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Message-Id: <20220416002756.4087977-4-roman.gushchin@linux.dev>
Date: Fri, 15 Apr 2022 17:27:54 -0700
From: Roman Gushchin <roman.gushchin@...ux.dev>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Dave Chinner <dchinner@...hat.com>,
linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Shakeel Butt <shakeelb@...gle.com>,
Yang Shi <shy828301@...il.com>,
Roman Gushchin <roman.gushchin@...ux.dev>
Subject: [PATCH rfc 3/5] mm: introduce memcg interfaces for shrinker sysfs
This commit introduces "count_memcg" and "scan_memcg" interfaces
for memcg-aware shrinkers.
Count_memcg using the following format:
<cgroup inode number1> <count2>
<cgroup inode number2> <count2>
...
Memory cgroups with 0 associated objects are skipped.
If the output doesn't fit into a page (sysfs limitation), a separate
line with "..." is added at the end.
It's possible to write a minimum number to the "count_memcg" interface
to filter the output.
Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
---
mm/shrinker_debug.c | 216 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 216 insertions(+)
diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
index 817d578f993c..24f78f5feb22 100644
--- a/mm/shrinker_debug.c
+++ b/mm/shrinker_debug.c
@@ -3,6 +3,7 @@
#include <linux/slab.h>
#include <linux/kobject.h>
#include <linux/shrinker.h>
+#include <linux/memcontrol.h>
/* defined in vmscan.c */
extern struct rw_semaphore shrinker_rwsem;
@@ -207,8 +208,223 @@ static const struct attribute_group shrinker_default_group = {
.attrs = shrinker_default_attrs,
};
+#ifdef CONFIG_MEMCG
+static ssize_t count_memcg_show(struct shrinker_kobj *skobj,
+ struct shrinker_attribute *attr, char *buf)
+{
+ unsigned long nr, total;
+ struct shrinker *shrinker;
+ struct mem_cgroup *memcg;
+ ssize_t ret = 0;
+ int nid;
+
+ down_read(&shrinker_rwsem);
+ rcu_read_lock();
+
+ shrinker = skobj->shrinker;
+ if (!shrinker) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ memcg = mem_cgroup_iter(NULL, NULL, NULL);
+ do {
+ if (!mem_cgroup_online(memcg))
+ continue;
+
+ /*
+ * Display a PAGE_SIZE of data, reserve last 50 characters
+ * for "...".
+ */
+ if (ret > PAGE_SIZE - 50) {
+ ret += sprintf(buf + ret, "...\n");
+ mem_cgroup_iter_break(NULL, memcg);
+ break;
+ }
+
+ total = 0;
+ for_each_node(nid) {
+ struct shrink_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .nid = nid,
+ .memcg = memcg,
+ };
+
+ nr = shrinker->count_objects(shrinker, &sc);
+ if (nr == SHRINK_EMPTY)
+ nr = 0;
+ total += nr;
+
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ break;
+
+ cond_resched();
+ }
+
+ if (!total || total < attr->private)
+ continue;
+
+ ret += sprintf(buf + ret, "%lu %lu\n", mem_cgroup_ino(memcg),
+ total);
+
+ cond_resched();
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
+out:
+ rcu_read_unlock();
+ up_read(&shrinker_rwsem);
+ return ret;
+}
+
+static ssize_t count_memcg_store(struct shrinker_kobj *skobj,
+ struct shrinker_attribute *attr,
+ const char *buf, size_t size)
+{
+ unsigned long min_count;
+
+ if (kstrtoul(buf, 10, &min_count))
+ return -EINVAL;
+
+ attr->private = min_count;
+
+ return size;
+}
+
+static struct shrinker_attribute count_memcg_attribute = __ATTR_RW(count_memcg);
+
+static ssize_t scan_memcg_show(struct shrinker_kobj *skobj,
+ struct shrinker_attribute *attr, char *buf)
+{
+ /*
+ * Display the number of objects freed on the last scan.
+ */
+ return sprintf(buf, "%lu\n", attr->private);
+}
+
+static ssize_t scan_memcg_store(struct shrinker_kobj *skobj,
+ struct shrinker_attribute *attr,
+ const char *buf, size_t size)
+{
+ unsigned long nr, nr_to_scan = 0, freed = 0, total = 0, ino;
+ unsigned long *count_per_node = NULL;
+ struct mem_cgroup *memcg;
+ struct shrinker *shrinker;
+ ssize_t ret = size;
+ int nid;
+
+ if (sscanf(buf, "%lu %lu", &ino, &nr_to_scan) < 2)
+ return -EINVAL;
+
+ memcg = mem_cgroup_get_from_ino(ino);
+ if (!memcg || IS_ERR(memcg))
+ return -ENOENT;
+
+ if (!mem_cgroup_online(memcg)) {
+ mem_cgroup_put(memcg);
+ return -ENOENT;
+ }
+
+ down_read(&shrinker_rwsem);
+
+ shrinker = skobj->shrinker;
+ if (!shrinker) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ if (shrinker->flags & SHRINKER_NUMA_AWARE) {
+ count_per_node = kzalloc(sizeof(unsigned long) * nr_node_ids,
+ GFP_KERNEL);
+ if (!count_per_node) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ for_each_node(nid) {
+ struct shrink_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .nid = nid,
+ .memcg = memcg,
+ };
+
+ nr = shrinker->count_objects(shrinker, &sc);
+ if (nr == SHRINK_EMPTY)
+ nr = 0;
+ count_per_node[nid] = nr;
+ total += nr;
+
+ cond_resched();
+ }
+ }
+
+ for_each_node(nid) {
+ struct shrink_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .nid = nid,
+ .memcg = memcg,
+ };
+
+ if (shrinker->flags & SHRINKER_NUMA_AWARE) {
+ sc.nr_to_scan = nr_to_scan * count_per_node[nid] /
+ (total ? total : 1);
+ sc.nr_scanned = sc.nr_to_scan;
+ } else {
+ sc.nr_to_scan = nr_to_scan;
+ sc.nr_scanned = sc.nr_to_scan;
+ }
+
+ nr = shrinker->scan_objects(shrinker, &sc);
+ if (nr == SHRINK_STOP || nr == SHRINK_EMPTY)
+ nr = 0;
+
+ freed += nr;
+
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ break;
+
+ cond_resched();
+ }
+ attr->private = freed;
+out:
+ up_read(&shrinker_rwsem);
+ mem_cgroup_put(memcg);
+ kfree(count_per_node);
+ return ret;
+}
+
+static struct shrinker_attribute scan_memcg_attribute = __ATTR_RW(scan_memcg);
+
+static struct attribute *shrinker_memcg_attrs[] = {
+ &count_memcg_attribute.attr,
+ &scan_memcg_attribute.attr,
+ NULL,
+};
+
+static umode_t memcg_attrs_visible(struct kobject *kobj, struct attribute *attr,
+ int i)
+{
+ struct shrinker_kobj *skobj = to_shrinker_kobj(kobj);
+ struct shrinker *shrinker;
+ int ret = 0;
+
+ lockdep_assert_held(&shrinker_rwsem);
+
+ shrinker = skobj->shrinker;
+ if (shrinker && (shrinker->flags & SHRINKER_MEMCG_AWARE))
+ ret = 0644;
+
+ return ret;
+}
+
+static const struct attribute_group shrinker_memcg_group = {
+ .attrs = shrinker_memcg_attrs,
+ .is_visible = memcg_attrs_visible,
+};
+#endif /* CONFIG_MEMCG */
static const struct attribute_group *shrinker_sysfs_groups[] = {
&shrinker_default_group,
+#ifdef CONFIG_MEMCG
+ &shrinker_memcg_group,
+#endif
NULL,
};
--
2.35.1
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