[v6.6] INFO: task hung in ret_from_fork_asm

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11e1d9b4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=b7ded3f62b62288cfd99
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122aa31a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e83fe765543a/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b7ded3...@syzkaller.appspotmail.com

INFO: task kworker/u4:0:11 blocked for more than 143 seconds.
stack:24024 pid:11 ppid:2 flags:0x00004000
__writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:1997
wb_writeback+0x464/0xba0 fs/fs-writeback.c:2107
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
Not tainted syzkaller #0
<TASK>
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
INFO: task kworker/u4:6:1088 blocked for more than 152 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6 state:D stack:23560 pid:1088 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>

Showing all locks held in the system:
ffff888145668938
((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffff88807cd7a0e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607
#3:
){+.+.}-{3:3}
, at: hfsplus_find_init+0x154/0x1d0 fs/hfsplus/bfind.c:28


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