INFO: task kworker/u4:2:148 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D
 stack:21712 pid:  148 ppid:     2 flags:0x00004000
Workqueue: writeback wb_workfn
 (flush-7:0)

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
 hfs_write_inode+0x3e1/0xa20 fs/hfs/inode.c:458
 write_inode fs/fs-writeback.c:1505 [inline]
 __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
 writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
 wb_writeback+0x46f/0xbe0 fs/fs-writeback.c:2116
 wb_check_background_flush fs/fs-writeback.c:2182 [inline]
 wb_do_writeback fs/fs-writeback.c:2270 [inline]
 wb_workfn+0xbd6/0xf20 fs/fs-writeback.c:2298
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
 #0: 
ffff8881423b6138
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: 
ffffc90000ce7d00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: 
ffff8880210680e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff8880214120b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
1 lock held by khungtaskd/27:
 #0: 
ffffffff8c31eaa0
 (
rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:2/148:
 #0: 
ffff8881423b6138
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: 
ffffc9000172fd00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: 
ffff88802026a0e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff88802026e0b0
 (
&tree->tree_lock){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
4 locks held by kworker/u4:3/1226:
 #0: ffff8881423b6138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90004f67d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: 
ffff888022b020e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff88807e93a0b0
 (
&tree->tree_lock
){+.+.}-{3:3}
, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1