path: root/mm/page_ext.c (plain)
blob: a7be1c7a79f66d4627b8429d82314afaa4b24b9c

1	#include <linux/mm.h>
2	#include <linux/mmzone.h>
3	#include <linux/bootmem.h>
4	#include <linux/page_ext.h>
5	#include <linux/memory.h>
6	#include <linux/vmalloc.h>
7	#include <linux/kmemleak.h>
8	#include <linux/page_owner.h>
9	#include <linux/page_idle.h>
10
11	/*
12	* struct page extension
13	*
14	* This is the feature to manage memory for extended data per page.
15	*
16	* Until now, we must modify struct page itself to store extra data per page.
17	* This requires rebuilding the kernel and it is really time consuming process.
18	* And, sometimes, rebuild is impossible due to third party module dependency.
19	* At last, enlarging struct page could cause un-wanted system behaviour change.
20	*
21	* This feature is intended to overcome above mentioned problems. This feature
22	* allocates memory for extended data per page in certain place rather than
23	* the struct page itself. This memory can be accessed by the accessor
24	* functions provided by this code. During the boot process, it checks whether
25	* allocation of huge chunk of memory is needed or not. If not, it avoids
26	* allocating memory at all. With this advantage, we can include this feature
27	* into the kernel in default and can avoid rebuild and solve related problems.
28	*
29	* To help these things to work well, there are two callbacks for clients. One
30	* is the need callback which is mandatory if user wants to avoid useless
31	* memory allocation at boot-time. The other is optional, init callback, which
32	* is used to do proper initialization after memory is allocated.
33	*
34	* The need callback is used to decide whether extended memory allocation is
35	* needed or not. Sometimes users want to deactivate some features in this
36	* boot and extra memory would be unneccessary. In this case, to avoid
37	* allocating huge chunk of memory, each clients represent their need of
38	* extra memory through the need callback. If one of the need callbacks
39	* returns true, it means that someone needs extra memory so that
40	* page extension core should allocates memory for page extension. If
41	* none of need callbacks return true, memory isn't needed at all in this boot
42	* and page extension core can skip to allocate memory. As result,
43	* none of memory is wasted.
44	*
45	* When need callback returns true, page_ext checks if there is a request for
46	* extra memory through size in struct page_ext_operations. If it is non-zero,
47	* extra space is allocated for each page_ext entry and offset is returned to
48	* user through offset in struct page_ext_operations.
49	*
50	* The init callback is used to do proper initialization after page extension
51	* is completely initialized. In sparse memory system, extra memory is
52	* allocated some time later than memmap is allocated. In other words, lifetime
53	* of memory for page extension isn't same with memmap for struct page.
54	* Therefore, clients can't store extra data until page extension is
55	* initialized, even if pages are allocated and used freely. This could
56	* cause inadequate state of extra data per page, so, to prevent it, client
57	* can utilize this callback to initialize the state of it correctly.
58	*/
59
60	static struct page_ext_operations *page_ext_ops[] = {
61	&debug_guardpage_ops,
62	#ifdef CONFIG_PAGE_POISONING
63	&page_poisoning_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
73	static unsigned long total_usage;
74	static unsigned long extra_mem;
75
76	static 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
94	static 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
105	static unsigned long get_entry_size(void)
106	{
107	return sizeof(struct page_ext) + extra_mem;
108	}
109
110	static 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
118	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
119	{
120	pgdat->node_page_ext = NULL;
121	}
122
123	struct page_ext *lookup_page_ext(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	#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
131	/*
132	* The sanity checks the page allocator does upon freeing a
133	* page can reach here before the page_ext arrays are
134	* allocated when feeding a range of pages to the allocator
135	* for the first time during bootup or memory hotplug.
136	*
137	* This check is also necessary for ensuring page poisoning
138	* works as expected when enabled
139	*/
140	if (unlikely(!base))
141	return NULL;
142	#endif
143	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
144	MAX_ORDER_NR_PAGES);
145	return get_entry(base, index);
146	}
147
148	static int __init alloc_node_page_ext(int nid)
149	{
150	struct page_ext *base;
151	unsigned long table_size;
152	unsigned long nr_pages;
153
154	nr_pages = NODE_DATA(nid)->node_spanned_pages;
155	if (!nr_pages)
156	return 0;
157
158	/*
159	* Need extra space if node range is not aligned with
160	* MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
161	* checks buddy's status, range could be out of exact node range.
162	*/
163	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
164	!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
165	nr_pages += MAX_ORDER_NR_PAGES;
166
167	table_size = get_entry_size() * nr_pages;
168
169	base = memblock_virt_alloc_try_nid_nopanic(
170	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
171	BOOTMEM_ALLOC_ACCESSIBLE, nid);
172	if (!base)
173	return -ENOMEM;
174	NODE_DATA(nid)->node_page_ext = base;
175	total_usage += table_size;
176	return 0;
177	}
178
179	void __init page_ext_init_flatmem(void)
180	{
181
182	int nid, fail;
183
184	if (!invoke_need_callbacks())
185	return;
186
187	for_each_online_node(nid) {
188	fail = alloc_node_page_ext(nid);
189	if (fail)
190	goto fail;
191	}
192	pr_info("allocated %ld bytes of page_ext\n", total_usage);
193	invoke_init_callbacks();
194	return;
195
196	fail:
197	pr_crit("allocation of page_ext failed.\n");
198	panic("Out of memory");
199	}
200
201	#else /* CONFIG_FLAT_NODE_MEM_MAP */
202
203	struct page_ext *lookup_page_ext(struct page *page)
204	{
205	unsigned long pfn = page_to_pfn(page);
206	struct mem_section *section = __pfn_to_section(pfn);
207	#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
208	/*
209	* The sanity checks the page allocator does upon freeing a
210	* page can reach here before the page_ext arrays are
211	* allocated when feeding a range of pages to the allocator
212	* for the first time during bootup or memory hotplug.
213	*
214	* This check is also necessary for ensuring page poisoning
215	* works as expected when enabled
216	*/
217	if (!section->page_ext)
218	return NULL;
219	#endif
220	return get_entry(section->page_ext, pfn);
221	}
222
223	static void *__meminit alloc_page_ext(size_t size, int nid)
224	{
225	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
226	void *addr = NULL;
227
228	addr = alloc_pages_exact_nid(nid, size, flags);
229	if (addr) {
230	kmemleak_alloc(addr, size, 1, flags);
231	return addr;
232	}
233
234	if (node_state(nid, N_HIGH_MEMORY))
235	addr = vzalloc_node(size, nid);
236	else
237	addr = vzalloc(size);
238
239	return addr;
240	}
241
242	static int __meminit init_section_page_ext(unsigned long pfn, int nid)
243	{
244	struct mem_section *section;
245	struct page_ext *base;
246	unsigned long table_size;
247
248	section = __pfn_to_section(pfn);
249
250	if (section->page_ext)
251	return 0;
252
253	table_size = get_entry_size() * PAGES_PER_SECTION;
254	base = alloc_page_ext(table_size, nid);
255
256	/*
257	* The value stored in section->page_ext is (base - pfn)
258	* and it does not point to the memory block allocated above,
259	* causing kmemleak false positives.
260	*/
261	kmemleak_not_leak(base);
262
263	if (!base) {
264	pr_err("page ext allocation failure\n");
265	return -ENOMEM;
266	}
267
268	/*
269	* The passed "pfn" may not be aligned to SECTION. For the calculation
270	* we need to apply a mask.
271	*/
272	pfn &= PAGE_SECTION_MASK;
273	section->page_ext = (void *)base - get_entry_size() * pfn;
274	total_usage += table_size;
275	return 0;
276	}
277	#ifdef CONFIG_MEMORY_HOTPLUG
278	static void free_page_ext(void *addr)
279	{
280	if (is_vmalloc_addr(addr)) {
281	vfree(addr);
282	} else {
283	struct page *page = virt_to_page(addr);
284	size_t table_size;
285
286	table_size = get_entry_size() * PAGES_PER_SECTION;
287
288	BUG_ON(PageReserved(page));
289	kmemleak_free(addr);
290	free_pages_exact(addr, table_size);
291	}
292	}
293
294	static void __free_page_ext(unsigned long pfn)
295	{
296	struct mem_section *ms;
297	struct page_ext *base;
298
299	ms = __pfn_to_section(pfn);
300	if (!ms || !ms->page_ext)
301	return;
302	base = get_entry(ms->page_ext, pfn);
303	free_page_ext(base);
304	ms->page_ext = NULL;
305	}
306
307	static int __meminit online_page_ext(unsigned long start_pfn,
308	unsigned long nr_pages,
309	int nid)
310	{
311	unsigned long start, end, pfn;
312	int fail = 0;
313
314	start = SECTION_ALIGN_DOWN(start_pfn);
315	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
316
317	if (nid == -1) {
318	/*
319	* In this case, "nid" already exists and contains valid memory.
320	* "start_pfn" passed to us is a pfn which is an arg for
321	* online__pages(), and start_pfn should exist.
322	*/
323	nid = pfn_to_nid(start_pfn);
324	VM_BUG_ON(!node_state(nid, N_ONLINE));
325	}
326
327	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
328	if (!pfn_present(pfn))
329	continue;
330	fail = init_section_page_ext(pfn, nid);
331	}
332	if (!fail)
333	return 0;
334
335	/* rollback */
336	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
337	__free_page_ext(pfn);
338
339	return -ENOMEM;
340	}
341
342	static int __meminit offline_page_ext(unsigned long start_pfn,
343	unsigned long nr_pages, int nid)
344	{
345	unsigned long start, end, pfn;
346
347	start = SECTION_ALIGN_DOWN(start_pfn);
348	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
349
350	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
351	__free_page_ext(pfn);
352	return 0;
353
354	}
355
356	static int __meminit page_ext_callback(struct notifier_block *self,
357	unsigned long action, void *arg)
358	{
359	struct memory_notify *mn = arg;
360	int ret = 0;
361
362	switch (action) {
363	case MEM_GOING_ONLINE:
364	ret = online_page_ext(mn->start_pfn,
365	mn->nr_pages, mn->status_change_nid);
366	break;
367	case MEM_OFFLINE:
368	offline_page_ext(mn->start_pfn,
369	mn->nr_pages, mn->status_change_nid);
370	break;
371	case MEM_CANCEL_ONLINE:
372	offline_page_ext(mn->start_pfn,
373	mn->nr_pages, mn->status_change_nid);
374	break;
375	case MEM_GOING_OFFLINE:
376	break;
377	case MEM_ONLINE:
378	case MEM_CANCEL_OFFLINE:
379	break;
380	}
381
382	return notifier_from_errno(ret);
383	}
384
385	#endif
386
387	void __init page_ext_init(void)
388	{
389	unsigned long pfn;
390	int nid;
391
392	if (!invoke_need_callbacks())
393	return;
394
395	for_each_node_state(nid, N_MEMORY) {
396	unsigned long start_pfn, end_pfn;
397
398	start_pfn = node_start_pfn(nid);
399	end_pfn = node_end_pfn(nid);
400	/*
401	* start_pfn and end_pfn may not be aligned to SECTION and the
402	* page->flags of out of node pages are not initialized. So we
403	* scan [start_pfn, the biggest section's pfn < end_pfn) here.
404	*/
405	for (pfn = start_pfn; pfn < end_pfn;
406	pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
407
408	if (!pfn_valid(pfn))
409	continue;
410	/*
411	* Nodes's pfns can be overlapping.
412	* We know some arch can have a nodes layout such as
413	* -------------pfn-------------->
414	* N0 | N1 | N2 | N0 | N1 | N2|....
415	*
416	* Take into account DEFERRED_STRUCT_PAGE_INIT.
417	*/
418	if (early_pfn_to_nid(pfn) != nid)
419	continue;
420	if (init_section_page_ext(pfn, nid))
421	goto oom;
422	}
423	}
424	hotplug_memory_notifier(page_ext_callback, 0);
425	pr_info("allocated %ld bytes of page_ext\n", total_usage);
426	invoke_init_callbacks();
427	return;
428
429	oom:
430	panic("Out of memory");
431	}
432
433	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
434	{
435	}
436
437	#endif
438