hugetlb: fix sparse warnings
[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/seq_file.h>
11 #include <linux/sysctl.h>
12 #include <linux/highmem.h>
13 #include <linux/mmu_notifier.h>
14 #include <linux/nodemask.h>
15 #include <linux/pagemap.h>
16 #include <linux/mempolicy.h>
17 #include <linux/cpuset.h>
18 #include <linux/mutex.h>
19 #include <linux/bootmem.h>
20 #include <linux/sysfs.h>
21
22 #include <asm/page.h>
23 #include <asm/pgtable.h>
24 #include <asm/io.h>
25
26 #include <linux/hugetlb.h>
27 #include "internal.h"
28
29 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
30 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
31 unsigned long hugepages_treat_as_movable;
32
33 static int max_hstate;
34 unsigned int default_hstate_idx;
35 struct hstate hstates[HUGE_MAX_HSTATE];
36
37 __initdata LIST_HEAD(huge_boot_pages);
38
39 /* for command line parsing */
40 static struct hstate * __initdata parsed_hstate;
41 static unsigned long __initdata default_hstate_max_huge_pages;
42 static unsigned long __initdata default_hstate_size;
43
44 #define for_each_hstate(h) \
45         for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
46
47 /*
48  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
49  */
50 static DEFINE_SPINLOCK(hugetlb_lock);
51
52 /*
53  * Region tracking -- allows tracking of reservations and instantiated pages
54  *                    across the pages in a mapping.
55  *
56  * The region data structures are protected by a combination of the mmap_sem
57  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
58  * must either hold the mmap_sem for write, or the mmap_sem for read and
59  * the hugetlb_instantiation mutex:
60  *
61  *      down_write(&mm->mmap_sem);
62  * or
63  *      down_read(&mm->mmap_sem);
64  *      mutex_lock(&hugetlb_instantiation_mutex);
65  */
66 struct file_region {
67         struct list_head link;
68         long from;
69         long to;
70 };
71
72 static long region_add(struct list_head *head, long f, long t)
73 {
74         struct file_region *rg, *nrg, *trg;
75
76         /* Locate the region we are either in or before. */
77         list_for_each_entry(rg, head, link)
78                 if (f <= rg->to)
79                         break;
80
81         /* Round our left edge to the current segment if it encloses us. */
82         if (f > rg->from)
83                 f = rg->from;
84
85         /* Check for and consume any regions we now overlap with. */
86         nrg = rg;
87         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
88                 if (&rg->link == head)
89                         break;
90                 if (rg->from > t)
91                         break;
92
93                 /* If this area reaches higher then extend our area to
94                  * include it completely.  If this is not the first area
95                  * which we intend to reuse, free it. */
96                 if (rg->to > t)
97                         t = rg->to;
98                 if (rg != nrg) {
99                         list_del(&rg->link);
100                         kfree(rg);
101                 }
102         }
103         nrg->from = f;
104         nrg->to = t;
105         return 0;
106 }
107
108 static long region_chg(struct list_head *head, long f, long t)
109 {
110         struct file_region *rg, *nrg;
111         long chg = 0;
112
113         /* Locate the region we are before or in. */
114         list_for_each_entry(rg, head, link)
115                 if (f <= rg->to)
116                         break;
117
118         /* If we are below the current region then a new region is required.
119          * Subtle, allocate a new region at the position but make it zero
120          * size such that we can guarantee to record the reservation. */
121         if (&rg->link == head || t < rg->from) {
122                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
123                 if (!nrg)
124                         return -ENOMEM;
125                 nrg->from = f;
126                 nrg->to   = f;
127                 INIT_LIST_HEAD(&nrg->link);
128                 list_add(&nrg->link, rg->link.prev);
129
130                 return t - f;
131         }
132
133         /* Round our left edge to the current segment if it encloses us. */
134         if (f > rg->from)
135                 f = rg->from;
136         chg = t - f;
137
138         /* Check for and consume any regions we now overlap with. */
139         list_for_each_entry(rg, rg->link.prev, link) {
140                 if (&rg->link == head)
141                         break;
142                 if (rg->from > t)
143                         return chg;
144
145                 /* We overlap with this area, if it extends futher than
146                  * us then we must extend ourselves.  Account for its
147                  * existing reservation. */
148                 if (rg->to > t) {
149                         chg += rg->to - t;
150                         t = rg->to;
151                 }
152                 chg -= rg->to - rg->from;
153         }
154         return chg;
155 }
156
157 static long region_truncate(struct list_head *head, long end)
158 {
159         struct file_region *rg, *trg;
160         long chg = 0;
161
162         /* Locate the region we are either in or before. */
163         list_for_each_entry(rg, head, link)
164                 if (end <= rg->to)
165                         break;
166         if (&rg->link == head)
167                 return 0;
168
169         /* If we are in the middle of a region then adjust it. */
170         if (end > rg->from) {
171                 chg = rg->to - end;
172                 rg->to = end;
173                 rg = list_entry(rg->link.next, typeof(*rg), link);
174         }
175
176         /* Drop any remaining regions. */
177         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
178                 if (&rg->link == head)
179                         break;
180                 chg += rg->to - rg->from;
181                 list_del(&rg->link);
182                 kfree(rg);
183         }
184         return chg;
185 }
186
187 static long region_count(struct list_head *head, long f, long t)
188 {
189         struct file_region *rg;
190         long chg = 0;
191
192         /* Locate each segment we overlap with, and count that overlap. */
193         list_for_each_entry(rg, head, link) {
194                 int seg_from;
195                 int seg_to;
196
197                 if (rg->to <= f)
198                         continue;
199                 if (rg->from >= t)
200                         break;
201
202                 seg_from = max(rg->from, f);
203                 seg_to = min(rg->to, t);
204
205                 chg += seg_to - seg_from;
206         }
207
208         return chg;
209 }
210
211 /*
212  * Convert the address within this vma to the page offset within
213  * the mapping, in pagecache page units; huge pages here.
214  */
215 static pgoff_t vma_hugecache_offset(struct hstate *h,
216                         struct vm_area_struct *vma, unsigned long address)
217 {
218         return ((address - vma->vm_start) >> huge_page_shift(h)) +
219                         (vma->vm_pgoff >> huge_page_order(h));
220 }
221
222 /*
223  * Return the size of the pages allocated when backing a VMA. In the majority
224  * cases this will be same size as used by the page table entries.
225  */
226 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
227 {
228         struct hstate *hstate;
229
230         if (!is_vm_hugetlb_page(vma))
231                 return PAGE_SIZE;
232
233         hstate = hstate_vma(vma);
234
235         return 1UL << (hstate->order + PAGE_SHIFT);
236 }
237
238 /*
239  * Return the page size being used by the MMU to back a VMA. In the majority
240  * of cases, the page size used by the kernel matches the MMU size. On
241  * architectures where it differs, an architecture-specific version of this
242  * function is required.
243  */
244 #ifndef vma_mmu_pagesize
245 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
246 {
247         return vma_kernel_pagesize(vma);
248 }
249 #endif
250
251 /*
252  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
253  * bits of the reservation map pointer, which are always clear due to
254  * alignment.
255  */
256 #define HPAGE_RESV_OWNER    (1UL << 0)
257 #define HPAGE_RESV_UNMAPPED (1UL << 1)
258 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
259
260 /*
261  * These helpers are used to track how many pages are reserved for
262  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
263  * is guaranteed to have their future faults succeed.
264  *
265  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
266  * the reserve counters are updated with the hugetlb_lock held. It is safe
267  * to reset the VMA at fork() time as it is not in use yet and there is no
268  * chance of the global counters getting corrupted as a result of the values.
269  *
270  * The private mapping reservation is represented in a subtly different
271  * manner to a shared mapping.  A shared mapping has a region map associated
272  * with the underlying file, this region map represents the backing file
273  * pages which have ever had a reservation assigned which this persists even
274  * after the page is instantiated.  A private mapping has a region map
275  * associated with the original mmap which is attached to all VMAs which
276  * reference it, this region map represents those offsets which have consumed
277  * reservation ie. where pages have been instantiated.
278  */
279 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
280 {
281         return (unsigned long)vma->vm_private_data;
282 }
283
284 static void set_vma_private_data(struct vm_area_struct *vma,
285                                                         unsigned long value)
286 {
287         vma->vm_private_data = (void *)value;
288 }
289
290 struct resv_map {
291         struct kref refs;
292         struct list_head regions;
293 };
294
295 static struct resv_map *resv_map_alloc(void)
296 {
297         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
298         if (!resv_map)
299                 return NULL;
300
301         kref_init(&resv_map->refs);
302         INIT_LIST_HEAD(&resv_map->regions);
303
304         return resv_map;
305 }
306
307 static void resv_map_release(struct kref *ref)
308 {
309         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
310
311         /* Clear out any active regions before we release the map. */
312         region_truncate(&resv_map->regions, 0);
313         kfree(resv_map);
314 }
315
316 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
317 {
318         VM_BUG_ON(!is_vm_hugetlb_page(vma));
319         if (!(vma->vm_flags & VM_SHARED))
320                 return (struct resv_map *)(get_vma_private_data(vma) &
321                                                         ~HPAGE_RESV_MASK);
322         return NULL;
323 }
324
325 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
326 {
327         VM_BUG_ON(!is_vm_hugetlb_page(vma));
328         VM_BUG_ON(vma->vm_flags & VM_SHARED);
329
330         set_vma_private_data(vma, (get_vma_private_data(vma) &
331                                 HPAGE_RESV_MASK) | (unsigned long)map);
332 }
333
334 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
335 {
336         VM_BUG_ON(!is_vm_hugetlb_page(vma));
337         VM_BUG_ON(vma->vm_flags & VM_SHARED);
338
339         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
340 }
341
342 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
343 {
344         VM_BUG_ON(!is_vm_hugetlb_page(vma));
345
346         return (get_vma_private_data(vma) & flag) != 0;
347 }
348
349 /* Decrement the reserved pages in the hugepage pool by one */
350 static void decrement_hugepage_resv_vma(struct hstate *h,
351                         struct vm_area_struct *vma)
352 {
353         if (vma->vm_flags & VM_NORESERVE)
354                 return;
355
356         if (vma->vm_flags & VM_SHARED) {
357                 /* Shared mappings always use reserves */
358                 h->resv_huge_pages--;
359         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
360                 /*
361                  * Only the process that called mmap() has reserves for
362                  * private mappings.
363                  */
364                 h->resv_huge_pages--;
365         }
366 }
367
368 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
369 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
370 {
371         VM_BUG_ON(!is_vm_hugetlb_page(vma));
372         if (!(vma->vm_flags & VM_SHARED))
373                 vma->vm_private_data = (void *)0;
374 }
375
376 /* Returns true if the VMA has associated reserve pages */
377 static int vma_has_reserves(struct vm_area_struct *vma)
378 {
379         if (vma->vm_flags & VM_SHARED)
380                 return 1;
381         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
382                 return 1;
383         return 0;
384 }
385
386 static void clear_gigantic_page(struct page *page,
387                         unsigned long addr, unsigned long sz)
388 {
389         int i;
390         struct page *p = page;
391
392         might_sleep();
393         for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
394                 cond_resched();
395                 clear_user_highpage(p, addr + i * PAGE_SIZE);
396         }
397 }
398 static void clear_huge_page(struct page *page,
399                         unsigned long addr, unsigned long sz)
400 {
401         int i;
402
403         if (unlikely(sz > MAX_ORDER_NR_PAGES)) {
404                 clear_gigantic_page(page, addr, sz);
405                 return;
406         }
407
408         might_sleep();
409         for (i = 0; i < sz/PAGE_SIZE; i++) {
410                 cond_resched();
411                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
412         }
413 }
414
415 static void copy_gigantic_page(struct page *dst, struct page *src,
416                            unsigned long addr, struct vm_area_struct *vma)
417 {
418         int i;
419         struct hstate *h = hstate_vma(vma);
420         struct page *dst_base = dst;
421         struct page *src_base = src;
422         might_sleep();
423         for (i = 0; i < pages_per_huge_page(h); ) {
424                 cond_resched();
425                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
426
427                 i++;
428                 dst = mem_map_next(dst, dst_base, i);
429                 src = mem_map_next(src, src_base, i);
430         }
431 }
432 static void copy_huge_page(struct page *dst, struct page *src,
433                            unsigned long addr, struct vm_area_struct *vma)
434 {
435         int i;
436         struct hstate *h = hstate_vma(vma);
437
438         if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
439                 copy_gigantic_page(dst, src, addr, vma);
440                 return;
441         }
442
443         might_sleep();
444         for (i = 0; i < pages_per_huge_page(h); i++) {
445                 cond_resched();
446                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
447         }
448 }
449
450 static void enqueue_huge_page(struct hstate *h, struct page *page)
451 {
452         int nid = page_to_nid(page);
453         list_add(&page->lru, &h->hugepage_freelists[nid]);
454         h->free_huge_pages++;
455         h->free_huge_pages_node[nid]++;
456 }
457
458 static struct page *dequeue_huge_page(struct hstate *h)
459 {
460         int nid;
461         struct page *page = NULL;
462
463         for (nid = 0; nid < MAX_NUMNODES; ++nid) {
464                 if (!list_empty(&h->hugepage_freelists[nid])) {
465                         page = list_entry(h->hugepage_freelists[nid].next,
466                                           struct page, lru);
467                         list_del(&page->lru);
468                         h->free_huge_pages--;
469                         h->free_huge_pages_node[nid]--;
470                         break;
471                 }
472         }
473         return page;
474 }
475
476 static struct page *dequeue_huge_page_vma(struct hstate *h,
477                                 struct vm_area_struct *vma,
478                                 unsigned long address, int avoid_reserve)
479 {
480         int nid;
481         struct page *page = NULL;
482         struct mempolicy *mpol;
483         nodemask_t *nodemask;
484         struct zonelist *zonelist = huge_zonelist(vma, address,
485                                         htlb_alloc_mask, &mpol, &nodemask);
486         struct zone *zone;
487         struct zoneref *z;
488
489         /*
490          * A child process with MAP_PRIVATE mappings created by their parent
491          * have no page reserves. This check ensures that reservations are
492          * not "stolen". The child may still get SIGKILLed
493          */
494         if (!vma_has_reserves(vma) &&
495                         h->free_huge_pages - h->resv_huge_pages == 0)
496                 return NULL;
497
498         /* If reserves cannot be used, ensure enough pages are in the pool */
499         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
500                 return NULL;
501
502         for_each_zone_zonelist_nodemask(zone, z, zonelist,
503                                                 MAX_NR_ZONES - 1, nodemask) {
504                 nid = zone_to_nid(zone);
505                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
506                     !list_empty(&h->hugepage_freelists[nid])) {
507                         page = list_entry(h->hugepage_freelists[nid].next,
508                                           struct page, lru);
509                         list_del(&page->lru);
510                         h->free_huge_pages--;
511                         h->free_huge_pages_node[nid]--;
512
513                         if (!avoid_reserve)
514                                 decrement_hugepage_resv_vma(h, vma);
515
516                         break;
517                 }
518         }
519         mpol_cond_put(mpol);
520         return page;
521 }
522
523 static void update_and_free_page(struct hstate *h, struct page *page)
524 {
525         int i;
526
527         VM_BUG_ON(h->order >= MAX_ORDER);
528
529         h->nr_huge_pages--;
530         h->nr_huge_pages_node[page_to_nid(page)]--;
531         for (i = 0; i < pages_per_huge_page(h); i++) {
532                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
533                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
534                                 1 << PG_private | 1<< PG_writeback);
535         }
536         set_compound_page_dtor(page, NULL);
537         set_page_refcounted(page);
538         arch_release_hugepage(page);
539         __free_pages(page, huge_page_order(h));
540 }
541
542 struct hstate *size_to_hstate(unsigned long size)
543 {
544         struct hstate *h;
545
546         for_each_hstate(h) {
547                 if (huge_page_size(h) == size)
548                         return h;
549         }
550         return NULL;
551 }
552
553 static void free_huge_page(struct page *page)
554 {
555         /*
556          * Can't pass hstate in here because it is called from the
557          * compound page destructor.
558          */
559         struct hstate *h = page_hstate(page);
560         int nid = page_to_nid(page);
561         struct address_space *mapping;
562
563         mapping = (struct address_space *) page_private(page);
564         set_page_private(page, 0);
565         BUG_ON(page_count(page));
566         INIT_LIST_HEAD(&page->lru);
567
568         spin_lock(&hugetlb_lock);
569         if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
570                 update_and_free_page(h, page);
571                 h->surplus_huge_pages--;
572                 h->surplus_huge_pages_node[nid]--;
573         } else {
574                 enqueue_huge_page(h, page);
575         }
576         spin_unlock(&hugetlb_lock);
577         if (mapping)
578                 hugetlb_put_quota(mapping, 1);
579 }
580
581 /*
582  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
583  * balanced by operating on them in a round-robin fashion.
584  * Returns 1 if an adjustment was made.
585  */
586 static int adjust_pool_surplus(struct hstate *h, int delta)
587 {
588         static int prev_nid;
589         int nid = prev_nid;
590         int ret = 0;
591
592         VM_BUG_ON(delta != -1 && delta != 1);
593         do {
594                 nid = next_node(nid, node_online_map);
595                 if (nid == MAX_NUMNODES)
596                         nid = first_node(node_online_map);
597
598                 /* To shrink on this node, there must be a surplus page */
599                 if (delta < 0 && !h->surplus_huge_pages_node[nid])
600                         continue;
601                 /* Surplus cannot exceed the total number of pages */
602                 if (delta > 0 && h->surplus_huge_pages_node[nid] >=
603                                                 h->nr_huge_pages_node[nid])
604                         continue;
605
606                 h->surplus_huge_pages += delta;
607                 h->surplus_huge_pages_node[nid] += delta;
608                 ret = 1;
609                 break;
610         } while (nid != prev_nid);
611
612         prev_nid = nid;
613         return ret;
614 }
615
616 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
617 {
618         set_compound_page_dtor(page, free_huge_page);
619         spin_lock(&hugetlb_lock);
620         h->nr_huge_pages++;
621         h->nr_huge_pages_node[nid]++;
622         spin_unlock(&hugetlb_lock);
623         put_page(page); /* free it into the hugepage allocator */
624 }
625
626 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
627 {
628         struct page *page;
629
630         if (h->order >= MAX_ORDER)
631                 return NULL;
632
633         page = alloc_pages_node(nid,
634                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
635                                                 __GFP_REPEAT|__GFP_NOWARN,
636                 huge_page_order(h));
637         if (page) {
638                 if (arch_prepare_hugepage(page)) {
639                         __free_pages(page, huge_page_order(h));
640                         return NULL;
641                 }
642                 prep_new_huge_page(h, page, nid);
643         }
644
645         return page;
646 }
647
648 /*
649  * Use a helper variable to find the next node and then
650  * copy it back to hugetlb_next_nid afterwards:
651  * otherwise there's a window in which a racer might
652  * pass invalid nid MAX_NUMNODES to alloc_pages_node.
653  * But we don't need to use a spin_lock here: it really
654  * doesn't matter if occasionally a racer chooses the
655  * same nid as we do.  Move nid forward in the mask even
656  * if we just successfully allocated a hugepage so that
657  * the next caller gets hugepages on the next node.
658  */
659 static int hstate_next_node(struct hstate *h)
660 {
661         int next_nid;
662         next_nid = next_node(h->hugetlb_next_nid, node_online_map);
663         if (next_nid == MAX_NUMNODES)
664                 next_nid = first_node(node_online_map);
665         h->hugetlb_next_nid = next_nid;
666         return next_nid;
667 }
668
669 static int alloc_fresh_huge_page(struct hstate *h)
670 {
671         struct page *page;
672         int start_nid;
673         int next_nid;
674         int ret = 0;
675
676         start_nid = h->hugetlb_next_nid;
677
678         do {
679                 page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
680                 if (page)
681                         ret = 1;
682                 next_nid = hstate_next_node(h);
683         } while (!page && h->hugetlb_next_nid != start_nid);
684
685         if (ret)
686                 count_vm_event(HTLB_BUDDY_PGALLOC);
687         else
688                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
689
690         return ret;
691 }
692
693 static struct page *alloc_buddy_huge_page(struct hstate *h,
694                         struct vm_area_struct *vma, unsigned long address)
695 {
696         struct page *page;
697         unsigned int nid;
698
699         if (h->order >= MAX_ORDER)
700                 return NULL;
701
702         /*
703          * Assume we will successfully allocate the surplus page to
704          * prevent racing processes from causing the surplus to exceed
705          * overcommit
706          *
707          * This however introduces a different race, where a process B
708          * tries to grow the static hugepage pool while alloc_pages() is
709          * called by process A. B will only examine the per-node
710          * counters in determining if surplus huge pages can be
711          * converted to normal huge pages in adjust_pool_surplus(). A
712          * won't be able to increment the per-node counter, until the
713          * lock is dropped by B, but B doesn't drop hugetlb_lock until
714          * no more huge pages can be converted from surplus to normal
715          * state (and doesn't try to convert again). Thus, we have a
716          * case where a surplus huge page exists, the pool is grown, and
717          * the surplus huge page still exists after, even though it
718          * should just have been converted to a normal huge page. This
719          * does not leak memory, though, as the hugepage will be freed
720          * once it is out of use. It also does not allow the counters to
721          * go out of whack in adjust_pool_surplus() as we don't modify
722          * the node values until we've gotten the hugepage and only the
723          * per-node value is checked there.
724          */
725         spin_lock(&hugetlb_lock);
726         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
727                 spin_unlock(&hugetlb_lock);
728                 return NULL;
729         } else {
730                 h->nr_huge_pages++;
731                 h->surplus_huge_pages++;
732         }
733         spin_unlock(&hugetlb_lock);
734
735         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
736                                         __GFP_REPEAT|__GFP_NOWARN,
737                                         huge_page_order(h));
738
739         if (page && arch_prepare_hugepage(page)) {
740                 __free_pages(page, huge_page_order(h));
741                 return NULL;
742         }
743
744         spin_lock(&hugetlb_lock);
745         if (page) {
746                 /*
747                  * This page is now managed by the hugetlb allocator and has
748                  * no users -- drop the buddy allocator's reference.
749                  */
750                 put_page_testzero(page);
751                 VM_BUG_ON(page_count(page));
752                 nid = page_to_nid(page);
753                 set_compound_page_dtor(page, free_huge_page);
754                 /*
755                  * We incremented the global counters already
756                  */
757                 h->nr_huge_pages_node[nid]++;
758                 h->surplus_huge_pages_node[nid]++;
759                 __count_vm_event(HTLB_BUDDY_PGALLOC);
760         } else {
761                 h->nr_huge_pages--;
762                 h->surplus_huge_pages--;
763                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
764         }
765         spin_unlock(&hugetlb_lock);
766
767         return page;
768 }
769
770 /*
771  * Increase the hugetlb pool such that it can accomodate a reservation
772  * of size 'delta'.
773  */
774 static int gather_surplus_pages(struct hstate *h, int delta)
775 {
776         struct list_head surplus_list;
777         struct page *page, *tmp;
778         int ret, i;
779         int needed, allocated;
780
781         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
782         if (needed <= 0) {
783                 h->resv_huge_pages += delta;
784                 return 0;
785         }
786
787         allocated = 0;
788         INIT_LIST_HEAD(&surplus_list);
789
790         ret = -ENOMEM;
791 retry:
792         spin_unlock(&hugetlb_lock);
793         for (i = 0; i < needed; i++) {
794                 page = alloc_buddy_huge_page(h, NULL, 0);
795                 if (!page) {
796                         /*
797                          * We were not able to allocate enough pages to
798                          * satisfy the entire reservation so we free what
799                          * we've allocated so far.
800                          */
801                         spin_lock(&hugetlb_lock);
802                         needed = 0;
803                         goto free;
804                 }
805
806                 list_add(&page->lru, &surplus_list);
807         }
808         allocated += needed;
809
810         /*
811          * After retaking hugetlb_lock, we need to recalculate 'needed'
812          * because either resv_huge_pages or free_huge_pages may have changed.
813          */
814         spin_lock(&hugetlb_lock);
815         needed = (h->resv_huge_pages + delta) -
816                         (h->free_huge_pages + allocated);
817         if (needed > 0)
818                 goto retry;
819
820         /*
821          * The surplus_list now contains _at_least_ the number of extra pages
822          * needed to accomodate the reservation.  Add the appropriate number
823          * of pages to the hugetlb pool and free the extras back to the buddy
824          * allocator.  Commit the entire reservation here to prevent another
825          * process from stealing the pages as they are added to the pool but
826          * before they are reserved.
827          */
828         needed += allocated;
829         h->resv_huge_pages += delta;
830         ret = 0;
831 free:
832         /* Free the needed pages to the hugetlb pool */
833         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
834                 if ((--needed) < 0)
835                         break;
836                 list_del(&page->lru);
837                 enqueue_huge_page(h, page);
838         }
839
840         /* Free unnecessary surplus pages to the buddy allocator */
841         if (!list_empty(&surplus_list)) {
842                 spin_unlock(&hugetlb_lock);
843                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
844                         list_del(&page->lru);
845                         /*
846                          * The page has a reference count of zero already, so
847                          * call free_huge_page directly instead of using
848                          * put_page.  This must be done with hugetlb_lock
849                          * unlocked which is safe because free_huge_page takes
850                          * hugetlb_lock before deciding how to free the page.
851                          */
852                         free_huge_page(page);
853                 }
854                 spin_lock(&hugetlb_lock);
855         }
856
857         return ret;
858 }
859
860 /*
861  * When releasing a hugetlb pool reservation, any surplus pages that were
862  * allocated to satisfy the reservation must be explicitly freed if they were
863  * never used.
864  */
865 static void return_unused_surplus_pages(struct hstate *h,
866                                         unsigned long unused_resv_pages)
867 {
868         static int nid = -1;
869         struct page *page;
870         unsigned long nr_pages;
871
872         /*
873          * We want to release as many surplus pages as possible, spread
874          * evenly across all nodes. Iterate across all nodes until we
875          * can no longer free unreserved surplus pages. This occurs when
876          * the nodes with surplus pages have no free pages.
877          */
878         unsigned long remaining_iterations = num_online_nodes();
879
880         /* Uncommit the reservation */
881         h->resv_huge_pages -= unused_resv_pages;
882
883         /* Cannot return gigantic pages currently */
884         if (h->order >= MAX_ORDER)
885                 return;
886
887         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
888
889         while (remaining_iterations-- && nr_pages) {
890                 nid = next_node(nid, node_online_map);
891                 if (nid == MAX_NUMNODES)
892                         nid = first_node(node_online_map);
893
894                 if (!h->surplus_huge_pages_node[nid])
895                         continue;
896
897                 if (!list_empty(&h->hugepage_freelists[nid])) {
898                         page = list_entry(h->hugepage_freelists[nid].next,
899                                           struct page, lru);
900                         list_del(&page->lru);
901                         update_and_free_page(h, page);
902                         h->free_huge_pages--;
903                         h->free_huge_pages_node[nid]--;
904                         h->surplus_huge_pages--;
905                         h->surplus_huge_pages_node[nid]--;
906                         nr_pages--;
907                         remaining_iterations = num_online_nodes();
908                 }
909         }
910 }
911
912 /*
913  * Determine if the huge page at addr within the vma has an associated
914  * reservation.  Where it does not we will need to logically increase
915  * reservation and actually increase quota before an allocation can occur.
916  * Where any new reservation would be required the reservation change is
917  * prepared, but not committed.  Once the page has been quota'd allocated
918  * an instantiated the change should be committed via vma_commit_reservation.
919  * No action is required on failure.
920  */
921 static int vma_needs_reservation(struct hstate *h,
922                         struct vm_area_struct *vma, unsigned long addr)
923 {
924         struct address_space *mapping = vma->vm_file->f_mapping;
925         struct inode *inode = mapping->host;
926
927         if (vma->vm_flags & VM_SHARED) {
928                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
929                 return region_chg(&inode->i_mapping->private_list,
930                                                         idx, idx + 1);
931
932         } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
933                 return 1;
934
935         } else  {
936                 int err;
937                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
938                 struct resv_map *reservations = vma_resv_map(vma);
939
940                 err = region_chg(&reservations->regions, idx, idx + 1);
941                 if (err < 0)
942                         return err;
943                 return 0;
944         }
945 }
946 static void vma_commit_reservation(struct hstate *h,
947                         struct vm_area_struct *vma, unsigned long addr)
948 {
949         struct address_space *mapping = vma->vm_file->f_mapping;
950         struct inode *inode = mapping->host;
951
952         if (vma->vm_flags & VM_SHARED) {
953                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
954                 region_add(&inode->i_mapping->private_list, idx, idx + 1);
955
956         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
957                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
958                 struct resv_map *reservations = vma_resv_map(vma);
959
960                 /* Mark this page used in the map. */
961                 region_add(&reservations->regions, idx, idx + 1);
962         }
963 }
964
965 static struct page *alloc_huge_page(struct vm_area_struct *vma,
966                                     unsigned long addr, int avoid_reserve)
967 {
968         struct hstate *h = hstate_vma(vma);
969         struct page *page;
970         struct address_space *mapping = vma->vm_file->f_mapping;
971         struct inode *inode = mapping->host;
972         unsigned int chg;
973
974         /*
975          * Processes that did not create the mapping will have no reserves and
976          * will not have accounted against quota. Check that the quota can be
977          * made before satisfying the allocation
978          * MAP_NORESERVE mappings may also need pages and quota allocated
979          * if no reserve mapping overlaps.
980          */
981         chg = vma_needs_reservation(h, vma, addr);
982         if (chg < 0)
983                 return ERR_PTR(chg);
984         if (chg)
985                 if (hugetlb_get_quota(inode->i_mapping, chg))
986                         return ERR_PTR(-ENOSPC);
987
988         spin_lock(&hugetlb_lock);
989         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
990         spin_unlock(&hugetlb_lock);
991
992         if (!page) {
993                 page = alloc_buddy_huge_page(h, vma, addr);
994                 if (!page) {
995                         hugetlb_put_quota(inode->i_mapping, chg);
996                         return ERR_PTR(-VM_FAULT_OOM);
997                 }
998         }
999
1000         set_page_refcounted(page);
1001         set_page_private(page, (unsigned long) mapping);
1002
1003         vma_commit_reservation(h, vma, addr);
1004
1005         return page;
1006 }
1007
1008 __attribute__((weak)) int alloc_bootmem_huge_page(struct hstate *h)
1009 {
1010         struct huge_bootmem_page *m;
1011         int nr_nodes = nodes_weight(node_online_map);
1012
1013         while (nr_nodes) {
1014                 void *addr;
1015
1016                 addr = __alloc_bootmem_node_nopanic(
1017                                 NODE_DATA(h->hugetlb_next_nid),
1018                                 huge_page_size(h), huge_page_size(h), 0);
1019
1020                 if (addr) {
1021                         /*
1022                          * Use the beginning of the huge page to store the
1023                          * huge_bootmem_page struct (until gather_bootmem
1024                          * puts them into the mem_map).
1025                          */
1026                         m = addr;
1027                         if (m)
1028                                 goto found;
1029                 }
1030                 hstate_next_node(h);
1031                 nr_nodes--;
1032         }
1033         return 0;
1034
1035 found:
1036         BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1037         /* Put them into a private list first because mem_map is not up yet */
1038         list_add(&m->list, &huge_boot_pages);
1039         m->hstate = h;
1040         return 1;
1041 }
1042
1043 static void prep_compound_huge_page(struct page *page, int order)
1044 {
1045         if (unlikely(order > (MAX_ORDER - 1)))
1046                 prep_compound_gigantic_page(page, order);
1047         else
1048                 prep_compound_page(page, order);
1049 }
1050
1051 /* Put bootmem huge pages into the standard lists after mem_map is up */
1052 static void __init gather_bootmem_prealloc(void)
1053 {
1054         struct huge_bootmem_page *m;
1055
1056         list_for_each_entry(m, &huge_boot_pages, list) {
1057                 struct page *page = virt_to_page(m);
1058                 struct hstate *h = m->hstate;
1059                 __ClearPageReserved(page);
1060                 WARN_ON(page_count(page) != 1);
1061                 prep_compound_huge_page(page, h->order);
1062                 prep_new_huge_page(h, page, page_to_nid(page));
1063         }
1064 }
1065
1066 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1067 {
1068         unsigned long i;
1069
1070         for (i = 0; i < h->max_huge_pages; ++i) {
1071                 if (h->order >= MAX_ORDER) {
1072                         if (!alloc_bootmem_huge_page(h))
1073                                 break;
1074                 } else if (!alloc_fresh_huge_page(h))
1075                         break;
1076         }
1077         h->max_huge_pages = i;
1078 }
1079
1080 static void __init hugetlb_init_hstates(void)
1081 {
1082         struct hstate *h;
1083
1084         for_each_hstate(h) {
1085                 /* oversize hugepages were init'ed in early boot */
1086                 if (h->order < MAX_ORDER)
1087                         hugetlb_hstate_alloc_pages(h);
1088         }
1089 }
1090
1091 static char * __init memfmt(char *buf, unsigned long n)
1092 {
1093         if (n >= (1UL << 30))
1094                 sprintf(buf, "%lu GB", n >> 30);
1095         else if (n >= (1UL << 20))
1096                 sprintf(buf, "%lu MB", n >> 20);
1097         else
1098                 sprintf(buf, "%lu KB", n >> 10);
1099         return buf;
1100 }
1101
1102 static void __init report_hugepages(void)
1103 {
1104         struct hstate *h;
1105
1106         for_each_hstate(h) {
1107                 char buf[32];
1108                 printk(KERN_INFO "HugeTLB registered %s page size, "
1109                                  "pre-allocated %ld pages\n",
1110                         memfmt(buf, huge_page_size(h)),
1111                         h->free_huge_pages);
1112         }
1113 }
1114
1115 #ifdef CONFIG_HIGHMEM
1116 static void try_to_free_low(struct hstate *h, unsigned long count)
1117 {
1118         int i;
1119
1120         if (h->order >= MAX_ORDER)
1121                 return;
1122
1123         for (i = 0; i < MAX_NUMNODES; ++i) {
1124                 struct page *page, *next;
1125                 struct list_head *freel = &h->hugepage_freelists[i];
1126                 list_for_each_entry_safe(page, next, freel, lru) {
1127                         if (count >= h->nr_huge_pages)
1128                                 return;
1129                         if (PageHighMem(page))
1130                                 continue;
1131                         list_del(&page->lru);
1132                         update_and_free_page(h, page);
1133                         h->free_huge_pages--;
1134                         h->free_huge_pages_node[page_to_nid(page)]--;
1135                 }
1136         }
1137 }
1138 #else
1139 static inline void try_to_free_low(struct hstate *h, unsigned long count)
1140 {
1141 }
1142 #endif
1143
1144 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1145 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
1146 {
1147         unsigned long min_count, ret;
1148
1149         if (h->order >= MAX_ORDER)
1150                 return h->max_huge_pages;
1151
1152         /*
1153          * Increase the pool size
1154          * First take pages out of surplus state.  Then make up the
1155          * remaining difference by allocating fresh huge pages.
1156          *
1157          * We might race with alloc_buddy_huge_page() here and be unable
1158          * to convert a surplus huge page to a normal huge page. That is
1159          * not critical, though, it just means the overall size of the
1160          * pool might be one hugepage larger than it needs to be, but
1161          * within all the constraints specified by the sysctls.
1162          */
1163         spin_lock(&hugetlb_lock);
1164         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1165                 if (!adjust_pool_surplus(h, -1))
1166                         break;
1167         }
1168
1169         while (count > persistent_huge_pages(h)) {
1170                 /*
1171                  * If this allocation races such that we no longer need the
1172                  * page, free_huge_page will handle it by freeing the page
1173                  * and reducing the surplus.
1174                  */
1175                 spin_unlock(&hugetlb_lock);
1176                 ret = alloc_fresh_huge_page(h);
1177                 spin_lock(&hugetlb_lock);
1178                 if (!ret)
1179                         goto out;
1180
1181         }
1182
1183         /*
1184          * Decrease the pool size
1185          * First return free pages to the buddy allocator (being careful
1186          * to keep enough around to satisfy reservations).  Then place
1187          * pages into surplus state as needed so the pool will shrink
1188          * to the desired size as pages become free.
1189          *
1190          * By placing pages into the surplus state independent of the
1191          * overcommit value, we are allowing the surplus pool size to
1192          * exceed overcommit. There are few sane options here. Since
1193          * alloc_buddy_huge_page() is checking the global counter,
1194          * though, we'll note that we're not allowed to exceed surplus
1195          * and won't grow the pool anywhere else. Not until one of the
1196          * sysctls are changed, or the surplus pages go out of use.
1197          */
1198         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1199         min_count = max(count, min_count);
1200         try_to_free_low(h, min_count);
1201         while (min_count < persistent_huge_pages(h)) {
1202                 struct page *page = dequeue_huge_page(h);
1203                 if (!page)
1204                         break;
1205                 update_and_free_page(h, page);
1206         }
1207         while (count < persistent_huge_pages(h)) {
1208                 if (!adjust_pool_surplus(h, 1))
1209                         break;
1210         }
1211 out:
1212         ret = persistent_huge_pages(h);
1213         spin_unlock(&hugetlb_lock);
1214         return ret;
1215 }
1216
1217 #define HSTATE_ATTR_RO(_name) \
1218         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1219
1220 #define HSTATE_ATTR(_name) \
1221         static struct kobj_attribute _name##_attr = \
1222                 __ATTR(_name, 0644, _name##_show, _name##_store)
1223
1224 static struct kobject *hugepages_kobj;
1225 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1226
1227 static struct hstate *kobj_to_hstate(struct kobject *kobj)
1228 {
1229         int i;
1230         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1231                 if (hstate_kobjs[i] == kobj)
1232                         return &hstates[i];
1233         BUG();
1234         return NULL;
1235 }
1236
1237 static ssize_t nr_hugepages_show(struct kobject *kobj,
1238                                         struct kobj_attribute *attr, char *buf)
1239 {
1240         struct hstate *h = kobj_to_hstate(kobj);
1241         return sprintf(buf, "%lu\n", h->nr_huge_pages);
1242 }
1243 static ssize_t nr_hugepages_store(struct kobject *kobj,
1244                 struct kobj_attribute *attr, const char *buf, size_t count)
1245 {
1246         int err;
1247         unsigned long input;
1248         struct hstate *h = kobj_to_hstate(kobj);
1249
1250         err = strict_strtoul(buf, 10, &input);
1251         if (err)
1252                 return 0;
1253
1254         h->max_huge_pages = set_max_huge_pages(h, input);
1255
1256         return count;
1257 }
1258 HSTATE_ATTR(nr_hugepages);
1259
1260 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1261                                         struct kobj_attribute *attr, char *buf)
1262 {
1263         struct hstate *h = kobj_to_hstate(kobj);
1264         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1265 }
1266 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1267                 struct kobj_attribute *attr, const char *buf, size_t count)
1268 {
1269         int err;
1270         unsigned long input;
1271         struct hstate *h = kobj_to_hstate(kobj);
1272
1273         err = strict_strtoul(buf, 10, &input);
1274         if (err)
1275                 return 0;
1276
1277         spin_lock(&hugetlb_lock);
1278         h->nr_overcommit_huge_pages = input;
1279         spin_unlock(&hugetlb_lock);
1280
1281         return count;
1282 }
1283 HSTATE_ATTR(nr_overcommit_hugepages);
1284
1285 static ssize_t free_hugepages_show(struct kobject *kobj,
1286                                         struct kobj_attribute *attr, char *buf)
1287 {
1288         struct hstate *h = kobj_to_hstate(kobj);
1289         return sprintf(buf, "%lu\n", h->free_huge_pages);
1290 }
1291 HSTATE_ATTR_RO(free_hugepages);
1292
1293 static ssize_t resv_hugepages_show(struct kobject *kobj,
1294                                         struct kobj_attribute *attr, char *buf)
1295 {
1296         struct hstate *h = kobj_to_hstate(kobj);
1297         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1298 }
1299 HSTATE_ATTR_RO(resv_hugepages);
1300
1301 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1302                                         struct kobj_attribute *attr, char *buf)
1303 {
1304         struct hstate *h = kobj_to_hstate(kobj);
1305         return sprintf(buf, "%lu\n", h->surplus_huge_pages);
1306 }
1307 HSTATE_ATTR_RO(surplus_hugepages);
1308
1309 static struct attribute *hstate_attrs[] = {
1310         &nr_hugepages_attr.attr,
1311         &nr_overcommit_hugepages_attr.attr,
1312         &free_hugepages_attr.attr,
1313         &resv_hugepages_attr.attr,
1314         &surplus_hugepages_attr.attr,
1315         NULL,
1316 };
1317
1318 static struct attribute_group hstate_attr_group = {
1319         .attrs = hstate_attrs,
1320 };
1321
1322 static int __init hugetlb_sysfs_add_hstate(struct hstate *h)
1323 {
1324         int retval;
1325
1326         hstate_kobjs[h - hstates] = kobject_create_and_add(h->name,
1327                                                         hugepages_kobj);
1328         if (!hstate_kobjs[h - hstates])
1329                 return -ENOMEM;
1330
1331         retval = sysfs_create_group(hstate_kobjs[h - hstates],
1332                                                         &hstate_attr_group);
1333         if (retval)
1334                 kobject_put(hstate_kobjs[h - hstates]);
1335
1336         return retval;
1337 }
1338
1339 static void __init hugetlb_sysfs_init(void)
1340 {
1341         struct hstate *h;
1342         int err;
1343
1344         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1345         if (!hugepages_kobj)
1346                 return;
1347
1348         for_each_hstate(h) {
1349                 err = hugetlb_sysfs_add_hstate(h);
1350                 if (err)
1351                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1352                                                                 h->name);
1353         }
1354 }
1355
1356 static void __exit hugetlb_exit(void)
1357 {
1358         struct hstate *h;
1359
1360         for_each_hstate(h) {
1361                 kobject_put(hstate_kobjs[h - hstates]);
1362         }
1363
1364         kobject_put(hugepages_kobj);
1365 }
1366 module_exit(hugetlb_exit);
1367
1368 static int __init hugetlb_init(void)
1369 {
1370         /* Some platform decide whether they support huge pages at boot
1371          * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1372          * there is no such support
1373          */
1374         if (HPAGE_SHIFT == 0)
1375                 return 0;
1376
1377         if (!size_to_hstate(default_hstate_size)) {
1378                 default_hstate_size = HPAGE_SIZE;
1379                 if (!size_to_hstate(default_hstate_size))
1380                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1381         }
1382         default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1383         if (default_hstate_max_huge_pages)
1384                 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1385
1386         hugetlb_init_hstates();
1387
1388         gather_bootmem_prealloc();
1389
1390         report_hugepages();
1391
1392         hugetlb_sysfs_init();
1393
1394         return 0;
1395 }
1396 module_init(hugetlb_init);
1397
1398 /* Should be called on processing a hugepagesz=... option */
1399 void __init hugetlb_add_hstate(unsigned order)
1400 {
1401         struct hstate *h;
1402         unsigned long i;
1403
1404         if (size_to_hstate(PAGE_SIZE << order)) {
1405                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1406                 return;
1407         }
1408         BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1409         BUG_ON(order == 0);
1410         h = &hstates[max_hstate++];
1411         h->order = order;
1412         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1413         h->nr_huge_pages = 0;
1414         h->free_huge_pages = 0;
1415         for (i = 0; i < MAX_NUMNODES; ++i)
1416                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1417         h->hugetlb_next_nid = first_node(node_online_map);
1418         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1419                                         huge_page_size(h)/1024);
1420
1421         parsed_hstate = h;
1422 }
1423
1424 static int __init hugetlb_nrpages_setup(char *s)
1425 {
1426         unsigned long *mhp;
1427         static unsigned long *last_mhp;
1428
1429         /*
1430          * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1431          * so this hugepages= parameter goes to the "default hstate".
1432          */
1433         if (!max_hstate)
1434                 mhp = &default_hstate_max_huge_pages;
1435         else
1436                 mhp = &parsed_hstate->max_huge_pages;
1437
1438         if (mhp == last_mhp) {
1439                 printk(KERN_WARNING "hugepages= specified twice without "
1440                         "interleaving hugepagesz=, ignoring\n");
1441                 return 1;
1442         }
1443
1444         if (sscanf(s, "%lu", mhp) <= 0)
1445                 *mhp = 0;
1446
1447         /*
1448          * Global state is always initialized later in hugetlb_init.
1449          * But we need to allocate >= MAX_ORDER hstates here early to still
1450          * use the bootmem allocator.
1451          */
1452         if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1453                 hugetlb_hstate_alloc_pages(parsed_hstate);
1454
1455         last_mhp = mhp;
1456
1457         return 1;
1458 }
1459 __setup("hugepages=", hugetlb_nrpages_setup);
1460
1461 static int __init hugetlb_default_setup(char *s)
1462 {
1463         default_hstate_size = memparse(s, &s);
1464         return 1;
1465 }
1466 __setup("default_hugepagesz=", hugetlb_default_setup);
1467
1468 static unsigned int cpuset_mems_nr(unsigned int *array)
1469 {
1470         int node;
1471         unsigned int nr = 0;
1472
1473         for_each_node_mask(node, cpuset_current_mems_allowed)
1474                 nr += array[node];
1475
1476         return nr;
1477 }
1478
1479 #ifdef CONFIG_SYSCTL
1480 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1481                            struct file *file, void __user *buffer,
1482                            size_t *length, loff_t *ppos)
1483 {
1484         struct hstate *h = &default_hstate;
1485         unsigned long tmp;
1486
1487         if (!write)
1488                 tmp = h->max_huge_pages;
1489
1490         table->data = &tmp;
1491         table->maxlen = sizeof(unsigned long);
1492         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1493
1494         if (write)
1495                 h->max_huge_pages = set_max_huge_pages(h, tmp);
1496
1497         return 0;
1498 }
1499
1500 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1501                         struct file *file, void __user *buffer,
1502                         size_t *length, loff_t *ppos)
1503 {
1504         proc_dointvec(table, write, file, buffer, length, ppos);
1505         if (hugepages_treat_as_movable)
1506                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1507         else
1508                 htlb_alloc_mask = GFP_HIGHUSER;
1509         return 0;
1510 }
1511
1512 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1513                         struct file *file, void __user *buffer,
1514                         size_t *length, loff_t *ppos)
1515 {
1516         struct hstate *h = &default_hstate;
1517         unsigned long tmp;
1518
1519         if (!write)
1520                 tmp = h->nr_overcommit_huge_pages;
1521
1522         table->data = &tmp;
1523         table->maxlen = sizeof(unsigned long);
1524         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1525
1526         if (write) {
1527                 spin_lock(&hugetlb_lock);
1528                 h->nr_overcommit_huge_pages = tmp;
1529                 spin_unlock(&hugetlb_lock);
1530         }
1531
1532         return 0;
1533 }
1534
1535 #endif /* CONFIG_SYSCTL */
1536
1537 void hugetlb_report_meminfo(struct seq_file *m)
1538 {
1539         struct hstate *h = &default_hstate;
1540         seq_printf(m,
1541                         "HugePages_Total:   %5lu\n"
1542                         "HugePages_Free:    %5lu\n"
1543                         "HugePages_Rsvd:    %5lu\n"
1544                         "HugePages_Surp:    %5lu\n"
1545                         "Hugepagesize:   %8lu kB\n",
1546                         h->nr_huge_pages,
1547                         h->free_huge_pages,
1548                         h->resv_huge_pages,
1549                         h->surplus_huge_pages,
1550                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1551 }
1552
1553 int hugetlb_report_node_meminfo(int nid, char *buf)
1554 {
1555         struct hstate *h = &default_hstate;
1556         return sprintf(buf,
1557                 "Node %d HugePages_Total: %5u\n"
1558                 "Node %d HugePages_Free:  %5u\n"
1559                 "Node %d HugePages_Surp:  %5u\n",
1560                 nid, h->nr_huge_pages_node[nid],
1561                 nid, h->free_huge_pages_node[nid],
1562                 nid, h->surplus_huge_pages_node[nid]);
1563 }
1564
1565 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1566 unsigned long hugetlb_total_pages(void)
1567 {
1568         struct hstate *h = &default_hstate;
1569         return h->nr_huge_pages * pages_per_huge_page(h);
1570 }
1571
1572 static int hugetlb_acct_memory(struct hstate *h, long delta)
1573 {
1574         int ret = -ENOMEM;
1575
1576         spin_lock(&hugetlb_lock);
1577         /*
1578          * When cpuset is configured, it breaks the strict hugetlb page
1579          * reservation as the accounting is done on a global variable. Such
1580          * reservation is completely rubbish in the presence of cpuset because
1581          * the reservation is not checked against page availability for the
1582          * current cpuset. Application can still potentially OOM'ed by kernel
1583          * with lack of free htlb page in cpuset that the task is in.
1584          * Attempt to enforce strict accounting with cpuset is almost
1585          * impossible (or too ugly) because cpuset is too fluid that
1586          * task or memory node can be dynamically moved between cpusets.
1587          *
1588          * The change of semantics for shared hugetlb mapping with cpuset is
1589          * undesirable. However, in order to preserve some of the semantics,
1590          * we fall back to check against current free page availability as
1591          * a best attempt and hopefully to minimize the impact of changing
1592          * semantics that cpuset has.
1593          */
1594         if (delta > 0) {
1595                 if (gather_surplus_pages(h, delta) < 0)
1596                         goto out;
1597
1598                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1599                         return_unused_surplus_pages(h, delta);
1600                         goto out;
1601                 }
1602         }
1603
1604         ret = 0;
1605         if (delta < 0)
1606                 return_unused_surplus_pages(h, (unsigned long) -delta);
1607
1608 out:
1609         spin_unlock(&hugetlb_lock);
1610         return ret;
1611 }
1612
1613 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
1614 {
1615         struct resv_map *reservations = vma_resv_map(vma);
1616
1617         /*
1618          * This new VMA should share its siblings reservation map if present.
1619          * The VMA will only ever have a valid reservation map pointer where
1620          * it is being copied for another still existing VMA.  As that VMA
1621          * has a reference to the reservation map it cannot dissappear until
1622          * after this open call completes.  It is therefore safe to take a
1623          * new reference here without additional locking.
1624          */
1625         if (reservations)
1626                 kref_get(&reservations->refs);
1627 }
1628
1629 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
1630 {
1631         struct hstate *h = hstate_vma(vma);
1632         struct resv_map *reservations = vma_resv_map(vma);
1633         unsigned long reserve;
1634         unsigned long start;
1635         unsigned long end;
1636
1637         if (reservations) {
1638                 start = vma_hugecache_offset(h, vma, vma->vm_start);
1639                 end = vma_hugecache_offset(h, vma, vma->vm_end);
1640
1641                 reserve = (end - start) -
1642                         region_count(&reservations->regions, start, end);
1643
1644                 kref_put(&reservations->refs, resv_map_release);
1645
1646                 if (reserve) {
1647                         hugetlb_acct_memory(h, -reserve);
1648                         hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
1649                 }
1650         }
1651 }
1652
1653 /*
1654  * We cannot handle pagefaults against hugetlb pages at all.  They cause
1655  * handle_mm_fault() to try to instantiate regular-sized pages in the
1656  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
1657  * this far.
1658  */
1659 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1660 {
1661         BUG();
1662         return 0;
1663 }
1664
1665 struct vm_operations_struct hugetlb_vm_ops = {
1666         .fault = hugetlb_vm_op_fault,
1667         .open = hugetlb_vm_op_open,
1668         .close = hugetlb_vm_op_close,
1669 };
1670
1671 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
1672                                 int writable)
1673 {
1674         pte_t entry;
1675
1676         if (writable) {
1677                 entry =
1678                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
1679         } else {
1680                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
1681         }
1682         entry = pte_mkyoung(entry);
1683         entry = pte_mkhuge(entry);
1684
1685         return entry;
1686 }
1687
1688 static void set_huge_ptep_writable(struct vm_area_struct *vma,
1689                                    unsigned long address, pte_t *ptep)
1690 {
1691         pte_t entry;
1692
1693         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
1694         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
1695                 update_mmu_cache(vma, address, entry);
1696         }
1697 }
1698
1699
1700 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
1701                             struct vm_area_struct *vma)
1702 {
1703         pte_t *src_pte, *dst_pte, entry;
1704         struct page *ptepage;
1705         unsigned long addr;
1706         int cow;
1707         struct hstate *h = hstate_vma(vma);
1708         unsigned long sz = huge_page_size(h);
1709
1710         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
1711
1712         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
1713                 src_pte = huge_pte_offset(src, addr);
1714                 if (!src_pte)
1715                         continue;
1716                 dst_pte = huge_pte_alloc(dst, addr, sz);
1717                 if (!dst_pte)
1718                         goto nomem;
1719
1720                 /* If the pagetables are shared don't copy or take references */
1721                 if (dst_pte == src_pte)
1722                         continue;
1723
1724                 spin_lock(&dst->page_table_lock);
1725                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
1726                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
1727                         if (cow)
1728                                 huge_ptep_set_wrprotect(src, addr, src_pte);
1729                         entry = huge_ptep_get(src_pte);
1730                         ptepage = pte_page(entry);
1731                         get_page(ptepage);
1732                         set_huge_pte_at(dst, addr, dst_pte, entry);
1733                 }
1734                 spin_unlock(&src->page_table_lock);
1735                 spin_unlock(&dst->page_table_lock);
1736         }
1737         return 0;
1738
1739 nomem:
1740         return -ENOMEM;
1741 }
1742
1743 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1744                             unsigned long end, struct page *ref_page)
1745 {
1746         struct mm_struct *mm = vma->vm_mm;
1747         unsigned long address;
1748         pte_t *ptep;
1749         pte_t pte;
1750         struct page *page;
1751         struct page *tmp;
1752         struct hstate *h = hstate_vma(vma);
1753         unsigned long sz = huge_page_size(h);
1754
1755         /*
1756          * A page gathering list, protected by per file i_mmap_lock. The
1757          * lock is used to avoid list corruption from multiple unmapping
1758          * of the same page since we are using page->lru.
1759          */
1760         LIST_HEAD(page_list);
1761
1762         WARN_ON(!is_vm_hugetlb_page(vma));
1763         BUG_ON(start & ~huge_page_mask(h));
1764         BUG_ON(end & ~huge_page_mask(h));
1765
1766         mmu_notifier_invalidate_range_start(mm, start, end);
1767         spin_lock(&mm->page_table_lock);
1768         for (address = start; address < end; address += sz) {
1769                 ptep = huge_pte_offset(mm, address);
1770                 if (!ptep)
1771                         continue;
1772
1773                 if (huge_pmd_unshare(mm, &address, ptep))
1774                         continue;
1775
1776                 /*
1777                  * If a reference page is supplied, it is because a specific
1778                  * page is being unmapped, not a range. Ensure the page we
1779                  * are about to unmap is the actual page of interest.
1780                  */
1781                 if (ref_page) {
1782                         pte = huge_ptep_get(ptep);
1783                         if (huge_pte_none(pte))
1784                                 continue;
1785                         page = pte_page(pte);
1786                         if (page != ref_page)
1787                                 continue;
1788
1789                         /*
1790                          * Mark the VMA as having unmapped its page so that
1791                          * future faults in this VMA will fail rather than
1792                          * looking like data was lost
1793                          */
1794                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
1795                 }
1796
1797                 pte = huge_ptep_get_and_clear(mm, address, ptep);
1798                 if (huge_pte_none(pte))
1799                         continue;
1800
1801                 page = pte_page(pte);
1802                 if (pte_dirty(pte))
1803                         set_page_dirty(page);
1804                 list_add(&page->lru, &page_list);
1805         }
1806         spin_unlock(&mm->page_table_lock);
1807         flush_tlb_range(vma, start, end);
1808         mmu_notifier_invalidate_range_end(mm, start, end);
1809         list_for_each_entry_safe(page, tmp, &page_list, lru) {
1810                 list_del(&page->lru);
1811                 put_page(page);
1812         }
1813 }
1814
1815 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1816                           unsigned long end, struct page *ref_page)
1817 {
1818         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1819         __unmap_hugepage_range(vma, start, end, ref_page);
1820         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1821 }
1822
1823 /*
1824  * This is called when the original mapper is failing to COW a MAP_PRIVATE
1825  * mappping it owns the reserve page for. The intention is to unmap the page
1826  * from other VMAs and let the children be SIGKILLed if they are faulting the
1827  * same region.
1828  */
1829 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
1830                                 struct page *page, unsigned long address)
1831 {
1832         struct hstate *h = hstate_vma(vma);
1833         struct vm_area_struct *iter_vma;
1834         struct address_space *mapping;
1835         struct prio_tree_iter iter;
1836         pgoff_t pgoff;
1837
1838         /*
1839          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1840          * from page cache lookup which is in HPAGE_SIZE units.
1841          */
1842         address = address & huge_page_mask(h);
1843         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1844                 + (vma->vm_pgoff >> PAGE_SHIFT);
1845         mapping = (struct address_space *)page_private(page);
1846
1847         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1848                 /* Do not unmap the current VMA */
1849                 if (iter_vma == vma)
1850                         continue;
1851
1852                 /*
1853                  * Unmap the page from other VMAs without their own reserves.
1854                  * They get marked to be SIGKILLed if they fault in these
1855                  * areas. This is because a future no-page fault on this VMA
1856                  * could insert a zeroed page instead of the data existing
1857                  * from the time of fork. This would look like data corruption
1858                  */
1859                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1860                         unmap_hugepage_range(iter_vma,
1861                                 address, address + huge_page_size(h),
1862                                 page);
1863         }
1864
1865         return 1;
1866 }
1867
1868 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1869                         unsigned long address, pte_t *ptep, pte_t pte,
1870                         struct page *pagecache_page)
1871 {
1872         struct hstate *h = hstate_vma(vma);
1873         struct page *old_page, *new_page;
1874         int avoidcopy;
1875         int outside_reserve = 0;
1876
1877         old_page = pte_page(pte);
1878
1879 retry_avoidcopy:
1880         /* If no-one else is actually using this page, avoid the copy
1881          * and just make the page writable */
1882         avoidcopy = (page_count(old_page) == 1);
1883         if (avoidcopy) {
1884                 set_huge_ptep_writable(vma, address, ptep);
1885                 return 0;
1886         }
1887
1888         /*
1889          * If the process that created a MAP_PRIVATE mapping is about to
1890          * perform a COW due to a shared page count, attempt to satisfy
1891          * the allocation without using the existing reserves. The pagecache
1892          * page is used to determine if the reserve at this address was
1893          * consumed or not. If reserves were used, a partial faulted mapping
1894          * at the time of fork() could consume its reserves on COW instead
1895          * of the full address range.
1896          */
1897         if (!(vma->vm_flags & VM_SHARED) &&
1898                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1899                         old_page != pagecache_page)
1900                 outside_reserve = 1;
1901
1902         page_cache_get(old_page);
1903         new_page = alloc_huge_page(vma, address, outside_reserve);
1904
1905         if (IS_ERR(new_page)) {
1906                 page_cache_release(old_page);
1907
1908                 /*
1909                  * If a process owning a MAP_PRIVATE mapping fails to COW,
1910                  * it is due to references held by a child and an insufficient
1911                  * huge page pool. To guarantee the original mappers
1912                  * reliability, unmap the page from child processes. The child
1913                  * may get SIGKILLed if it later faults.
1914                  */
1915                 if (outside_reserve) {
1916                         BUG_ON(huge_pte_none(pte));
1917                         if (unmap_ref_private(mm, vma, old_page, address)) {
1918                                 BUG_ON(page_count(old_page) != 1);
1919                                 BUG_ON(huge_pte_none(pte));
1920                                 goto retry_avoidcopy;
1921                         }
1922                         WARN_ON_ONCE(1);
1923                 }
1924
1925                 return -PTR_ERR(new_page);
1926         }
1927
1928         spin_unlock(&mm->page_table_lock);
1929         copy_huge_page(new_page, old_page, address, vma);
1930         __SetPageUptodate(new_page);
1931         spin_lock(&mm->page_table_lock);
1932
1933         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
1934         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1935                 /* Break COW */
1936                 huge_ptep_clear_flush(vma, address, ptep);
1937                 set_huge_pte_at(mm, address, ptep,
1938                                 make_huge_pte(vma, new_page, 1));
1939                 /* Make the old page be freed below */
1940                 new_page = old_page;
1941         }
1942         page_cache_release(new_page);
1943         page_cache_release(old_page);
1944         return 0;
1945 }
1946
1947 /* Return the pagecache page at a given address within a VMA */
1948 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
1949                         struct vm_area_struct *vma, unsigned long address)
1950 {
1951         struct address_space *mapping;
1952         pgoff_t idx;
1953
1954         mapping = vma->vm_file->f_mapping;
1955         idx = vma_hugecache_offset(h, vma, address);
1956
1957         return find_lock_page(mapping, idx);
1958 }
1959
1960 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1961                         unsigned long address, pte_t *ptep, int write_access)
1962 {
1963         struct hstate *h = hstate_vma(vma);
1964         int ret = VM_FAULT_SIGBUS;
1965         pgoff_t idx;
1966         unsigned long size;
1967         struct page *page;
1968         struct address_space *mapping;
1969         pte_t new_pte;
1970
1971         /*
1972          * Currently, we are forced to kill the process in the event the
1973          * original mapper has unmapped pages from the child due to a failed
1974          * COW. Warn that such a situation has occured as it may not be obvious
1975          */
1976         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
1977                 printk(KERN_WARNING
1978                         "PID %d killed due to inadequate hugepage pool\n",
1979                         current->pid);
1980                 return ret;
1981         }
1982
1983         mapping = vma->vm_file->f_mapping;
1984         idx = vma_hugecache_offset(h, vma, address);
1985
1986         /*
1987          * Use page lock to guard against racing truncation
1988          * before we get page_table_lock.
1989          */
1990 retry:
1991         page = find_lock_page(mapping, idx);
1992         if (!page) {
1993                 size = i_size_read(mapping->host) >> huge_page_shift(h);
1994                 if (idx >= size)
1995                         goto out;
1996                 page = alloc_huge_page(vma, address, 0);
1997                 if (IS_ERR(page)) {
1998                         ret = -PTR_ERR(page);
1999                         goto out;
2000                 }
2001                 clear_huge_page(page, address, huge_page_size(h));
2002                 __SetPageUptodate(page);
2003
2004                 if (vma->vm_flags & VM_SHARED) {
2005                         int err;
2006                         struct inode *inode = mapping->host;
2007
2008                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2009                         if (err) {
2010                                 put_page(page);
2011                                 if (err == -EEXIST)
2012                                         goto retry;
2013                                 goto out;
2014                         }
2015
2016                         spin_lock(&inode->i_lock);
2017                         inode->i_blocks += blocks_per_huge_page(h);
2018                         spin_unlock(&inode->i_lock);
2019                 } else
2020                         lock_page(page);
2021         }
2022
2023         /*
2024          * If we are going to COW a private mapping later, we examine the
2025          * pending reservations for this page now. This will ensure that
2026          * any allocations necessary to record that reservation occur outside
2027          * the spinlock.
2028          */
2029         if (write_access && !(vma->vm_flags & VM_SHARED))
2030                 if (vma_needs_reservation(h, vma, address) < 0) {
2031                         ret = VM_FAULT_OOM;
2032                         goto backout_unlocked;
2033                 }
2034
2035         spin_lock(&mm->page_table_lock);
2036         size = i_size_read(mapping->host) >> huge_page_shift(h);
2037         if (idx >= size)
2038                 goto backout;
2039
2040         ret = 0;
2041         if (!huge_pte_none(huge_ptep_get(ptep)))
2042                 goto backout;
2043
2044         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2045                                 && (vma->vm_flags & VM_SHARED)));
2046         set_huge_pte_at(mm, address, ptep, new_pte);
2047
2048         if (write_access && !(vma->vm_flags & VM_SHARED)) {
2049                 /* Optimization, do the COW without a second fault */
2050                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2051         }
2052
2053         spin_unlock(&mm->page_table_lock);
2054         unlock_page(page);
2055 out:
2056         return ret;
2057
2058 backout:
2059         spin_unlock(&mm->page_table_lock);
2060 backout_unlocked:
2061         unlock_page(page);
2062         put_page(page);
2063         goto out;
2064 }
2065
2066 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2067                         unsigned long address, int write_access)
2068 {
2069         pte_t *ptep;
2070         pte_t entry;
2071         int ret;
2072         struct page *pagecache_page = NULL;
2073         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2074         struct hstate *h = hstate_vma(vma);
2075
2076         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2077         if (!ptep)
2078                 return VM_FAULT_OOM;
2079
2080         /*
2081          * Serialize hugepage allocation and instantiation, so that we don't
2082          * get spurious allocation failures if two CPUs race to instantiate
2083          * the same page in the page cache.
2084          */
2085         mutex_lock(&hugetlb_instantiation_mutex);
2086         entry = huge_ptep_get(ptep);
2087         if (huge_pte_none(entry)) {
2088                 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
2089                 goto out_mutex;
2090         }
2091
2092         ret = 0;
2093
2094         /*
2095          * If we are going to COW the mapping later, we examine the pending
2096          * reservations for this page now. This will ensure that any
2097          * allocations necessary to record that reservation occur outside the
2098          * spinlock. For private mappings, we also lookup the pagecache
2099          * page now as it is used to determine if a reservation has been
2100          * consumed.
2101          */
2102         if (write_access && !pte_write(entry)) {
2103                 if (vma_needs_reservation(h, vma, address) < 0) {
2104                         ret = VM_FAULT_OOM;
2105                         goto out_mutex;
2106                 }
2107
2108                 if (!(vma->vm_flags & VM_SHARED))
2109                         pagecache_page = hugetlbfs_pagecache_page(h,
2110                                                                 vma, address);
2111         }
2112
2113         spin_lock(&mm->page_table_lock);
2114         /* Check for a racing update before calling hugetlb_cow */
2115         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2116                 goto out_page_table_lock;
2117
2118
2119         if (write_access) {
2120                 if (!pte_write(entry)) {
2121                         ret = hugetlb_cow(mm, vma, address, ptep, entry,
2122                                                         pagecache_page);
2123                         goto out_page_table_lock;
2124                 }
2125                 entry = pte_mkdirty(entry);
2126         }
2127         entry = pte_mkyoung(entry);
2128         if (huge_ptep_set_access_flags(vma, address, ptep, entry, write_access))
2129                 update_mmu_cache(vma, address, entry);
2130
2131 out_page_table_lock:
2132         spin_unlock(&mm->page_table_lock);
2133
2134         if (pagecache_page) {
2135                 unlock_page(pagecache_page);
2136                 put_page(pagecache_page);
2137         }
2138
2139 out_mutex:
2140         mutex_unlock(&hugetlb_instantiation_mutex);
2141
2142         return ret;
2143 }
2144
2145 /* Can be overriden by architectures */
2146 __attribute__((weak)) struct page *
2147 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2148                pud_t *pud, int write)
2149 {
2150         BUG();
2151         return NULL;
2152 }
2153
2154 static int huge_zeropage_ok(pte_t *ptep, int write, int shared)
2155 {
2156         if (!ptep || write || shared)
2157                 return 0;
2158         else
2159                 return huge_pte_none(huge_ptep_get(ptep));
2160 }
2161
2162 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2163                         struct page **pages, struct vm_area_struct **vmas,
2164                         unsigned long *position, int *length, int i,
2165                         int write)
2166 {
2167         unsigned long pfn_offset;
2168         unsigned long vaddr = *position;
2169         int remainder = *length;
2170         struct hstate *h = hstate_vma(vma);
2171         int zeropage_ok = 0;
2172         int shared = vma->vm_flags & VM_SHARED;
2173
2174         spin_lock(&mm->page_table_lock);
2175         while (vaddr < vma->vm_end && remainder) {
2176                 pte_t *pte;
2177                 struct page *page;
2178
2179                 /*
2180                  * Some archs (sparc64, sh*) have multiple pte_ts to
2181                  * each hugepage.  We have to make * sure we get the
2182                  * first, for the page indexing below to work.
2183                  */
2184                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2185                 if (huge_zeropage_ok(pte, write, shared))
2186                         zeropage_ok = 1;
2187
2188                 if (!pte ||
2189                     (huge_pte_none(huge_ptep_get(pte)) && !zeropage_ok) ||
2190                     (write && !pte_write(huge_ptep_get(pte)))) {
2191                         int ret;
2192
2193                         spin_unlock(&mm->page_table_lock);
2194                         ret = hugetlb_fault(mm, vma, vaddr, write);
2195                         spin_lock(&mm->page_table_lock);
2196                         if (!(ret & VM_FAULT_ERROR))
2197                                 continue;
2198
2199                         remainder = 0;
2200                         if (!i)
2201                                 i = -EFAULT;
2202                         break;
2203                 }
2204
2205                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2206                 page = pte_page(huge_ptep_get(pte));
2207 same_page:
2208                 if (pages) {
2209                         if (zeropage_ok)
2210                                 pages[i] = ZERO_PAGE(0);
2211                         else
2212                                 pages[i] = mem_map_offset(page, pfn_offset);
2213                         get_page(pages[i]);
2214                 }
2215
2216                 if (vmas)
2217                         vmas[i] = vma;
2218
2219                 vaddr += PAGE_SIZE;
2220                 ++pfn_offset;
2221                 --remainder;
2222                 ++i;
2223                 if (vaddr < vma->vm_end && remainder &&
2224                                 pfn_offset < pages_per_huge_page(h)) {
2225                         /*
2226                          * We use pfn_offset to avoid touching the pageframes
2227                          * of this compound page.
2228                          */
2229                         goto same_page;
2230                 }
2231         }
2232         spin_unlock(&mm->page_table_lock);
2233         *length = remainder;
2234         *position = vaddr;
2235
2236         return i;
2237 }
2238
2239 void hugetlb_change_protection(struct vm_area_struct *vma,
2240                 unsigned long address, unsigned long end, pgprot_t newprot)
2241 {
2242         struct mm_struct *mm = vma->vm_mm;
2243         unsigned long start = address;
2244         pte_t *ptep;
2245         pte_t pte;
2246         struct hstate *h = hstate_vma(vma);
2247
2248         BUG_ON(address >= end);
2249         flush_cache_range(vma, address, end);
2250
2251         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2252         spin_lock(&mm->page_table_lock);
2253         for (; address < end; address += huge_page_size(h)) {
2254                 ptep = huge_pte_offset(mm, address);
2255                 if (!ptep)
2256                         continue;
2257                 if (huge_pmd_unshare(mm, &address, ptep))
2258                         continue;
2259                 if (!huge_pte_none(huge_ptep_get(ptep))) {
2260                         pte = huge_ptep_get_and_clear(mm, address, ptep);
2261                         pte = pte_mkhuge(pte_modify(pte, newprot));
2262                         set_huge_pte_at(mm, address, ptep, pte);
2263                 }
2264         }
2265         spin_unlock(&mm->page_table_lock);
2266         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2267
2268         flush_tlb_range(vma, start, end);
2269 }
2270
2271 int hugetlb_reserve_pages(struct inode *inode,
2272                                         long from, long to,
2273                                         struct vm_area_struct *vma)
2274 {
2275         long ret, chg;
2276         struct hstate *h = hstate_inode(inode);
2277
2278         if (vma && vma->vm_flags & VM_NORESERVE)
2279                 return 0;
2280
2281         /*
2282          * Shared mappings base their reservation on the number of pages that
2283          * are already allocated on behalf of the file. Private mappings need
2284          * to reserve the full area even if read-only as mprotect() may be
2285          * called to make the mapping read-write. Assume !vma is a shm mapping
2286          */
2287         if (!vma || vma->vm_flags & VM_SHARED)
2288                 chg = region_chg(&inode->i_mapping->private_list, from, to);
2289         else {
2290                 struct resv_map *resv_map = resv_map_alloc();
2291                 if (!resv_map)
2292                         return -ENOMEM;
2293
2294                 chg = to - from;
2295
2296                 set_vma_resv_map(vma, resv_map);
2297                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2298         }
2299
2300         if (chg < 0)
2301                 return chg;
2302
2303         if (hugetlb_get_quota(inode->i_mapping, chg))
2304                 return -ENOSPC;
2305         ret = hugetlb_acct_memory(h, chg);
2306         if (ret < 0) {
2307                 hugetlb_put_quota(inode->i_mapping, chg);
2308                 return ret;
2309         }
2310         if (!vma || vma->vm_flags & VM_SHARED)
2311                 region_add(&inode->i_mapping->private_list, from, to);
2312         return 0;
2313 }
2314
2315 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2316 {
2317         struct hstate *h = hstate_inode(inode);
2318         long chg = region_truncate(&inode->i_mapping->private_list, offset);
2319
2320         spin_lock(&inode->i_lock);
2321         inode->i_blocks -= blocks_per_huge_page(h);
2322         spin_unlock(&inode->i_lock);
2323
2324         hugetlb_put_quota(inode->i_mapping, (chg - freed));
2325         hugetlb_acct_memory(h, -(chg - freed));
2326 }