From 2430a8d5172c257158091368b81e27fdce535475 Mon Sep 17 00:00:00 2001
From: SJ Park <sj@kernel.org>
Date: Fri, 10 Jul 2026 06:46:45 -0700
Subject: [PATCH] mm/damon/sysfs: implement probe/weight file

Implement a new sysfs file, 'weight', under probe directory.  Users will
be able to set the probe weight and enable the attributes only monitoring
using it.

Link: https://lore.kernel.org/20260710134651.18084-17-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/damon/sysfs.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 6d7e36c9e509..b5fe036f7801 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1065,6 +1065,7 @@ static const struct kobj_type damon_sysfs_filters_ktype = {
 
 struct damon_sysfs_probe {
 	struct kobject kobj;
+	unsigned int weight;
 	struct damon_sysfs_filters *filters;
 };
 
@@ -1100,12 +1101,35 @@ static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *probe)
 	}
 }
 
+static ssize_t weight_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_probe *probe = container_of(kobj,
+			struct damon_sysfs_probe, kobj);
+
+	return sysfs_emit(buf, "%u\n", probe->weight);
+}
+
+static ssize_t weight_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_probe *probe = container_of(kobj,
+			struct damon_sysfs_probe, kobj);
+	int err = kstrtouint(buf, 0, &probe->weight);
+
+	return err ? err : count;
+}
+
 static void damon_sysfs_probe_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_probe, kobj));
 }
 
+static struct kobj_attribute damon_sysfs_probe_weight_attr =
+		__ATTR_RW_MODE(weight, 0600);
+
 static struct attribute *damon_sysfs_probe_attrs[] = {
+	&damon_sysfs_probe_weight_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_probe);
@@ -1965,6 +1989,7 @@ static int damon_sysfs_set_probes(struct damon_ctx *ctx,
 			return -ENOMEM;
 		damon_add_probe(ctx, p);
 		sys_probe = sys_probes->probes_arr[i];
+		p->weight = sys_probe->weight;
 		err = damon_sysfs_set_probe(p, sys_probe);
 		if (err)
 			return err;