INFO: task syz.0.16:5070 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.16 state:D stack:26680 pid: 5070 ppid: 4793 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093 do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85 __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x48/0x60 kernel/sched/completion.c:138 flush_workqueue+0x664/0x13d0 kernel/workqueue.c:2882 nbd_start_device_ioctl drivers/block/nbd.c:1380 [inline] __nbd_ioctl drivers/block/nbd.c:1442 [inline] nbd_ioctl+0xac5/0xe70 drivers/block/nbd.c:1482 blkdev_ioctl+0x33b/0x700 block/ioctl.c:604 block_ioctl+0xac/0xf0 block/fops.c:496 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f2097d9c079 RSP: 002b:00007f2097000028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f2097fc7fa0 RCX: 00007f2097d9c079 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 00007f2097e2ea4c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2097fc7fa0 R15: 00007ffe7b13bdc8 Showing all locks held in the system: 3 locks held by kworker/u4:0/9: 1 lock held by khungtaskd/27: #0: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 2 locks held by kworker/u5:0/146: #0: ffff888147350938 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc900016afd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by getty/3950: #0: ffff88802cb0a098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158 3 locks held by kworker/1:10/4250: #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc90002fbfd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 #2: ffff888055a4f240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x26a/0x33e0 drivers/net/netdevsim/fib.c:1480 2 locks held by kworker/u5:1/4276: #0: ffff888020e12138 ((wq_completion)nbd1-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000314fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:2/4278: #0: ffff888020f0a138 ((wq_completion)nbd4-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000315fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:3/5079: #0: ffff888020dd6138 ((wq_completion)nbd2-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000336fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:5/5112: #0: ffff888020efb938 ((wq_completion)nbd3-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000337fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:6/5136: #0: ffff888021073938 ((wq_completion)nbd7-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000350fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u4:5/5157: 2 locks held by kworker/u5:7/5161: #0: ffff888147359938 ((wq_completion)nbd5-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc900035efd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:8/5185: #0: ffff888020f9e138 ((wq_completion)nbd6-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000365fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:9/5208: #0: ffff88814735b938 ((wq_completion)nbd8-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc900037cfd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/u5:11/5259: #0: ffff88802109a138 ((wq_completion)nbd9-recv){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc90003b0fd00 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline] watchdog+0xe0f/0xe50 kernel/hung_task.c:369 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 240 Comm: kworker/u4:3 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: bat_events batadv_nc_worker RIP: 0010:hlock_class kernel/locking/lockdep.c:197 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4687 [inline] RIP: 0010:__lock_acquire+0x5e4/0x7d10 kernel/locking/lockdep.c:4962 Code: 24 89 c3 81 e3 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 c0 40 1d 90 be 08 00 00 00 e8 14 23 61 00 48 0f a3 1d cc 35 c0 0e <73> 1a 48 8d 04 5b c1 e0 06 48 8d 98 80 bf b5 8f 49 b8 00 00 00 00 RSP: 0018:ffffc90002097820 EFLAGS: 00000057 RAX: 0000000000000001 RBX: 0000000000000015 RCX: ffffffff815d0aec RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d40c0 RBP: ffffc90002097a70 R08: ffffffff901d40c7 R09: 1ffffffff203a818 R10: dffffc0000000000 R11: fffffbfff203a819 R12: ffff88801def8b60 R13: ffff88801def8000 R14: 0000000000000002 R15: ffff88801def8b40 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055558eeb24e8 CR3: 000000002b45f000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline] batadv_nc_worker+0xc9/0x5c0 net/batman-adv/network-coding.c:723 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287