INFO: task syz-executor:9611 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25880 pid:9611  tgid:9611  ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 fib6_rules_net_exit_batch+0x20/0xc0
 ops_undo_list+0x4b4/0x8d0
 setup_net+0x2f6/0x350
 copy_net_ns+0x4f9/0x720
 create_new_namespaces+0x3f0/0x6b0
 unshare_nsproxy_namespaces+0x149/0x190
 ksys_unshare+0x57d/0xa00
 __x64_sys_unshare+0x38/0x50
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f845df9f3a7
RSP: 002b:00007ffd3607bec8 EFLAGS: 00000202 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f845e225f40 RCX: 00007f845df9f3a7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00007f845e2267b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffd3607c108 R15: 0000000000000000
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:unwind_next_frame+0x511/0x2550
Code: b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 27 48 63 03 48 01 d8 48 8d 4b 04 48 39 e8 4c 0f 46 f9 48 8d 43 fc 4c 0f 47 e0 <4c> 0f 46 eb 4d 39 e7 76 a9 e9 7c fd ff ff 89 d9 80 e1 07 80 c1 03
RSP: 0018:ffffc90000146a40 EFLAGS: 00000287
RAX: ffffffff90730674 RBX: ffffffff90730678 RCX: ffffffff9073067c
RDX: ffffffff90730654 RSI: ffffffff90f22cd0 RDI: ffffffff8c4b9320
RBP: ffffffff81b1c7f8 R08: 000000000000000d R09: 0000000000000000
R10: ffffc90000146b38 R11: ffffffff81b1c860 R12: ffffffff90730684
R13: ffffffff9073066c R14: ffffc90000146ae8 R15: ffffffff9073067c
FS:  0000000000000000(0000) GS:ffff88818d979000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f74faa6064c CR3: 00000001688f2000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x2a0/0x5f0
 skb_ext_add+0x1b6/0x8e0
 br_nf_forward_ip+0xc3/0xa30
 nf_hook_slow+0xc5/0x220
 NF_HOOK+0x23e/0x3f0
 __br_forward+0x397/0x540
 br_handle_frame_finish+0x1175/0x1990
 br_nf_hook_thresh+0x3dd/0x4c0
 br_nf_pre_routing_finish_ipv6+0x90c/0xc40
 br_nf_pre_routing_ipv6+0x382/0x6f0
 br_handle_frame+0x127f/0x1510
 __netif_receive_skb_core+0x989/0x30b0
 process_backlog+0x706/0x1860
 __napi_poll+0xaa/0x330
 net_rx_action+0x61d/0xf50
 handle_softirqs+0x225/0x840
 run_ksoftirqd+0x36/0x60
 smpboot_thread_fn+0x57c/0xa80
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
