[PATCH] Hugetlb: Remove duplicate i_size check
[linux-2.6.git] / mm / hugetlb.c
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/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <asm/page.h>
15 #include <asm/pgtable.h>
16
17 #include <linux/hugetlb.h>
18
19 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
20 static unsigned long nr_huge_pages, free_huge_pages;
21 unsigned long max_huge_pages;
22 static struct list_head hugepage_freelists[MAX_NUMNODES];
23 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
24 static unsigned int free_huge_pages_node[MAX_NUMNODES];
25
26 /*
27  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
28  */
29 static DEFINE_SPINLOCK(hugetlb_lock);
30
31 static void enqueue_huge_page(struct page *page)
32 {
33         int nid = page_to_nid(page);
34         list_add(&page->lru, &hugepage_freelists[nid]);
35         free_huge_pages++;
36         free_huge_pages_node[nid]++;
37 }
38
39 static struct page *dequeue_huge_page(void)
40 {
41         int nid = numa_node_id();
42         struct page *page = NULL;
43
44         if (list_empty(&hugepage_freelists[nid])) {
45                 for (nid = 0; nid < MAX_NUMNODES; ++nid)
46                         if (!list_empty(&hugepage_freelists[nid]))
47                                 break;
48         }
49         if (nid >= 0 && nid < MAX_NUMNODES &&
50             !list_empty(&hugepage_freelists[nid])) {
51                 page = list_entry(hugepage_freelists[nid].next,
52                                   struct page, lru);
53                 list_del(&page->lru);
54                 free_huge_pages--;
55                 free_huge_pages_node[nid]--;
56         }
57         return page;
58 }
59
60 static struct page *alloc_fresh_huge_page(void)
61 {
62         static int nid = 0;
63         struct page *page;
64         page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
65                                         HUGETLB_PAGE_ORDER);
66         nid = (nid + 1) % num_online_nodes();
67         if (page) {
68                 spin_lock(&hugetlb_lock);
69                 nr_huge_pages++;
70                 nr_huge_pages_node[page_to_nid(page)]++;
71                 spin_unlock(&hugetlb_lock);
72         }
73         return page;
74 }
75
76 void free_huge_page(struct page *page)
77 {
78         BUG_ON(page_count(page));
79
80         INIT_LIST_HEAD(&page->lru);
81         page[1].mapping = NULL;
82
83         spin_lock(&hugetlb_lock);
84         enqueue_huge_page(page);
85         spin_unlock(&hugetlb_lock);
86 }
87
88 struct page *alloc_huge_page(void)
89 {
90         struct page *page;
91         int i;
92
93         spin_lock(&hugetlb_lock);
94         page = dequeue_huge_page();
95         if (!page) {
96                 spin_unlock(&hugetlb_lock);
97                 return NULL;
98         }
99         spin_unlock(&hugetlb_lock);
100         set_page_count(page, 1);
101         page[1].mapping = (void *)free_huge_page;
102         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
103                 clear_highpage(&page[i]);
104         return page;
105 }
106
107 static int __init hugetlb_init(void)
108 {
109         unsigned long i;
110         struct page *page;
111
112         if (HPAGE_SHIFT == 0)
113                 return 0;
114
115         for (i = 0; i < MAX_NUMNODES; ++i)
116                 INIT_LIST_HEAD(&hugepage_freelists[i]);
117
118         for (i = 0; i < max_huge_pages; ++i) {
119                 page = alloc_fresh_huge_page();
120                 if (!page)
121                         break;
122                 spin_lock(&hugetlb_lock);
123                 enqueue_huge_page(page);
124                 spin_unlock(&hugetlb_lock);
125         }
126         max_huge_pages = free_huge_pages = nr_huge_pages = i;
127         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
128         return 0;
129 }
130 module_init(hugetlb_init);
131
132 static int __init hugetlb_setup(char *s)
133 {
134         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
135                 max_huge_pages = 0;
136         return 1;
137 }
138 __setup("hugepages=", hugetlb_setup);
139
140 #ifdef CONFIG_SYSCTL
141 static void update_and_free_page(struct page *page)
142 {
143         int i;
144         nr_huge_pages--;
145         nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
146         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
147                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
148                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
149                                 1 << PG_private | 1<< PG_writeback);
150                 set_page_count(&page[i], 0);
151         }
152         set_page_count(page, 1);
153         __free_pages(page, HUGETLB_PAGE_ORDER);
154 }
155
156 #ifdef CONFIG_HIGHMEM
157 static void try_to_free_low(unsigned long count)
158 {
159         int i, nid;
160         for (i = 0; i < MAX_NUMNODES; ++i) {
161                 struct page *page, *next;
162                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
163                         if (PageHighMem(page))
164                                 continue;
165                         list_del(&page->lru);
166                         update_and_free_page(page);
167                         nid = page_zone(page)->zone_pgdat->node_id;
168                         free_huge_pages--;
169                         free_huge_pages_node[nid]--;
170                         if (count >= nr_huge_pages)
171                                 return;
172                 }
173         }
174 }
175 #else
176 static inline void try_to_free_low(unsigned long count)
177 {
178 }
179 #endif
180
181 static unsigned long set_max_huge_pages(unsigned long count)
182 {
183         while (count > nr_huge_pages) {
184                 struct page *page = alloc_fresh_huge_page();
185                 if (!page)
186                         return nr_huge_pages;
187                 spin_lock(&hugetlb_lock);
188                 enqueue_huge_page(page);
189                 spin_unlock(&hugetlb_lock);
190         }
191         if (count >= nr_huge_pages)
192                 return nr_huge_pages;
193
194         spin_lock(&hugetlb_lock);
195         try_to_free_low(count);
196         while (count < nr_huge_pages) {
197                 struct page *page = dequeue_huge_page();
198                 if (!page)
199                         break;
200                 update_and_free_page(page);
201         }
202         spin_unlock(&hugetlb_lock);
203         return nr_huge_pages;
204 }
205
206 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
207                            struct file *file, void __user *buffer,
208                            size_t *length, loff_t *ppos)
209 {
210         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
211         max_huge_pages = set_max_huge_pages(max_huge_pages);
212         return 0;
213 }
214 #endif /* CONFIG_SYSCTL */
215
216 int hugetlb_report_meminfo(char *buf)
217 {
218         return sprintf(buf,
219                         "HugePages_Total: %5lu\n"
220                         "HugePages_Free:  %5lu\n"
221                         "Hugepagesize:    %5lu kB\n",
222                         nr_huge_pages,
223                         free_huge_pages,
224                         HPAGE_SIZE/1024);
225 }
226
227 int hugetlb_report_node_meminfo(int nid, char *buf)
228 {
229         return sprintf(buf,
230                 "Node %d HugePages_Total: %5u\n"
231                 "Node %d HugePages_Free:  %5u\n",
232                 nid, nr_huge_pages_node[nid],
233                 nid, free_huge_pages_node[nid]);
234 }
235
236 int is_hugepage_mem_enough(size_t size)
237 {
238         return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
239 }
240
241 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
242 unsigned long hugetlb_total_pages(void)
243 {
244         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
245 }
246
247 /*
248  * We cannot handle pagefaults against hugetlb pages at all.  They cause
249  * handle_mm_fault() to try to instantiate regular-sized pages in the
250  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
251  * this far.
252  */
253 static struct page *hugetlb_nopage(struct vm_area_struct *vma,
254                                 unsigned long address, int *unused)
255 {
256         BUG();
257         return NULL;
258 }
259
260 struct vm_operations_struct hugetlb_vm_ops = {
261         .nopage = hugetlb_nopage,
262 };
263
264 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page)
265 {
266         pte_t entry;
267
268         if (vma->vm_flags & VM_WRITE) {
269                 entry =
270                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
271         } else {
272                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
273         }
274         entry = pte_mkyoung(entry);
275         entry = pte_mkhuge(entry);
276
277         return entry;
278 }
279
280 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
281                             struct vm_area_struct *vma)
282 {
283         pte_t *src_pte, *dst_pte, entry;
284         struct page *ptepage;
285         unsigned long addr;
286
287         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
288                 src_pte = huge_pte_offset(src, addr);
289                 if (!src_pte)
290                         continue;
291                 dst_pte = huge_pte_alloc(dst, addr);
292                 if (!dst_pte)
293                         goto nomem;
294                 spin_lock(&dst->page_table_lock);
295                 spin_lock(&src->page_table_lock);
296                 if (!pte_none(*src_pte)) {
297                         entry = *src_pte;
298                         ptepage = pte_page(entry);
299                         get_page(ptepage);
300                         add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
301                         set_huge_pte_at(dst, addr, dst_pte, entry);
302                 }
303                 spin_unlock(&src->page_table_lock);
304                 spin_unlock(&dst->page_table_lock);
305         }
306         return 0;
307
308 nomem:
309         return -ENOMEM;
310 }
311
312 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
313                           unsigned long end)
314 {
315         struct mm_struct *mm = vma->vm_mm;
316         unsigned long address;
317         pte_t *ptep;
318         pte_t pte;
319         struct page *page;
320
321         WARN_ON(!is_vm_hugetlb_page(vma));
322         BUG_ON(start & ~HPAGE_MASK);
323         BUG_ON(end & ~HPAGE_MASK);
324
325         spin_lock(&mm->page_table_lock);
326
327         /* Update high watermark before we lower rss */
328         update_hiwater_rss(mm);
329
330         for (address = start; address < end; address += HPAGE_SIZE) {
331                 ptep = huge_pte_offset(mm, address);
332                 if (!ptep)
333                         continue;
334
335                 pte = huge_ptep_get_and_clear(mm, address, ptep);
336                 if (pte_none(pte))
337                         continue;
338
339                 page = pte_page(pte);
340                 put_page(page);
341                 add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
342         }
343
344         spin_unlock(&mm->page_table_lock);
345         flush_tlb_range(vma, start, end);
346 }
347
348 static struct page *find_lock_huge_page(struct address_space *mapping,
349                         unsigned long idx)
350 {
351         struct page *page;
352         int err;
353
354 retry:
355         page = find_lock_page(mapping, idx);
356         if (page)
357                 goto out;
358
359         if (hugetlb_get_quota(mapping))
360                 goto out;
361         page = alloc_huge_page();
362         if (!page) {
363                 hugetlb_put_quota(mapping);
364                 goto out;
365         }
366
367         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
368         if (err) {
369                 put_page(page);
370                 hugetlb_put_quota(mapping);
371                 if (err == -EEXIST)
372                         goto retry;
373                 page = NULL;
374         }
375 out:
376         return page;
377 }
378
379 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
380                         unsigned long address, int write_access)
381 {
382         int ret = VM_FAULT_SIGBUS;
383         unsigned long idx;
384         unsigned long size;
385         pte_t *pte;
386         struct page *page;
387         struct address_space *mapping;
388
389         pte = huge_pte_alloc(mm, address);
390         if (!pte)
391                 goto out;
392
393         mapping = vma->vm_file->f_mapping;
394         idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
395                 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
396
397         /*
398          * Use page lock to guard against racing truncation
399          * before we get page_table_lock.
400          */
401         page = find_lock_huge_page(mapping, idx);
402         if (!page)
403                 goto out;
404
405         spin_lock(&mm->page_table_lock);
406         size = i_size_read(mapping->host) >> HPAGE_SHIFT;
407         if (idx >= size)
408                 goto backout;
409
410         ret = VM_FAULT_MINOR;
411         if (!pte_none(*pte))
412                 goto backout;
413
414         add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
415         set_huge_pte_at(mm, address, pte, make_huge_pte(vma, page));
416         spin_unlock(&mm->page_table_lock);
417         unlock_page(page);
418 out:
419         return ret;
420
421 backout:
422         spin_unlock(&mm->page_table_lock);
423         hugetlb_put_quota(mapping);
424         unlock_page(page);
425         put_page(page);
426         goto out;
427 }
428
429 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
430                         struct page **pages, struct vm_area_struct **vmas,
431                         unsigned long *position, int *length, int i)
432 {
433         unsigned long vpfn, vaddr = *position;
434         int remainder = *length;
435
436         vpfn = vaddr/PAGE_SIZE;
437         spin_lock(&mm->page_table_lock);
438         while (vaddr < vma->vm_end && remainder) {
439                 pte_t *pte;
440                 struct page *page;
441
442                 /*
443                  * Some archs (sparc64, sh*) have multiple pte_ts to
444                  * each hugepage.  We have to make * sure we get the
445                  * first, for the page indexing below to work.
446                  */
447                 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
448
449                 if (!pte || pte_none(*pte)) {
450                         int ret;
451
452                         spin_unlock(&mm->page_table_lock);
453                         ret = hugetlb_fault(mm, vma, vaddr, 0);
454                         spin_lock(&mm->page_table_lock);
455                         if (ret == VM_FAULT_MINOR)
456                                 continue;
457
458                         remainder = 0;
459                         if (!i)
460                                 i = -EFAULT;
461                         break;
462                 }
463
464                 if (pages) {
465                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
466                         get_page(page);
467                         pages[i] = page;
468                 }
469
470                 if (vmas)
471                         vmas[i] = vma;
472
473                 vaddr += PAGE_SIZE;
474                 ++vpfn;
475                 --remainder;
476                 ++i;
477         }
478         spin_unlock(&mm->page_table_lock);
479         *length = remainder;
480         *position = vaddr;
481
482         return i;
483 }