INFO: task syz.5.1472:22452 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.1472      state:D stack:23368 pid:22452 tgid:22451 ppid:22035  task_flags:0x400140 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
 __se_sys_quotactl+0x353/0x950
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8e9218ec29
RSP: 002b:00007f8e92f84038 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f8e923d5fa0 RCX: 00007f8e9218ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000100
RBP: 00007f8e92211e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e923d6038 R14: 00007f8e923d5fa0 R15: 00007fff2c8b3648
 </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
1 lock held by udevd/5297:
 #0: ffff888136639f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
2 locks held by getty/5680:
 #0: ffff8880225c50a0 (&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/21000:
1 lock held by syz.5.1472/22452:
 #0: ffff8881219f00e0 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.6.1606/24206:
 #0: ffff8881219f00e0 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
2 locks held by syz-executor/24646:
 #0: ffff8880333de0e0 (&type->s_umount_key#55){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffffffff8e13fa40 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570
2 locks held by udevd/24790:
1 lock held by syz.1.1760/25412:
 #0: ffffffff8e847750 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_mount_permission+0x27a/0x970
1 lock held by syz.7.1762/25447:
1 lock held by modprobe/25455:

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

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: 25447 Comm: syz.7.1762 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:io_serial_in+0x77/0xc0
Code: e8 ae df 6f fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ff 5c d3 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 0a 8e 2d 06 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc9000618f038 EFLAGS: 00000006
RAX: 1ffffffff33bf005 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 0000000000017e06 RDI: 0000000000017e07
RBP: ffffc9000618f210 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff854fcd90 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff99df8460 R15: 0000000000000000
FS:  00007feecf2326c0(0000) GS:ffff8881a3c12000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055afd025d000 CR3: 000000003f560000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x584/0x1ba0
 console_flush_all+0x728/0xc40
 console_unlock+0xc4/0x270
 vprintk_emit+0x5b7/0x7a0
 _printk+0xcf/0x120
 __ext4_warning+0x1f5/0x200
 __ext4_read_dirblock+0x14e/0x760
 dx_probe+0xa8/0x1150
 __ext4_find_entry+0x596/0x1f20
 ext4_lookup+0x13d/0x6c0
 lookup_one_qstr_excl+0x131/0x360
 filename_create+0x224/0x3c0
 do_mkdirat+0xa0/0x590
 __x64_sys_mkdir+0x6c/0x80
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feece38ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007feecf232038 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007feece5d5fa0 RCX: 00007feece38ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000300
RBP: 00007feece411e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feece5d6038 R14: 00007feece5d5fa0 R15: 00007fff42bfe578
 </TASK>
