INFO: task syz.8.351:8542 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.351       state:D stack:28936 pid:8542  tgid:8541  ppid:7582   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x5fd/0x8f0
 down_read+0x98/0x2e0
 super_lock+0x2a9/0x3b0
 __iterate_supers+0x126/0x290
 ksys_sync+0x94/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb127b8eba9
RSP: 002b:00007fb128a4c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fb127dd5fa0 RCX: 00007fb127b8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fb127dd5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb127dd6038 R14: 00007fb127dd5fa0 R15: 00007ffe59bc2bc8
 </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 getty/5677:
 #0: ffff888020ee00a0 (&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
3 locks held by syz-executor/5861:
1 lock held by syz.8.351/8542:
 #0: ffff88810839a0e0 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
2 locks held by syz-executor/8784:
1 lock held by syz-executor/9123:
2 locks held by syz-executor/9959:

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

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: 9959 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:lock_acquire+0x180/0x360
Code: 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 7b 51 03 11 48 3b 44 24 58 0f 85 f2 00 00 00 <48> 83 c4 60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 65 8b
RSP: 0018:ffffc90006ef7620 EFLAGS: 00000246
RAX: 0acee9000c2d2f00 RBX: 0000000000000000 RCX: 0acee9000c2d2f00
RDX: 0000000000000000 RSI: ffffffff8dba8965 RDI: ffffffff8be33980
RBP: ffffffff824205e4 R08: 0000000000000000 R09: ffffffff824205e4
R10: ffffc90006ef7740 R11: fffff52000ddef16 R12: 0000000000000000
R13: ffff888122217530 R14: 0000000000000001 R15: 0000000000000246
FS:  000055555dbfd500(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa02bdff000 CR3: 0000000041710000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 _raw_spin_lock+0x2e/0x40
 writeback_single_inode+0x34/0x6a0
 sync_inode_metadata+0xb9/0x110
 f2fs_write_checkpoint+0xb06/0x1df0
 kill_f2fs_super+0x2c3/0x6c0
 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: 0033:0x7f25a658fed7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffde5e48ee8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f25a6611c05 RCX: 00007f25a658fed7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffde5e48fa0
RBP: 00007ffde5e48fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffde5e4a030
R13: 00007f25a6611c05 R14: 000000000005bb80 R15: 00007ffde5e4a070
 </TASK>
