mm/damon: introduce data access-as-a-data attribute

index 7b1b6050a8286..7a42cbe791845 100644
@@ -745,12 +745,14 @@ struct damon_intervals_goal {
 /**
  * enum damon_filter_type - Type of &struct damon_filter
  *
- * @DAMON_FILTER_TYPE_ANON:	Anonymous pages.
- * @DAMON_FILTER_TYPE_MEMCG:	Specific memcg's pages.
+ * @DAMON_FILTER_TYPE_ANON:		Anonymous pages.
+ * @DAMON_FILTER_TYPE_MEMCG:		Specific memcg's pages.
+ * @DAMON_FILTER_TYPE_PGIDLE_UNSET:	Pgidle is unset.
  */
 enum damon_filter_type {
 	DAMON_FILTER_TYPE_ANON,
 	DAMON_FILTER_TYPE_MEMCG,
+	DAMON_FILTER_TYPE_PGIDLE_UNSET,
 };
 
 /**

index 9ddd1ec8202b7..6f756f8493894 100644
@@ -132,6 +132,12 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
 			matched = filter->memcg_id == mem_cgroup_id(memcg);
 		rcu_read_unlock();
 		break;
+	case DAMON_FILTER_TYPE_PGIDLE_UNSET:
+		if (!folio)
+			matched = false;
+		else
+			matched = damon_folio_young(folio);
+		break;
 	default:
 		break;
 	}

index dcb739ce0a729..3593bf9c7b7aa 100644
@@ -781,6 +781,10 @@ damon_sysfs_filter_type_names[] = {
 		.type = DAMON_FILTER_TYPE_MEMCG,
 		.name = "memcg",
 	},
+	{
+		.type = DAMON_FILTER_TYPE_PGIDLE_UNSET,
+		.name = "pgidle_unset",
+	},
 };
 
 static ssize_t type_show(struct kobject *kobj,

index 7a42cbe791845..1780c14942e63 100644
@@ -742,6 +742,27 @@ struct damon_intervals_goal {
 	unsigned long max_sample_us;
 };
 
+/**
+ * enum damon_prep_action - DAMON probing preparation action.
+ *
+ * @DAMON_PREP_SET_PGIDLE:	Set the probing memory as idle page.
+ */
+enum damon_prep_action {
+	DAMON_PREP_SET_PGIDLE,
+};
+
+/**
+ * struct damon_prep - DAMON probing preparation request.
+ *
+ * @action:	Action to do to the probing memory for the preparation.
+ */
+struct damon_prep {
+	enum damon_prep_action action;
+/* private: */
+	/* siblings list. */
+	struct list_head list;
+};
+
 /**
  * enum damon_filter_type - Type of &struct damon_filter
  *

@@ -783,6 +804,8 @@ struct damon_filter {
 struct damon_probe {
 	unsigned int weight;
 /* private: */
+	/* Preparation actions to apply to each probing memory. */
+	struct list_head preps;
 	/* Filters for assessing if a given region is for this probe. */
 	struct list_head filters;
 	/* Siblings list. */

@@ -962,6 +985,12 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 	return r->ar.end - r->ar.start;
 }
 
+#define damon_for_each_prep(p, probe) \
+	list_for_each_entry(p, &(probe)->preps, list)
+
+#define damon_for_each_prep_safe(p, next, probe) \
+	list_for_each_entry_safe(p, next, &(probe)->preps, list)
+
 #define damon_for_each_filter(f, p) \
 	list_for_each_entry(f, &(p)->filters, list)
 

@@ -1015,6 +1044,9 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 
 #ifdef CONFIG_DAMON
 
+struct damon_prep *damon_new_prep(enum damon_prep_action action);
+void damon_add_prep(struct damon_probe *p, struct damon_prep *prep);
+
 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);

index 53c3f97e3f126..85774dbca64b8 100644
@@ -112,6 +112,28 @@ int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id)
 	return err;
 }
 
+struct damon_prep *damon_new_prep(enum damon_prep_action action)
+{
+	struct damon_prep *prep;
+
+	prep = kmalloc_obj(*prep);
+	if (!prep)
+		return NULL;
+	prep->action = action;
+	INIT_LIST_HEAD(&prep->list);
+	return prep;
+}
+
+void damon_add_prep(struct damon_probe *p, struct damon_prep *prep)
+{
+	list_add_tail(&prep->list, &p->preps);
+}
+
+static void damon_free_prep(struct damon_prep *p)
+{
+	kfree(p);
+}
+
 struct damon_filter *damon_new_filter(enum damon_filter_type type,
 		bool matching, bool allow)
 {

@@ -168,6 +190,7 @@ struct damon_probe *damon_new_probe(void)
 	if (!p)
 		return NULL;
 	p->weight = 0;
+	INIT_LIST_HEAD(&p->preps);
 	INIT_LIST_HEAD(&p->filters);
 	INIT_LIST_HEAD(&p->list);
 	return p;

@@ -185,8 +208,11 @@ static void damon_del_probe(struct damon_probe *p)
 
 static void damon_free_probe(struct damon_probe *p)
 {
+	struct damon_prep *prep, *prep_next;
 	struct damon_filter *f, *next;
 
+	damon_for_each_prep_safe(prep, prep_next, p)
+		damon_free_prep(prep);
 	damon_for_each_filter_safe(f, next, p)
 		damon_free_filter(f);
 	kfree(p);

index 85774dbca64b8..87ac428358ec0 100644
@@ -129,11 +129,34 @@ void damon_add_prep(struct damon_probe *p, struct damon_prep *prep)
 	list_add_tail(&prep->list, &p->preps);
 }
 
+static void damon_del_prep(struct damon_prep *p)
+{
+	list_del(&p->list);
+}
+
 static void damon_free_prep(struct damon_prep *p)
 {
 	kfree(p);
 }
 
+static void damon_destroy_prep(struct damon_prep *p)
+{
+	damon_del_prep(p);
+	damon_free_prep(p);
+}
+
+static struct damon_prep *damon_nth_prep(int n, struct damon_probe *p)
+{
+	struct damon_prep *prep;
+	int i = 0;
+
+	damon_for_each_prep(prep, p) {
+		if (i++ == n)
+			return prep;
+	}
+	return NULL;
+}
+
 struct damon_filter *damon_new_filter(enum damon_filter_type type,
 		bool matching, bool allow)
 {

@@ -1706,6 +1729,36 @@ static int damon_commit_targets(
 	return err;
 }
 
+static void damon_commit_prep(struct damon_prep *dst, struct damon_prep *src)
+{
+	dst->action = src->action;
+}
+
+static int damon_commit_preps(struct damon_probe *dst, struct damon_probe *src)
+{
+	struct damon_prep *dst_prep, *next, *src_prep, *new_prep;
+	int i = 0, j = 0;
+
+	damon_for_each_prep_safe(dst_prep, next, dst) {
+		src_prep = damon_nth_prep(i++, src);
+		if (src_prep)
+			damon_commit_prep(dst_prep, src_prep);
+		else
+			damon_destroy_prep(dst_prep);
+	}
+
+	damon_for_each_prep_safe(src_prep, next, src) {
+		if (j++ < i)
+			continue;
+
+		new_prep = damon_new_prep(src_prep->action);
+		if (!new_prep)
+			return -ENOMEM;
+		damon_add_prep(dst, new_prep);
+	}
+	return 0;
+}
+
 static void damon_commit_filter(struct damon_filter *dst,
 		struct damon_filter *src)
 {

@@ -1764,6 +1817,9 @@ static int damon_commit_probes(struct damon_ctx *dst, struct damon_ctx *src)
 		src_probe = damon_nth_probe(i++, src);
 		if (src_probe) {
 			dst_probe->weight = src_probe->weight;
+			err = damon_commit_preps(dst_probe, src_probe);
+			if (err)
+				return err;
 			err = damon_commit_filters(dst_probe, src_probe);
 			if (err)
 				return err;

@@ -1781,6 +1837,9 @@ static int damon_commit_probes(struct damon_ctx *dst, struct damon_ctx *src)
 			return -ENOMEM;
 		damon_add_probe(dst, new_probe);
 		new_probe->weight = src_probe->weight;
+		err = damon_commit_preps(new_probe, src_probe);
+		if (err)
+			return err;
 		err = damon_commit_filters(new_probe, src_probe);
 		if (err)
 			return err;

index 1780c14942e63..871d26adf6ae5 100644
@@ -630,6 +630,7 @@ enum damon_ops_id {
  * @update:			Update operations-related data structures.
  * @prepare_access_checks:	Prepare next access check of target regions.
  * @check_accesses:		Check the accesses to target regions.
+ * @prep_probes:		Prepare applying probes for each region.
  * @apply_probes:		Apply probes for each region.
  * @get_scheme_score:		Get the score of a region for a scheme.
  * @apply_scheme:		Apply a DAMON-based operation scheme.

@@ -657,6 +658,9 @@ enum damon_ops_id {
  * last preparation and update the number of observed accesses of each region.
  * It should also return max number of observed accesses that made as a result
  * of its update.  The value will be used for regions adjustment threshold.
+ * @prep_probes should execute required &struct damon_prep for next &struct
+ * damon_probe applications to each region.  It should also set
+ * &damon_region->sampling_addr of each region if ``set_samples`` is true.
  * @apply_probes should apply the data attribute probes to each region and
  * accordingly update the probe hits counter of the region.  It should also
  * set &damon_region->sampling_addr of each region if ``set_samples`` is true.

@@ -679,6 +683,7 @@ struct damon_operations {
 	void (*update)(struct damon_ctx *context);
 	void (*prepare_access_checks)(struct damon_ctx *context);
 	unsigned int (*check_accesses)(struct damon_ctx *context);
+	void (*prep_probes)(struct damon_ctx *context, bool set_samples);
 	unsigned int (*apply_probes)(struct damon_ctx *context,
 			bool set_samples, bool return_max_wsum);
 	int (*get_scheme_score)(struct damon_ctx *context,

index 87ac428358ec0..df22621765911 100644
@@ -157,6 +157,18 @@ static struct damon_prep *damon_nth_prep(int n, struct damon_probe *p)
 	return NULL;
 }
 
+static bool damon_has_prep(struct damon_ctx *c)
+{
+	struct damon_prep *prep;
+	struct damon_probe *probe;
+
+	damon_for_each_probe(probe, c) {
+		damon_for_each_prep(prep, probe)
+			return true;
+	}
+	return false;
+}
+
 struct damon_filter *damon_new_filter(enum damon_filter_type type,
 		bool matching, bool allow)
 {

@@ -3906,14 +3918,19 @@ static int kdamond_fn(void *data)
 		unsigned long next_ops_update_sis = ctx->next_ops_update_sis;
 		unsigned long sample_interval = ctx->attrs.sample_interval;
 		bool access_check_disabled = damon_has_probe_weights(ctx);
+		bool do_prep;
 		unsigned int max_merge_score = 0, max_wsum;
 		bool get_max_wsum;
 
 		if (kdamond_wait_activation(ctx))
 			break;
 
+		do_prep = ctx->ops.prep_probes && damon_has_prep(ctx);
+
 		if (!access_check_disabled && ctx->ops.prepare_access_checks)
 			ctx->ops.prepare_access_checks(ctx);
+		if (do_prep)
+			ctx->ops.prep_probes(ctx, access_check_disabled);
 
 		kdamond_usleep(sample_interval);
 		ctx->passed_sample_intervals++;

@@ -3928,7 +3945,8 @@ static int kdamond_fn(void *data)
 			else
 				get_max_wsum = false;
 			max_wsum = ctx->ops.apply_probes(ctx,
-					access_check_disabled, get_max_wsum);
+					access_check_disabled && !do_prep,
+					get_max_wsum);
 			if (get_max_wsum)
 				max_merge_score = max_wsum;
 		}

index 6f756f8493894..c1e7d7a4f40df 100644
@@ -105,6 +105,40 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
 	return max_nr_accesses;
 }
 
+static void damon_pa_prep_probes_region(struct damon_region *r,
+		struct damon_probe *probe, struct damon_ctx *ctx)
+{
+	struct damon_prep *p;
+
+	damon_for_each_prep(p, probe) {
+		switch (p->action) {
+		case DAMON_PREP_SET_PGIDLE:
+			damon_pa_mkold(damon_pa_phys_addr(r->sampling_addr,
+						ctx->addr_unit));
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+static void damon_pa_prep_probes(struct damon_ctx *ctx, bool set_samples)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+	struct damon_probe *p;
+
+	damon_for_each_target(t, ctx) {
+		damon_for_each_region(r, t) {
+			if (set_samples)
+				r->sampling_addr = damon_rand(ctx, r->ar.start,
+						r->ar.end);
+			damon_for_each_probe(p, ctx)
+				damon_pa_prep_probes_region(r, p, ctx);
+		}
+	}
+}
+
 static bool damon_pa_filter_match(struct damon_filter *filter,
 		struct folio *folio)
 {

@@ -448,6 +482,7 @@ static int __init damon_pa_initcall(void)
 		.update = NULL,
 		.prepare_access_checks = damon_pa_prepare_access_checks,
 		.check_accesses = damon_pa_check_accesses,
+		.prep_probes = damon_pa_prep_probes,
 		.apply_probes = damon_pa_apply_probes,
 		.target_valid = NULL,
 		.apply_scheme = damon_pa_apply_scheme,

index 3593bf9c7b7aa..09641257d3a89 100644
@@ -749,6 +749,35 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 	.default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * preps directory
+ */
+
+struct damon_sysfs_preps {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_preps *damon_sysfs_preps_alloc(void)
+{
+	return kzalloc_obj(struct damon_sysfs_preps);
+}
+
+static void damon_sysfs_preps_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_preps, kobj));
+}
+
+static struct attribute *damon_sysfs_preps_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_preps);
+
+static const struct kobj_type damon_sysfs_preps_ktype = {
+	.release = damon_sysfs_preps_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_preps_groups,
+};
+
 /*
  * filter directory
  */

@@ -1069,6 +1098,7 @@ static const struct kobj_type damon_sysfs_filters_ktype = {
 struct damon_sysfs_probe {
 	struct kobject kobj;
 	unsigned int weight;
+	struct damon_sysfs_preps *preps;
 	struct damon_sysfs_filters *filters;
 };
 

@@ -1079,25 +1109,48 @@ static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
 
 static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *probe)
 {
+	struct damon_sysfs_preps *preps;
 	struct damon_sysfs_filters *filters;
 	int err;
 
-	filters = damon_sysfs_filters_alloc();
-	if (!filters)
+	preps = damon_sysfs_preps_alloc();
+	if (!preps)
 		return -ENOMEM;
+	probe->preps = preps;
+
+	err = kobject_init_and_add(&preps->kobj, &damon_sysfs_preps_ktype,
+			&probe->kobj, "preps");
+	if (err)
+		goto put_preps_out;
+
+	filters = damon_sysfs_filters_alloc();
+	if (!filters) {
+		err = -ENOMEM;
+		goto del_preps_out;
+	}
 	probe->filters = filters;
 
 	err = kobject_init_and_add(&filters->kobj, &damon_sysfs_filters_ktype,
 			&probe->kobj, "filters");
-	if (err) {
-		kobject_put(&filters->kobj);
-		probe->filters = NULL;
-	}
+	if (err)
+		goto put_filters_out;
+	return err;
+
+put_filters_out:
+	kobject_put(&filters->kobj);
+	probe->filters = NULL;
+del_preps_out:
+	kobject_del(&preps->kobj);
+put_preps_out:
+	kobject_put(&preps->kobj);
+	probe->preps = NULL;
 	return err;
 }
 
 static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *probe)
 {
+	if (probe->preps)
+		kobject_put(&probe->preps->kobj);
 	if (probe->filters) {
 		damon_sysfs_filters_rm_dirs(probe->filters);
 		kobject_put(&probe->filters->kobj);

index 09641257d3a89..1d2d9950716e1 100644
@@ -755,6 +755,7 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 
 struct damon_sysfs_preps {
 	struct kobject kobj;
+	int nr;
 };
 
 static struct damon_sysfs_preps *damon_sysfs_preps_alloc(void)

@@ -762,12 +763,60 @@ static struct damon_sysfs_preps *damon_sysfs_preps_alloc(void)
 	return kzalloc_obj(struct damon_sysfs_preps);
 }
 
+static void damon_sysfs_preps_rm_dirs(struct damon_sysfs_preps *preps)
+{
+	preps->nr = 0;
+}
+
+static int damon_sysfs_preps_add_dirs(struct damon_sysfs_preps *preps,
+		int nr_preps)
+{
+	preps->nr = nr_preps;
+	return 0;
+}
+
+static ssize_t nr_preps_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_preps *preps = container_of(kobj,
+			struct damon_sysfs_preps, kobj);
+
+	return sysfs_emit(buf, "%d\n", preps->nr);
+}
+
+static ssize_t nr_preps_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_preps *preps;
+	int nr, err = kstrtoint(buf, 0, &nr);
+
+	if (err)
+		return err;
+	if (nr < 0)
+		return -EINVAL;
+
+	preps = container_of(kobj, struct damon_sysfs_preps, kobj);
+
+	if (!mutex_trylock(&damon_sysfs_lock))
+		return -EBUSY;
+	err = damon_sysfs_preps_add_dirs(preps, nr);
+	mutex_unlock(&damon_sysfs_lock);
+	if (err)
+		return err;
+
+	return count;
+}
+
 static void damon_sysfs_preps_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_preps, kobj));
 }
 
+static struct kobj_attribute damon_sysfs_preps_nr_attr =
+		__ATTR_RW_MODE(nr_preps, 0600);
+
 static struct attribute *damon_sysfs_preps_attrs[] = {
+	&damon_sysfs_preps_nr_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_preps);

@@ -1149,8 +1198,10 @@ static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *probe)
 
 static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *probe)
 {
-	if (probe->preps)
+	if (probe->preps) {
+		damon_sysfs_preps_rm_dirs(probe->preps);
 		kobject_put(&probe->preps->kobj);
+	}
 	if (probe->filters) {
 		damon_sysfs_filters_rm_dirs(probe->filters);
 		kobject_put(&probe->filters->kobj);

index 1d2d9950716e1..3749abb781566 100644
@@ -749,12 +749,50 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 	.default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * prep directory
+ */
+
+struct damon_sysfs_prep {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_prep *damon_sysfs_prep_alloc(void)
+{
+	struct damon_sysfs_prep *prep;
+
+	prep = kzalloc_obj(struct damon_sysfs_prep);
+	if (!prep)
+		return prep;
+	return prep;
+}
+
+static void damon_sysfs_prep_release(struct kobject *kobj)
+{
+	struct damon_sysfs_prep *prep = container_of(kobj,
+			struct damon_sysfs_prep, kobj);
+
+	kfree(prep);
+}
+
+static struct attribute *damon_sysfs_prep_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_prep);
+
+static const struct kobj_type damon_sysfs_prep_ktype = {
+	.release = damon_sysfs_prep_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_prep_groups,
+};
+
 /*
  * preps directory
  */
 
 struct damon_sysfs_preps {
 	struct kobject kobj;
+	struct damon_sysfs_prep **preps_arr;
 	int nr;
 };
 

@@ -765,13 +803,53 @@ static struct damon_sysfs_preps *damon_sysfs_preps_alloc(void)
 
 static void damon_sysfs_preps_rm_dirs(struct damon_sysfs_preps *preps)
 {
+	struct damon_sysfs_prep **preps_arr = preps->preps_arr;
+	int i;
+
+	for (i = 0; i < preps->nr; i++) {
+		kobject_del(&preps_arr[i]->kobj);
+		kobject_put(&preps_arr[i]->kobj);
+	}
 	preps->nr = 0;
+	kfree(preps_arr);
+	preps->preps_arr = NULL;
 }
 
 static int damon_sysfs_preps_add_dirs(struct damon_sysfs_preps *preps,
 		int nr_preps)
 {
-	preps->nr = nr_preps;
+	struct damon_sysfs_prep **preps_arr, *prep;
+	int err, i;
+
+	damon_sysfs_preps_rm_dirs(preps);
+	if (!nr_preps)
+		return 0;
+
+	preps_arr = kmalloc_objs(*preps_arr, nr_preps,
+				   GFP_KERNEL | __GFP_NOWARN);
+	if (!preps_arr)
+		return -ENOMEM;
+	preps->preps_arr = preps_arr;
+
+	for (i = 0; i < nr_preps; i++) {
+		prep = damon_sysfs_prep_alloc();
+		if (!prep) {
+			damon_sysfs_preps_rm_dirs(preps);
+			return -ENOMEM;
+		}
+
+		err = kobject_init_and_add(&prep->kobj,
+				&damon_sysfs_prep_ktype, &preps->kobj, "%d",
+				i);
+		if (err) {
+			kobject_put(&prep->kobj);
+			damon_sysfs_preps_rm_dirs(preps);
+			return err;
+		}
+
+		preps_arr[i] = prep;
+		preps->nr++;
+	}
 	return 0;
 }
 

index 3749abb781566..1ecf194f71ddb 100644
@@ -755,6 +755,7 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 
 struct damon_sysfs_prep {
 	struct kobject kobj;
+	enum damon_prep_action action;
 };
 
 static struct damon_sysfs_prep *damon_sysfs_prep_alloc(void)

@@ -764,9 +765,61 @@ static struct damon_sysfs_prep *damon_sysfs_prep_alloc(void)
 	prep = kzalloc_obj(struct damon_sysfs_prep);
 	if (!prep)
 		return prep;
+	prep->action = DAMON_PREP_SET_PGIDLE;
 	return prep;
 }
 
+struct damon_sysfs_prep_action_name {
+	const enum damon_prep_action action;
+	const char *name;
+};
+
+static const struct damon_sysfs_prep_action_name
+damon_sysfs_prep_action_names[] = {
+	{
+		.action = DAMON_PREP_SET_PGIDLE,
+		.name = "set_pgidle",
+	},
+};
+
+static ssize_t prep_action_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_prep *prep = container_of(kobj,
+			struct damon_sysfs_prep, kobj);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damon_sysfs_prep_action_names); i++) {
+		const struct damon_sysfs_prep_action_name *action_name;
+
+		action_name = &damon_sysfs_prep_action_names[i];
+		if (action_name->action == prep->action)
+			return sysfs_emit(buf, "%s\n", action_name->name);
+	}
+	return -EINVAL;
+}
+
+static ssize_t prep_action_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_prep *prep = container_of(kobj,
+			struct damon_sysfs_prep, kobj);
+	ssize_t ret = -EINVAL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damon_sysfs_prep_action_names); i++) {
+		const struct damon_sysfs_prep_action_name *action_name;
+
+		action_name = &damon_sysfs_prep_action_names[i];
+		if (sysfs_streq(buf, action_name->name)) {
+			prep->action = action_name->action;
+			ret = count;
+			break;
+		}
+	}
+	return ret;
+}
+
 static void damon_sysfs_prep_release(struct kobject *kobj)
 {
 	struct damon_sysfs_prep *prep = container_of(kobj,

@@ -775,7 +828,11 @@ static void damon_sysfs_prep_release(struct kobject *kobj)
 	kfree(prep);
 }
 
+static struct kobj_attribute damon_sysfs_prep_prep_action_attr =
+		__ATTR_RW_MODE(prep_action, 0600);
+
 static struct attribute *damon_sysfs_prep_attrs[] = {
+	&damon_sysfs_prep_prep_action_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_prep);

index 1ecf194f71ddb..494387a9906c0 100644
@@ -2176,6 +2176,23 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
 	return damon_set_attrs(ctx, &attrs);
 }
 
+static int damon_sysfs_set_preps(struct damon_probe *probe,
+		struct damon_sysfs_preps *sys_preps)
+{
+	int i;
+
+	for (i = 0; i < sys_preps->nr; i++) {
+		struct damon_sysfs_prep *sys_prep = sys_preps->preps_arr[i];
+		struct damon_prep *prep;
+
+		prep = damon_new_prep(sys_prep->action);
+		if (!prep)
+			return -ENOMEM;
+		damon_add_prep(probe, prep);
+	}
+	return 0;
+}
+
 static int damon_sysfs_set_filters(struct damon_probe *probe,
 		struct damon_sysfs_filters *sys_filters)
 {

@@ -2211,7 +2228,15 @@ static int damon_sysfs_set_probe(struct damon_probe *probe,
 		struct damon_sysfs_probe *sys_probe)
 {
 	struct damon_sysfs_filters *sys_filters;
+	struct damon_sysfs_preps *sys_preps;
+	int err;
 
+	sys_preps = sys_probe->preps;
+	if (sys_preps) {
+		err = damon_sysfs_set_preps(probe, sys_preps);
+		if (err)
+			return err;
+	}
 	sys_filters = sys_probe->filters;
 	if (!sys_filters)
 		return 0;

@@ -827,7 +827,10 @@ static ssize_t prep_action_store(struct kobject *kobj,
 
                action_name = &damon_sysfs_prep_action_names[i];
                if (sysfs_streq(buf, action_name->name)) {
+                       if (!mutex_trylock(&damon_sysfs_lock))
+                               return -EBUSY;
                        prep->action = action_name->action;
+                       mutex_unlock(&damon_sysfs_lock);
                        ret = count;
                        break;
                }