1// SPDX-License-Identifier: GPL-2.0
2#include <linux/mm.h>
3#include <linux/mmzone.h>
4#include <linux/memblock.h>
5#include <linux/page_ext.h>
6#include <linux/memory.h>
7#include <linux/vmalloc.h>
8#include <linux/kmemleak.h>
9#include <linux/page_owner.h>
10#include <linux/page_idle.h>
11
12/*
13 * struct page extension
14 *
15 * This is the feature to manage memory for extended data per page.
16 *
17 * Until now, we must modify struct page itself to store extra data per page.
18 * This requires rebuilding the kernel and it is really time consuming process.
19 * And, sometimes, rebuild is impossible due to third party module dependency.
20 * At last, enlarging struct page could cause un-wanted system behaviour change.
21 *
22 * This feature is intended to overcome above mentioned problems. This feature
23 * allocates memory for extended data per page in certain place rather than
24 * the struct page itself. This memory can be accessed by the accessor
25 * functions provided by this code. During the boot process, it checks whether
26 * allocation of huge chunk of memory is needed or not. If not, it avoids
27 * allocating memory at all. With this advantage, we can include this feature
28 * into the kernel in default and can avoid rebuild and solve related problems.
29 *
30 * To help these things to work well, there are two callbacks for clients. One
31 * is the need callback which is mandatory if user wants to avoid useless
32 * memory allocation at boot-time. The other is optional, init callback, which
33 * is used to do proper initialization after memory is allocated.
34 *
35 * The need callback is used to decide whether extended memory allocation is
36 * needed or not. Sometimes users want to deactivate some features in this
37 * boot and extra memory would be unneccessary. In this case, to avoid
38 * allocating huge chunk of memory, each clients represent their need of
39 * extra memory through the need callback. If one of the need callbacks
40 * returns true, it means that someone needs extra memory so that
41 * page extension core should allocates memory for page extension. If
42 * none of need callbacks return true, memory isn't needed at all in this boot
43 * and page extension core can skip to allocate memory. As result,
44 * none of memory is wasted.
45 *
46 * When need callback returns true, page_ext checks if there is a request for
47 * extra memory through size in struct page_ext_operations. If it is non-zero,
48 * extra space is allocated for each page_ext entry and offset is returned to
49 * user through offset in struct page_ext_operations.
50 *
51 * The init callback is used to do proper initialization after page extension
52 * is completely initialized. In sparse memory system, extra memory is
53 * allocated some time later than memmap is allocated. In other words, lifetime
54 * of memory for page extension isn't same with memmap for struct page.
55 * Therefore, clients can't store extra data until page extension is
56 * initialized, even if pages are allocated and used freely. This could
57 * cause inadequate state of extra data per page, so, to prevent it, client
58 * can utilize this callback to initialize the state of it correctly.
59 */
60
61static struct page_ext_operations *page_ext_ops[] = {
62#ifdef CONFIG_DEBUG_PAGEALLOC
63 &debug_guardpage_ops,
64#endif
65#ifdef CONFIG_PAGE_OWNER
66 &page_owner_ops,
67#endif
68#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
69 &page_idle_ops,
70#endif
71};
72
73static unsigned long total_usage;
74static unsigned long extra_mem;
75
76static bool __init invoke_need_callbacks(void)
77{
78 int i;
79 int entries = ARRAY_SIZE(page_ext_ops);
80 bool need = false;
81
82 for (i = 0; i < entries; i++) {
83 if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
84 page_ext_ops[i]->offset = sizeof(struct page_ext) +
85 extra_mem;
86 extra_mem += page_ext_ops[i]->size;
87 need = true;
88 }
89 }
90
91 return need;
92}
93
94static void __init invoke_init_callbacks(void)
95{
96 int i;
97 int entries = ARRAY_SIZE(page_ext_ops);
98
99 for (i = 0; i < entries; i++) {
100 if (page_ext_ops[i]->init)
101 page_ext_ops[i]->init();
102 }
103}
104
105static unsigned long get_entry_size(void)
106{
107 return sizeof(struct page_ext) + extra_mem;
108}
109
110static inline struct page_ext *get_entry(void *base, unsigned long index)
111{
112 return base + get_entry_size() * index;
113}
114
115#if !defined(CONFIG_SPARSEMEM)
116
117
118void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
119{
120 pgdat->node_page_ext = NULL;
121}
122
123struct page_ext *lookup_page_ext(const struct page *page)
124{
125 unsigned long pfn = page_to_pfn(page);
126 unsigned long index;
127 struct page_ext *base;
128
129 base = NODE_DATA(page_to_nid(page))->node_page_ext;
130 /*
131 * The sanity checks the page allocator does upon freeing a
132 * page can reach here before the page_ext arrays are
133 * allocated when feeding a range of pages to the allocator
134 * for the first time during bootup or memory hotplug.
135 */
136 if (unlikely(!base))
137 return NULL;
138 index = pfn - round_down(node_start_pfn(page_to_nid(page)),
139 MAX_ORDER_NR_PAGES);
140 return get_entry(base, index);
141}
142
143static int __init alloc_node_page_ext(int nid)
144{
145 struct page_ext *base;
146 unsigned long table_size;
147 unsigned long nr_pages;
148
149 nr_pages = NODE_DATA(nid)->node_spanned_pages;
150 if (!nr_pages)
151 return 0;
152
153 /*
154 * Need extra space if node range is not aligned with
155 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
156 * checks buddy's status, range could be out of exact node range.
157 */
158 if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
159 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
160 nr_pages += MAX_ORDER_NR_PAGES;
161
162 table_size = get_entry_size() * nr_pages;
163
164 base = memblock_alloc_try_nid(
165 table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
166 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
167 if (!base)
168 return -ENOMEM;
169 NODE_DATA(nid)->node_page_ext = base;
170 total_usage += table_size;
171 return 0;
172}
173
174void __init page_ext_init_flatmem(void)
175{
176
177 int nid, fail;
178
179 if (!invoke_need_callbacks())
180 return;
181
182 for_each_online_node(nid) {
183 fail = alloc_node_page_ext(nid);
184 if (fail)
185 goto fail;
186 }
187 pr_info("allocated %ld bytes of page_ext\n", total_usage);
188 invoke_init_callbacks();
189 return;
190
191fail:
192 pr_crit("allocation of page_ext failed.\n");
193 panic("Out of memory");
194}
195
196#else /* CONFIG_FLAT_NODE_MEM_MAP */
197
198struct page_ext *lookup_page_ext(const struct page *page)
199{
200 unsigned long pfn = page_to_pfn(page);
201 struct mem_section *section = __pfn_to_section(pfn);
202 /*
203 * The sanity checks the page allocator does upon freeing a
204 * page can reach here before the page_ext arrays are
205 * allocated when feeding a range of pages to the allocator
206 * for the first time during bootup or memory hotplug.
207 */
208 if (!section->page_ext)
209 return NULL;
210 return get_entry(section->page_ext, pfn);
211}
212
213static void *__meminit alloc_page_ext(size_t size, int nid)
214{
215 gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
216 void *addr = NULL;
217
218 addr = alloc_pages_exact_nid(nid, size, flags);
219 if (addr) {
220 kmemleak_alloc(addr, size, 1, flags);
221 return addr;
222 }
223
224 addr = vzalloc_node(size, nid);
225
226 return addr;
227}
228
229static int __meminit init_section_page_ext(unsigned long pfn, int nid)
230{
231 struct mem_section *section;
232 struct page_ext *base;
233 unsigned long table_size;
234
235 section = __pfn_to_section(pfn);
236
237 if (section->page_ext)
238 return 0;
239
240 table_size = get_entry_size() * PAGES_PER_SECTION;
241 base = alloc_page_ext(table_size, nid);
242
243 /*
244 * The value stored in section->page_ext is (base - pfn)
245 * and it does not point to the memory block allocated above,
246 * causing kmemleak false positives.
247 */
248 kmemleak_not_leak(base);
249
250 if (!base) {
251 pr_err("page ext allocation failure\n");
252 return -ENOMEM;
253 }
254
255 /*
256 * The passed "pfn" may not be aligned to SECTION. For the calculation
257 * we need to apply a mask.
258 */
259 pfn &= PAGE_SECTION_MASK;
260 section->page_ext = (void *)base - get_entry_size() * pfn;
261 total_usage += table_size;
262 return 0;
263}
264#ifdef CONFIG_MEMORY_HOTPLUG
265static void free_page_ext(void *addr)
266{
267 if (is_vmalloc_addr(addr)) {
268 vfree(addr);
269 } else {
270 struct page *page = virt_to_page(addr);
271 size_t table_size;
272
273 table_size = get_entry_size() * PAGES_PER_SECTION;
274
275 BUG_ON(PageReserved(page));
276 kmemleak_free(addr);
277 free_pages_exact(addr, table_size);
278 }
279}
280
281static void __free_page_ext(unsigned long pfn)
282{
283 struct mem_section *ms;
284 struct page_ext *base;
285
286 ms = __pfn_to_section(pfn);
287 if (!ms || !ms->page_ext)
288 return;
289 base = get_entry(ms->page_ext, pfn);
290 free_page_ext(base);
291 ms->page_ext = NULL;
292}
293
294static int __meminit online_page_ext(unsigned long start_pfn,
295 unsigned long nr_pages,
296 int nid)
297{
298 unsigned long start, end, pfn;
299 int fail = 0;
300
301 start = SECTION_ALIGN_DOWN(start_pfn);
302 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
303
304 if (nid == NUMA_NO_NODE) {
305 /*
306 * In this case, "nid" already exists and contains valid memory.
307 * "start_pfn" passed to us is a pfn which is an arg for
308 * online__pages(), and start_pfn should exist.
309 */
310 nid = pfn_to_nid(start_pfn);
311 VM_BUG_ON(!node_state(nid, N_ONLINE));
312 }
313
314 for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
315 if (!pfn_present(pfn))
316 continue;
317 fail = init_section_page_ext(pfn, nid);
318 }
319 if (!fail)
320 return 0;
321
322 /* rollback */
323 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
324 __free_page_ext(pfn);
325
326 return -ENOMEM;
327}
328
329static int __meminit offline_page_ext(unsigned long start_pfn,
330 unsigned long nr_pages, int nid)
331{
332 unsigned long start, end, pfn;
333
334 start = SECTION_ALIGN_DOWN(start_pfn);
335 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
336
337 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
338 __free_page_ext(pfn);
339 return 0;
340
341}
342
343static int __meminit page_ext_callback(struct notifier_block *self,
344 unsigned long action, void *arg)
345{
346 struct memory_notify *mn = arg;
347 int ret = 0;
348
349 switch (action) {
350 case MEM_GOING_ONLINE:
351 ret = online_page_ext(mn->start_pfn,
352 mn->nr_pages, mn->status_change_nid);
353 break;
354 case MEM_OFFLINE:
355 offline_page_ext(mn->start_pfn,
356 mn->nr_pages, mn->status_change_nid);
357 break;
358 case MEM_CANCEL_ONLINE:
359 offline_page_ext(mn->start_pfn,
360 mn->nr_pages, mn->status_change_nid);
361 break;
362 case MEM_GOING_OFFLINE:
363 break;
364 case MEM_ONLINE:
365 case MEM_CANCEL_OFFLINE:
366 break;
367 }
368
369 return notifier_from_errno(ret);
370}
371
372#endif
373
374void __init page_ext_init(void)
375{
376 unsigned long pfn;
377 int nid;
378
379 if (!invoke_need_callbacks())
380 return;
381
382 for_each_node_state(nid, N_MEMORY) {
383 unsigned long start_pfn, end_pfn;
384
385 start_pfn = node_start_pfn(nid);
386 end_pfn = node_end_pfn(nid);
387 /*
388 * start_pfn and end_pfn may not be aligned to SECTION and the
389 * page->flags of out of node pages are not initialized. So we
390 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
391 */
392 for (pfn = start_pfn; pfn < end_pfn;
393 pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
394
395 if (!pfn_valid(pfn))
396 continue;
397 /*
398 * Nodes's pfns can be overlapping.
399 * We know some arch can have a nodes layout such as
400 * -------------pfn-------------->
401 * N0 | N1 | N2 | N0 | N1 | N2|....
402 */
403 if (pfn_to_nid(pfn) != nid)
404 continue;
405 if (init_section_page_ext(pfn, nid))
406 goto oom;
407 cond_resched();
408 }
409 }
410 hotplug_memory_notifier(page_ext_callback, 0);
411 pr_info("allocated %ld bytes of page_ext\n", total_usage);
412 invoke_init_callbacks();
413 return;
414
415oom:
416 panic("Out of memory");
417}
418
419void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
420{
421}
422
423#endif
424