INFO: task syz-executor:11099 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:19304 pid:11099 tgid:11099 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: 0033:0x7f9c2458ff17
RSP: 002b:00007ffc7c06dc08 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9c24611c05 RCX: 00007f9c2458ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc7c06dcc0
RBP: 00007ffc7c06dcc0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffc7c06ed50
R13: 00007f9c24611c05 R14: 000000000004602f R15: 00007ffc7c06ed90
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
2 locks held by kworker/u10:0/27:
 #0: ffff88801da8e148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000060fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
1 lock held by khungtaskd/34:
 #0: ffffffff8e139ee0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5671:
 #0: ffff8880212540a0 (&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/11099:
 #0: ffff88810bb000e0 (&type->s_umount_key#70){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
3 locks held by kworker/1:6/12044:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003a2fbc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888011dfe240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
2 locks held by dhcpcd/13259:
 #0: ffff888113a0a008 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240
 #1: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
3 locks held by kworker/1:8/13560:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002fffbc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff88812b6c9240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
1 lock held by syz.1.1128/13714:
 #0: ffff88810bb000e0 (&type->s_umount_key#70){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.6.1402/15172:
 #0: ffff88810bb000e0 (&type->s_umount_key#70){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.6.1402/15187:
 #0: ffff88810bb000e0 (&type->s_umount_key#70){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.0.1415/15296:
 #0: ffff88810bb000e0 (&type->s_umount_key#70){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz-executor/15500:
 #0: ffffffff8e13f978 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
2 locks held by syz.8.1449/15605:
1 lock held by dhcpcd-run-hook/15612:

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

NMI backtrace for cpu 1
CPU: 1 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5830 Comm: syz-executor 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:__x64_sys_read+0x2d/0x90
Code: fa 41 57 41 56 41 54 53 48 89 fb 49 bc 00 00 00 00 00 fc ff df e8 43 0d 8c ff 48 8d 7b 70 48 89 f8 48 c1 e8 03 42 80 3c 20 00 <74> 05 e8 4c 7b ef ff 4c 8b 73 70 48 8d 7b 68 48 89 f8 48 c1 e8 03
RSP: 0018:ffffc9000342fec8 EFLAGS: 00000246
RAX: 1ffff92000685ff9 RBX: ffffc9000342ff58 RCX: ffff888107391cc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000342ffc8
RBP: ffffc9000342ff48 R08: ffffffff8fa38a37 R09: 1ffffffff1f47146
R10: dffffc0000000000 R11: fffffbfff1f47147 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffc9000342ff58 R15: ffff888107391cc0
FS:  0000555570c18500(0000) GS:ffff8880b861b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005586c239d048 CR3: 000000010ab56000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb46278d5bd
Code: a8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb b5 e8 a8 48 00 00 0f 1f 84 00 00 00 00 00 80 3d a1 af 1f 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec
RSP: 002b:00007ffeecc70cd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb46278d5bd
RDX: 0000000000000004 RSI: 00007ffeecc70cec RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000000e173529 R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffeecc71100
R13: 0000000000000004 R14: 00007ffeecc70cec R15: 00007ffeecc70d80
 </TASK>
