INFO: task syz.0.2890:13232 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2890      state:D stack:27592 pid:13232 tgid:13231 ppid:5615   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7f7/0x1550
 sync_bdevs+0x27e/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe8d1b9cdd9
RSP: 002b:00007fe8d29a6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fe8d1e15fa0 RCX: 00007fe8d1b9cdd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe8d1e15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe8d1e16038 R14: 00007fe8d1e15fa0 R15: 00007ffecc9cfc28
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:1/13:
 #0: ffff888111612140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90000127c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8fdcea00 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x11e/0x14c0
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u10:2/68:
3 locks held by kworker/0:2/795:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90004edfc40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff888172154230 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
2 locks held by getty/5438:
 #0: ffff8881117d00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
1 lock held by udevd/5864:
 #0: ffff88810a572350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
5 locks held by kworker/1:6/9371:
 #0: ffff8881052a9540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc900092c7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff88810c40d1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30
 #3: ffff88810c31a568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x217a/0x4f30
 #4: ffff88810c38a260 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21a2/0x4f30
1 lock held by syz.0.2890/13232:
 #0: ffff88810a572350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.5.3572/14901:
 #0: ffff88810a572350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz-executor/16986:
 #0: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
1 lock held by syz-executor/17451:
 #0: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770

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

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+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x388/0x470
 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: 17451 Comm: syz-executor 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:lock_acquire+0xc1/0x350
Code: 11 85 c0 0f 85 bf 00 00 00 65 48 8b 05 20 31 97 11 83 b8 8c 0b 00 00 00 0f 85 aa 00 00 00 4c 89 74 24 10 4d 89 fe 9c 41 5f fa <48> c7 c7 11 d5 fb 8d e8 53 42 06 0a 65 ff 05 9c 76 97 11 45 31 c9
RSP: 0018:ffffc9000676f4b8 EFLAGS: 00000046
RAX: ffff88816df5bb00 RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8176e273 RDI: 1ffffffff1d2b9ac
RBP: ffffffff8176e256 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc9000676f678 R11: ffffffff81b0d880 R12: 0000000000000002
R13: ffffffff8e95cd60 R14: 0000000000000000 R15: 0000000000000246
FS:  0000555567caf500(0000) GS:ffff8882a9293000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe88a947e20 CR3: 000000000e74a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0xc3/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 save_stack+0x122/0x230
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xb6f/0xce0
 vfree+0x1d1/0x2f0
 kcov_close+0x28/0x50
 __fput+0x44f/0xa60
 task_work_run+0x1d9/0x270
 do_exit+0x70f/0x22c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 do_syscall_64+0x33e/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb00655d60e
Code: Unable to access opcode bytes at 0x7fb00655d5e4.
RSP: 002b:00007ffd58b2b6c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: 0000000000000020 RBX: 0000555567caf500 RCX: 00007fb00655d60e
RDX: 0000000000000020 RSI: 00007fb007344670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd58b2b744 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007fb007344670 R15: 0000000000000000
 </TASK>
