INFO: task syz.0.2078:9848 blocked for more than 143 seconds.
      Not tainted 5.15.189-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2078      state:D stack:22336 pid: 9848 ppid:  4186 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 perf_pending_task_sync+0x13c/0x1c0 kernel/events/core.c:5127
 _free_event+0x34/0xe60 kernel/events/core.c:5133
 put_event kernel/events/core.c:5258 [inline]
 perf_event_release_kernel+0x832/0x8c0 kernel/events/core.c:5383
 perf_release+0x37/0x40 kernel/events/core.c:5393
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 get_signal+0x1222/0x12c0 kernel/signal.c:2672
 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1d822dfbe9
RSP: 002b:00007f1d80546fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: fffffffffffffffc RBX: 00007f1d82506fa0 RCX: 00007f1d822dfbe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000004b200000
RBP: 00007f1d82362e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f1d82507038 R14: 00007f1d82506fa0 R15: 00007ffffa8fe5a8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3953:
 #0: ffff88814c98c098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002d032e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
2 locks held by kworker/1:9/4290:
 #0: ffff888016872138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc900033bfd00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
4 locks held by kworker/u4:8/4605:
 #0: ffff8880169cd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc9000339fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8d22a2d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x132/0xb80 net/core/net_namespace.c:589
 #3: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #3: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x320/0x6b0 kernel/rcu/tree_exp.h:845
3 locks held by kworker/0:6/13112:
 #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc900032ffd00 (fqdir_free_work){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8c120cf0 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0xa1/0x4b0 kernel/rcu/tree.c:4043
2 locks held by syz.4.3578/14122:
 #0: ffffffff8d22a2d0 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x32e/0x5b0 net/core/net_namespace.c:499
 #1: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #1: ffffffff8c120de8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x347/0x6b0 kernel/rcu/tree_exp.h:845

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 14122 Comm: syz.4.3578 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:asm_sysvec_apic_timer_interrupt+0x0/0x20 arch/x86/include/asm/idtentry.h:675
Code: e9 e5 04 00 00 90 90 90 90 90 0f 01 ca fc 6a ff e8 e5 03 00 00 48 89 c4 48 89 e7 e8 7a 1b e8 ff e9 c5 04 00 00 90 90 90 90 90 <0f> 01 ca fc 6a ff e8 c5 03 00 00 48 89 c4 48 89 e7 e8 ca 19 e8 ff
RSP: 0018:ffffc9000322f1a8 EFLAGS: 00000006
RAX: 1ffff1100f05b95f RBX: ffff8880782dcaf8 RCX: 0000000000080000
RDX: ffffc9000f3de000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: dffffc0000000000 R08: 0000000000000004 R09: 0000000000000003
R10: fffff52000645e40 R11: 1ffff92000645e40 R12: ffff88801f23de80
R13: ffff8880782dc800 R14: 00000000000002f0 R15: ffff888016a50000
FS:  00007f886f8726c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f10770612f8 CR3: 000000013fe25000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
RIP: 0010:neigh_flush_dev+0x8ba/0x990 net/core/neighbour.c:340
Code: ff ff 4c 89 f7 e8 76 07 e3 f9 e9 ac fe ff ff 44 89 f1 80 e1 07 38 c1 0f 8c bf fe ff ff 4c 89 f7 e8 ab 07 e3 f9 e9 b2 fe ff ff <e8> 41 a4 9e f9 4c 89 e8 e9 97 f8 ff ff e8 34 a4 9e f9 4c 89 e8 e9
RSP: 0018:ffffc9000322f1d0 EFLAGS: 00000206
 __neigh_ifdown+0x39/0x3a0 net/core/neighbour.c:391
 neigh_ifdown+0x1b/0x30 net/core/neighbour.c:408
 rt6_disable_ip+0x602/0x690 net/ipv6/route.c:4922
 addrconf_ifdown+0x149/0x1970 net/ipv6/addrconf.c:3776
 addrconf_notify+0x445/0xf00 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
 call_netdevice_notifiers net/core/dev.c:2075 [inline]
 unregister_netdevice_many+0xf57/0x18f0 net/core/dev.c:11134
 ip_tunnel_delete_nets+0x318/0x360 net/ipv4/ip_tunnel.c:1151
 ops_exit_list net/core/net_namespace.c:177 [inline]
 setup_net+0x822/0x9f0 net/core/net_namespace.c:365
 copy_net_ns+0x348/0x5b0 net/core/net_namespace.c:503
 create_new_namespaces+0x3d3/0x6f0 kernel/nsproxy.c:110
 copy_namespaces+0x37d/0x3e0 kernel/nsproxy.c:178
 copy_process+0x180f/0x3e00 kernel/fork.c:2293
 kernel_clone+0x219/0x930 kernel/fork.c:2679
 __do_sys_clone kernel/fork.c:2796 [inline]
 __se_sys_clone kernel/fork.c:2780 [inline]
 __x64_sys_clone+0x170/0x1c0 kernel/fork.c:2780
 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: 0033:0x7f887160abe9
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:00007f886f871fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f8871831fa0 RCX: 00007f887160abe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040089000
RBP: 00007f887168de19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f8871832038 R14: 00007f8871831fa0 R15: 00007ffe7e144198
 </TASK>