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>
10 * struct page extension
12 * This is the feature to manage memory for extended data per page.
14 * Until now, we must modify struct page itself to store extra data per page.
15 * This requires rebuilding the kernel and it is really time consuming process.
16 * And, sometimes, rebuild is impossible due to third party module dependency.
17 * At last, enlarging struct page could cause un-wanted system behaviour change.
19 * This feature is intended to overcome above mentioned problems. This feature
20 * allocates memory for extended data per page in certain place rather than
21 * the struct page itself. This memory can be accessed by the accessor
22 * functions provided by this code. During the boot process, it checks whether
23 * allocation of huge chunk of memory is needed or not. If not, it avoids
24 * allocating memory at all. With this advantage, we can include this feature
25 * into the kernel in default and can avoid rebuild and solve related problems.
27 * To help these things to work well, there are two callbacks for clients. One
28 * is the need callback which is mandatory if user wants to avoid useless
29 * memory allocation at boot-time. The other is optional, init callback, which
30 * is used to do proper initialization after memory is allocated.
32 * The need callback is used to decide whether extended memory allocation is
33 * needed or not. Sometimes users want to deactivate some features in this
34 * boot and extra memory would be unneccessary. In this case, to avoid
35 * allocating huge chunk of memory, each clients represent their need of
36 * extra memory through the need callback. If one of the need callbacks
37 * returns true, it means that someone needs extra memory so that
38 * page extension core should allocates memory for page extension. If
39 * none of need callbacks return true, memory isn't needed at all in this boot
40 * and page extension core can skip to allocate memory. As result,
41 * none of memory is wasted.
43 * The init callback is used to do proper initialization after page extension
44 * is completely initialized. In sparse memory system, extra memory is
45 * allocated some time later than memmap is allocated. In other words, lifetime
46 * of memory for page extension isn't same with memmap for struct page.
47 * Therefore, clients can't store extra data until page extension is
48 * initialized, even if pages are allocated and used freely. This could
49 * cause inadequate state of extra data per page, so, to prevent it, client
50 * can utilize this callback to initialize the state of it correctly.
53 static struct page_ext_operations *page_ext_ops[] = {
55 #ifdef CONFIG_PAGE_POISONING
60 static unsigned long total_usage;
62 static bool __init invoke_need_callbacks(void)
65 int entries = ARRAY_SIZE(page_ext_ops);
67 for (i = 0; i < entries; i++) {
68 if (page_ext_ops[i]->need && page_ext_ops[i]->need())
75 static void __init invoke_init_callbacks(void)
78 int entries = ARRAY_SIZE(page_ext_ops);
80 for (i = 0; i < entries; i++) {
81 if (page_ext_ops[i]->init)
82 page_ext_ops[i]->init();
86 #if !defined(CONFIG_SPARSEMEM)
89 void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
91 pgdat->node_page_ext = NULL;
94 struct page_ext *lookup_page_ext(struct page *page)
96 unsigned long pfn = page_to_pfn(page);
98 struct page_ext *base;
100 base = NODE_DATA(page_to_nid(page))->node_page_ext;
101 #ifdef CONFIG_DEBUG_VM
103 * The sanity checks the page allocator does upon freeing a
104 * page can reach here before the page_ext arrays are
105 * allocated when feeding a range of pages to the allocator
106 * for the first time during bootup or memory hotplug.
111 offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
113 return base + offset;
116 static int __init alloc_node_page_ext(int nid)
118 struct page_ext *base;
119 unsigned long table_size;
120 unsigned long nr_pages;
122 nr_pages = NODE_DATA(nid)->node_spanned_pages;
127 * Need extra space if node range is not aligned with
128 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
129 * checks buddy's status, range could be out of exact node range.
131 if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
132 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
133 nr_pages += MAX_ORDER_NR_PAGES;
135 table_size = sizeof(struct page_ext) * nr_pages;
137 base = memblock_virt_alloc_try_nid_nopanic(
138 table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
139 BOOTMEM_ALLOC_ACCESSIBLE, nid);
142 NODE_DATA(nid)->node_page_ext = base;
143 total_usage += table_size;
147 void __init page_ext_init_flatmem(void)
152 if (!invoke_need_callbacks())
155 for_each_online_node(nid) {
156 fail = alloc_node_page_ext(nid);
160 pr_info("allocated %ld bytes of page_ext\n", total_usage);
161 invoke_init_callbacks();
165 pr_crit("allocation of page_ext failed.\n");
166 panic("Out of memory");
169 #else /* CONFIG_FLAT_NODE_MEM_MAP */
171 struct page_ext *lookup_page_ext(struct page *page)
173 unsigned long pfn = page_to_pfn(page);
174 struct mem_section *section = __pfn_to_section(pfn);
175 #ifdef CONFIG_DEBUG_VM
177 * The sanity checks the page allocator does upon freeing a
178 * page can reach here before the page_ext arrays are
179 * allocated when feeding a range of pages to the allocator
180 * for the first time during bootup or memory hotplug.
182 if (!section->page_ext)
185 return section->page_ext + pfn;
188 static void *__meminit alloc_page_ext(size_t size, int nid)
190 gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
193 addr = alloc_pages_exact_nid(nid, size, flags);
195 kmemleak_alloc(addr, size, 1, flags);
199 if (node_state(nid, N_HIGH_MEMORY))
200 addr = vzalloc_node(size, nid);
202 addr = vzalloc(size);
207 static int __meminit init_section_page_ext(unsigned long pfn, int nid)
209 struct mem_section *section;
210 struct page_ext *base;
211 unsigned long table_size;
213 section = __pfn_to_section(pfn);
215 if (section->page_ext)
218 table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
219 base = alloc_page_ext(table_size, nid);
222 * The value stored in section->page_ext is (base - pfn)
223 * and it does not point to the memory block allocated above,
224 * causing kmemleak false positives.
226 kmemleak_not_leak(base);
229 pr_err("page ext allocation failure\n");
234 * The passed "pfn" may not be aligned to SECTION. For the calculation
235 * we need to apply a mask.
237 pfn &= PAGE_SECTION_MASK;
238 section->page_ext = base - pfn;
239 total_usage += table_size;
242 #ifdef CONFIG_MEMORY_HOTPLUG
243 static void free_page_ext(void *addr)
245 if (is_vmalloc_addr(addr)) {
248 struct page *page = virt_to_page(addr);
251 table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
253 BUG_ON(PageReserved(page));
254 free_pages_exact(addr, table_size);
258 static void __free_page_ext(unsigned long pfn)
260 struct mem_section *ms;
261 struct page_ext *base;
263 ms = __pfn_to_section(pfn);
264 if (!ms || !ms->page_ext)
266 base = ms->page_ext + pfn;
271 static int __meminit online_page_ext(unsigned long start_pfn,
272 unsigned long nr_pages,
275 unsigned long start, end, pfn;
278 start = SECTION_ALIGN_DOWN(start_pfn);
279 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
283 * In this case, "nid" already exists and contains valid memory.
284 * "start_pfn" passed to us is a pfn which is an arg for
285 * online__pages(), and start_pfn should exist.
287 nid = pfn_to_nid(start_pfn);
288 VM_BUG_ON(!node_state(nid, N_ONLINE));
291 for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
292 if (!pfn_present(pfn))
294 fail = init_section_page_ext(pfn, nid);
300 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
301 __free_page_ext(pfn);
306 static int __meminit offline_page_ext(unsigned long start_pfn,
307 unsigned long nr_pages, int nid)
309 unsigned long start, end, pfn;
311 start = SECTION_ALIGN_DOWN(start_pfn);
312 end = SECTION_ALIGN_UP(start_pfn + nr_pages);
314 for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
315 __free_page_ext(pfn);
320 static int __meminit page_ext_callback(struct notifier_block *self,
321 unsigned long action, void *arg)
323 struct memory_notify *mn = arg;
327 case MEM_GOING_ONLINE:
328 ret = online_page_ext(mn->start_pfn,
329 mn->nr_pages, mn->status_change_nid);
332 offline_page_ext(mn->start_pfn,
333 mn->nr_pages, mn->status_change_nid);
335 case MEM_CANCEL_ONLINE:
336 offline_page_ext(mn->start_pfn,
337 mn->nr_pages, mn->status_change_nid);
339 case MEM_GOING_OFFLINE:
342 case MEM_CANCEL_OFFLINE:
346 return notifier_from_errno(ret);
351 void __init page_ext_init(void)
356 if (!invoke_need_callbacks())
359 for_each_node_state(nid, N_MEMORY) {
360 unsigned long start_pfn, end_pfn;
362 start_pfn = node_start_pfn(nid);
363 end_pfn = node_end_pfn(nid);
365 * start_pfn and end_pfn may not be aligned to SECTION and the
366 * page->flags of out of node pages are not initialized. So we
367 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
369 for (pfn = start_pfn; pfn < end_pfn;
370 pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
375 * Nodes's pfns can be overlapping.
376 * We know some arch can have a nodes layout such as
377 * -------------pfn-------------->
378 * N0 | N1 | N2 | N0 | N1 | N2|....
380 if (pfn_to_nid(pfn) != nid)
382 if (init_section_page_ext(pfn, nid))
386 hotplug_memory_notifier(page_ext_callback, 0);
387 pr_info("allocated %ld bytes of page_ext\n", total_usage);
388 invoke_init_callbacks();
392 panic("Out of memory");
395 void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)