diff --git a/include/linux/damon.h b/include/linux/damon.h
index 63050eb2206a..cb6a50032a1e 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -958,6 +958,11 @@ struct damon_ctx {
 
 	/* @rnd_state:	Per-ctx PRNG state for damon_rand(). */
 	struct rnd_state rnd_state;
+	/*
+	 * number of regions after last merge.  Read kdamond_split_regions()
+	 * for more details.
+	 */
+	unsigned long last_nr_regions;
 };
 
 /* Get a random number in [@l, @r) using @ctx's lockless PRNG. */
diff --git a/mm/damon/core.c b/mm/damon/core.c
index eb1fcdabc007..09722257ce73 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -3795,7 +3795,6 @@ static noinline_for_stack void kdamond_split_regions(struct damon_ctx *ctx)
 	struct damon_target *t;
 	unsigned long nr_regions = 0;
 	unsigned long max_nr_regions = ctx->attrs.max_nr_regions;
-	static unsigned long last_nr_regions;
 	int nr_subregions = 2;
 
 	damon_for_each_target(t, ctx)
@@ -3811,7 +3810,7 @@ static noinline_for_stack void kdamond_split_regions(struct damon_ctx *ctx)
 	}
 
 	/* Maybe the middle of the region has different access frequency */
-	if (last_nr_regions == nr_regions &&
+	if (ctx->last_nr_regions == nr_regions &&
 			nr_regions < max_nr_regions / 3)
 		nr_subregions = 3;
 
@@ -3820,7 +3819,7 @@ static noinline_for_stack void kdamond_split_regions(struct damon_ctx *ctx)
 				       ctx->min_region_sz);
 
 done:
-	last_nr_regions = nr_regions;
+	ctx->last_nr_regions = nr_regions;
 }
 
 /*