INFO: task syz.3.20:6117 blocked for more than 143 seconds. Not tainted 6.16.0-next-20250731-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.3.20 state:D stack:27240 pid:6117 tgid:6117 ppid:5989 task_flags:0x400040 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115 __mutex_lock_common kernel/locking/mutex.c:676 [inline] __mutex_lock+0x7e6/0x1360 kernel/locking/mutex.c:760 comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 chrdev_open+0x4c9/0x5e0 fs/char_dev.c:414 do_dentry_open+0x953/0x13f0 fs/open.c:965 vfs_open+0x3b/0x340 fs/open.c:1095 do_open fs/namei.c:3887 [inline] path_openat+0x2ee5/0x3830 fs/namei.c:4046 do_filp_open+0x1fa/0x410 fs/namei.c:4073 do_sys_openat2+0x121/0x1c0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f45d6b8eb69 RSP: 002b:00007ffd5b016298 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f45d6db5fa0 RCX: 00007f45d6b8eb69 RDX: 0000000000000400 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007f45d6c11df1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f45d6db5fa0 R14: 00007f45d6db5fa0 R15: 0000000000000004 Showing all locks held in the system: 4 locks held by kworker/u8:1/13: 1 lock held by khungtaskd/31: #0: ffffffff8e539f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e539f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e539f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 2 locks held by getty/5609: #0: ffff88814d4d50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000362b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222 2 locks held by syz.1.18/6116: 1 lock held by syz.3.20/6117: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.2.19/6118: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.0.17/6119: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.4.21/6217: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.5.22/6225: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.6.23/6226: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.7.24/6227: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.8.25/6290: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.9.26/6328: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.1.27/6329: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.0.28/6330: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.2.29/6353: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.3.30/6410: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.5.32/6423: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.4.31/6424: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.6.33/6451: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.7.34/6518: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.8.35/6555: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.9.36/6556: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.1.37/6561: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.0.38/6591: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.2.39/6644: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.3.40/6651: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.4.41/6652: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 1 lock held by syz.5.42/6681: #0: ffff88814c51b8f8 (&dev->mutex#4){+.+.}-{4:4}, at: comedi_open+0xc0/0x590 drivers/comedi/comedi_fops.c:2863 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-next-20250731-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline] watchdog+0xf93/0xfe0 kernel/hung_task.c:491 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 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: 13 Comm: kworker/u8:1 Not tainted 6.16.0-next-20250731-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: bat_events batadv_nc_worker RIP: 0010:check_wait_context kernel/locking/lockdep.c:4877 [inline] RIP: 0010:__lock_acquire+0x4c1/0xd20 kernel/locking/lockdep.c:5187 Code: 05 b0 f8 43 11 85 c0 0f 84 02 01 00 00 41 b4 03 83 bf c0 0a 00 00 00 0f 84 d7 04 00 00 44 3b bf e8 0a 00 00 0f 8d 04 01 00 00 <49> 63 df 48 8d 04 9b 4c 8d 3c c7 49 81 c7 10 0b 00 00 eb 1d 44 89 RSP: 0018:ffffc900001278f0 EFLAGS: 00000093 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000ffffffff RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff88801d2b0000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8b4c15b2 R10: dffffc0000000000 R11: fffffbfff1fc6867 R12: ffffffffffffff05 R13: 0000000000000001 R14: ffff88801d2b0b40 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812580a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe3a4bb6900 CR3: 000000000e336000 CR4: 00000000003526f0 Call Trace: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] batadv_nc_worker+0xef/0x610 net/batman-adv/network-coding.c:719 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245