mm/damon/lru_sort: use damon_commit_ctx()

DAMON_LRU_SORT manually manipulates the DAMON context struct for online
parameters update.  Since the struct contains not only input parameters
but also internal status and operation results, it is not that simple. 
Indeed, we found and fixed a few bugs in the code.  Now DAMON core layer
provides a function for the usage, namely damon_commit_ctx().  Replace the
manual manipulation logic with the function.  The core layer function
could have its own bugs, but this change removes a source of bugs.

Link: https://lkml.kernel.org/r/20240618181809.82078-12-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/lru_sort.c

@@ -199,15 +199,22 @@ static void damon_lru_sort_copy_quota_status(struct damos_quota *dst,
 
 static int damon_lru_sort_apply_parameters(void)
 {
+	struct damon_ctx *param_ctx;
+	struct damon_target *param_target;
 	struct damos *scheme, *hot_scheme, *cold_scheme;
 	struct damos *old_hot_scheme = NULL, *old_cold_scheme = NULL;
 	unsigned int hot_thres, cold_thres;
-	int err = 0;
+	int err;
 
-	err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
+	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
 	if (err)
 		return err;
 
+	err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
+	if (err)
+		goto out;
+
+	err = -ENOMEM;
 	damon_for_each_scheme(scheme, ctx) {
 		if (!old_hot_scheme) {
 			old_hot_scheme = scheme;
@@ -220,7 +227,7 @@ static int damon_lru_sort_apply_parameters(void)
 		hot_thres_access_freq / 1000;
 	hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
 	if (!hot_scheme)
-		return -ENOMEM;
+		goto out;
 	if (old_hot_scheme)
 		damon_lru_sort_copy_quota_status(&hot_scheme->quota,
 				&old_hot_scheme->quota);
@@ -229,18 +236,24 @@ static int damon_lru_sort_apply_parameters(void)
 	cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
 	if (!cold_scheme) {
 		damon_destroy_scheme(hot_scheme);
-		return -ENOMEM;
+		goto out;
 	}
 	if (old_cold_scheme)
 		damon_lru_sort_copy_quota_status(&cold_scheme->quota,
 				&old_cold_scheme->quota);
 
-	damon_set_schemes(ctx, &hot_scheme, 1);
-	damon_add_scheme(ctx, cold_scheme);
+	damon_set_schemes(param_ctx, &hot_scheme, 1);
+	damon_add_scheme(param_ctx, cold_scheme);
 
-	return damon_set_region_biggest_system_ram_default(target,
+	err = damon_set_region_biggest_system_ram_default(param_target,
 					&monitor_region_start,
 					&monitor_region_end);
+	if (err)
+		goto out;
+	err = damon_commit_ctx(ctx, param_ctx);
+out:
+	damon_destroy_ctx(param_ctx);
+	return err;
 }
 
 static int damon_lru_sort_turn(bool on)