[RFC PATCH 10/19] mm/damon/sysfs: implement probe dir

SeongJae Park
2026-04-26T20:52:38Z

Implement sysfs directory for letting users install each data probe.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/sysfs.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 119 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index ccd19fc062f31..fac4e37aa2851 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -747,12 +747,43 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
.default_groups = damon_sysfs_intervals_groups,
};

+/*
+ * probe directory
+ */
+
+struct damon_sysfs_probe {
+ struct kobject kobj;
+};
+
+static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
+{
+ return kzalloc_obj(struct damon_sysfs_probe);
+}
+
+static void damon_sysfs_probe_release(struct kobject *kobj)
+{
+ kfree(container_of(kobj, struct damon_sysfs_probe, kobj));
+}
+
+static struct attribute *damon_sysfs_probe_attrs[] = {
+ NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_probe);
+
+const struct kobj_type damon_sysfs_probe_ktype = {
+ .release = damon_sysfs_probe_release,
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_groups = damon_sysfs_probe_groups,
+};
+
/*
* probes directory
*/

struct damon_sysfs_probes {
struct kobject kobj;
+ struct damon_sysfs_probe **probes_arr;
+ int nr;
};

static struct damon_sysfs_probes *damon_sysfs_probes_alloc(void)
@@ -760,12 +791,99 @@ static struct damon_sysfs_probes *damon_sysfs_probes_alloc(void)
return kzalloc_obj(struct damon_sysfs_probes);
}

+static void damon_sysfs_probes_rm_dirs(
+ struct damon_sysfs_probes *probes)
+{
+ struct damon_sysfs_probe **probes_arr = probes->probes_arr;
+ int i;
+
+ for (i = 0; i < probes->nr; i++)
+ kobject_put(&probes_arr[i]->kobj);
+ probes->nr = 0;
+ kfree(probes_arr);
+ probes->probes_arr = NULL;
+}
+
+static int damon_sysfs_probes_add_dirs(
+ struct damon_sysfs_probes *probes, int nr_probes)
+{
+ struct damon_sysfs_probe **probes_arr, *probe;
+ int err, i;
+
+ damon_sysfs_probes_rm_dirs(probes);
+ if (!nr_probes)
+ return 0;
+
+ probes_arr = kmalloc_objs(*probes_arr, nr_probes,
+ GFP_KERNEL | __GFP_NOWARN);
+ if (!probes_arr)
+ return -ENOMEM;
+ probes->probes_arr = probes_arr;
+
+ for (i = 0; i < nr_probes; i++) {
+ probe = damon_sysfs_probe_alloc();
+ if (!probe) {
+ damon_sysfs_probes_rm_dirs(probes);
+ return -ENOMEM;
+ }
+
+ err = kobject_init_and_add(&probe->kobj,
+ &damon_sysfs_probe_ktype, &probes->kobj,
+ "%d", i);
+ if (err) {
+ kobject_put(&probe->kobj);
+ damon_sysfs_probes_rm_dirs(probes);
+ return err;
+ }
+
+ probes_arr[i] = probe;
+ probes->nr++;
+ }
+ return 0;
+}
+
+static ssize_t nr_probes_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct damon_sysfs_probes *probes = container_of(kobj,
+ struct damon_sysfs_probes, kobj);
+
+ return sysfs_emit(buf, "%d\n", probes->nr);
+}
+
+static ssize_t nr_probes_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ struct damon_sysfs_probes *probes;
+ int nr, err = kstrtoint(buf, 0, &nr);
+
+ if (err)
+ return err;
+ if (nr < 0 || nr > DAMON_MAX_PROBES)
+ return -EINVAL;
+
+ probes = container_of(kobj, struct damon_sysfs_probes, kobj);
+
+ if (!mutex_trylock(&damon_sysfs_lock))
+ return -EBUSY;
+ err = damon_sysfs_probes_add_dirs(probes, nr);
+ mutex_unlock(&damon_sysfs_lock);
+ if (err)
+ return err;
+
+ return count;
+}
+
static void damon_sysfs_probes_release(struct kobject *kobj)
{
kfree(container_of(kobj, struct damon_sysfs_probes, kobj));
}

+static struct kobj_attribute damon_sysfs_probes_nr_probes =
+ __ATTR_RW_MODE(nr_probes, 0600);
+
static struct attribute *damon_sysfs_probes_attrs[] = {
+ &damon_sysfs_probes_nr_probes.attr,
NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_probes);
@@ -862,6 +980,7 @@ static void damon_sysfs_attrs_rm_dirs(struct damon_sysfs_attrs *attrs)
kobject_put(&attrs->nr_regions_range->kobj);
damon_sysfs_intervals_rm_dirs(attrs->intervals);
kobject_put(&attrs->intervals->kobj);
+ damon_sysfs_probes_rm_dirs(attrs->probes);
kobject_put(&attrs->probes->kobj);
}

--
2.47.3