INFO: task kworker/u8:7:16874 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:7    state:D stack:23752 pid:16874 tgid:16874 ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5820
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 addrconf_verify_work+0x19/0x30
 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 kworker/u10:0:8019 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u10:0   state:D stack:24584 pid:8019  tgid:8019  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5820
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 linkwatch_event+0xe/0x60
 process_scheduled_works+0xc3d/0x1630
 worker_thread+0xa47/0xfb0
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
locks held by kworker/1:1/33: 3, on CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90000a87c40 (netdev_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: netdev_work_proc+0x6f/0x770
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 kworker/1:3/1295: 3, on CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006e77c40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: 
ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20
locks held by dhcpcd/5339: 1, on CPU#1:
 #0: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x2fb/0x1c50
locks held by getty/5422: 2, on CPU#0:
 #0: ffff888174c830a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by sshd/5571: 2, last CPU#0:
 #0: ffff8881bd4ddcf8 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x2d8/0x9f0
 #1: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550
locks held by kworker/u8:2/5626: 4, last CPU#0:
 #0: ffff88816d699140 ((wq_completion)krds_cp_wq#12/2){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000457fc40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170c80 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff888115e10260 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: __inet6_bind+0x301/0xf30
locks held by kworker/u8:3/5646: 3, last CPU#0:
 #0: ffff88816d69d140 ((wq_completion)krds_cp_wq#12/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90004ed7c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c171280 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
locks held by kworker/u8:4/16233: 3, last CPU#0:
 #0: ffff8880202f2940 ((wq_completion)krds_cp_wq#23/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90007337c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff888030f81c60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_close+0x1d/0x110
locks held by kworker/u8:6/16873: 4, last CPU#0:
 #0: ffff888112017140 ((wq_completion)krds_cp_wq#10/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000eadfc40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88801f7c8980 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: __inet_dev_addr_type+0x159/0x560
locks held by kworker/u8:7/16874: 3, on CPU#1:
 #0: ffff88817495b140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000eb8fc40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}
, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30
locks held by kworker/u8:8/16875: 4, last CPU#1:
 #0: ffff88816d69d140 ((wq_completion)krds_cp_wq#12/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000ebafc40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c171280 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff8881ae8faae0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_sock_set_nodelay+0x2a/0x180
locks held by kworker/u8:9/16876: 3, last CPU#1:
 #0: ffff88817260e140 ((wq_completion)krds_cp_wq#12/6){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000ebe7c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170080 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
locks held by kworker/u10:10/480: 2, last CPU#1:
 #0: ffff8881000ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90008fafc40 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/1:2/4356: 4, last CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900074ffc40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816993e270 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_damage_work+0x15b/0xf20
 #3: ffff888103324128 (&dev->master_mutex){+.+.}-{4:4}, at: drm_master_internal_acquire+0x20/0x80
locks held by kworker/u8:0/7957: 5, on CPU#1:
 #0: ffff8881012d5940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003be7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff902412e8 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810
 #3: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x28e/0x8d0
 #4: ffffffff902f3ce0 (flowtable_lock){+.+.}-{4:4}, at: nf_flow_table_cleanup+0x21/0xb0
locks held by kworker/u8:5/7959: 2, last CPU#0:
 #0: ffff888174939140 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000660fc40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/u8:10/7960: 4, last CPU#0:
 #0: ffff88816d69b140 ((wq_completion)krds_cp_wq#12/3){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900061b7c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170980 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff88802ec48fe0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: __inet6_bind+0x301/0xf30
locks held by kworker/u8:12/7965: 3, last CPU#1:
 #0: ffff88817260e940 ((wq_completion)krds_cp_wq#12/4){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003bf7c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170680 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
locks held by kworker/u8:13/7966: 3, last CPU#1:
 #0: ffff88816d69f140 ((wq_completion)krds_cp_wq#12/1){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003c07c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170f80 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
locks held by kworker/1:4/7986: 2, last CPU#1:
 #0: ffff888100069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000ed8fc40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/u8:14/7999: 4, last CPU#1:
 #0: ffff888172608940 ((wq_completion)krds_cp_wq#12/7){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006647c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff888172917c80 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff88802ec49d60 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: __inet6_bind+0x301/0xf30
locks held by kworker/u8:15/8003: 4, last CPU#1:
 #0: ffff88817260c940 ((wq_completion)krds_cp_wq#12/5){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000e6bfc40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff88816c170380 (&tc->t_conn_path_lock){+.+.}-{4:4}, at: rds_tcp_conn_path_connect+0x1cc/0x920
 #3: ffff8881ae8fb860 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: __inet6_bind+0x301/0xf30
locks held by kworker/u10:0/8019: 3, on CPU#1:
 #0: ffff8881000ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90008087c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60
locks held by syz-executor/8107: 1, on CPU#1:
 #0: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/8111: 1, on CPU#0:
 #0: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/8124: 1, on CPU#1:
 #0: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/8128: 1, on CPU#0:
 #0: ffffffff9024fb40 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x470/0x19f0
locks held by syz-executor/8143: 1, last CPU#1:
 #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550
locks held by syz-executor/8144: 1, on CPU#1:
 #0: ffff88801ed18ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_open+0x1f3/0x360

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

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+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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 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:io_serial_out+0x7c/0xc0
Code: 82 56 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ac 4a c6 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90000157900 EFLAGS: 00000002
RAX: 000000000000000d RBX: 000000000000000d RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85713070 R12: dffffc0000000000
R13: 000000000000000a R14: ffffffff9ad2d020 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88818d6de000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2a47e87e20 CR3: 000000016c0cc000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __serial8250_console_fifo_write+0x238/0x3e0
 serial8250_console_write+0xaa1/0x1200
 nbcon_emit_next_record+0xef5/0x1a90
 nbcon_kthread_func+0x679/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
