INFO: task kworker/u8:4:12904 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:19680 pid:12904 tgid:12904 ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 addrconf_dad_work+0x116/0x15c0
 process_scheduled_works+0xc3d/0x1630
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
INFO: task syz.0.5495:18356 blocked for more than 143 seconds.
      Not tainted syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.5495      state:D stack:26888 pid:18356 tgid:18350 ppid:5629   task_flags:0x40054c flags:0x00080003
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 tun_chr_close+0x3e/0x1c0
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 do_exit+0x73a/0x2360
 do_group_exit+0x22d/0x2f0
 get_signal+0x121b/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 exit_to_user_mode_loop+0x10e/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f086159e159
RSP: 002b:00007f0862394028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffed RBX: 00007f0861826360 RCX: 00007f086159e159
RDX: 0000200000002280 RSI: 0000000000008914 RDI: 0000000000000006
RBP: 00007f0861635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f08618263f8 R14: 00007f0861826360 R15: 00007ffcbb678588
 </TASK>
INFO: task syz.1.5499:18373 blocked for more than 144 seconds.
      Not tainted syzkaller #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.5499      state:D stack:26784 pid:18373 tgid:18371 ppid:5628   task_flags:0x40054c flags:0x00080001
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 tun_chr_close+0x3e/0x1c0
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 do_exit+0x73a/0x2360
 do_group_exit+0x22d/0x2f0
 get_signal+0x121b/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 exit_to_user_mode_loop+0x10e/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faca6d9e159
RSP: 002b:00007faca7c7a028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 000000000000002c RBX: 00007faca7025fa0 RCX: 00007faca6d9e159
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007faca6e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faca7026038 R14: 00007faca7025fa0 R15: 00007fff574354c8
 </TASK>
INFO: task syz-executor:18380 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25544 pid:18380 tgid:18380 ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 rtnl_newlink+0xc10/0x1c30
 rtnetlink_rcv_msg+0x802/0xc00
 netlink_rcv_skb+0x226/0x4a0
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x13a/0x180
 __sys_sendto+0x408/0x5a0
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3f6095e98e
RSP: 002b:00007ffc70775718 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055557fd6e500 RCX: 00007f3f6095e98e
RDX: 000000000000002c RSI: 00007f3f61754670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffc70775794 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f3f61754670 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:18388 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:25544 pid:18388 tgid:18388 ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 rtnl_newlink+0xc10/0x1c30
 rtnetlink_rcv_msg+0x802/0xc00
 netlink_rcv_skb+0x226/0x4a0
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x13a/0x180
 __sys_sendto+0x408/0x5a0
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f901b15e98e
RSP: 002b:00007ffdb4ea88f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000555581b97500 RCX: 00007f901b15e98e
RDX: 000000000000002c RSI: 00007f901bf54670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffdb4ea8974 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f901bf54670 R15: 0000000000000000
 </TASK>
INFO: task syz.2.5504:18396 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.5504      state:D stack:23944 pid:18396 tgid:18396 ppid:5636   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 tun_chr_close+0x3e/0x1c0
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x204/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe436d9e159
RSP: 002b:00007ffcce7fcbc8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fe437027da0 RCX: 00007fe436d9e159
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fe437027da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007fe437027cb0 R11: 0000000000000246 R12: 000000000005d95b
R13: 00007fe437025fac R14: 000000000005d916 R15: 00007fe437025fa0
 </TASK>
INFO: task syz.2.5504:18399 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.5504      state:D stack:28808 pid:18399 tgid:18396 ppid:5636   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 devinet_ioctl+0x2fb/0x1c50
 inet_ioctl+0x42a/0x560
 sock_do_ioctl+0x101/0x320
 sock_ioctl+0x57a/0x7e0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe436d9e159
RSP: 002b:00007fe437bdf028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe437026090 RCX: 00007fe436d9e159
RDX: 0000200000000080 RSI: 0000000000008914 RDI: 0000000000000004
RBP: 00007fe436e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe437026128 R14: 00007fe437026090 R15: 00007ffcce7fca68
 </TASK>

Showing all locks held in the system:
locks held by pr/ttyS0/16: 5, last CPU#1:
 #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60
 #1: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: process_backlog+0x3de/0x18b0
 #2: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: netif_receive_skb+0x102/0xbf0
 #3: ffff88823c639a70 (bh_lock#4){+.-.}-{3:3}, at: do_xdp_generic+0x6d9/0x12f0
 #4: ffff88823c639620 (bh_lock){+.-.}-{3:3}, at: napi_skb_cache_get+0x16c/0x7e0
locks held by khungtaskd/35: 1, last CPU#0:
 #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5422: 2, on CPU#1:
 #0: ffff88817a9610a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034832e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by kworker/u8:2/5486: 2, last CPU#0:
 #0: ffff888177953940 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900041afc40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/u8:3/5705: 4, last CPU#0:
 #0: ffff88810d53b940 ((wq_completion)krds_cp_wq#3/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006597c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff888114101280 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff88816f1e8f60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sock_set_nodelay+0x2a/0x180
locks held by kworker/1:14/6547: 3, last CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90007b27c40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20
locks held by kworker/0:18/10214: 2, last CPU#0:
 #0: ffff888100069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900036efc40 ((gc_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/u8:4/12904: 3, on CPU#0:
 #0: ffff8881774e5940 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900045a7c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x116/0x15c0
locks held by kworker/u8:5/18334: 3, last CPU#0:
 #0: ffff88810f6dd940 ((wq_completion)krds_cp_wq#6/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003d07c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff8881140cb980 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
locks held by syz.0.5495/18356: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
locks held by syz.1.5499/18373: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
locks held by syz-executor/18380: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xc10/0x1c30
locks held by syz-executor/18388: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xc10/0x1c30
locks held by syz.2.5504/18396: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
locks held by syz.2.5504/18399: 1, on CPU#1:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x2fb/0x1c50
locks held by syz-executor/18402: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18411: 1, on CPU#1:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18416: 1, on CPU#1:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18423: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18432: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18438: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/18447: 1, on CPU#0:
 #0: ffffffff90250d40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0

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

NMI backtrace for cpu 0
CPU: 0 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+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 16 Comm: pr/ttyS0 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:lock_acquire+0x3e/0x350
Code: cb 45 89 c7 41 89 cd 89 54 24 04 41 89 f6 49 89 fc 65 48 8b 05 6b 56 f1 11 48 89 44 24 50 0f 1f 44 00 00 65 8b 05 6a 56 f1 11 <83> f8 08 0f 83 9b 01 00 00 89 c0 48 0f a3 05 97 fd d6 0e 73 0d e8
RSP: 0018:ffffc90000a17b38 EFLAGS: 00000292
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88823c639620
RBP: ffff88823c639620 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88823c639a70 R12: ffff88823c639620
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8882a8cd9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb5cfb178ea CR3: 0000000176356000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 napi_skb_cache_get+0x184/0x7e0
 napi_build_skb+0x33/0x550
 skb_pp_cow_data+0x317/0x18e0
 do_xdp_generic+0x78f/0x12f0
 __netif_receive_skb_core+0x10e3/0x30c0
 netif_receive_skb+0x1fe/0xbf0
 NF_HOOK+0xa4/0x3a0
 br_handle_frame_finish+0x1136/0x1950
 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+0x989/0x30c0
 process_backlog+0x727/0x18b0
 __napi_poll+0xaa/0x330
 net_rx_action+0x61d/0xf50
 handle_softirqs+0x226/0x860
 __irq_exit_rcu+0xcb/0x220
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80
Code: f7 e8 5d c5 bc f5 f7 c3 00 02 00 00 74 05 e8 50 02 e9 f5 9c 58 a9 00 02 00 00 75 29 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> f4 de ad f5 65 48 8b 05 9c 71 ad 07 48 85 c0 74 18 5b 41 5e c3
RSP: 0018:ffffc90000157ca8 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000206 RCX: 8000000000000001
RDX: 0000000000000000 RSI: ffffffff8e47497c RDI: 0000000000000001
RBP: ffffc90000157e18 R08: ffffffff907a177f R09: 1ffffffff20f42ef
R10: dffffc0000000000 R11: fffffbfff20f42f0 R12: 0000000000000002
R13: ffff888102ee0000 R14: ffffffff9ad32080 R15: dffffc0000000000
 nbcon_kthread_func+0x6c4/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
