INFO: task syz-executor:5854 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:17736 pid:5854  tgid:5854  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: 0033:0x7f6fbe98fed7
RSP: 002b:00007ffefef137c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f6fbea11c05 RCX: 00007f6fbe98fed7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffefef13880
RBP: 00007ffefef13880 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffefef14910
R13: 00007f6fbea11c05 R14: 0000000000025fe0 R15: 00007ffefef14950
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u9:1/28:
 #0: ffff888100685148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000061fbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5673:
 #0: ffff88801c7990a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029032f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
1 lock held by syz-executor/5854:
 #0: ffff888031b3c0e0 (&type->s_umount_key#61){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
3 locks held by kworker/0:3/5890:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000410fbc0 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888109327240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x26b/0x3180
2 locks held by bch-copygc/loop/7707:
 #0: ffff88802ef84398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: bch2_trans_srcu_lock+0xaf/0x220
 #1: ffff88802efa6710 (&c->gc_lock){++++}-{4:4}, at: bch2_btree_update_start+0x542/0x1de0
3 locks held by kworker/1:6/7819:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000457fbc0 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8e13fb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
1 lock held by syz.9.316/8564:
 #0: ffff888031b3c0e0 (&type->s_umount_key#61){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
2 locks held by syz-executor/8886:
1 lock held by syz.5.457/9983:
 #0: ffff888031b3c0e0 (&type->s_umount_key#61){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.5.457/9986:
 #0: ffff888031b3c0e0 (&type->s_umount_key#61){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz-executor/10126:
1 lock held by syz.0.485/10212:
 #0: ffff888031b3c0e0 (&type->s_umount_key#61){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by rm/10328:

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

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+0x439/0x7d0
 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: 10126 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:rcu_is_watching+0x10/0xb0
Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 30 40 fa 10 <e8> 1b 01 d4 09 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df
RSP: 0018:ffffc90003caf758 EFLAGS: 00000282
RAX: 0000000000000001 RBX: ffffffff8212a6ca RCX: ffff88810897d640
RDX: 0000000000000001 RSI: ffffffff8dba93b2 RDI: ffffffff8be33e80
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8172d195
R10: ffffc90003caf898 R11: ffffffff81ac4b00 R12: 1ffff92000795f09
R13: ffffc90003caf880 R14: ffffc90003caf848 R15: ffffffff8172d195
FS:  000055557ab6d500(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd2e5071ff8 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 unwind_next_frame+0xd4/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 save_stack+0xf5/0x1f0
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xbc4/0xd30
 vfree+0x25a/0x400
 kcov_close+0x28/0x50
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21f7/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f993df8eba9
Code: Unable to access opcode bytes at 0x7f993df8eb7f.
RSP: 002b:00007fff6e872238 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f993df8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043
RBP: 00007f993e01340f R08: 00007fff6e86ffd6 R09: 00000000000927c0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000020
R13: 00000000000927c0 R14: 000000000004a158 R15: 00007fff6e8723f0
 </TASK>
