INFO: task syz-executor:8021 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:21464 pid:8021  tgid:8021  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: 0033:0x7f0336f8fed7
RSP: 002b:00007ffed1644b98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f0337011c05 RCX: 00007f0336f8fed7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffed1644c50
RBP: 00007ffed1644c50 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffed1645ce0
R13: 00007f0337011c05 R14: 000000000003108e R15: 00007ffed1645d20
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u9:7/4487:
 #0: ffff88801b396148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90008c1fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
3 locks held by udevd/5298:
 #0: ffff88804b039f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
 #1: ffff88804b024008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffffffff99b05388 (&____s->seqcount#2){----}-{0:0}, at: ktime_get_coarse_real_ts64_mg+0x52/0x1e0
2 locks held by getty/5681:
 #0: ffff88810eb510a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000291b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
1 lock held by udevd/5995:
1 lock held by syz-executor/8021:
 #0: ffff88811e4ca0e0 (&type->s_umount_key#58){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
2 locks held by bch-rebalance/l/8278:
2 locks held by syz-executor/8651:
1 lock held by syz.2.465/10864:
 #0: ffff88811e4ca0e0 (&type->s_umount_key#58){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.8.524/11486:
 #0: ffff8880393300e0 (&type->s_umount_key#62/1){+.+.}-{4:4}, at: alloc_super+0x204/0x970
1 lock held by rm/11500:

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

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+0x439/0x7d0
 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: 6087 Comm: kworker/u8:5 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: bat_events batadv_nc_worker
RIP: 0010:batadv_nc_worker+0xd9/0x610
Code: 20 00 74 08 48 89 df e8 65 54 db f6 4a 8d 2c fd 00 00 00 00 48 03 2b e8 d5 22 5f f6 4c 8d 2d 00 00 00 00 48 c7 c7 e0 a0 13 8e <31> f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 41 55 e8 61 66 55 f6
RSP: 0018:ffffc90002c67a20 EFLAGS: 00000283
RAX: 0000000000000001 RBX: ffff88812002b680 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffffffff8dbaa007 RDI: ffffffff8e13a0e0
RBP: ffff888106674420 R08: 0000000000000000 R09: ffffffff8b4806b2
R10: dffffc0000000000 R11: ffffffff8b4805e0 R12: dffffc0000000000
R13: ffffffff8b4806b2 R14: ffff88811fe58d80 R15: 0000000000000084
FS:  0000000000000000(0000) GS:ffff8880b8614000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000005e000 CR3: 0000000022d42000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
