INFO: task kworker/u8:4:69 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:4 state:D stack:11624 pid:69 tgid:69 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7026
rxrpc_destroy_all_calls+0x564/0x660 net/rxrpc/call_object.c:757
rxrpc_exit_net+0x6f/0xc0 net/rxrpc/net_ns.c:112
ops_exit_list net/core/net_namespace.c:199 [inline]
ops_undo_list+0x497/0x990 net/core/net_namespace.c:252
cleanup_net+0x4de/0x820 net/core/net_namespace.c:695
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4b9/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Showing all locks held in the system:
3 locks held by kworker/u8:2/37:
1 lock held by khungtaskd/39:
#0: ffffffff8d7aa500 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d7aa500 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8d7aa500 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:4/69:
#0: ffff88801a294938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88801a294938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000154fba0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000154fba0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8ea6ac60 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x820 net/core/net_namespace.c:669
2 locks held by getty/5558:
#0: ffff88823bf688a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e7e2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
7 locks held by kworker/u8:16/6940:
3 locks held by kworker/1:3/10446:
#0: ffff88813fe19138 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88813fe19138 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc90003ea7ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc90003ea7ba0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffff88805b41f260 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x224/0x3e0 drivers/net/netdevsim/fib.c:1490
2 locks held by kworker/u8:23/22072:
#0: ffff88813fe29138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88813fe29138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc90006017ba0 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc90006017ba0 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
2 locks held by syz.5.5974/22398:
4 locks held by syz.4.5987/22439:
6 locks held by modprobe/22440:
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 39 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4b9/0x870 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: 37 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:preempt_count_add+0x23/0x1a0 kernel/sched/core.c:5789
Code: 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 49 bf 00 00 00 00 00 fc ff df 48 c7 c0 60 83 d0 98 48 c1 e8 03 42 0f b6 04 38 <84> c0 0f 85 f1 00 00 00 83 3d ce 3a 41 17 00 75 07 65 8b 05 95 07
RSP: 0018:ffffc90000ac70a0 EFLAGS: 00000806
RAX: 0000000000000004 RBX: ffff8880379dc690 RCX: 711d72d82914fe00
RDX: 0000000000000000 RSI: ffffffff8b3f4d40 RDI: 0000000000000001
RBP: ffffc90000ac7150 R08: ffffffff8ef76a77 R09: 1ffffffff1deed4e
R10: dffffc0000000000 R11: fffffbfff1deed4f R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000a06 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888126ccb000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc42adeff8 CR3: 0000000051ef2000 CR4: 00000000003526f0
Call Trace:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:109 [inline]
_raw_spin_lock_irqsave+0x8c/0xf0 kernel/locking/spinlock.c:162
rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
__rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
rt_spin_lock+0x14a/0x3e0 kernel/locking/spinlock_rt.c:57
spin_lock include/linux/spinlock_rt.h:44 [inline]
ref_tracker_alloc+0x1cb/0x450 lib/ref_tracker.c:280
__netdev_tracker_alloc include/linux/netdevice.h:4375 [inline]
netdev_hold include/linux/netdevice.h:4404 [inline]
___neigh_create+0xd17/0x2360 net/core/neighbour.c:665
ip6_finish_output2+0xa55/0x14c0 net/ipv6/ip6_output.c:128
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247
NF_HOOK include/linux/netfilter.h:318 [inline]
ndisc_send_skb+0xbce/0x1510 net/ipv6/ndisc.c:512
addrconf_dad_completed+0x7c6/0xd70 net/ipv6/addrconf.c:4360
addrconf_dad_work+0xd0d/0x15a0 include/linux/rwlock_rt.h:-1
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4b9/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245