INFO: task kworker/u8:2:5453 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:23752 pid:5453  tgid:5453  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>

Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#1:
 #0: ffffffff8ec36278 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60
 #1: ffffffff9ad250d8 (&port_lock_key){-...}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0
locks held by khungtaskd/34: 1, last CPU#0:
 #0: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by kswapd0/90: 2, last CPU#0:
 #0: ffffffff8ee8f5e0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xa08/0x32c0
 #1: ffff888116f880e8 (&type->s_umount_key#69){++++}-{4:4}, at: super_cache_scan+0x94/0x500
locks held by kswapd1/91: 2, last CPU#0:
 #0: ffffffff8ee8f5e0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xa08/0x32c0
 #1: ffff888116f880e8 (&type->s_umount_key#69){++++}-{4:4}, at: super_cache_scan+0x94/0x500
locks held by kworker/u9:6/1110: 3, last CPU#1:
 #0: ffff8881000ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90007447c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff8881a71907a0 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x420
locks held by jbd2/sda1-8/5003: 1, last CPU#1:
 #0: ffffffff8eeab310 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60
locks held by syslogd/5024: 1, on CPU#0:
 #0: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_check_open_permission+0x1d3/0x470
locks held by udevd/5042: 1, on CPU#0:
 #0: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_perm+0x251/0x560
locks held by dhcpcd/5337: 2, last CPU#1:
 #0: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_number_perm+0x219/0x5f0
 #1: ffffffff8eeab310 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60
locks held by getty/5421: 2, on CPU#1:
 #0: ffff88811456e0a0 (&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 kworker/u8:2/5453: 3, on CPU#1:
 #0: ffff8881133a9140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003fffc40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff9024ccc0 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30
locks held by syz-executor/5526: 1, last CPU#0:
 #0: ffffffff8eeab310 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60
locks held by kworker/1:4/5672: 5, last CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006877c40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffc90006877770 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
 #3: ffffc90006877798 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
 #4: ffffffff8eeab310 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60
locks held by syz.4.2706/12282: 1, last CPU#0:
 #0: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550
locks held by syz-executor/14736: 1, on CPU#0:
 #0: ffffffff9024ccc0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
locks held by kworker/1:9/14894: 4, on CPU#1:
 #0: ffff888100069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003dffc40 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff9024ccc0 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0xac/0x1110
 #3: ffff8881a71907a0 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_check_chans_work+0x1a1/0x1110
locks held by syz.8.3964/15354: 1, on CPU#0:
 #0: ffffffff9024ccc0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
locks held by syz-executor/16497: 1, on CPU#0:
 #0: ffffffff8ee8f5e0 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim+0xf6/0x360
locks held by syz-executor/16500: 4, last CPU#0:
 #0: ffff888116de4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff8881b30b7950 (&type->i_mutex_dir_key#3){++++}-{4:4}, at: chmod_common+0x186/0x470
 #2: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_number_perm+0x219/0x5f0
 #3: ffffffff8eeab310 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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: 52 57 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 4c 05 c7 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: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85705b30 R12: dffffc0000000000
R13: 0000000000000020 R14: ffffffff9ad25100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a8ce6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f705e06c308 CR3: 0000000163f5e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __serial8250_console_fifo_write+0x1e6/0x3e0
 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>
