1
2#include <linux/init.h>
3#include <linux/memblock.h>
4#include <linux/fs.h>
5#include <linux/sysfs.h>
6#include <linux/kobject.h>
7#include <linux/memory_hotplug.h>
8#include <linux/mm.h>
9#include <linux/mmzone.h>
10#include <linux/pagemap.h>
11#include <linux/rmap.h>
12#include <linux/mmu_notifier.h>
13#include <linux/page_ext.h>
14#include <linux/page_idle.h>
15
16#define BITMAP_CHUNK_SIZE sizeof(u64)
17#define BITMAP_CHUNK_BITS (BITMAP_CHUNK_SIZE * BITS_PER_BYTE)
18
19
20
21
22
23
24
25
26
27
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29
30
31
32static struct page *page_idle_get_page(unsigned long pfn)
33{
34 struct page *page = pfn_to_online_page(pfn);
35
36 if (!page || !PageLRU(page) ||
37 !get_page_unless_zero(page))
38 return NULL;
39
40 if (unlikely(!PageLRU(page))) {
41 put_page(page);
42 page = NULL;
43 }
44 return page;
45}
46
47static bool page_idle_clear_pte_refs_one(struct page *page,
48 struct vm_area_struct *vma,
49 unsigned long addr, void *arg)
50{
51 struct page_vma_mapped_walk pvmw = {
52 .page = page,
53 .vma = vma,
54 .address = addr,
55 };
56 bool referenced = false;
57
58 while (page_vma_mapped_walk(&pvmw)) {
59 addr = pvmw.address;
60 if (pvmw.pte) {
61
62
63
64
65 if (ptep_clear_young_notify(vma, addr, pvmw.pte))
66 referenced = true;
67 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
68 if (pmdp_clear_young_notify(vma, addr, pvmw.pmd))
69 referenced = true;
70 } else {
71
72 WARN_ON_ONCE(1);
73 }
74 }
75
76 if (referenced) {
77 clear_page_idle(page);
78
79
80
81
82
83 set_page_young(page);
84 }
85 return true;
86}
87
88static void page_idle_clear_pte_refs(struct page *page)
89{
90
91
92
93
94 static const struct rmap_walk_control rwc = {
95 .rmap_one = page_idle_clear_pte_refs_one,
96 .anon_lock = page_lock_anon_vma_read,
97 };
98 bool need_lock;
99
100 if (!page_mapped(page) ||
101 !page_rmapping(page))
102 return;
103
104 need_lock = !PageAnon(page) || PageKsm(page);
105 if (need_lock && !trylock_page(page))
106 return;
107
108 rmap_walk(page, (struct rmap_walk_control *)&rwc);
109
110 if (need_lock)
111 unlock_page(page);
112}
113
114static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
115 struct bin_attribute *attr, char *buf,
116 loff_t pos, size_t count)
117{
118 u64 *out = (u64 *)buf;
119 struct page *page;
120 unsigned long pfn, end_pfn;
121 int bit;
122
123 if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
124 return -EINVAL;
125
126 pfn = pos * BITS_PER_BYTE;
127 if (pfn >= max_pfn)
128 return 0;
129
130 end_pfn = pfn + count * BITS_PER_BYTE;
131 if (end_pfn > max_pfn)
132 end_pfn = max_pfn;
133
134 for (; pfn < end_pfn; pfn++) {
135 bit = pfn % BITMAP_CHUNK_BITS;
136 if (!bit)
137 *out = 0ULL;
138 page = page_idle_get_page(pfn);
139 if (page) {
140 if (page_is_idle(page)) {
141
142
143
144
145
146 page_idle_clear_pte_refs(page);
147 if (page_is_idle(page))
148 *out |= 1ULL << bit;
149 }
150 put_page(page);
151 }
152 if (bit == BITMAP_CHUNK_BITS - 1)
153 out++;
154 cond_resched();
155 }
156 return (char *)out - buf;
157}
158
159static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
160 struct bin_attribute *attr, char *buf,
161 loff_t pos, size_t count)
162{
163 const u64 *in = (u64 *)buf;
164 struct page *page;
165 unsigned long pfn, end_pfn;
166 int bit;
167
168 if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
169 return -EINVAL;
170
171 pfn = pos * BITS_PER_BYTE;
172 if (pfn >= max_pfn)
173 return -ENXIO;
174
175 end_pfn = pfn + count * BITS_PER_BYTE;
176 if (end_pfn > max_pfn)
177 end_pfn = max_pfn;
178
179 for (; pfn < end_pfn; pfn++) {
180 bit = pfn % BITMAP_CHUNK_BITS;
181 if ((*in >> bit) & 1) {
182 page = page_idle_get_page(pfn);
183 if (page) {
184 page_idle_clear_pte_refs(page);
185 set_page_idle(page);
186 put_page(page);
187 }
188 }
189 if (bit == BITMAP_CHUNK_BITS - 1)
190 in++;
191 cond_resched();
192 }
193 return (char *)in - buf;
194}
195
196static struct bin_attribute page_idle_bitmap_attr =
197 __BIN_ATTR(bitmap, 0600,
198 page_idle_bitmap_read, page_idle_bitmap_write, 0);
199
200static struct bin_attribute *page_idle_bin_attrs[] = {
201 &page_idle_bitmap_attr,
202 NULL,
203};
204
205static const struct attribute_group page_idle_attr_group = {
206 .bin_attrs = page_idle_bin_attrs,
207 .name = "page_idle",
208};
209
210static int __init page_idle_init(void)
211{
212 int err;
213
214 err = sysfs_create_group(mm_kobj, &page_idle_attr_group);
215 if (err) {
216 pr_err("page_idle: register sysfs failed\n");
217 return err;
218 }
219 return 0;
220}
221subsys_initcall(page_idle_init);
222