hugetlb.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
1/*
2 * Generic hugetlb support.
3 * (C) William Irwin, April 2004
4 */
5#include <linux/gfp.h>
6#include <linux/list.h>
7#include <linux/init.h>
8#include <linux/module.h>
9#include <linux/mm.h>
10#include <linux/hugetlb.h>
11#include <linux/sysctl.h>
12#include <linux/highmem.h>
13#include <linux/nodemask.h>
14
15const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
16static unsigned long nr_huge_pages, free_huge_pages;
17unsigned long max_huge_pages;
18static struct list_head hugepage_freelists[MAX_NUMNODES];
19static unsigned int nr_huge_pages_node[MAX_NUMNODES];
20static unsigned int free_huge_pages_node[MAX_NUMNODES];
21static DEFINE_SPINLOCK(hugetlb_lock);
22
23static void enqueue_huge_page(struct page *page)
24{
25	int nid = page_to_nid(page);
26	list_add(&page->lru, &hugepage_freelists[nid]);
27	free_huge_pages++;
28	free_huge_pages_node[nid]++;
29}
30
31static struct page *dequeue_huge_page(void)
32{
33	int nid = numa_node_id();
34	struct page *page = NULL;
35
36	if (list_empty(&hugepage_freelists[nid])) {
37		for (nid = 0; nid < MAX_NUMNODES; ++nid)
38			if (!list_empty(&hugepage_freelists[nid]))
39				break;
40	}
41	if (nid >= 0 && nid < MAX_NUMNODES &&
42	    !list_empty(&hugepage_freelists[nid])) {
43		page = list_entry(hugepage_freelists[nid].next,
44				  struct page, lru);
45		list_del(&page->lru);
46		free_huge_pages--;
47		free_huge_pages_node[nid]--;
48	}
49	return page;
50}
51
52static struct page *alloc_fresh_huge_page(void)
53{
54	static int nid = 0;
55	struct page *page;
56	page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
57					HUGETLB_PAGE_ORDER);
58	nid = (nid + 1) % num_online_nodes();
59	if (page) {
60		nr_huge_pages++;
61		nr_huge_pages_node[page_to_nid(page)]++;
62	}
63	return page;
64}
65
66void free_huge_page(struct page *page)
67{
68	BUG_ON(page_count(page));
69
70	INIT_LIST_HEAD(&page->lru);
71	page[1].mapping = NULL;
72
73	spin_lock(&hugetlb_lock);
74	enqueue_huge_page(page);
75	spin_unlock(&hugetlb_lock);
76}
77
78struct page *alloc_huge_page(void)
79{
80	struct page *page;
81	int i;
82
83	spin_lock(&hugetlb_lock);
84	page = dequeue_huge_page();
85	if (!page) {
86		spin_unlock(&hugetlb_lock);
87		return NULL;
88	}
89	spin_unlock(&hugetlb_lock);
90	set_page_count(page, 1);
91	page[1].mapping = (void *)free_huge_page;
92	for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
93		clear_highpage(&page[i]);
94	return page;
95}
96
97static int __init hugetlb_init(void)
98{
99	unsigned long i;
100	struct page *page;
101
102	for (i = 0; i < MAX_NUMNODES; ++i)
103		INIT_LIST_HEAD(&hugepage_freelists[i]);
104
105	for (i = 0; i < max_huge_pages; ++i) {
106		page = alloc_fresh_huge_page();
107		if (!page)
108			break;
109		spin_lock(&hugetlb_lock);
110		enqueue_huge_page(page);
111		spin_unlock(&hugetlb_lock);
112	}
113	max_huge_pages = free_huge_pages = nr_huge_pages = i;
114	printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
115	return 0;
116}
117module_init(hugetlb_init);
118
119static int __init hugetlb_setup(char *s)
120{
121	if (sscanf(s, "%lu", &max_huge_pages) <= 0)
122		max_huge_pages = 0;
123	return 1;
124}
125__setup("hugepages=", hugetlb_setup);
126
127#ifdef CONFIG_SYSCTL
128static void update_and_free_page(struct page *page)
129{
130	int i;
131	nr_huge_pages--;
132	nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
133	for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
134		page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
135				1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
136				1 << PG_private | 1<< PG_writeback);
137		set_page_count(&page[i], 0);
138	}
139	set_page_count(page, 1);
140	__free_pages(page, HUGETLB_PAGE_ORDER);
141}
142
143#ifdef CONFIG_HIGHMEM
144static void try_to_free_low(unsigned long count)
145{
146	int i, nid;
147	for (i = 0; i < MAX_NUMNODES; ++i) {
148		struct page *page, *next;
149		list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
150			if (PageHighMem(page))
151				continue;
152			list_del(&page->lru);
153			update_and_free_page(page);
154			nid = page_zone(page)->zone_pgdat->node_id;
155			free_huge_pages--;
156			free_huge_pages_node[nid]--;
157			if (count >= nr_huge_pages)
158				return;
159		}
160	}
161}
162#else
163static inline void try_to_free_low(unsigned long count)
164{
165}
166#endif
167
168static unsigned long set_max_huge_pages(unsigned long count)
169{
170	while (count > nr_huge_pages) {
171		struct page *page = alloc_fresh_huge_page();
172		if (!page)
173			return nr_huge_pages;
174		spin_lock(&hugetlb_lock);
175		enqueue_huge_page(page);
176		spin_unlock(&hugetlb_lock);
177	}
178	if (count >= nr_huge_pages)
179		return nr_huge_pages;
180
181	spin_lock(&hugetlb_lock);
182	try_to_free_low(count);
183	while (count < nr_huge_pages) {
184		struct page *page = dequeue_huge_page();
185		if (!page)
186			break;
187		update_and_free_page(page);
188	}
189	spin_unlock(&hugetlb_lock);
190	return nr_huge_pages;
191}
192
193int hugetlb_sysctl_handler(struct ctl_table *table, int write,
194			   struct file *file, void __user *buffer,
195			   size_t *length, loff_t *ppos)
196{
197	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
198	max_huge_pages = set_max_huge_pages(max_huge_pages);
199	return 0;
200}
201#endif /* CONFIG_SYSCTL */
202
203int hugetlb_report_meminfo(char *buf)
204{
205	return sprintf(buf,
206			"HugePages_Total: %5lu\n"
207			"HugePages_Free:  %5lu\n"
208			"Hugepagesize:    %5lu kB\n",
209			nr_huge_pages,
210			free_huge_pages,
211			HPAGE_SIZE/1024);
212}
213
214int hugetlb_report_node_meminfo(int nid, char *buf)
215{
216	return sprintf(buf,
217		"Node %d HugePages_Total: %5u\n"
218		"Node %d HugePages_Free:  %5u\n",
219		nid, nr_huge_pages_node[nid],
220		nid, free_huge_pages_node[nid]);
221}
222
223int is_hugepage_mem_enough(size_t size)
224{
225	return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
226}
227
228/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
229unsigned long hugetlb_total_pages(void)
230{
231	return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
232}
233EXPORT_SYMBOL(hugetlb_total_pages);
234
235/*
236 * We cannot handle pagefaults against hugetlb pages at all.  They cause
237 * handle_mm_fault() to try to instantiate regular-sized pages in the
238 * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
239 * this far.
240 */
241static struct page *hugetlb_nopage(struct vm_area_struct *vma,
242				unsigned long address, int *unused)
243{
244	BUG();
245	return NULL;
246}
247
248struct vm_operations_struct hugetlb_vm_ops = {
249	.nopage = hugetlb_nopage,
250};
251
252void zap_hugepage_range(struct vm_area_struct *vma,
253			unsigned long start, unsigned long length)
254{
255	struct mm_struct *mm = vma->vm_mm;
256
257	spin_lock(&mm->page_table_lock);
258	unmap_hugepage_range(vma, start, start + length);
259	spin_unlock(&mm->page_table_lock);
260}
261