summaryrefslogtreecommitdiff
path: root/mm/shrinker_debug.c
blob: 12ea5486a3e959e299217fc6c1dcef634ae9a291 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
// 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>

#include "internal.h"

/* defined in vmscan.c */
extern struct mutex shrinker_mutex;
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 = 0, nid;

	count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);
	if (!count_per_node)
		return -ENOMEM;

	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();

	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];

	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;
	}

	sc.nid = nid;
	sc.memcg = memcg;
	sc.nr_to_scan = nr_to_scan;
	sc.nr_scanned = nr_to_scan;

	shrinker->scan_objects(shrinker, &sc);

	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_mutex);

	/* 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", 0440, entry, shrinker,
			    &shrinker_debugfs_count_fops);
	debugfs_create_file("scan", 0220, 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;

	mutex_lock(&shrinker_mutex);

	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;
	}

	mutex_unlock(&shrinker_mutex);

	kfree_const(old);

	return ret;
}
EXPORT_SYMBOL(shrinker_debugfs_rename);

struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker,
				       int *debugfs_id)
{
	struct dentry *entry = shrinker->debugfs_entry;

	lockdep_assert_held(&shrinker_mutex);

	*debugfs_id = entry ? shrinker->debugfs_id : -1;
	shrinker->debugfs_entry = NULL;

	return entry;
}

void shrinker_debugfs_remove(struct dentry *debugfs_entry, int debugfs_id)
{
	debugfs_remove_recursive(debugfs_entry);
	ida_free(&shrinker_debugfs_ida, 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 */
	mutex_lock(&shrinker_mutex);
	list_for_each_entry(shrinker, &shrinker_list, list)
		if (!shrinker->debugfs_entry) {
			ret = shrinker_debugfs_add(shrinker);
			if (ret)
				break;
		}
	mutex_unlock(&shrinker_mutex);

	return ret;
}
late_initcall(shrinker_debugfs_init);