INFO: task syz-executor:7158 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:18856 pid:7158  tgid:7158  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: 0033:0x7f3c2e18fed7
RSP: 002b:00007fff96069928 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f3c2e211c05 RCX: 00007f3c2e18fed7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff960699e0
RBP: 00007fff960699e0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff9606aa70
R13: 00007f3c2e211c05 R14: 000000000002ebdf R15: 00007fff9606aab0
 </TASK>

Showing all locks held in the system:
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/u9:2/148:
 #0: ffff88810073e948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000175fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
2 locks held by getty/5675:
 #0: ffff888027e3f0a0 (&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
2 locks held by sshd/5770:
6 locks held by kworker/u8:4/5876:
 #0: ffff88801b2f7148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000347fbc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8f52cc50 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x800
 #3: ffff88811b8630e8 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x10a/0x3d0
 #4: ffff88811b861250 (&devlink->lock_key#20){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x11c/0x3d0
 #5: ffffffff8e13f880 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570
1 lock held by syz-executor/7158:
 #0: ffff88803374e0e0 (&type->s_umount_key#60){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
3 locks held by kworker/0:7/7564:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90003b3fbc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888023a88240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
2 locks held by bch-copygc/loop/8737:
 #0: ffff888125e04398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: bch2_trans_srcu_lock+0xaf/0x220
 #1: ffff888125e26710 (&c->gc_lock){++++}-{4:4}, at: bch2_btree_update_start+0x542/0x1de0
1 lock held by syz.1.349/9077:
 #0: ffff88803374e0e0 (&type->s_umount_key#60){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.615/11797:
 #0: ffff88803374e0e0 (&type->s_umount_key#60){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.5.650/12182:
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730
1 lock held by syz-executor/12192:
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
1 lock held by dhcpcd-run-hook/12208:

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

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: 5592 Comm: dhcpcd 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:syscall_return_via_sysret+0x85/0x87
Code: 73 0e 65 48 0f b3 3d 38 3c a2 11 48 89 c7 eb 08 48 89 c7 48 0f ba ef 3f 48 81 cf 00 08 00 00 48 81 cf 00 10 00 00 0f 22 df 58 <5f> 5c 0f 01 f8 0f 00 2d 77 fe ff ff 48 0f 07 cc 90 90 90 56 48 8b
RSP: 0018:fffffe0000049ff0 EFLAGS: 00000006
RAX: fffffffffffffffc RBX: 0000556caa2e9e10 RCX: 00007fde3f1a5ad5
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 000000010eea1000
RBP: 00007fffe464acf0 R08: 0000000000000008 R09: 0000000000000000
R10: 00007fffe464acf0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000556c9bab6610 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fde3f0d8740(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff8827e0a8 CR3: 000000010eea0000 CR4: 00000000000006f0
Call Trace:
 <ENTRY_TRAMPOLINE>
 </ENTRY_TRAMPOLINE>
