diff --git a/include/linux/damon.h b/include/linux/damon.h
index 97f4a224e950..e0ad3d9aaeed 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -192,6 +192,20 @@ struct damos_watermarks {
 	bool activated;
 };
 
+/**
+ * struct damos_stat - Statistics on a given scheme.
+ * @nr_tried:	Total number of regions that the scheme is tried to be applied.
+ * @sz_tried:	Total size of regions that the scheme is tried to be applied.
+ * @nr_applied:	Total number of regions that the scheme is applied.
+ * @sz_applied:	Total size of regions that the scheme is applied.
+ */
+struct damos_stat {
+	unsigned long nr_tried;
+	unsigned long sz_tried;
+	unsigned long nr_applied;
+	unsigned long sz_applied;
+};
+
 /**
  * struct damos - Represents a Data Access Monitoring-based Operation Scheme.
  * @min_sz_region:	Minimum size of target regions.
@@ -203,8 +217,7 @@ struct damos_watermarks {
  * @action:		&damo_action to be applied to the target regions.
  * @quota:		Control the aggressiveness of this scheme.
  * @wmarks:		Watermarks for automated (in)activation of this scheme.
- * @stat_count:		Total number of regions that this scheme is applied.
- * @stat_sz:		Total size of regions that this scheme is applied.
+ * @stat:		Statistics of this scheme.
  * @list:		List head for siblings.
  *
  * For each aggregation interval, DAMON finds regions which fit in the
@@ -235,8 +248,7 @@ struct damos {
 	enum damos_action action;
 	struct damos_quota quota;
 	struct damos_watermarks wmarks;
-	unsigned long stat_count;
-	unsigned long stat_sz;
+	struct damos_stat stat;
 	struct list_head list;
 };
 
@@ -281,7 +293,8 @@ struct damon_ctx;
  * as an integer in [0, &DAMOS_MAX_SCORE].
  * @apply_scheme is called from @kdamond when a region for user provided
  * DAMON-based operation scheme is found.  It should apply the scheme's action
- * to the region.
+ * to the region and return bytes of the region that the action is successfully
+ * applied.
  * @target_valid should check whether the target is still valid for the
  * monitoring.
  * @cleanup is called from @kdamond just before its termination.
@@ -295,8 +308,9 @@ struct damon_primitive {
 	int (*get_scheme_score)(struct damon_ctx *context,
 			struct damon_target *t, struct damon_region *r,
 			struct damos *scheme);
-	int (*apply_scheme)(struct damon_ctx *context, struct damon_target *t,
-			struct damon_region *r, struct damos *scheme);
+	unsigned long (*apply_scheme)(struct damon_ctx *context,
+			struct damon_target *t, struct damon_region *r,
+			struct damos *scheme);
 	bool (*target_valid)(void *target);
 	void (*cleanup)(struct damon_ctx *context);
 };
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 70771cf7da89..6d59047b8923 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -112,8 +112,7 @@ struct damos *damon_new_scheme(
 	scheme->min_age_region = min_age_region;
 	scheme->max_age_region = max_age_region;
 	scheme->action = action;
-	scheme->stat_count = 0;
-	scheme->stat_sz = 0;
+	scheme->stat = (struct damos_stat){};
 	INIT_LIST_HEAD(&scheme->list);
 
 	scheme->quota.ms = quota->ms;
@@ -603,6 +602,7 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
 		struct damos_quota *quota = &s->quota;
 		unsigned long sz = r->ar.end - r->ar.start;
 		struct timespec64 begin, end;
+		unsigned long sz_applied = 0;
 
 		if (!s->wmarks.activated)
 			continue;
@@ -665,7 +665,7 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
 				damon_split_region_at(c, t, r, sz);
 			}
 			ktime_get_coarse_ts64(&begin);
-			c->primitive.apply_scheme(c, t, r, s);
+			sz_applied = c->primitive.apply_scheme(c, t, r, s);
 			ktime_get_coarse_ts64(&end);
 			quota->total_charged_ns += timespec64_to_ns(&end) -
 				timespec64_to_ns(&begin);
@@ -679,8 +679,11 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
 			r->age = 0;
 
 update_stat:
-		s->stat_count++;
-		s->stat_sz += sz;
+		s->stat.nr_tried++;
+		s->stat.sz_tried += sz;
+		if (sz_applied)
+			s->stat.nr_applied++;
+		s->stat.sz_applied += sz_applied;
 	}
 }
 
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 5b628990ae6e..ef79b7b7716d 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -117,7 +117,7 @@ static ssize_t sprint_schemes(struct damon_ctx *c, char *buf, ssize_t len)
 				s->quota.weight_age,
 				s->wmarks.metric, s->wmarks.interval,
 				s->wmarks.high, s->wmarks.mid, s->wmarks.low,
-				s->stat_count, s->stat_sz);
+				s->stat.nr_tried, s->stat.sz_tried);
 		if (!rc)
 			return -ENOMEM;
 
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 4318134cbc4c..5e8244f65a1a 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -213,14 +213,15 @@ bool damon_pa_target_valid(void *t)
 	return true;
 }
 
-static int damon_pa_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
-		struct damon_region *r, struct damos *scheme)
+static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
+		struct damon_target *t, struct damon_region *r,
+		struct damos *scheme)
 {
-	unsigned long addr;
+	unsigned long addr, applied;
 	LIST_HEAD(page_list);
 
 	if (scheme->action != DAMOS_PAGEOUT)
-		return -EINVAL;
+		return 0;
 
 	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
 		struct page *page = damon_get_page(PHYS_PFN(addr));
@@ -241,9 +242,9 @@ static int damon_pa_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
 			put_page(page);
 		}
 	}
-	reclaim_pages(&page_list);
+	applied = reclaim_pages(&page_list);
 	cond_resched();
-	return 0;
+	return applied * PAGE_SIZE;
 }
 
 static int damon_pa_scheme_score(struct damon_ctx *context,
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 68d9e4134816..a10df3fd3d02 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -572,32 +572,34 @@ bool damon_va_target_valid(void *target)
 }
 
 #ifndef CONFIG_ADVISE_SYSCALLS
-static int damos_madvise(struct damon_target *target, struct damon_region *r,
-			int behavior)
+static unsigned long damos_madvise(struct damon_target *target,
+		struct damon_region *r, int behavior)
 {
-	return -EINVAL;
+	return 0;
 }
 #else
-static int damos_madvise(struct damon_target *target, struct damon_region *r,
-			int behavior)
+static unsigned long damos_madvise(struct damon_target *target,
+		struct damon_region *r, int behavior)
 {
 	struct mm_struct *mm;
-	int ret = -ENOMEM;
+	unsigned long start = PAGE_ALIGN(r->ar.start);
+	unsigned long len = PAGE_ALIGN(r->ar.end - r->ar.start);
+	unsigned long applied;
 
 	mm = damon_get_mm(target);
 	if (!mm)
-		goto out;
+		return 0;
 
-	ret = do_madvise(mm, PAGE_ALIGN(r->ar.start),
-			PAGE_ALIGN(r->ar.end - r->ar.start), behavior);
+	applied = do_madvise(mm, start, len, behavior) ? 0 : len;
 	mmput(mm);
-out:
-	return ret;
+
+	return applied;
 }
 #endif	/* CONFIG_ADVISE_SYSCALLS */
 
-static int damon_va_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
-		struct damon_region *r, struct damos *scheme)
+static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx,
+		struct damon_target *t, struct damon_region *r,
+		struct damos *scheme)
 {
 	int madv_action;
 
@@ -620,7 +622,7 @@ static int damon_va_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
 	case DAMOS_STAT:
 		return 0;
 	default:
-		return -EINVAL;
+		return 0;
 	}
 
 	return damos_madvise(t, r, madv_action);
