INFO: task kworker/u4:4:463 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:4    state:D
 stack:19616 pid:  463 ppid:     2 flags:0x00004000
Workqueue: writeback wb_workfn
 (flush-7:0)

Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 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+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
 hfsplus_cat_write_inode+0x1e3/0x820 fs/hfsplus/inode.c:588
 write_inode fs/fs-writeback.c:1505 [inline]
 __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1940
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
 wb_writeback+0x455/0xb90 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+0xb47/0xe60 fs/fs-writeback.c:2298
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 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: 
ffff888142b90938
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: 
ffffc90000ce7d00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: 
ffff88807d3260e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff88807a46c0b0
 (
&tree->tree_lock
){+.+.}-{3:3}
, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
1 lock held by khungtaskd/27:
 #0: 
ffffffff8c11c760
 (
rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:2/154:
 #0: 
ffff888142b90938
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: 
ffffc90001f97d00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: 
ffff888027b1c0e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff8880765d00b0