mm/damon/sysfs: implement addr_unit file under context dir

Only DAMON kernel API callers can use addr_unit parameter.  Implement a
sysfs file to let DAMON sysfs ABI users use it.

Additionally, addr_unit must be set to a non-zero value.

Link: https://lkml.kernel.org/r/20250828171242.59810-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: ze zuo <zuoze1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 6d2b0dab50cbaa4f303529e523fd32c01c305454..98bf15d403b23e4b1e6c2bd688f43bf5e7b8a1e3 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -834,6 +834,7 @@ static const struct damon_sysfs_ops_name damon_sysfs_ops_names[] = {
 struct damon_sysfs_context {
        struct kobject kobj;
        enum damon_ops_id ops_id;
+       unsigned long addr_unit;
        struct damon_sysfs_attrs *attrs;
        struct damon_sysfs_targets *targets;
        struct damon_sysfs_schemes *schemes;
@@ -849,6 +850,7 @@ static struct damon_sysfs_context *damon_sysfs_context_alloc(
                return NULL;
        context->kobj = (struct kobject){};
        context->ops_id = ops_id;
+       context->addr_unit = 1;
        return context;
 }
 
@@ -997,6 +999,32 @@ static ssize_t operations_store(struct kobject *kobj,
        return -EINVAL;
 }
 
+static ssize_t addr_unit_show(struct kobject *kobj,
+               struct kobj_attribute *attr, char *buf)
+{
+       struct damon_sysfs_context *context = container_of(kobj,
+                       struct damon_sysfs_context, kobj);
+
+       return sysfs_emit(buf, "%lu\n", context->addr_unit);
+}
+
+static ssize_t addr_unit_store(struct kobject *kobj,
+               struct kobj_attribute *attr, const char *buf, size_t count)
+{
+       struct damon_sysfs_context *context = container_of(kobj,
+                       struct damon_sysfs_context, kobj);
+       unsigned long input_addr_unit;
+       int err = kstrtoul(buf, 0, &input_addr_unit);
+
+       if (err)
+               return err;
+       if (!input_addr_unit)
+               return -EINVAL;
+
+       context->addr_unit = input_addr_unit;
+       return count;
+}
+
 static void damon_sysfs_context_release(struct kobject *kobj)
 {
        kfree(container_of(kobj, struct damon_sysfs_context, kobj));
@@ -1008,9 +1036,13 @@ static struct kobj_attribute damon_sysfs_context_avail_operations_attr =
 static struct kobj_attribute damon_sysfs_context_operations_attr =
                __ATTR_RW_MODE(operations, 0600);
 
+static struct kobj_attribute damon_sysfs_context_addr_unit_attr =
+               __ATTR_RW_MODE(addr_unit, 0600);
+
 static struct attribute *damon_sysfs_context_attrs[] = {
        &damon_sysfs_context_avail_operations_attr.attr,
        &damon_sysfs_context_operations_attr.attr,
+       &damon_sysfs_context_addr_unit_attr.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_context);
@@ -1397,6 +1429,7 @@ static int damon_sysfs_apply_inputs(struct damon_ctx *ctx,
        err = damon_select_ops(ctx, sys_ctx->ops_id);
        if (err)
                return err;
+       ctx->addr_unit = sys_ctx->addr_unit;
        err = damon_sysfs_set_attrs(ctx, sys_ctx->attrs);
        if (err)
                return err;