mm/damon/core: introduce damon_filter

Define a data structure for constructing damon_probe's attributes check,
namely damon_filter.  It is very similar to damos_filter but works only
for monitoring purposes.  Also embed that into damon_probe, implement
essential handling of the link, with fundamental helpers.

Link: https://lore.kernel.org/20260518234119.97569-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 66 insertions, 0 deletions

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 43d71eb24ccb..f8b679dd944d 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -731,11 +731,37 @@ struct damon_intervals_goal {
 };
 
 /**
+ * enum damon_filter_type - Type of &struct damon_filter
+ *
+ * @DAMON_FILTER_TYPE_ANON:	Anonymous pages.
+ */
+enum damon_filter_type {
+	DAMON_FILTER_TYPE_ANON,
+};
+
+/**
+ * struct damon_filter - DAMON region filter for &struct damon_probe.
+ *
+ * @type:	Type of the region.
+ * @matching:	Whether this filter is for the type-matching ones.
+ * @allow:	Whether the @type-@matching ones should pass this filter.
+ * @list:	Siblings list.
+ */
+struct damon_filter {
+	enum damon_filter_type type;
+	bool matching;
+	bool allow;
+	struct list_head list;
+};
+
+/**
  * struct damon_probe - Data region attribute probe.
  *
+ * @filters:	Filters for assessing if a given region is for this probe.
  * @list:	Siblings list.
  */
 struct damon_probe {
+	struct list_head filters;
 	struct list_head list;
 };
 
@@ -910,6 +936,12 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 	return r->ar.end - r->ar.start;
 }
 
+#define damon_for_each_filter(f, p) \
+	list_for_each_entry(f, &(p)->filters, list)
+
+#define damon_for_each_filter_safe(f, next, p) \
+	list_for_each_entry_safe(f, next, &(p)->filters, list)
+
 #define damon_for_each_probe(p, ctx) \
 	list_for_each_entry(p, &(ctx)->probes, list)
 
@@ -957,6 +989,10 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 
 #ifdef CONFIG_DAMON
 
+struct damon_filter *damon_new_filter(enum damon_filter_type type,
+		bool matching, bool allow);
+void damon_add_filter(struct damon_probe *probe, struct damon_filter *f);
+
 struct damon_probe *damon_new_probe(void);
 void damon_add_probe(struct damon_ctx *ctx, struct damon_probe *probe);
 
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 8a55cc61d297..d01417955a3b 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -113,6 +113,31 @@ int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id)
 	return err;
 }
 
+struct damon_filter *damon_new_filter(enum damon_filter_type type,
+		bool matching, bool allow)
+{
+	struct damon_filter *filter;
+
+	filter = kmalloc_obj(*filter);
+	if (!filter)
+		return NULL;
+	filter->type = type;
+	filter->matching = matching;
+	filter->allow = allow;
+	INIT_LIST_HEAD(&filter->list);
+	return filter;
+}
+
+void damon_add_filter(struct damon_probe *p, struct damon_filter *f)
+{
+	list_add_tail(&f->list, &p->filters);
+}
+
+static void damon_free_filter(struct damon_filter *f)
+{
+	kfree(f);
+}
+
 struct damon_probe *damon_new_probe(void)
 {
 	struct damon_probe *p;
@@ -120,6 +145,7 @@ struct damon_probe *damon_new_probe(void)
 	p = kmalloc_obj(*p);
 	if (!p)
 		return NULL;
+	INIT_LIST_HEAD(&p->filters);
 	INIT_LIST_HEAD(&p->list);
 	return p;
 }
@@ -136,6 +162,10 @@ static void damon_del_probe(struct damon_probe *p)
 
 static void damon_free_probe(struct damon_probe *p)
 {
+	struct damon_filter *f, *next;
+
+	damon_for_each_filter_safe(f, next, p)
+		damon_free_filter(f);
 	kfree(p);
 }