From 204ab9ab9310cd79c710037992e6ad681c8fa6b9 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Tue, 16 Dec 2025 00:01:21 -0800 Subject: [PATCH] mm/damon/sysfs-schemes: implement max_nr_snapshots file Add a new DAMON sysfs file for setting and getting the newly introduced per-DAMON-snapshot level DAMOS deactivation control parameter, max_nr_snapshots. The file has a name same to the parameter and placed under the damos stat directory. Link: https://lkml.kernel.org/r/20251216080128.42991-9-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Michal Hocko Cc: Mike Rapoport Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/damon/sysfs-schemes.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index b7fcd7590ab38..19bc2288cd68c 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -205,6 +205,7 @@ struct damon_sysfs_stats { unsigned long sz_ops_filter_passed; unsigned long qt_exceeds; unsigned long nr_snapshots; + unsigned long max_nr_snapshots; }; static struct damon_sysfs_stats *damon_sysfs_stats_alloc(void) @@ -275,6 +276,28 @@ static ssize_t nr_snapshots_show(struct kobject *kobj, return sysfs_emit(buf, "%lu\n", stats->nr_snapshots); } +static ssize_t max_nr_snapshots_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct damon_sysfs_stats *stats = container_of(kobj, + struct damon_sysfs_stats, kobj); + + return sysfs_emit(buf, "%lu\n", stats->max_nr_snapshots); +} + +static ssize_t max_nr_snapshots_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + struct damon_sysfs_stats *stats = container_of(kobj, + struct damon_sysfs_stats, kobj); + unsigned long max_nr_snapshots, err = kstrtoul(buf, 0, &max_nr_snapshots); + + if (err) + return err; + stats->max_nr_snapshots = max_nr_snapshots; + return count; +} + static void damon_sysfs_stats_release(struct kobject *kobj) { kfree(container_of(kobj, struct damon_sysfs_stats, kobj)); @@ -301,6 +324,9 @@ static struct kobj_attribute damon_sysfs_stats_qt_exceeds_attr = static struct kobj_attribute damon_sysfs_stats_nr_snapshots_attr = __ATTR_RO_MODE(nr_snapshots, 0400); +static struct kobj_attribute damon_sysfs_stats_max_nr_snapshots_attr = + __ATTR_RW_MODE(max_nr_snapshots, 0600); + static struct attribute *damon_sysfs_stats_attrs[] = { &damon_sysfs_stats_nr_tried_attr.attr, &damon_sysfs_stats_sz_tried_attr.attr, @@ -309,6 +335,7 @@ static struct attribute *damon_sysfs_stats_attrs[] = { &damon_sysfs_stats_sz_ops_filter_passed_attr.attr, &damon_sysfs_stats_qt_exceeds_attr.attr, &damon_sysfs_stats_nr_snapshots_attr.attr, + &damon_sysfs_stats_max_nr_snapshots_attr.attr, NULL, }; ATTRIBUTE_GROUPS(damon_sysfs_stats); @@ -2732,6 +2759,7 @@ static struct damos *damon_sysfs_mk_scheme( damon_destroy_scheme(scheme); return NULL; } + scheme->max_nr_snapshots = sysfs_scheme->stats->max_nr_snapshots; return scheme; } -- 2.47.3