INFO: task syz.9.5945:22955 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.9.5945      state:D stack:27696 pid:22955 tgid:22944 ppid:20758  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x14ef/0x4fb0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 sync_bdevs+0x27e/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f93e7d9acb9
RSP: 002b:00007f93e8c80028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f93e8016180 RCX: 00007f93e7d9acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f93e8016180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f93e8016218 R14: 00007f93e8016180 R15: 00007ffca44618f8
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/1:0/24:
 #0: ffff888100075948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0
 #1: ffffc900001e7bc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0
 #2: ffff8881bb08a240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
1 lock held by khungtaskd/35:
 #0: ffffffff8e35a360 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
6 locks held by kworker/0:2/798:
 #0: ffff8881056b8548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0
 #1: ffffc900055e7bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0
 #2: ffff88810c32f198 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30
 #3: ffff88810c11a518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x217a/0x4f30
 #4: ffff88810c3e1a68 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21a2/0x4f30
 #5: ffffffff8f0550f0 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x14e/0x1840
1 lock held by klogd/5269:
2 locks held by getty/5658:
 #0: ffff8881683b20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
2 locks held by sshd/5804:
1 lock held by udevd/9938:
 #0: ffff88810ab32358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.9.5945/22955:
 #0: ffff88810ab32358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.8.6501/24513:
 #0: ffffffff8e360c78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
1 lock held by syz-executor/27050:
 #0: ffffffff8e360c78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 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+0xf90/0xfe0
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 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: 27272 Comm: syz.6.7549 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:stack_trace_consume_entry+0x56/0x280
Code: 84 c0 0f 85 09 01 00 00 44 8b 4f 10 4c 8d 77 08 4d 89 f5 49 c1 ed 03 41 0f b6 44 15 00 84 c0 0f 85 22 01 00 00 45 3b 0e 73 3a <48> 8d 5f 0c 49 89 df 49 c1 ef 03 41 0f b6 04 17 84 c0 0f 85 47 01
RSP: 0018:ffffc900017a75d8 EFLAGS: 00000287
RAX: 0000000000000000 RBX: ffffc900017a76e0 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: ffffffff818595fb RDI: ffffc900017a76e0
RBP: 1ffff920002f4ede R08: ffffc900017a76f0 R09: 0000000000000006
R10: ffffc900017a7678 R11: ffffffff81ae5d00 R12: ffff88801d6c9d40
R13: 1ffff920002f4edd R14: ffffc900017a76e8 R15: ffffc900017a7628
FS:  00007fb31cff66c0(0000) GS:ffff88818e321000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e885b54de0 CR3: 0000000115da8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0x10f/0x150
 stack_trace_save+0xa9/0x100
 save_stack+0x122/0x230
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xbb9/0xd10
 vfree+0x25a/0x400
 kcov_close+0x28/0x50
 __fput+0x44f/0xa70
 task_work_run+0x1d9/0x270
 do_exit+0x69b/0x2310
 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+0x2b7/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb31ed9a94b
Code: Unable to access opcode bytes at 0x7fb31ed9a921.
RSP: 002b:00007fb31cff3f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fb31ed9a94b
RDX: 00007fb31cff4fd0 RSI: 0000000080085502 RDI: 0000000000000003
RBP: 00007fb31cff4fd0 R08: 0000000000000000 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000080085502
R13: 0000000800000000 R14: 0000000000000000 R15: 00007fb31ee092c1
 </TASK>
