+0x5c7/0xb40 drivers/comedi/drivers/c6xdigio.c:201
Code: 44 88 64 24 10 31 ed eb 19 e8 b5 95 e6 f8 83 c5 01 bf 14 00 00 00 89 ee e8 16 90 e6 f8 83 fd 14 74 19 e8 9c 95 e6 f8 89 da ec <31> ff 41 89 c4 89 c6 e8 9d 8f e6 f8 45 84 e4 78 ce 41 c1 e7 0c 44
RSP: 0018:ffffc90021f07a88 EFLAGS: 00000246
RAX: 00000000000800ff RBX: 0000000000006485 RCX: ffffc900061b3000
RDX: 0000000000006485 RSI: ffffffff89233aa4 RDI: ffff88807cd3a540
RBP: 0000000000000008 R08: 0000000000000005 R09: 0000000000000014
R10: 0000000000000008 R11: 0000000000000000 R12: 00000000000800ff
R13: 0000000000006484 R14: 0000000000000fff R15: 000000000000001f
FS:  00007f9cac2e86c0(0000) GS:ffff888123dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560dcf846300 CR3: 000000007204d000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 parse_insn+0x83f/0x19f0 drivers/comedi/comedi_fops.c:1565
 do_insn_ioctl+0x152/0x4e0 drivers/comedi/comedi_fops.c:1790
 comedi_unlocked_ioctl+0xf68/0x3310 drivers/comedi/comedi_fops.c:2422
 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+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9cab39de59
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:00007f9cac2e8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9cab625fa0 RCX: 00007f9cab39de59
RDX: 0000200000000000 RSI: 000000008028640c RDI: 0000000000000003
RBP: 00007f9cab433e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9cab626038 R14: 00007f9cab625fa0 R15: 00007fffbff10b18
 </TASK>