INFO: task syz.3.20:5960 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.3.20 state:D stack:26664 pid:5960 ppid:5904 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747 comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 chrdev_open+0x59e/0x670 fs/char_dev.c:414 do_dentry_open+0x8c6/0x1500 fs/open.c:929 do_open fs/namei.c:3640 [inline] path_openat+0x274b/0x3190 fs/namei.c:3797 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe262f8f749 RSP: 002b:00007ffd71537858 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fe2631e5fa0 RCX: 00007fe262f8f749 RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007fe263013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe2631e5fa0 R14: 00007fe2631e5fa0 R15: 0000000000000004 INFO: task syz.1.18:6008 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.1.18 state:D stack:26664 pid:6008 ppid:5905 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747 comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 chrdev_open+0x59e/0x670 fs/char_dev.c:414 do_dentry_open+0x8c6/0x1500 fs/open.c:929 do_open fs/namei.c:3640 [inline] path_openat+0x274b/0x3190 fs/namei.c:3797 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fbdd038f749 RSP: 002b:00007fffe71c0548 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fbdd05e5fa0 RCX: 00007fbdd038f749 RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007fbdd0413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbdd05e5fa0 R14: 00007fbdd05e5fa0 R15: 0000000000000004 INFO: task syz.2.19:6009 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.2.19 state:D stack:26664 pid:6009 ppid:5906 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747 comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 chrdev_open+0x59e/0x670 fs/char_dev.c:414 do_dentry_open+0x8c6/0x1500 fs/open.c:929 do_open fs/namei.c:3640 [inline] path_openat+0x274b/0x3190 fs/namei.c:3797 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f6c6bb8f749 RSP: 002b:00007ffe1872e6d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f6c6bde5fa0 RCX: 00007f6c6bb8f749 RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007f6c6bc13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6c6bde5fa0 R14: 00007f6c6bde5fa0 R15: 0000000000000004 Showing all locks held in the system: 3 locks held by kworker/u4:0/11: #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #1: ffffc90000107d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90000107d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286 2 locks held by kworker/u4:1/12: 1 lock held by khungtaskd/28: #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633 3 locks held by kworker/u4:2/41: #0: ffff88802c76d938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff88802c76d938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #1: ffffc90000b1fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90000b1fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711 #2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4158 2 locks held by getty/5526: #0: ffff88802d38c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217 2 locks held by syz.0.17/5959: 1 lock held by syz.3.20/5960: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.1.18/6008: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.2.19/6009: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.4.21/6066: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.5.22/6068: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.7.24/6119: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.6.23/6120: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.9.26/6173: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.8.25/6174: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.0.27/6216: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.3.28/6220: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.1.29/6264: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.2.30/6268: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.4.31/6313: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.5.32/6317: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.6.33/6373: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.7.34/6381: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.8.35/6423: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.9.36/6424: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.0.37/6462: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.3.38/6472: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.1.39/6514: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.2.40/6516: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.4.41/6559: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.5.42/6571: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz.6.43/6622: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 1 lock held by syz-executor/6625: #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline] #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469 1 lock held by syz.7.44/6630: #0: ffff88802b8778f8 (&dev->mutex#3){+.+.}-{3:3}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2816 2 locks held by syz-executor/6641: #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline] #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469 #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline] #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x448/0x830 kernel/rcu/tree_exp.h:1004 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xf41/0xf80 kernel/hung_task.c:379 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5959 Comm: syz.0.17 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:multiq3_encoder_reset drivers/comedi/drivers/multiq3.c:226 [inline] RIP: 0010:multiq3_attach+0x62a/0x940 drivers/comedi/drivers/multiq3.c:316 Code: 00 74 08 48 89 df e8 15 a8 db f9 8b 13 83 c2 0e b0 01 ee 41 80 3c 2c 00 74 08 48 89 df e8 fe a7 db f9 8b 13 83 c2 0c 31 c0 ee <41> 80 3c 2c 00 74 08 48 89 df e8 e7 a7 db f9 8b 13 83 c2 0e b0 18 RSP: 0018:ffffc90003557ab8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88802b8779d0 RCX: ffff88802271da00 RDX: 000000000000200c RSI: 0000000002018272 RDI: 0000000000000000 RBP: dffffc0000000000 R08: 0000000000000040 R09: 1ffffffff21b28b0 R10: dffffc0000000000 R11: fffffbfff21b28b1 R12: 1ffff1100570ef3a R13: 000000000153e480 R14: 1ffff1100f680a92 R15: 00000000002a7c91 FS: 000055556c15e500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f29f25ae010 CR3: 000000001c6f4000 CR4: 00000000003506f0 Call Trace: comedi_device_attach+0x518/0x710 drivers/comedi/drivers.c:1006 do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline] comedi_unlocked_ioctl+0x606/0xfe0 drivers/comedi/comedi_fops.c:2178 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f1e6fb8f749 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:00007ffe16127688 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f1e6fde5fa0 RCX: 00007f1e6fb8f749 RDX: 00002000000000c0 RSI: 0000000040946400 RDI: 0000000000000003 RBP: 00007f1e6fc13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1e6fde5fa0 R14: 00007f1e6fde5fa0 R15: 0000000000000003