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mm-damon-hide-kdamond-and-kdamond_lock-of-damon_ctx.patch removed from -mm tree

merged mm-stable Andrew Morton 1 participant 1 message Jan 27

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The quilt patch titled
Subject: mm/damon: hide kdamond and kdamond_lock of damon_ctx
has been removed from the -mm tree. Its filename was
mm-damon-hide-kdamond-and-kdamond_lock-of-damon_ctx.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: SeongJae Park <[email protected]>
Subject: mm/damon: hide kdamond and kdamond_lock of damon_ctx
Date: Thu, 15 Jan 2026 07:20:45 -0800

There is no DAMON API caller that directly access 'kdamond' and 'kdamond_lock' fields of 'struct damon_ctx'. Keeping those exposed could only encourage creative but error-prone usages. Hide them from DAMON API callers by marking those as private fields.

---

 include/linux/damon.h |   29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)
include/linux/damon.h renamed from include/linux/damon.h~mm-damon-hide-kdamond-and-kdamond_lock-of-damon_ctx +14 -15
@@ -759,23 +759,20 @@ struct damon_attrs {
  * of the monitoring.
  *
  * @attrs:		Monitoring attributes for accuracy/overhead control.
- * @kdamond:		Kernel thread who does the monitoring.
- * @kdamond_lock:	Mutex for the synchronizations with @kdamond.
  *
- * For each monitoring context, one kernel thread for the monitoring is
- * created.  The pointer to the thread is stored in @kdamond.
+ * For each monitoring context, one kernel thread for the monitoring, namely
+ * kdamond, is created.  The pid of kdamond can be retrieved using
+ * damon_kdamond_pid().
  *
- * Once started, the monitoring thread runs until explicitly required to be
- * terminated or every monitoring target is invalid.  The validity of the
- * targets is checked via the &damon_operations.target_valid of @ops.  The
- * termination can also be explicitly requested by calling damon_stop().
- * The thread sets @kdamond to NULL when it terminates. Therefore, users can
- * know whether the monitoring is ongoing or terminated by reading @kdamond.
- * Reads and writes to @kdamond from outside of the monitoring thread must
- * be protected by @kdamond_lock.
+ * Once started, kdamond runs until explicitly required to be terminated or
+ * every monitoring target is invalid.  The validity of the targets is checked
+ * via the &damon_operations.target_valid of @ops.  The termination can also be
+ * explicitly requested by calling damon_stop().  To know if a kdamond is
+ * running, damon_is_running() can be used.
  *
- * Note that the monitoring thread protects only @kdamond via @kdamond_lock.
- * Accesses to other fields must be protected by themselves.
+ * While the kdamond is running, all accesses to &struct damon_ctx from a
+ * thread other than the kdamond should be made using safe DAMON APIs,
+ * including damon_call() and damos_walk().
  *
  * @ops:	Set of monitoring operations for given use cases.
  * @addr_unit:	Scale factor for core to ops address conversion.
@@ -816,10 +813,12 @@ struct damon_ctx {
 	struct damos_walk_control *walk_control;
 	struct mutex walk_control_lock;
 
-/* public: */
+	/* Working thread of the given DAMON context */
 	struct task_struct *kdamond;
+	/* Protects @kdamond field access */
 	struct mutex kdamond_lock;
 
+/* public: */
 	struct damon_operations ops;
 	unsigned long addr_unit;
 	unsigned long min_sz_region;

_

Patches currently in -mm which might be from [email protected] are

selftests-damon-sysfs_memcg_path_leaksh-use-kmemleak.patch selftests-damon-wss_estimation-test-for-up-to-160-mib-working-set-size.patch selftests-damon-access_memory-add-repeat-mode.patch selftests-damon-wss_estimation-ensure-number-of-collected-wss.patch selftests-damon-wss_estimation-deduplicate-failed-samples-output.patch mm-damon-remove-damon_operations-cleanup.patch mm-damon-core-cleanup-targets-and-regions-at-once-on-kdamond-termination.patch mm-damon-core-cancel-damos_walk-before-damon_ctx-kdamond-reset.patch mm-damon-core-process-damon_call_control-requests-on-a-local-list.patch mm-damon-document-damon_call_control-dealloc_on_cancel-repeat-behavior.patch mm-damon-core-rename-damos_filter_out-to-damos_core_filter_out.patch mm-damon-rename-damon_min_region-to-damon_min_region_sz.patch mm-damon-rename-min_sz_region-of-damon_ctx-to-min_region_sz.patch docs-mm-damon-index-simplify-the-intro.patch docs-mm-damon-design-link-repology-instead-of-fedora-package.patch docs-mm-damon-design-document-damon-sample-modules.patch docs-mm-damon-design-add-reference-to-damon_stat-usage.patch docs-admin-guide-mm-damon-usage-introduce-damon-modules-at-the-beginning.patch docs-admin-guide-mm-damon-usage-update-stats-update-process-for-refresh_ms.patch docs-mm-damon-maintainer-profile-fix-wrong-maitnainers-section-name.patch docs-mm-damon-maintainer-profile-remove-damon-tests-perf-suggestion.patch maple_tree-start-using-maple-copy-node-for-destination-fix.patch