mm/damon/sysfs: add pause file under context dir

Add pause DAMON sysfs file under the context directory.  It exposes the
damon_ctx->pause API parameter to the users so that they can use the
pause/resume feature.

Link: https://lore.kernel.org/20260427151231.113429-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
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: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index eefa959aa30aea554cdfa6a0bcb302e9fa794abd..d5863cc33d23032a85ca23ebd42228c9ea16922f 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -866,6 +866,7 @@ struct damon_sysfs_context {
        struct damon_sysfs_attrs *attrs;
        struct damon_sysfs_targets *targets;
        struct damon_sysfs_schemes *schemes;
+       bool pause;
 };
 
 static struct damon_sysfs_context *damon_sysfs_context_alloc(
@@ -878,6 +879,7 @@ static struct damon_sysfs_context *damon_sysfs_context_alloc(
        context->kobj = (struct kobject){};
        context->ops_id = ops_id;
        context->addr_unit = 1;
+       context->pause = false;
        return context;
 }
 
@@ -1053,6 +1055,30 @@ static ssize_t addr_unit_store(struct kobject *kobj,
        return count;
 }
 
+static ssize_t pause_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, "%c\n", context->pause ? 'Y' : 'N');
+}
+
+static ssize_t pause_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);
+       bool pause;
+       int err = kstrtobool(buf, &pause);
+
+       if (err)
+               return err;
+       context->pause = pause;
+       return count;
+}
+
+
 static void damon_sysfs_context_release(struct kobject *kobj)
 {
        kfree(container_of(kobj, struct damon_sysfs_context, kobj));
@@ -1067,10 +1093,14 @@ static struct kobj_attribute damon_sysfs_context_operations_attr =
 static struct kobj_attribute damon_sysfs_context_addr_unit_attr =
                __ATTR_RW_MODE(addr_unit, 0600);
 
+static struct kobj_attribute damon_sysfs_context_pause_attr =
+               __ATTR_RW_MODE(pause, 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,
+       &damon_sysfs_context_pause_attr.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_context);
@@ -1470,6 +1500,7 @@ static int damon_sysfs_apply_inputs(struct damon_ctx *ctx,
        if (sys_ctx->ops_id == DAMON_OPS_PADDR)
                ctx->min_region_sz = max(
                                DAMON_MIN_REGION_SZ / sys_ctx->addr_unit, 1);
+       ctx->pause = sys_ctx->pause;
        err = damon_sysfs_set_attrs(ctx, sys_ctx->attrs);
        if (err)
                return err;