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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#include <linux/page_table_check.h>
12#include <linux/rcupdate.h>
13
14/*
15 * struct page extension
16 *
17 * This is the feature to manage memory for extended data per page.
18 *
19 * Until now, we must modify struct page itself to store extra data per page.
20 * This requires rebuilding the kernel and it is really time consuming process.
21 * And, sometimes, rebuild is impossible due to third party module dependency.
22 * At last, enlarging struct page could cause un-wanted system behaviour change.
23 *
24 * This feature is intended to overcome above mentioned problems. This feature
25 * allocates memory for extended data per page in certain place rather than
26 * the struct page itself. This memory can be accessed by the accessor
27 * functions provided by this code. During the boot process, it checks whether
28 * allocation of huge chunk of memory is needed or not. If not, it avoids
29 * allocating memory at all. With this advantage, we can include this feature
30 * into the kernel in default and can avoid rebuild and solve related problems.
31 *
32 * To help these things to work well, there are two callbacks for clients. One
33 * is the need callback which is mandatory if user wants to avoid useless
34 * memory allocation at boot-time. The other is optional, init callback, which
35 * is used to do proper initialization after memory is allocated.
36 *
37 * The need callback is used to decide whether extended memory allocation is
38 * needed or not. Sometimes users want to deactivate some features in this
39 * boot and extra memory would be unnecessary. In this case, to avoid
40 * allocating huge chunk of memory, each clients represent their need of
41 * extra memory through the need callback. If one of the need callbacks
42 * returns true, it means that someone needs extra memory so that
43 * page extension core should allocates memory for page extension. If
44 * none of need callbacks return true, memory isn't needed at all in this boot
45 * and page extension core can skip to allocate memory. As result,
46 * none of memory is wasted.
47 *
48 * When need callback returns true, page_ext checks if there is a request for
49 * extra memory through size in struct page_ext_operations. If it is non-zero,
50 * extra space is allocated for each page_ext entry and offset is returned to
51 * user through offset in struct page_ext_operations.
52 *
53 * The init callback is used to do proper initialization after page extension
54 * is completely initialized. In sparse memory system, extra memory is
55 * allocated some time later than memmap is allocated. In other words, lifetime
56 * of memory for page extension isn't same with memmap for struct page.
57 * Therefore, clients can't store extra data until page extension is
58 * initialized, even if pages are allocated and used freely. This could
59 * cause inadequate state of extra data per page, so, to prevent it, client
60 * can utilize this callback to initialize the state of it correctly.
61 */
62
63#ifdef CONFIG_SPARSEMEM
64#define PAGE_EXT_INVALID (0x1)
65#endif
66
67#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
68static bool need_page_idle(void)
69{
70 return true;
71}
72static struct page_ext_operations page_idle_ops __initdata = {
73 .need = need_page_idle,
74 .need_shared_flags = true,
75};
76#endif
77
78static struct page_ext_operations *page_ext_ops[] __initdata = {
79#ifdef CONFIG_PAGE_OWNER
80 &page_owner_ops,
81#endif
82#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
83 &page_idle_ops,
84#endif
85#ifdef CONFIG_PAGE_TABLE_CHECK
86 &page_table_check_ops,
87#endif
88};
89
90unsigned long page_ext_size;
91
92static unsigned long total_usage;
93
94bool early_page_ext __meminitdata;
95static int __init setup_early_page_ext(char *str)
96{
97 early_page_ext = true;
98 return 0;
99}
100early_param("early_page_ext", setup_early_page_ext);
101
102static bool __init invoke_need_callbacks(void)
103{
104 int i;
105 int entries = ARRAY_SIZE(page_ext_ops);
106 bool need = false;
107
108 for (i = 0; i < entries; i++) {
109 if (page_ext_ops[i]->need()) {
110 if (page_ext_ops[i]->need_shared_flags) {
111 page_ext_size = sizeof(struct page_ext);
112 break;
113 }
114 }
115 }
116
117 for (i = 0; i < entries; i++) {
118 if (page_ext_ops[i]->need()) {
119 page_ext_ops[i]->offset = page_ext_size;
120 page_ext_size += page_ext_ops[i]->size;
121 need = true;
122 }
123 }
124
125 return need;
126}
127
128static void __init invoke_init_callbacks(void)
129{
130 int i;
131 int entries = ARRAY_SIZE(page_ext_ops);
132
133 for (i = 0; i < entries; i++) {
134 if (page_ext_ops[i]->init)
135 page_ext_ops[i]->init();
136 }
137}
138
139static inline struct page_ext *get_entry(void *base, unsigned long index)
140{
141 return base + page_ext_size * index;
142}
143
144#ifndef CONFIG_SPARSEMEM
145void __init page_ext_init_flatmem_late(void)
146{
147 invoke_init_callbacks();
148}
149
150void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
151{
152 pgdat->node_page_ext = NULL;
153}
154
155static struct page_ext *lookup_page_ext(const struct page *page)
156{
157 unsigned long pfn = page_to_pfn(page);
158 unsigned long index;
159 struct page_ext *base;
160
161 WARN_ON_ONCE(!rcu_read_lock_held());
162 base = NODE_DATA(page_to_nid(page))->node_page_ext;
163 /*
164 * The sanity checks the page allocator does upon freeing a
165 * page can reach here before the page_ext arrays are
166 * allocated when feeding a range of pages to the allocator
167 * for the first time during bootup or memory hotplug.
168 */
169 if (unlikely(!base))
170 return NULL;
171 index = pfn - round_down(node_start_pfn(page_to_nid(page)),
172 MAX_ORDER_NR_PAGES);
173 return get_entry(base, index);
174}
175
176static int __init alloc_node_page_ext(int nid)
177{
178 struct page_ext *base;
179 unsigned long table_size;
180 unsigned long nr_pages;
181
182 nr_pages = NODE_DATA(nid)->node_spanned_pages;
183 if (!nr_pages)
184 return 0;
185
186 /*
187 * Need extra space if node range is not aligned with
188 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
189 * checks buddy's status, range could be out of exact node range.
190 */
191 if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
192 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
193 nr_pages += MAX_ORDER_NR_PAGES;
194
195 table_size = page_ext_size * nr_pages;
196
197 base = memblock_alloc_try_nid(
198 table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
199 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
200 if (!base)
201 return -ENOMEM;
202 NODE_DATA(nid)->node_page_ext = base;
203 total_usage += table_size;
204 return 0;
205}
206
207void __init page_ext_init_flatmem(void)
208{
209
210 int nid, fail;
211
212 if (!invoke_need_callbacks())
213 return;
214
215 for_each_online_node(nid) {
216 fail = alloc_node_page_ext(nid);
217 if (fail)
218 goto fail;
219 }
220 pr_info("allocated %ld bytes of page_ext\n", total_usage);
221 return;
222
223fail:
224 pr_crit("allocation of page_ext failed.\n");
225 panic("Out of memory");
226}
227
228#else /* CONFIG_SPARSEMEM */
229static bool page_ext_invalid(struct page_ext *page_ext)
230{
231 return !page_ext || (((unsigned long)page_ext & PAGE_EXT_INVALID) == PAGE_EXT_INVALID);
232}
233
234static struct page_ext *lookup_page_ext(const struct page *page)
235{
236 unsigned long pfn = page_to_pfn(page);
237 struct mem_section *section = __pfn_to_section(pfn);
238 struct page_ext *page_ext = READ_ONCE(section->page_ext);
239
240 WARN_ON_ONCE(!rcu_read_lock_held());
241 /*
242 * The sanity checks the page allocator does upon freeing a
243 * page can reach here before the page_ext arrays are
244 * allocated when feeding a range of pages to the allocator
245 * for the first time during bootup or memory hotplug.
246 */
247 if (page_ext_invalid(page_ext))
248 return NULL;
249 return get_entry(page_ext, pfn);
250}
251
252static void *__meminit alloc_page_ext(size_t size, int nid)
253{
254 gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
255 void *addr = NULL;
256
257 addr = alloc_pages_exact_nid(nid, size, flags);
258 if (addr) {
259 kmemleak_alloc(addr, size, 1, flags);
260 return addr;
261 }
262
263 addr = vzalloc_node(size, nid);
264
265 return addr;
266}
267
268static int __meminit init_section_page_ext(unsigned long pfn, int nid)
269{
270 struct mem_section *section;
271 struct page_ext *base;
272 unsigned long table_size;
273
274 section = __pfn_to_section(pfn);
275
276 if (section->page_ext)
277 return 0;
278
279 table_size = page_ext_size * PAGES_PER_SECTION;
280 base = alloc_page_ext(table_size, nid);
281
282 /*
283 * The value stored in section->page_ext is (base - pfn)
284 * and it does not point to the memory block allocated above,
285 * causing kmemleak false positives.
286 */
287 kmemleak_not_leak(base);
288
289 if (!base) {
290 pr_err("page ext allocation failure\n");
291 return -ENOMEM;
292 }
293
294 /*
295 * The passed "pfn" may not be aligned to SECTION. For the calculation
296 * we need to apply a mask.
297 */
298 pfn &= PAGE_SECTION_MASK;
299 section->page_ext = (void *)base - page_ext_size * pfn;
300 total_usage += table_size;
301 return 0;
302}
303
304static void free_page_ext(void *addr)
305{
306 if (is_vmalloc_addr(addr)) {
307 vfree(addr);
308 } else {
309 struct page *page = virt_to_page(addr);
310 size_t table_size;
311
312 table_size = page_ext_size * PAGES_PER_SECTION;
313
314 BUG_ON(PageReserved(page));
315 kmemleak_free(addr);
316 free_pages_exact(addr, table_size);
317 }
318}
319
320static void __free_page_ext(unsigned long pfn)
321{
322 struct mem_section *ms;
323 struct page_ext *base;
324
325 ms = __pfn_to_section(pfn);
326 if (!ms || !ms->page_ext)
327 return;
328
329 base = READ_ONCE(ms->page_ext);
330 /*
331 * page_ext here can be valid while doing the roll back
332 * operation in online_page_ext().
333 */
334 if (page_ext_invalid(base))
335 base = (void *)base - PAGE_EXT_INVALID;
336 WRITE_ONCE(ms->page_ext, NULL);
337
338 base = get_entry(base, pfn);
339 free_page_ext(base);
340}
341
342static void __invalidate_page_ext(unsigned long pfn)
343{
344 struct mem_section *ms;
345 void *val;
346
347 ms = __pfn_to_section(pfn);
348 if (!ms || !ms->page_ext)
349 return;
350 val = (void *)ms->page_ext + PAGE_EXT_INVALID;
351 WRITE_ONCE(ms->page_ext, val);
352}
353
354static int __meminit online_page_ext(unsigned long start_pfn,
355 unsigned long nr_pages,
356 int nid)
357{
358 unsigned long start, end, pfn;
359 int fail = 0;
360
361 start = SECTION_ALIGN_DOWN(start_pfn);
362 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
363
364 if (nid == NUMA_NO_NODE) {
365 /*
366 * In this case, "nid" already exists and contains valid memory.
367 * "start_pfn" passed to us is a pfn which is an arg for
368 * online__pages(), and start_pfn should exist.
369 */
370 nid = pfn_to_nid(start_pfn);
371 VM_BUG_ON(!node_online(nid));
372 }
373
374 for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION)
375 fail = init_section_page_ext(pfn, nid);
376 if (!fail)
377 return 0;
378
379 /* rollback */
380 end = pfn - PAGES_PER_SECTION;
381 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
382 __free_page_ext(pfn);
383
384 return -ENOMEM;
385}
386
387static void __meminit offline_page_ext(unsigned long start_pfn,
388 unsigned long nr_pages)
389{
390 unsigned long start, end, pfn;
391
392 start = SECTION_ALIGN_DOWN(start_pfn);
393 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
394
395 /*
396 * Freeing of page_ext is done in 3 steps to avoid
397 * use-after-free of it:
398 * 1) Traverse all the sections and mark their page_ext
399 * as invalid.
400 * 2) Wait for all the existing users of page_ext who
401 * started before invalidation to finish.
402 * 3) Free the page_ext.
403 */
404 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
405 __invalidate_page_ext(pfn);
406
407 synchronize_rcu();
408
409 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
410 __free_page_ext(pfn);
411}
412
413static int __meminit page_ext_callback(struct notifier_block *self,
414 unsigned long action, void *arg)
415{
416 struct memory_notify *mn = arg;
417 int ret = 0;
418
419 switch (action) {
420 case MEM_GOING_ONLINE:
421 ret = online_page_ext(mn->start_pfn,
422 mn->nr_pages, mn->status_change_nid);
423 break;
424 case MEM_OFFLINE:
425 offline_page_ext(mn->start_pfn,
426 mn->nr_pages);
427 break;
428 case MEM_CANCEL_ONLINE:
429 offline_page_ext(mn->start_pfn,
430 mn->nr_pages);
431 break;
432 case MEM_GOING_OFFLINE:
433 break;
434 case MEM_ONLINE:
435 case MEM_CANCEL_OFFLINE:
436 break;
437 }
438
439 return notifier_from_errno(ret);
440}
441
442void __init page_ext_init(void)
443{
444 unsigned long pfn;
445 int nid;
446
447 if (!invoke_need_callbacks())
448 return;
449
450 for_each_node_state(nid, N_MEMORY) {
451 unsigned long start_pfn, end_pfn;
452
453 start_pfn = node_start_pfn(nid);
454 end_pfn = node_end_pfn(nid);
455 /*
456 * start_pfn and end_pfn may not be aligned to SECTION and the
457 * page->flags of out of node pages are not initialized. So we
458 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
459 */
460 for (pfn = start_pfn; pfn < end_pfn;
461 pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
462
463 if (!pfn_valid(pfn))
464 continue;
465 /*
466 * Nodes's pfns can be overlapping.
467 * We know some arch can have a nodes layout such as
468 * -------------pfn-------------->
469 * N0 | N1 | N2 | N0 | N1 | N2|....
470 */
471 if (pfn_to_nid(pfn) != nid)
472 continue;
473 if (init_section_page_ext(pfn, nid))
474 goto oom;
475 cond_resched();
476 }
477 }
478 hotplug_memory_notifier(page_ext_callback, DEFAULT_CALLBACK_PRI);
479 pr_info("allocated %ld bytes of page_ext\n", total_usage);
480 invoke_init_callbacks();
481 return;
482
483oom:
484 panic("Out of memory");
485}
486
487void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
488{
489}
490
491#endif
492
493/**
494 * page_ext_get() - Get the extended information for a page.
495 * @page: The page we're interested in.
496 *
497 * Ensures that the page_ext will remain valid until page_ext_put()
498 * is called.
499 *
500 * Return: NULL if no page_ext exists for this page.
501 * Context: Any context. Caller may not sleep until they have called
502 * page_ext_put().
503 */
504struct page_ext *page_ext_get(struct page *page)
505{
506 struct page_ext *page_ext;
507
508 rcu_read_lock();
509 page_ext = lookup_page_ext(page);
510 if (!page_ext) {
511 rcu_read_unlock();
512 return NULL;
513 }
514
515 return page_ext;
516}
517
518/**
519 * page_ext_put() - Working with page extended information is done.
520 * @page_ext: Page extended information received from page_ext_get().
521 *
522 * The page extended information of the page may not be valid after this
523 * function is called.
524 *
525 * Return: None.
526 * Context: Any context with corresponding page_ext_get() is called.
527 */
528void page_ext_put(struct page_ext *page_ext)
529{
530 if (unlikely(!page_ext))
531 return;
532
533 rcu_read_unlock();
534}
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_PAGE_OWNER
63 &page_owner_ops,
64#endif
65#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
66 &page_idle_ops,
67#endif
68};
69
70unsigned long page_ext_size = sizeof(struct page_ext);
71
72static unsigned long total_usage;
73
74static bool __init invoke_need_callbacks(void)
75{
76 int i;
77 int entries = ARRAY_SIZE(page_ext_ops);
78 bool need = false;
79
80 for (i = 0; i < entries; i++) {
81 if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
82 page_ext_ops[i]->offset = page_ext_size;
83 page_ext_size += page_ext_ops[i]->size;
84 need = true;
85 }
86 }
87
88 return need;
89}
90
91static void __init invoke_init_callbacks(void)
92{
93 int i;
94 int entries = ARRAY_SIZE(page_ext_ops);
95
96 for (i = 0; i < entries; i++) {
97 if (page_ext_ops[i]->init)
98 page_ext_ops[i]->init();
99 }
100}
101
102static inline struct page_ext *get_entry(void *base, unsigned long index)
103{
104 return base + page_ext_size * index;
105}
106
107#if !defined(CONFIG_SPARSEMEM)
108
109
110void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
111{
112 pgdat->node_page_ext = NULL;
113}
114
115struct page_ext *lookup_page_ext(const struct page *page)
116{
117 unsigned long pfn = page_to_pfn(page);
118 unsigned long index;
119 struct page_ext *base;
120
121 base = NODE_DATA(page_to_nid(page))->node_page_ext;
122 /*
123 * The sanity checks the page allocator does upon freeing a
124 * page can reach here before the page_ext arrays are
125 * allocated when feeding a range of pages to the allocator
126 * for the first time during bootup or memory hotplug.
127 */
128 if (unlikely(!base))
129 return NULL;
130 index = pfn - round_down(node_start_pfn(page_to_nid(page)),
131 MAX_ORDER_NR_PAGES);
132 return get_entry(base, index);
133}
134
135static int __init alloc_node_page_ext(int nid)
136{
137 struct page_ext *base;
138 unsigned long table_size;
139 unsigned long nr_pages;
140
141 nr_pages = NODE_DATA(nid)->node_spanned_pages;
142 if (!nr_pages)
143 return 0;
144
145 /*
146 * Need extra space if node range is not aligned with
147 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
148 * checks buddy's status, range could be out of exact node range.
149 */
150 if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
151 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
152 nr_pages += MAX_ORDER_NR_PAGES;
153
154 table_size = page_ext_size * nr_pages;
155
156 base = memblock_alloc_try_nid(
157 table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
158 MEMBLOCK_ALLOC_ACCESSIBLE, nid);
159 if (!base)
160 return -ENOMEM;
161 NODE_DATA(nid)->node_page_ext = base;
162 total_usage += table_size;
163 return 0;
164}
165
166void __init page_ext_init_flatmem(void)
167{
168
169 int nid, fail;
170
171 if (!invoke_need_callbacks())
172 return;
173
174 for_each_online_node(nid) {
175 fail = alloc_node_page_ext(nid);
176 if (fail)
177 goto fail;
178 }
179 pr_info("allocated %ld bytes of page_ext\n", total_usage);
180 invoke_init_callbacks();
181 return;
182
183fail:
184 pr_crit("allocation of page_ext failed.\n");
185 panic("Out of memory");
186}
187
188#else /* CONFIG_FLAT_NODE_MEM_MAP */
189
190struct page_ext *lookup_page_ext(const struct page *page)
191{
192 unsigned long pfn = page_to_pfn(page);
193 struct mem_section *section = __pfn_to_section(pfn);
194 /*
195 * The sanity checks the page allocator does upon freeing a
196 * page can reach here before the page_ext arrays are
197 * allocated when feeding a range of pages to the allocator
198 * for the first time during bootup or memory hotplug.
199 */
200 if (!section->page_ext)
201 return NULL;
202 return get_entry(section->page_ext, pfn);
203}
204
205static void *__meminit alloc_page_ext(size_t size, int nid)
206{
207 gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
208 void *addr = NULL;
209
210 addr = alloc_pages_exact_nid(nid, size, flags);
211 if (addr) {
212 kmemleak_alloc(addr, size, 1, flags);
213 return addr;
214 }
215
216 addr = vzalloc_node(size, nid);
217
218 return addr;
219}
220
221static int __meminit init_section_page_ext(unsigned long pfn, int nid)
222{
223 struct mem_section *section;
224 struct page_ext *base;
225 unsigned long table_size;
226
227 section = __pfn_to_section(pfn);
228
229 if (section->page_ext)
230 return 0;
231
232 table_size = page_ext_size * PAGES_PER_SECTION;
233 base = alloc_page_ext(table_size, nid);
234
235 /*
236 * The value stored in section->page_ext is (base - pfn)
237 * and it does not point to the memory block allocated above,
238 * causing kmemleak false positives.
239 */
240 kmemleak_not_leak(base);
241
242 if (!base) {
243 pr_err("page ext allocation failure\n");
244 return -ENOMEM;
245 }
246
247 /*
248 * The passed "pfn" may not be aligned to SECTION. For the calculation
249 * we need to apply a mask.
250 */
251 pfn &= PAGE_SECTION_MASK;
252 section->page_ext = (void *)base - page_ext_size * pfn;
253 total_usage += table_size;
254 return 0;
255}
256#ifdef CONFIG_MEMORY_HOTPLUG
257static void free_page_ext(void *addr)
258{
259 if (is_vmalloc_addr(addr)) {
260 vfree(addr);
261 } else {
262 struct page *page = virt_to_page(addr);
263 size_t table_size;
264
265 table_size = page_ext_size * PAGES_PER_SECTION;
266
267 BUG_ON(PageReserved(page));
268 kmemleak_free(addr);
269 free_pages_exact(addr, table_size);
270 }
271}
272
273static void __free_page_ext(unsigned long pfn)
274{
275 struct mem_section *ms;
276 struct page_ext *base;
277
278 ms = __pfn_to_section(pfn);
279 if (!ms || !ms->page_ext)
280 return;
281 base = get_entry(ms->page_ext, pfn);
282 free_page_ext(base);
283 ms->page_ext = NULL;
284}
285
286static int __meminit online_page_ext(unsigned long start_pfn,
287 unsigned long nr_pages,
288 int nid)
289{
290 unsigned long start, end, pfn;
291 int fail = 0;
292
293 start = SECTION_ALIGN_DOWN(start_pfn);
294 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
295
296 if (nid == NUMA_NO_NODE) {
297 /*
298 * In this case, "nid" already exists and contains valid memory.
299 * "start_pfn" passed to us is a pfn which is an arg for
300 * online__pages(), and start_pfn should exist.
301 */
302 nid = pfn_to_nid(start_pfn);
303 VM_BUG_ON(!node_state(nid, N_ONLINE));
304 }
305
306 for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION)
307 fail = init_section_page_ext(pfn, nid);
308 if (!fail)
309 return 0;
310
311 /* rollback */
312 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
313 __free_page_ext(pfn);
314
315 return -ENOMEM;
316}
317
318static int __meminit offline_page_ext(unsigned long start_pfn,
319 unsigned long nr_pages, int nid)
320{
321 unsigned long start, end, pfn;
322
323 start = SECTION_ALIGN_DOWN(start_pfn);
324 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
325
326 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
327 __free_page_ext(pfn);
328 return 0;
329
330}
331
332static int __meminit page_ext_callback(struct notifier_block *self,
333 unsigned long action, void *arg)
334{
335 struct memory_notify *mn = arg;
336 int ret = 0;
337
338 switch (action) {
339 case MEM_GOING_ONLINE:
340 ret = online_page_ext(mn->start_pfn,
341 mn->nr_pages, mn->status_change_nid);
342 break;
343 case MEM_OFFLINE:
344 offline_page_ext(mn->start_pfn,
345 mn->nr_pages, mn->status_change_nid);
346 break;
347 case MEM_CANCEL_ONLINE:
348 offline_page_ext(mn->start_pfn,
349 mn->nr_pages, mn->status_change_nid);
350 break;
351 case MEM_GOING_OFFLINE:
352 break;
353 case MEM_ONLINE:
354 case MEM_CANCEL_OFFLINE:
355 break;
356 }
357
358 return notifier_from_errno(ret);
359}
360
361#endif
362
363void __init page_ext_init(void)
364{
365 unsigned long pfn;
366 int nid;
367
368 if (!invoke_need_callbacks())
369 return;
370
371 for_each_node_state(nid, N_MEMORY) {
372 unsigned long start_pfn, end_pfn;
373
374 start_pfn = node_start_pfn(nid);
375 end_pfn = node_end_pfn(nid);
376 /*
377 * start_pfn and end_pfn may not be aligned to SECTION and the
378 * page->flags of out of node pages are not initialized. So we
379 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
380 */
381 for (pfn = start_pfn; pfn < end_pfn;
382 pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
383
384 if (!pfn_valid(pfn))
385 continue;
386 /*
387 * Nodes's pfns can be overlapping.
388 * We know some arch can have a nodes layout such as
389 * -------------pfn-------------->
390 * N0 | N1 | N2 | N0 | N1 | N2|....
391 */
392 if (pfn_to_nid(pfn) != nid)
393 continue;
394 if (init_section_page_ext(pfn, nid))
395 goto oom;
396 cond_resched();
397 }
398 }
399 hotplug_memory_notifier(page_ext_callback, 0);
400 pr_info("allocated %ld bytes of page_ext\n", total_usage);
401 invoke_init_callbacks();
402 return;
403
404oom:
405 panic("Out of memory");
406}
407
408void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
409{
410}
411
412#endif