1 files changed, 286 insertions, 0 deletions
diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
new file mode 100644
index 000000000000..b05295bab322
--- /dev/null
+++ b/mm/shrinker_debug.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/shrinker.h>
+#include <linux/memcontrol.h>
+
+/* defined in vmscan.c */
+extern struct rw_semaphore shrinker_rwsem;
+extern struct list_head shrinker_list;
+
+static DEFINE_IDA(shrinker_debugfs_ida);
+static struct dentry *shrinker_debugfs_root;
+
+static unsigned long shrinker_count_objects(struct shrinker *shrinker,
+					    struct mem_cgroup *memcg,
+					    unsigned long *count_per_node)
+{
+	unsigned long nr, total = 0;
+	int nid;
+
+	for_each_node(nid) {
+		if (nid == 0 || (shrinker->flags & SHRINKER_NUMA_AWARE)) {
+			struct shrink_control sc = {
+				.gfp_mask = GFP_KERNEL,
+				.nid = nid,
+				.memcg = memcg,
+			};
+
+			nr = shrinker->count_objects(shrinker, &sc);
+			if (nr == SHRINK_EMPTY)
+				nr = 0;
+		} else {
+			nr = 0;
+		}
+
+		count_per_node[nid] = nr;
+		total += nr;
+	}
+
+	return total;
+}
+
+static int shrinker_debugfs_count_show(struct seq_file *m, void *v)
+{
+	struct shrinker *shrinker = m->private;
+	unsigned long *count_per_node;
+	struct mem_cgroup *memcg;
+	unsigned long total;
+	bool memcg_aware;
+	int ret, nid;
+
+	count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);
+	if (!count_per_node)
+		return -ENOMEM;
+
+	ret = down_read_killable(&shrinker_rwsem);
+	if (ret) {
+		kfree(count_per_node);
+		return ret;
+	}
+	rcu_read_lock();
+
+	memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE;
+
+	memcg = mem_cgroup_iter(NULL, NULL, NULL);
+	do {
+		if (memcg && !mem_cgroup_online(memcg))
+			continue;
+
+		total = shrinker_count_objects(shrinker,
+					       memcg_aware ? memcg : NULL,
+					       count_per_node);
+		if (total) {
+			seq_printf(m, "%lu", mem_cgroup_ino(memcg));
+			for_each_node(nid)
+				seq_printf(m, " %lu", count_per_node[nid]);
+			seq_putc(m, '\n');
+		}
+
+		if (!memcg_aware) {
+			mem_cgroup_iter_break(NULL, memcg);
+			break;
+		}
+
+		if (signal_pending(current)) {
+			mem_cgroup_iter_break(NULL, memcg);
+			ret = -EINTR;
+			break;
+		}
+	} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
+
+	rcu_read_unlock();
+	up_read(&shrinker_rwsem);
+
+	kfree(count_per_node);
+	return ret;
+}
+DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count);
+
+static int shrinker_debugfs_scan_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return nonseekable_open(inode, file);
+}
+
+static ssize_t shrinker_debugfs_scan_write(struct file *file,
+					   const char __user *buf,
+					   size_t size, loff_t *pos)
+{
+	struct shrinker *shrinker = file->private_data;
+	unsigned long nr_to_scan = 0, ino, read_len;
+	struct shrink_control sc = {
+		.gfp_mask = GFP_KERNEL,
+	};
+	struct mem_cgroup *memcg = NULL;
+	int nid;
+	char kbuf[72];
+	ssize_t ret;
+
+	read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1);
+	if (copy_from_user(kbuf, buf, read_len))
+		return -EFAULT;
+	kbuf[read_len] = '\0';
+
+	if (sscanf(kbuf, "%lu %d %lu", &ino, &nid, &nr_to_scan) != 3)
+		return -EINVAL;
+
+	if (nid < 0 || nid >= nr_node_ids)
+		return -EINVAL;
+
+	if (nr_to_scan == 0)
+		return size;
+
+	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
+		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;
+		}
+	} else if (ino != 0) {
+		return -EINVAL;
+	}
+
+	ret = down_read_killable(&shrinker_rwsem);
+	if (ret) {
+		mem_cgroup_put(memcg);
+		return ret;
+	}
+
+	sc.nid = nid;
+	sc.memcg = memcg;
+	sc.nr_to_scan = nr_to_scan;
+	sc.nr_scanned = nr_to_scan;
+
+	shrinker->scan_objects(shrinker, &sc);
+
+	up_read(&shrinker_rwsem);
+	mem_cgroup_put(memcg);
+
+	return size;
+}
+
+static const struct file_operations shrinker_debugfs_scan_fops = {
+	.owner	 = THIS_MODULE,
+	.open	 = shrinker_debugfs_scan_open,
+	.write	 = shrinker_debugfs_scan_write,
+};
+
+int shrinker_debugfs_add(struct shrinker *shrinker)
+{
+	struct dentry *entry;
+	char buf[128];
+	int id;
+
+	lockdep_assert_held(&shrinker_rwsem);
+
+	/* debugfs isn't initialized yet, add debugfs entries later. */
+	if (!shrinker_debugfs_root)
+		return 0;
+
+	id = ida_alloc(&shrinker_debugfs_ida, GFP_KERNEL);
+	if (id < 0)
+		return id;
+	shrinker->debugfs_id = id;
+
+	snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, id);
+
+	/* create debugfs entry */
+	entry = debugfs_create_dir(buf, shrinker_debugfs_root);
+	if (IS_ERR(entry)) {
+		ida_free(&shrinker_debugfs_ida, id);
+		return PTR_ERR(entry);
+	}
+	shrinker->debugfs_entry = entry;
+
+	debugfs_create_file("count", 0220, entry, shrinker,
+			    &shrinker_debugfs_count_fops);
+	debugfs_create_file("scan", 0440, entry, shrinker,
+			    &shrinker_debugfs_scan_fops);
+	return 0;
+}
+
+int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
+{
+	struct dentry *entry;
+	char buf[128];
+	const char *new, *old;
+	va_list ap;
+	int ret = 0;
+
+	va_start(ap, fmt);
+	new = kvasprintf_const(GFP_KERNEL, fmt, ap);
+	va_end(ap);
+
+	if (!new)
+		return -ENOMEM;
+
+	down_write(&shrinker_rwsem);
+
+	old = shrinker->name;
+	shrinker->name = new;
+
+	if (shrinker->debugfs_entry) {
+		snprintf(buf, sizeof(buf), "%s-%d", shrinker->name,
+			 shrinker->debugfs_id);
+
+		entry = debugfs_rename(shrinker_debugfs_root,
+				       shrinker->debugfs_entry,
+				       shrinker_debugfs_root, buf);
+		if (IS_ERR(entry))
+			ret = PTR_ERR(entry);
+		else
+			shrinker->debugfs_entry = entry;
+	}
+
+	up_write(&shrinker_rwsem);
+
+	kfree_const(old);
+
+	return ret;
+}
+EXPORT_SYMBOL(shrinker_debugfs_rename);
+
+void shrinker_debugfs_remove(struct shrinker *shrinker)
+{
+	lockdep_assert_held(&shrinker_rwsem);
+
+	kfree_const(shrinker->name);
+	shrinker->name = NULL;
+
+	if (!shrinker->debugfs_entry)
+		return;
+
+	debugfs_remove_recursive(shrinker->debugfs_entry);
+	ida_free(&shrinker_debugfs_ida, shrinker->debugfs_id);
+}
+
+static int __init shrinker_debugfs_init(void)
+{
+	struct shrinker *shrinker;
+	struct dentry *dentry;
+	int ret = 0;
+
+	dentry = debugfs_create_dir("shrinker", NULL);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+	shrinker_debugfs_root = dentry;
+
+	/* Create debugfs entries for shrinkers registered at boot */
+	down_write(&shrinker_rwsem);
+	list_for_each_entry(shrinker, &shrinker_list, list)
+		if (!shrinker->debugfs_entry) {
+			ret = shrinker_debugfs_add(shrinker);
+			if (ret)
+				break;
+		}
+	up_write(&shrinker_rwsem);
+
+	return ret;
+}
+late_initcall(shrinker_debugfs_init);