mm/damon/sysfs: support schemes prioritization

This commit makes DAMON sysfs interface supports the DAMOS' regions
prioritization weights feature under quotas limitation.  Specifically,
this commit adds 'weights' directory under each scheme directory and makes
kdamond 'state' file writing respects the contents in the directory.

    /sys/kernel/mm/damon/admin
    │ kdamonds/nr
    │ │ 0/state,pid
    │ │ │ contexts/nr
    │ │ │ │ 0/operations
    │ │ │ │ │ monitoring_attrs/intervals/sample_us,aggr_us,update_us
    │ │ │ │ │ │ nr_regions/min,max
    │ │ │ │ │ targets/nr
    │ │ │ │ │ │ 0/pid
    │ │ │ │ │ │ │ regions/nr
    │ │ │ │ │ │ │ │ 0/start,end
    │ │ │ │ │ │ │ │ ...
    │ │ │ │ │ │ ...
    │ │ │ │ │ schemes/nr
    │ │ │ │ │ │ 0/action
    │ │ │ │ │ │ │ access_pattern/
    │ │ │ │ │ │ │ │ sz/min,max
    │ │ │ │ │ │ │ │ nr_accesses/min,max
    │ │ │ │ │ │ │ │ age/min,max
    │ │ │ │ │ │ │ quotas/ms,bytes,reset_interval_ms
    │ │ │ │ │ │ │ │ weights/    <- NEW DIRECTORY
    │ │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
    │ │ │ │ │ │ ...
    │ │ │ │ ...
    │ │ ...

Link: https://lkml.kernel.org/r/20220228081314.5770-9-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/damon/sysfs.c

@@ -113,12 +113,130 @@ static struct kobj_type damon_sysfs_ul_range_ktype = {
 	.default_groups = damon_sysfs_ul_range_groups,
 };
 
+/*
+ * scheme/weights directory
+ */
+
+struct damon_sysfs_weights {
+	struct kobject kobj;
+	unsigned int sz;
+	unsigned int nr_accesses;
+	unsigned int age;
+};
+
+static struct damon_sysfs_weights *damon_sysfs_weights_alloc(unsigned int sz,
+		unsigned int nr_accesses, unsigned int age)
+{
+	struct damon_sysfs_weights *weights = kmalloc(sizeof(*weights),
+			GFP_KERNEL);
+
+	if (!weights)
+		return NULL;
+	weights->kobj = (struct kobject){};
+	weights->sz = sz;
+	weights->nr_accesses = nr_accesses;
+	weights->age = age;
+	return weights;
+}
+
+static ssize_t sz_permil_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+
+	return sysfs_emit(buf, "%u\n", weights->sz);
+}
+
+static ssize_t sz_permil_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+	int err = kstrtouint(buf, 0, &weights->sz);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static ssize_t nr_accesses_permil_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+
+	return sysfs_emit(buf, "%u\n", weights->nr_accesses);
+}
+
+static ssize_t nr_accesses_permil_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+	int err = kstrtouint(buf, 0, &weights->nr_accesses);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static ssize_t age_permil_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+
+	return sysfs_emit(buf, "%u\n", weights->age);
+}
+
+static ssize_t age_permil_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_weights *weights = container_of(kobj,
+			struct damon_sysfs_weights, kobj);
+	int err = kstrtouint(buf, 0, &weights->age);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static void damon_sysfs_weights_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_weights, kobj));
+}
+
+static struct kobj_attribute damon_sysfs_weights_sz_attr =
+		__ATTR_RW_MODE(sz_permil, 0600);
+
+static struct kobj_attribute damon_sysfs_weights_nr_accesses_attr =
+		__ATTR_RW_MODE(nr_accesses_permil, 0600);
+
+static struct kobj_attribute damon_sysfs_weights_age_attr =
+		__ATTR_RW_MODE(age_permil, 0600);
+
+static struct attribute *damon_sysfs_weights_attrs[] = {
+	&damon_sysfs_weights_sz_attr.attr,
+	&damon_sysfs_weights_nr_accesses_attr.attr,
+	&damon_sysfs_weights_age_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_weights);
+
+static struct kobj_type damon_sysfs_weights_ktype = {
+	.release = damon_sysfs_weights_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_weights_groups,
+};
+
 /*
  * quotas directory
  */
 
 struct damon_sysfs_quotas {
 	struct kobject kobj;
+	struct damon_sysfs_weights *weights;
 	unsigned long ms;
 	unsigned long sz;
 	unsigned long reset_interval_ms;
@@ -129,6 +247,29 @@ static struct damon_sysfs_quotas *damon_sysfs_quotas_alloc(void)
 	return kzalloc(sizeof(struct damon_sysfs_quotas), GFP_KERNEL);
 }
 
+static int damon_sysfs_quotas_add_dirs(struct damon_sysfs_quotas *quotas)
+{
+	struct damon_sysfs_weights *weights;
+	int err;
+
+	weights = damon_sysfs_weights_alloc(0, 0, 0);
+	if (!weights)
+		return -ENOMEM;
+
+	err = kobject_init_and_add(&weights->kobj, &damon_sysfs_weights_ktype,
+			&quotas->kobj, "weights");
+	if (err)
+		kobject_put(&weights->kobj);
+	else
+		quotas->weights = weights;
+	return err;
+}
+
+static void damon_sysfs_quotas_rm_dirs(struct damon_sysfs_quotas *quotas)
+{
+	kobject_put(&quotas->weights->kobj);
+}
+
 static ssize_t ms_show(struct kobject *kobj, struct kobj_attribute *attr,
 		char *buf)
 {
@@ -387,6 +528,9 @@ static int damon_sysfs_scheme_set_quotas(struct damon_sysfs_scheme *scheme)
 		return -ENOMEM;
 	err = kobject_init_and_add(&quotas->kobj, &damon_sysfs_quotas_ktype,
 			&scheme->kobj, "quotas");
+	if (err)
+		goto out;
+	err = damon_sysfs_quotas_add_dirs(quotas);
 	if (err)
 		goto out;
 	scheme->quotas = quotas;
@@ -419,6 +563,7 @@ static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 {
 	damon_sysfs_access_pattern_rm_dirs(scheme->access_pattern);
 	kobject_put(&scheme->access_pattern->kobj);
+	damon_sysfs_quotas_rm_dirs(scheme->quotas);
 	kobject_put(&scheme->quotas->kobj);
 }
 
@@ -1659,13 +1804,14 @@ static struct damos *damon_sysfs_mk_scheme(
 	struct damon_sysfs_access_pattern *pattern =
 		sysfs_scheme->access_pattern;
 	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
+	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
 	struct damos_quota quota = {
 		.ms = sysfs_quotas->ms,
 		.sz = sysfs_quotas->sz,
 		.reset_interval = sysfs_quotas->reset_interval_ms,
-		.weight_sz = 1000,
-		.weight_nr_accesses = 1000,
-		.weight_age = 1000,
+		.weight_sz = sysfs_weights->sz,
+		.weight_nr_accesses = sysfs_weights->nr_accesses,
+		.weight_age = sysfs_weights->age,
 	};
 	struct damos_watermarks wmarks = {
 		.metric = DAMOS_WMARK_NONE,