[Question] mm/damon: conflict between DAMON_STAT and DAMON_LRU_SORT?

[Liew Rui Yan <aethernet65535@gmail.com>]

TL;DR
=====
When CONFIG_DAMON_STAT_ENABLED_DEFAULT=y, enabling damon_lru_sort via sysfs
"enabled" parameter returns -EBUSY. Is this expected behavior? If yes, should
this limitation be documented?

Reproduction
============
Environment:
- Kernel: 7.0.0-rc3+ (x86_64)
- VM: Virtme-ng (4G RAM, 2 CPUs)
- Config: CONFIG_DAMON_STAT_ENABLED_DEFAULT=y, CONFIG_DAMON_LRU_SORT=y

Steps:
1. cd /sys/module/damon_lru_sort/parameters
2. (optional) tune parameters: hot_thres_access_freq, cold_min_age, etc.
3. echo Y > enabled

Result:
  bash: echo: write error: Device or resource busy

Workaround:
  Disable CONFIG_DAMON_STAT_ENABLED_DEFAULT, or disable damon_stat at runtime
  before enabling damon_lru_sort.

Questions
=========
1. Is this resource conflict between damon_stat and damon_lru_sort expected?
2. If yes, should this limitation be documented in:
   - Documentation/admin-guide/mm/damon/lru_sort.rst
   - Documentation/admin-guide/mm/damon/stat.rst

Additional Context
==================
- On major distros (Arch/Fedora), CONFIG_DAMON_STAT_ENABLED_DEFAULT is typically
  unset (disabled), so this issue may not affect most users.
- However, for kernel developers or custom builds enabling both modules, clearer
  documentation or error handling would improve debuggability.

Best regards,
Liew Rui Yan