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Date: Fri, 13 Mar 2026 19:17:02 +0800 Message-ID: <20260313111702.38667-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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