INFO: task syz-executor:5851 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21832 pid:5851  tgid:5851  ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 wb_wait_for_completion+0x15f/0x260
 __writeback_inodes_sb_nr+0x1f6/0x250
 sync_filesystem+0xa3/0x230
 generic_shutdown_super+0x6f/0x2c0
 bch2_kill_sb+0x41/0x50
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d0478ff17
RSP: 002b:00007ffc2cab0b48 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f6d04811c05 RCX: 00007f6d0478ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc2cab0c00
RBP: 00007ffc2cab0c00 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffc2cab1c90
R13: 00007f6d04811c05 R14: 0000000000014d9e R15: 00007ffc2cab1cd0
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u8:1/13:
 #0: ffff88801b2f7148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90000107bc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f52bdb0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x800
 #3: ffffffff8e13f880 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570
5 locks held by kworker/u9:0/26:
 #0: ffff888136639f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
 #1: ffff888136624008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffff888136624008 (psi_seq){-.-.}-{0:0}, at: psi_task_change+0xd9/0x340
 #3: ffffffff99d12440 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0xbb/0x420
 #4: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa5/0x2390
1 lock held by khungtaskd/34:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u9:2/53:
 #0: ffff888102a8e148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900007bfbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
2 locks held by getty/5674:
 #0: ffff8880201180a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
1 lock held by syz-executor/5851:
 #0: ffff88811a7dc0e0 (&type->s_umount_key#75){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 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+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 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: 8572 Comm: kworker/1:8 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
Workqueue: usb_hub_wq hub_event
RIP: 0010:asm_sysvec_apic_timer_interrupt+0x0/0x20
Code: 56 ac 79 0a e9 61 06 00 00 90 f3 0f 1e fa 0f 1f 00 fc 6a ff e8 11 05 00 00 48 89 c4 48 89 e7 e8 66 ab 79 0a e9 41 06 00 00 90 <f3> 0f 1e fa 0f 1f 00 fc 6a ff e8 f1 04 00 00 48 89 c4 48 89 e7 e8
RSP: 0018:ffffc900073c7298 EFLAGS: 00000083
RAX: ffffffff81a02717 RBX: ffffffff81a025d4 RCX: 0000000000100000
RDX: ffffc90028bb2000 RSI: 000000000000a4ee RDI: ffffffff8e12e1c0
RBP: ffffc900073c73d0 R08: ffffffff8fa39037 R09: 1ffffffff1f47206
R10: dffffc0000000000 R11: fffffbfff1f47207 R12: dffffc0000000000
R13: 1ffff92000e78e5c R14: 0000000000000200 R15: 0000000000000029
FS:  0000000000000000(0000) GS:ffff8881a3c18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32719ff8 CR3: 000000003cab0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
RIP: 0010:vprintk_emit+0x58f/0x7a0
Code: 85 32 01 00 00 e8 11 87 1f 00 41 89 df 4d 85 f6 48 8b 1c 24 75 07 e8 00 87 1f 00 eb 06 e8 f9 86 1f 00 fb 48 c7 c7 c0 e1 12 8e <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 b9 35
RSP: 0018:ffffc900073c72c0 EFLAGS: 00000283
 dev_vprintk_emit+0x337/0x3f0
 dev_printk_emit+0xe0/0x130
 _dev_info+0x10a/0x160
 usb_disconnect+0xdd/0x950
 hub_event+0x1cf5/0x4a20
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
