1 files changed, 36 insertions, 34 deletions

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 5846970cedce..1a231bde18f9 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1150,58 +1150,60 @@ destroy_targets_out:
 	return err;
 }
 
-/*
- * Search a target in a context that corresponds to the sysfs target input.
- *
- * Return: pointer to the target if found, NULL if not found, or negative
- * error code if the search failed.
- */
-static struct damon_target *damon_sysfs_existing_target(
-		struct damon_sysfs_target *sys_target, struct damon_ctx *ctx)
+static int damon_sysfs_update_target(struct damon_target *target,
+		struct damon_ctx *ctx,
+		struct damon_sysfs_target *sys_target)
 {
 	struct pid *pid;
-	struct damon_target *t;
+	struct damon_region *r, *next;
 
-	if (!damon_target_has_pid(ctx)) {
-		/* Up to only one target for paddr could exist */
-		damon_for_each_target(t, ctx)
-			return t;
-		return NULL;
-	}
+	if (!damon_target_has_pid(ctx))
+		return 0;
 
-	/* ops.id should be DAMON_OPS_VADDR or DAMON_OPS_FVADDR */
 	pid = find_get_pid(sys_target->pid);
 	if (!pid)
-		return ERR_PTR(-EINVAL);
-	damon_for_each_target(t, ctx) {
-		if (t->pid == pid) {
-			put_pid(pid);
-			return t;
-		}
+		return -EINVAL;
+
+	/* no change to the target */
+	if (pid == target->pid) {
+		put_pid(pid);
+		return 0;
 	}
-	put_pid(pid);
-	return NULL;
+
+	/* remove old monitoring results and update the target's pid */
+	damon_for_each_region_safe(r, next, target)
+		damon_destroy_region(r, target);
+	put_pid(target->pid);
+	target->pid = pid;
+	return 0;
 }
 
 static int damon_sysfs_set_targets(struct damon_ctx *ctx,
 		struct damon_sysfs_targets *sysfs_targets)
 {
-	int i, err;
+	struct damon_target *t, *next;
+	int i = 0, err;
 
 	/* Multiple physical address space monitoring targets makes no sense */
 	if (ctx->ops.id == DAMON_OPS_PADDR && sysfs_targets->nr > 1)
 		return -EINVAL;
 
-	for (i = 0; i < sysfs_targets->nr; i++) {
+	damon_for_each_target_safe(t, next, ctx) {
+		if (i < sysfs_targets->nr) {
+			damon_sysfs_update_target(t, ctx,
+					sysfs_targets->targets_arr[i]);
+		} else {
+			if (damon_target_has_pid(ctx))
+				put_pid(t->pid);
+			damon_destroy_target(t);
+		}
+		i++;
+	}
+
+	for (; i < sysfs_targets->nr; i++) {
 		struct damon_sysfs_target *st = sysfs_targets->targets_arr[i];
-		struct damon_target *t = damon_sysfs_existing_target(st, ctx);
-
-		if (IS_ERR(t))
-			return PTR_ERR(t);
-		if (!t)
-			err = damon_sysfs_add_target(st, ctx);
-		else
-			err = damon_sysfs_set_regions(t, st->regions);
+
+		err = damon_sysfs_add_target(st, ctx);
 		if (err)
 			return err;
 	}