INFO: task syz.1.409:9283 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.409       state:D stack:25608 pid:9283  tgid:9282  ppid:9088   task_flags:0x400040 flags:0x00080002
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
 user_get_super+0xc8/0x120
 __se_sys_quotactl+0x4da/0x950
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4163d8ec29
RSP: 002b:00007f4164c5f038 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f4163fd5fa0 RCX: 00007f4163d8ec29
RDX: 000000003a736e6f RSI: 0000200000000200 RDI: ffffffff80000801
RBP: 00007f4163e11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 00002000000002c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4163fd6038 R14: 00007f4163fd5fa0 R15: 00007fffed1fee38
 </TASK>
INFO: task syz.1.409:9284 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.409       state:D stack:28904 pid:9284  tgid:9282  ppid:9088   task_flags:0x400040 flags:0x00080002
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
 user_get_super+0xc8/0x120
 __se_sys_quotactl+0x4da/0x950
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4163d8ec29
RSP: 002b:00007f4164c3e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f4163fd6090 RCX: 00007f4163d8ec29
RDX: 000000003a736e6f RSI: 0000200000000040 RDI: ffffffff80000701
RBP: 00007f4163e11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000001800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4163fd6128 R14: 00007f4163fd6090 R15: 00007fffed1fee38
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
1 lock held by khungtaskd/34:
 #0: ffffffff8e33d320 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u10:1/36:
1 lock held by udevd/5296:
2 locks held by getty/5675:
 #0: ffff8880257890a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000290e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz-executor/5847:
1 lock held by udevd/8256:
 #0: ffff88801e459ea8 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: blkdev_read_iter+0x2f8/0x440
1 lock held by syz.1.409/9283:
 #0: ffff8880327200e0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.409/9284:
 #0: ffff8880327200e0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
2 locks held by syz.0.757/12285:
2 locks held by syz.7.758/12288:
 #0: ffff8880366a60e0 (&type->s_umount_key#53/1){+.+.}-{4:4}, at: alloc_super+0x1bb/0x930
 #1: ffffffff8e1e3aa8 (wq_pool_mutex){+.+.}-{4:4}, at: __alloc_workqueue+0x9f0/0x1b80
2 locks held by syz.4.759/12290:
1 lock held by udevadm/12299:

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

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+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 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: 2272 Comm: kworker/u10:4 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: btrfs-endio-meta btrfs_end_bio_work
RIP: 0010:io_serial_in+0x77/0xc0
Code: e8 ce 8c 69 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 4f 2e cf fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 1a b6 2b 06 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc9000afaf098 EFLAGS: 00000006
RAX: 1ffffffff3401e05 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffc9000afaf270 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff8556ce00 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff9a00f5a0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881a39fc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff591ecadc3 CR3: 0000000108f8a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x584/0x1ba0
 console_flush_all+0x6f3/0xb10
 console_unlock+0xbb/0x190
 vprintk_emit+0x4c5/0x590
 _printk+0xcf/0x120
 _btrfs_printk+0x562/0x5b0
 btrfs_validate_extent_buffer+0xbb5/0x1ba0
 end_bbio_meta_read+0x108/0x1e0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
