INFO: task syz.4.4597:22374 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.4597      state:D stack:24656 pid:22374 ppid:4271   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 rwsem_down_write_slowpath+0xc99/0x1160 kernel/locking/rwsem.c:1189
 net_ns_barrier+0x11/0x20 net/core/net_namespace.c:678
 nf_ct_iterate_destroy+0x12f/0x180 net/netfilter/nf_conntrack_core.c:2527
 nfnl_cthelper_del+0x380/0x620 net/netfilter/nfnetlink_cthelper.c:721
 nfnetlink_rcv_msg+0xcab/0x1290 net/netfilter/nfnetlink.c:302
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 nfnetlink_rcv+0x2b0/0x2470 net/netfilter/nfnetlink.c:659
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcc52d9e0d9
RSP: 002b:00007fcc53c51028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fcc53026090 RCX: 00007fcc52d9e0d9
RDX: 0000000004048010 RSI: 00002000000001c0 RDI: 0000000000000009
RBP: 00007fcc52e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcc53026128 R14: 00007fcc53026090 R15: 00007ffc2e55c718
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by getty/4025:
 #0: ffff88814cf3f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
4 locks held by kworker/u4:21/4478:
2 locks held by syz.4.4597/22374:
 #0: ffffffff9703c540 (nfnl_subsys_cthelper){+.+.}-{3:3}, at: nfnl_lock net/netfilter/nfnetlink.c:98 [inline]
 #0: ffffffff9703c540 (nfnl_subsys_cthelper){+.+.}-{3:3}, at: nfnetlink_rcv_msg+0xa58/0x1290 net/netfilter/nfnetlink.c:295
 #1: ffffffff8dd4f610 (pernet_ops_rwsem){++++}-{3:3}, at: net_ns_barrier+0x11/0x20 net/core/net_namespace.c:678
1 lock held by syz-executor/22597:
 #0: ffffffff8dd4f610 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16 Comm: rcu_preempt Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3742 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3798 [inline]
RIP: 0010:__lock_acquire+0x1477/0x7c40 kernel/locking/lockdep.c:5063
Code: e8 03 25 f8 03 00 00 48 8d b8 40 22 b1 90 be 08 00 00 00 e8 6b 59 6f 00 49 b8 00 00 00 00 00 fc ff df 48 0f a3 1d c9 0e 4d 0f <72> 25 48 c7 c0 40 91 c1 96 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85
RSP: 0018:ffffc900001579a0 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 00000000000000cd RCX: ffffffff81641365
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b12258
RBP: ffffc90000157bd0 R08: dffffc0000000000 R09: 1ffffffff216244b
R10: dffffc0000000000 R11: fffffbfff216244c R12: ffff88813feae4d8
R13: ffff88813feada00 R14: 91fc3059e3402e66 R15: 91fc3059e3402e66
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c1323ce088 CR3: 000000007e550000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
 prepare_to_swait_event+0x27/0x360 kernel/sched/swait.c:107
 rcu_gp_kthread+0x154/0x3b0 kernel/rcu/tree.c:1889
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>