Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm
[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 <linux/node.h>
28 #include "internal.h"
29
30 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
31 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
32 unsigned long hugepages_treat_as_movable;
33
34 static int max_hstate;
35 unsigned int default_hstate_idx;
36 struct hstate hstates[HUGE_MAX_HSTATE];
37
38 __initdata LIST_HEAD(huge_boot_pages);
39
40 /* for command line parsing */
41 static struct hstate * __initdata parsed_hstate;
42 static unsigned long __initdata default_hstate_max_huge_pages;
43 static unsigned long __initdata default_hstate_size;
44
45 #define for_each_hstate(h) \
46         for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
47
48 /*
49  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
50  */
51 static DEFINE_SPINLOCK(hugetlb_lock);
52
53 /*
54  * Region tracking -- allows tracking of reservations and instantiated pages
55  *                    across the pages in a mapping.
56  *
57  * The region data structures are protected by a combination of the mmap_sem
58  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
59  * must either hold the mmap_sem for write, or the mmap_sem for read and
60  * the hugetlb_instantiation mutex:
61  *
62  *      down_write(&mm->mmap_sem);
63  * or
64  *      down_read(&mm->mmap_sem);
65  *      mutex_lock(&hugetlb_instantiation_mutex);
66  */
67 struct file_region {
68         struct list_head link;
69         long from;
70         long to;
71 };
72
73 static long region_add(struct list_head *head, long f, long t)
74 {
75         struct file_region *rg, *nrg, *trg;
76
77         /* Locate the region we are either in or before. */
78         list_for_each_entry(rg, head, link)
79                 if (f <= rg->to)
80                         break;
81
82         /* Round our left edge to the current segment if it encloses us. */
83         if (f > rg->from)
84                 f = rg->from;
85
86         /* Check for and consume any regions we now overlap with. */
87         nrg = rg;
88         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
89                 if (&rg->link == head)
90                         break;
91                 if (rg->from > t)
92                         break;
93
94                 /* If this area reaches higher then extend our area to
95                  * include it completely.  If this is not the first area
96                  * which we intend to reuse, free it. */
97                 if (rg->to > t)
98                         t = rg->to;
99                 if (rg != nrg) {
100                         list_del(&rg->link);
101                         kfree(rg);
102                 }
103         }
104         nrg->from = f;
105         nrg->to = t;
106         return 0;
107 }
108
109 static long region_chg(struct list_head *head, long f, long t)
110 {
111         struct file_region *rg, *nrg;
112         long chg = 0;
113
114         /* Locate the region we are before or in. */
115         list_for_each_entry(rg, head, link)
116                 if (f <= rg->to)
117                         break;
118
119         /* If we are below the current region then a new region is required.
120          * Subtle, allocate a new region at the position but make it zero
121          * size such that we can guarantee to record the reservation. */
122         if (&rg->link == head || t < rg->from) {
123                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
124                 if (!nrg)
125                         return -ENOMEM;
126                 nrg->from = f;
127                 nrg->to   = f;
128                 INIT_LIST_HEAD(&nrg->link);
129                 list_add(&nrg->link, rg->link.prev);
130
131                 return t - f;
132         }
133
134         /* Round our left edge to the current segment if it encloses us. */
135         if (f > rg->from)
136                 f = rg->from;
137         chg = t - f;
138
139         /* Check for and consume any regions we now overlap with. */
140         list_for_each_entry(rg, rg->link.prev, link) {
141                 if (&rg->link == head)
142                         break;
143                 if (rg->from > t)
144                         return chg;
145
146                 /* We overlap with this area, if it extends futher than
147                  * us then we must extend ourselves.  Account for its
148                  * existing reservation. */
149                 if (rg->to > t) {
150                         chg += rg->to - t;
151                         t = rg->to;
152                 }
153                 chg -= rg->to - rg->from;
154         }
155         return chg;
156 }
157
158 static long region_truncate(struct list_head *head, long end)
159 {
160         struct file_region *rg, *trg;
161         long chg = 0;
162
163         /* Locate the region we are either in or before. */
164         list_for_each_entry(rg, head, link)
165                 if (end <= rg->to)
166                         break;
167         if (&rg->link == head)
168                 return 0;
169
170         /* If we are in the middle of a region then adjust it. */
171         if (end > rg->from) {
172                 chg = rg->to - end;
173                 rg->to = end;
174                 rg = list_entry(rg->link.next, typeof(*rg), link);
175         }
176
177         /* Drop any remaining regions. */
178         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
179                 if (&rg->link == head)
180                         break;
181                 chg += rg->to - rg->from;
182                 list_del(&rg->link);
183                 kfree(rg);
184         }
185         return chg;
186 }
187
188 static long region_count(struct list_head *head, long f, long t)
189 {
190         struct file_region *rg;
191         long chg = 0;
192
193         /* Locate each segment we overlap with, and count that overlap. */
194         list_for_each_entry(rg, head, link) {
195                 int seg_from;
196                 int seg_to;
197
198                 if (rg->to <= f)
199                         continue;
200                 if (rg->from >= t)
201                         break;
202
203                 seg_from = max(rg->from, f);
204                 seg_to = min(rg->to, t);
205
206                 chg += seg_to - seg_from;
207         }
208
209         return chg;
210 }
211
212 /*
213  * Convert the address within this vma to the page offset within
214  * the mapping, in pagecache page units; huge pages here.
215  */
216 static pgoff_t vma_hugecache_offset(struct hstate *h,
217                         struct vm_area_struct *vma, unsigned long address)
218 {
219         return ((address - vma->vm_start) >> huge_page_shift(h)) +
220                         (vma->vm_pgoff >> huge_page_order(h));
221 }
222
223 /*
224  * Return the size of the pages allocated when backing a VMA. In the majority
225  * cases this will be same size as used by the page table entries.
226  */
227 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
228 {
229         struct hstate *hstate;
230
231         if (!is_vm_hugetlb_page(vma))
232                 return PAGE_SIZE;
233
234         hstate = hstate_vma(vma);
235
236         return 1UL << (hstate->order + PAGE_SHIFT);
237 }
238 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
239
240 /*
241  * Return the page size being used by the MMU to back a VMA. In the majority
242  * of cases, the page size used by the kernel matches the MMU size. On
243  * architectures where it differs, an architecture-specific version of this
244  * function is required.
245  */
246 #ifndef vma_mmu_pagesize
247 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
248 {
249         return vma_kernel_pagesize(vma);
250 }
251 #endif
252
253 /*
254  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
255  * bits of the reservation map pointer, which are always clear due to
256  * alignment.
257  */
258 #define HPAGE_RESV_OWNER    (1UL << 0)
259 #define HPAGE_RESV_UNMAPPED (1UL << 1)
260 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
261
262 /*
263  * These helpers are used to track how many pages are reserved for
264  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
265  * is guaranteed to have their future faults succeed.
266  *
267  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
268  * the reserve counters are updated with the hugetlb_lock held. It is safe
269  * to reset the VMA at fork() time as it is not in use yet and there is no
270  * chance of the global counters getting corrupted as a result of the values.
271  *
272  * The private mapping reservation is represented in a subtly different
273  * manner to a shared mapping.  A shared mapping has a region map associated
274  * with the underlying file, this region map represents the backing file
275  * pages which have ever had a reservation assigned which this persists even
276  * after the page is instantiated.  A private mapping has a region map
277  * associated with the original mmap which is attached to all VMAs which
278  * reference it, this region map represents those offsets which have consumed
279  * reservation ie. where pages have been instantiated.
280  */
281 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
282 {
283         return (unsigned long)vma->vm_private_data;
284 }
285
286 static void set_vma_private_data(struct vm_area_struct *vma,
287                                                         unsigned long value)
288 {
289         vma->vm_private_data = (void *)value;
290 }
291
292 struct resv_map {
293         struct kref refs;
294         struct list_head regions;
295 };
296
297 static struct resv_map *resv_map_alloc(void)
298 {
299         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
300         if (!resv_map)
301                 return NULL;
302
303         kref_init(&resv_map->refs);
304         INIT_LIST_HEAD(&resv_map->regions);
305
306         return resv_map;
307 }
308
309 static void resv_map_release(struct kref *ref)
310 {
311         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
312
313         /* Clear out any active regions before we release the map. */
314         region_truncate(&resv_map->regions, 0);
315         kfree(resv_map);
316 }
317
318 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
319 {
320         VM_BUG_ON(!is_vm_hugetlb_page(vma));
321         if (!(vma->vm_flags & VM_MAYSHARE))
322                 return (struct resv_map *)(get_vma_private_data(vma) &
323                                                         ~HPAGE_RESV_MASK);
324         return NULL;
325 }
326
327 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
328 {
329         VM_BUG_ON(!is_vm_hugetlb_page(vma));
330         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
331
332         set_vma_private_data(vma, (get_vma_private_data(vma) &
333                                 HPAGE_RESV_MASK) | (unsigned long)map);
334 }
335
336 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
337 {
338         VM_BUG_ON(!is_vm_hugetlb_page(vma));
339         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
340
341         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
342 }
343
344 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
345 {
346         VM_BUG_ON(!is_vm_hugetlb_page(vma));
347
348         return (get_vma_private_data(vma) & flag) != 0;
349 }
350
351 /* Decrement the reserved pages in the hugepage pool by one */
352 static void decrement_hugepage_resv_vma(struct hstate *h,
353                         struct vm_area_struct *vma)
354 {
355         if (vma->vm_flags & VM_NORESERVE)
356                 return;
357
358         if (vma->vm_flags & VM_MAYSHARE) {
359                 /* Shared mappings always use reserves */
360                 h->resv_huge_pages--;
361         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
362                 /*
363                  * Only the process that called mmap() has reserves for
364                  * private mappings.
365                  */
366                 h->resv_huge_pages--;
367         }
368 }
369
370 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
371 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
372 {
373         VM_BUG_ON(!is_vm_hugetlb_page(vma));
374         if (!(vma->vm_flags & VM_MAYSHARE))
375                 vma->vm_private_data = (void *)0;
376 }
377
378 /* Returns true if the VMA has associated reserve pages */
379 static int vma_has_reserves(struct vm_area_struct *vma)
380 {
381         if (vma->vm_flags & VM_MAYSHARE)
382                 return 1;
383         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
384                 return 1;
385         return 0;
386 }
387
388 static void clear_gigantic_page(struct page *page,
389                         unsigned long addr, unsigned long sz)
390 {
391         int i;
392         struct page *p = page;
393
394         might_sleep();
395         for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
396                 cond_resched();
397                 clear_user_highpage(p, addr + i * PAGE_SIZE);
398         }
399 }
400 static void clear_huge_page(struct page *page,
401                         unsigned long addr, unsigned long sz)
402 {
403         int i;
404
405         if (unlikely(sz/PAGE_SIZE > MAX_ORDER_NR_PAGES)) {
406                 clear_gigantic_page(page, addr, sz);
407                 return;
408         }
409
410         might_sleep();
411         for (i = 0; i < sz/PAGE_SIZE; i++) {
412                 cond_resched();
413                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
414         }
415 }
416
417 static void copy_gigantic_page(struct page *dst, struct page *src,
418                            unsigned long addr, struct vm_area_struct *vma)
419 {
420         int i;
421         struct hstate *h = hstate_vma(vma);
422         struct page *dst_base = dst;
423         struct page *src_base = src;
424         might_sleep();
425         for (i = 0; i < pages_per_huge_page(h); ) {
426                 cond_resched();
427                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
428
429                 i++;
430                 dst = mem_map_next(dst, dst_base, i);
431                 src = mem_map_next(src, src_base, i);
432         }
433 }
434 static void copy_huge_page(struct page *dst, struct page *src,
435                            unsigned long addr, struct vm_area_struct *vma)
436 {
437         int i;
438         struct hstate *h = hstate_vma(vma);
439
440         if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
441                 copy_gigantic_page(dst, src, addr, vma);
442                 return;
443         }
444
445         might_sleep();
446         for (i = 0; i < pages_per_huge_page(h); i++) {
447                 cond_resched();
448                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
449         }
450 }
451
452 static void enqueue_huge_page(struct hstate *h, struct page *page)
453 {
454         int nid = page_to_nid(page);
455         list_add(&page->lru, &h->hugepage_freelists[nid]);
456         h->free_huge_pages++;
457         h->free_huge_pages_node[nid]++;
458 }
459
460 static struct page *dequeue_huge_page_vma(struct hstate *h,
461                                 struct vm_area_struct *vma,
462                                 unsigned long address, int avoid_reserve)
463 {
464         int nid;
465         struct page *page = NULL;
466         struct mempolicy *mpol;
467         nodemask_t *nodemask;
468         struct zonelist *zonelist = huge_zonelist(vma, address,
469                                         htlb_alloc_mask, &mpol, &nodemask);
470         struct zone *zone;
471         struct zoneref *z;
472
473         /*
474          * A child process with MAP_PRIVATE mappings created by their parent
475          * have no page reserves. This check ensures that reservations are
476          * not "stolen". The child may still get SIGKILLed
477          */
478         if (!vma_has_reserves(vma) &&
479                         h->free_huge_pages - h->resv_huge_pages == 0)
480                 return NULL;
481
482         /* If reserves cannot be used, ensure enough pages are in the pool */
483         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
484                 return NULL;
485
486         for_each_zone_zonelist_nodemask(zone, z, zonelist,
487                                                 MAX_NR_ZONES - 1, nodemask) {
488                 nid = zone_to_nid(zone);
489                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
490                     !list_empty(&h->hugepage_freelists[nid])) {
491                         page = list_entry(h->hugepage_freelists[nid].next,
492                                           struct page, lru);
493                         list_del(&page->lru);
494                         h->free_huge_pages--;
495                         h->free_huge_pages_node[nid]--;
496
497                         if (!avoid_reserve)
498                                 decrement_hugepage_resv_vma(h, vma);
499
500                         break;
501                 }
502         }
503         mpol_cond_put(mpol);
504         return page;
505 }
506
507 static void update_and_free_page(struct hstate *h, struct page *page)
508 {
509         int i;
510
511         VM_BUG_ON(h->order >= MAX_ORDER);
512
513         h->nr_huge_pages--;
514         h->nr_huge_pages_node[page_to_nid(page)]--;
515         for (i = 0; i < pages_per_huge_page(h); i++) {
516                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
517                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
518                                 1 << PG_private | 1<< PG_writeback);
519         }
520         set_compound_page_dtor(page, NULL);
521         set_page_refcounted(page);
522         arch_release_hugepage(page);
523         __free_pages(page, huge_page_order(h));
524 }
525
526 struct hstate *size_to_hstate(unsigned long size)
527 {
528         struct hstate *h;
529
530         for_each_hstate(h) {
531                 if (huge_page_size(h) == size)
532                         return h;
533         }
534         return NULL;
535 }
536
537 static void free_huge_page(struct page *page)
538 {
539         /*
540          * Can't pass hstate in here because it is called from the
541          * compound page destructor.
542          */
543         struct hstate *h = page_hstate(page);
544         int nid = page_to_nid(page);
545         struct address_space *mapping;
546
547         mapping = (struct address_space *) page_private(page);
548         set_page_private(page, 0);
549         BUG_ON(page_count(page));
550         INIT_LIST_HEAD(&page->lru);
551
552         spin_lock(&hugetlb_lock);
553         if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
554                 update_and_free_page(h, page);
555                 h->surplus_huge_pages--;
556                 h->surplus_huge_pages_node[nid]--;
557         } else {
558                 enqueue_huge_page(h, page);
559         }
560         spin_unlock(&hugetlb_lock);
561         if (mapping)
562                 hugetlb_put_quota(mapping, 1);
563 }
564
565 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
566 {
567         set_compound_page_dtor(page, free_huge_page);
568         spin_lock(&hugetlb_lock);
569         h->nr_huge_pages++;
570         h->nr_huge_pages_node[nid]++;
571         spin_unlock(&hugetlb_lock);
572         put_page(page); /* free it into the hugepage allocator */
573 }
574
575 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
576 {
577         int i;
578         int nr_pages = 1 << order;
579         struct page *p = page + 1;
580
581         /* we rely on prep_new_huge_page to set the destructor */
582         set_compound_order(page, order);
583         __SetPageHead(page);
584         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
585                 __SetPageTail(p);
586                 p->first_page = page;
587         }
588 }
589
590 int PageHuge(struct page *page)
591 {
592         compound_page_dtor *dtor;
593
594         if (!PageCompound(page))
595                 return 0;
596
597         page = compound_head(page);
598         dtor = get_compound_page_dtor(page);
599
600         return dtor == free_huge_page;
601 }
602
603 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
604 {
605         struct page *page;
606
607         if (h->order >= MAX_ORDER)
608                 return NULL;
609
610         page = alloc_pages_exact_node(nid,
611                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
612                                                 __GFP_REPEAT|__GFP_NOWARN,
613                 huge_page_order(h));
614         if (page) {
615                 if (arch_prepare_hugepage(page)) {
616                         __free_pages(page, huge_page_order(h));
617                         return NULL;
618                 }
619                 prep_new_huge_page(h, page, nid);
620         }
621
622         return page;
623 }
624
625 /*
626  * common helper functions for hstate_next_node_to_{alloc|free}.
627  * We may have allocated or freed a huge page based on a different
628  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
629  * be outside of *nodes_allowed.  Ensure that we use an allowed
630  * node for alloc or free.
631  */
632 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
633 {
634         nid = next_node(nid, *nodes_allowed);
635         if (nid == MAX_NUMNODES)
636                 nid = first_node(*nodes_allowed);
637         VM_BUG_ON(nid >= MAX_NUMNODES);
638
639         return nid;
640 }
641
642 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
643 {
644         if (!node_isset(nid, *nodes_allowed))
645                 nid = next_node_allowed(nid, nodes_allowed);
646         return nid;
647 }
648
649 /*
650  * returns the previously saved node ["this node"] from which to
651  * allocate a persistent huge page for the pool and advance the
652  * next node from which to allocate, handling wrap at end of node
653  * mask.
654  */
655 static int hstate_next_node_to_alloc(struct hstate *h,
656                                         nodemask_t *nodes_allowed)
657 {
658         int nid;
659
660         VM_BUG_ON(!nodes_allowed);
661
662         nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
663         h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
664
665         return nid;
666 }
667
668 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
669 {
670         struct page *page;
671         int start_nid;
672         int next_nid;
673         int ret = 0;
674
675         start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
676         next_nid = start_nid;
677
678         do {
679                 page = alloc_fresh_huge_page_node(h, next_nid);
680                 if (page) {
681                         ret = 1;
682                         break;
683                 }
684                 next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
685         } while (next_nid != start_nid);
686
687         if (ret)
688                 count_vm_event(HTLB_BUDDY_PGALLOC);
689         else
690                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
691
692         return ret;
693 }
694
695 /*
696  * helper for free_pool_huge_page() - return the previously saved
697  * node ["this node"] from which to free a huge page.  Advance the
698  * next node id whether or not we find a free huge page to free so
699  * that the next attempt to free addresses the next node.
700  */
701 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
702 {
703         int nid;
704
705         VM_BUG_ON(!nodes_allowed);
706
707         nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
708         h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
709
710         return nid;
711 }
712
713 /*
714  * Free huge page from pool from next node to free.
715  * Attempt to keep persistent huge pages more or less
716  * balanced over allowed nodes.
717  * Called with hugetlb_lock locked.
718  */
719 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
720                                                          bool acct_surplus)
721 {
722         int start_nid;
723         int next_nid;
724         int ret = 0;
725
726         start_nid = hstate_next_node_to_free(h, nodes_allowed);
727         next_nid = start_nid;
728
729         do {
730                 /*
731                  * If we're returning unused surplus pages, only examine
732                  * nodes with surplus pages.
733                  */
734                 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
735                     !list_empty(&h->hugepage_freelists[next_nid])) {
736                         struct page *page =
737                                 list_entry(h->hugepage_freelists[next_nid].next,
738                                           struct page, lru);
739                         list_del(&page->lru);
740                         h->free_huge_pages--;
741                         h->free_huge_pages_node[next_nid]--;
742                         if (acct_surplus) {
743                                 h->surplus_huge_pages--;
744                                 h->surplus_huge_pages_node[next_nid]--;
745                         }
746                         update_and_free_page(h, page);
747                         ret = 1;
748                         break;
749                 }
750                 next_nid = hstate_next_node_to_free(h, nodes_allowed);
751         } while (next_nid != start_nid);
752
753         return ret;
754 }
755
756 static struct page *alloc_buddy_huge_page(struct hstate *h,
757                         struct vm_area_struct *vma, unsigned long address)
758 {
759         struct page *page;
760         unsigned int nid;
761
762         if (h->order >= MAX_ORDER)
763                 return NULL;
764
765         /*
766          * Assume we will successfully allocate the surplus page to
767          * prevent racing processes from causing the surplus to exceed
768          * overcommit
769          *
770          * This however introduces a different race, where a process B
771          * tries to grow the static hugepage pool while alloc_pages() is
772          * called by process A. B will only examine the per-node
773          * counters in determining if surplus huge pages can be
774          * converted to normal huge pages in adjust_pool_surplus(). A
775          * won't be able to increment the per-node counter, until the
776          * lock is dropped by B, but B doesn't drop hugetlb_lock until
777          * no more huge pages can be converted from surplus to normal
778          * state (and doesn't try to convert again). Thus, we have a
779          * case where a surplus huge page exists, the pool is grown, and
780          * the surplus huge page still exists after, even though it
781          * should just have been converted to a normal huge page. This
782          * does not leak memory, though, as the hugepage will be freed
783          * once it is out of use. It also does not allow the counters to
784          * go out of whack in adjust_pool_surplus() as we don't modify
785          * the node values until we've gotten the hugepage and only the
786          * per-node value is checked there.
787          */
788         spin_lock(&hugetlb_lock);
789         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
790                 spin_unlock(&hugetlb_lock);
791                 return NULL;
792         } else {
793                 h->nr_huge_pages++;
794                 h->surplus_huge_pages++;
795         }
796         spin_unlock(&hugetlb_lock);
797
798         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
799                                         __GFP_REPEAT|__GFP_NOWARN,
800                                         huge_page_order(h));
801
802         if (page && arch_prepare_hugepage(page)) {
803                 __free_pages(page, huge_page_order(h));
804                 return NULL;
805         }
806
807         spin_lock(&hugetlb_lock);
808         if (page) {
809                 /*
810                  * This page is now managed by the hugetlb allocator and has
811                  * no users -- drop the buddy allocator's reference.
812                  */
813                 put_page_testzero(page);
814                 VM_BUG_ON(page_count(page));
815                 nid = page_to_nid(page);
816                 set_compound_page_dtor(page, free_huge_page);
817                 /*
818                  * We incremented the global counters already
819                  */
820                 h->nr_huge_pages_node[nid]++;
821                 h->surplus_huge_pages_node[nid]++;
822                 __count_vm_event(HTLB_BUDDY_PGALLOC);
823         } else {
824                 h->nr_huge_pages--;
825                 h->surplus_huge_pages--;
826                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
827         }
828         spin_unlock(&hugetlb_lock);
829
830         return page;
831 }
832
833 /*
834  * Increase the hugetlb pool such that it can accomodate a reservation
835  * of size 'delta'.
836  */
837 static int gather_surplus_pages(struct hstate *h, int delta)
838 {
839         struct list_head surplus_list;
840         struct page *page, *tmp;
841         int ret, i;
842         int needed, allocated;
843
844         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
845         if (needed <= 0) {
846                 h->resv_huge_pages += delta;
847                 return 0;
848         }
849
850         allocated = 0;
851         INIT_LIST_HEAD(&surplus_list);
852
853         ret = -ENOMEM;
854 retry:
855         spin_unlock(&hugetlb_lock);
856         for (i = 0; i < needed; i++) {
857                 page = alloc_buddy_huge_page(h, NULL, 0);
858                 if (!page) {
859                         /*
860                          * We were not able to allocate enough pages to
861                          * satisfy the entire reservation so we free what
862                          * we've allocated so far.
863                          */
864                         spin_lock(&hugetlb_lock);
865                         needed = 0;
866                         goto free;
867                 }
868
869                 list_add(&page->lru, &surplus_list);
870         }
871         allocated += needed;
872
873         /*
874          * After retaking hugetlb_lock, we need to recalculate 'needed'
875          * because either resv_huge_pages or free_huge_pages may have changed.
876          */
877         spin_lock(&hugetlb_lock);
878         needed = (h->resv_huge_pages + delta) -
879                         (h->free_huge_pages + allocated);
880         if (needed > 0)
881                 goto retry;
882
883         /*
884          * The surplus_list now contains _at_least_ the number of extra pages
885          * needed to accomodate the reservation.  Add the appropriate number
886          * of pages to the hugetlb pool and free the extras back to the buddy
887          * allocator.  Commit the entire reservation here to prevent another
888          * process from stealing the pages as they are added to the pool but
889          * before they are reserved.
890          */
891         needed += allocated;
892         h->resv_huge_pages += delta;
893         ret = 0;
894 free:
895         /* Free the needed pages to the hugetlb pool */
896         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
897                 if ((--needed) < 0)
898                         break;
899                 list_del(&page->lru);
900                 enqueue_huge_page(h, page);
901         }
902
903         /* Free unnecessary surplus pages to the buddy allocator */
904         if (!list_empty(&surplus_list)) {
905                 spin_unlock(&hugetlb_lock);
906                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
907                         list_del(&page->lru);
908                         /*
909                          * The page has a reference count of zero already, so
910                          * call free_huge_page directly instead of using
911                          * put_page.  This must be done with hugetlb_lock
912                          * unlocked which is safe because free_huge_page takes
913                          * hugetlb_lock before deciding how to free the page.
914                          */
915                         free_huge_page(page);
916                 }
917                 spin_lock(&hugetlb_lock);
918         }
919
920         return ret;
921 }
922
923 /*
924  * When releasing a hugetlb pool reservation, any surplus pages that were
925  * allocated to satisfy the reservation must be explicitly freed if they were
926  * never used.
927  * Called with hugetlb_lock held.
928  */
929 static void return_unused_surplus_pages(struct hstate *h,
930                                         unsigned long unused_resv_pages)
931 {
932         unsigned long nr_pages;
933
934         /* Uncommit the reservation */
935         h->resv_huge_pages -= unused_resv_pages;
936
937         /* Cannot return gigantic pages currently */
938         if (h->order >= MAX_ORDER)
939                 return;
940
941         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
942
943         /*
944          * We want to release as many surplus pages as possible, spread
945          * evenly across all nodes with memory. Iterate across these nodes
946          * until we can no longer free unreserved surplus pages. This occurs
947          * when the nodes with surplus pages have no free pages.
948          * free_pool_huge_page() will balance the the freed pages across the
949          * on-line nodes with memory and will handle the hstate accounting.
950          */
951         while (nr_pages--) {
952                 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
953                         break;
954         }
955 }
956
957 /*
958  * Determine if the huge page at addr within the vma has an associated
959  * reservation.  Where it does not we will need to logically increase
960  * reservation and actually increase quota before an allocation can occur.
961  * Where any new reservation would be required the reservation change is
962  * prepared, but not committed.  Once the page has been quota'd allocated
963  * an instantiated the change should be committed via vma_commit_reservation.
964  * No action is required on failure.
965  */
966 static long vma_needs_reservation(struct hstate *h,
967                         struct vm_area_struct *vma, unsigned long addr)
968 {
969         struct address_space *mapping = vma->vm_file->f_mapping;
970         struct inode *inode = mapping->host;
971
972         if (vma->vm_flags & VM_MAYSHARE) {
973                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
974                 return region_chg(&inode->i_mapping->private_list,
975                                                         idx, idx + 1);
976
977         } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
978                 return 1;
979
980         } else  {
981                 long err;
982                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
983                 struct resv_map *reservations = vma_resv_map(vma);
984
985                 err = region_chg(&reservations->regions, idx, idx + 1);
986                 if (err < 0)
987                         return err;
988                 return 0;
989         }
990 }
991 static void vma_commit_reservation(struct hstate *h,
992                         struct vm_area_struct *vma, unsigned long addr)
993 {
994         struct address_space *mapping = vma->vm_file->f_mapping;
995         struct inode *inode = mapping->host;
996
997         if (vma->vm_flags & VM_MAYSHARE) {
998                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
999                 region_add(&inode->i_mapping->private_list, idx, idx + 1);
1000
1001         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1002                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1003                 struct resv_map *reservations = vma_resv_map(vma);
1004
1005                 /* Mark this page used in the map. */
1006                 region_add(&reservations->regions, idx, idx + 1);
1007         }
1008 }
1009
1010 static struct page *alloc_huge_page(struct vm_area_struct *vma,
1011                                     unsigned long addr, int avoid_reserve)
1012 {
1013         struct hstate *h = hstate_vma(vma);
1014         struct page *page;
1015         struct address_space *mapping = vma->vm_file->f_mapping;
1016         struct inode *inode = mapping->host;
1017         long chg;
1018
1019         /*
1020          * Processes that did not create the mapping will have no reserves and
1021          * will not have accounted against quota. Check that the quota can be
1022          * made before satisfying the allocation
1023          * MAP_NORESERVE mappings may also need pages and quota allocated
1024          * if no reserve mapping overlaps.
1025          */
1026         chg = vma_needs_reservation(h, vma, addr);
1027         if (chg < 0)
1028                 return ERR_PTR(chg);
1029         if (chg)
1030                 if (hugetlb_get_quota(inode->i_mapping, chg))
1031                         return ERR_PTR(-ENOSPC);
1032
1033         spin_lock(&hugetlb_lock);
1034         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
1035         spin_unlock(&hugetlb_lock);
1036
1037         if (!page) {
1038                 page = alloc_buddy_huge_page(h, vma, addr);
1039                 if (!page) {
1040                         hugetlb_put_quota(inode->i_mapping, chg);
1041                         return ERR_PTR(-VM_FAULT_OOM);
1042                 }
1043         }
1044
1045         set_page_refcounted(page);
1046         set_page_private(page, (unsigned long) mapping);
1047
1048         vma_commit_reservation(h, vma, addr);
1049
1050         return page;
1051 }
1052
1053 int __weak alloc_bootmem_huge_page(struct hstate *h)
1054 {
1055         struct huge_bootmem_page *m;
1056         int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
1057
1058         while (nr_nodes) {
1059                 void *addr;
1060
1061                 addr = __alloc_bootmem_node_nopanic(
1062                                 NODE_DATA(hstate_next_node_to_alloc(h,
1063                                                 &node_states[N_HIGH_MEMORY])),
1064                                 huge_page_size(h), huge_page_size(h), 0);
1065
1066                 if (addr) {
1067                         /*
1068                          * Use the beginning of the huge page to store the
1069                          * huge_bootmem_page struct (until gather_bootmem
1070                          * puts them into the mem_map).
1071                          */
1072                         m = addr;
1073                         goto found;
1074                 }
1075                 nr_nodes--;
1076         }
1077         return 0;
1078
1079 found:
1080         BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1081         /* Put them into a private list first because mem_map is not up yet */
1082         list_add(&m->list, &huge_boot_pages);
1083         m->hstate = h;
1084         return 1;
1085 }
1086
1087 static void prep_compound_huge_page(struct page *page, int order)
1088 {
1089         if (unlikely(order > (MAX_ORDER - 1)))
1090                 prep_compound_gigantic_page(page, order);
1091         else
1092                 prep_compound_page(page, order);
1093 }
1094
1095 /* Put bootmem huge pages into the standard lists after mem_map is up */
1096 static void __init gather_bootmem_prealloc(void)
1097 {
1098         struct huge_bootmem_page *m;
1099
1100         list_for_each_entry(m, &huge_boot_pages, list) {
1101                 struct page *page = virt_to_page(m);
1102                 struct hstate *h = m->hstate;
1103                 __ClearPageReserved(page);
1104                 WARN_ON(page_count(page) != 1);
1105                 prep_compound_huge_page(page, h->order);
1106                 prep_new_huge_page(h, page, page_to_nid(page));
1107         }
1108 }
1109
1110 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1111 {
1112         unsigned long i;
1113
1114         for (i = 0; i < h->max_huge_pages; ++i) {
1115                 if (h->order >= MAX_ORDER) {
1116                         if (!alloc_bootmem_huge_page(h))
1117                                 break;
1118                 } else if (!alloc_fresh_huge_page(h,
1119                                          &node_states[N_HIGH_MEMORY]))
1120                         break;
1121         }
1122         h->max_huge_pages = i;
1123 }
1124
1125 static void __init hugetlb_init_hstates(void)
1126 {
1127         struct hstate *h;
1128
1129         for_each_hstate(h) {
1130                 /* oversize hugepages were init'ed in early boot */
1131                 if (h->order < MAX_ORDER)
1132                         hugetlb_hstate_alloc_pages(h);
1133         }
1134 }
1135
1136 static char * __init memfmt(char *buf, unsigned long n)
1137 {
1138         if (n >= (1UL << 30))
1139                 sprintf(buf, "%lu GB", n >> 30);
1140         else if (n >= (1UL << 20))
1141                 sprintf(buf, "%lu MB", n >> 20);
1142         else
1143                 sprintf(buf, "%lu KB", n >> 10);
1144         return buf;
1145 }
1146
1147 static void __init report_hugepages(void)
1148 {
1149         struct hstate *h;
1150
1151         for_each_hstate(h) {
1152                 char buf[32];
1153                 printk(KERN_INFO "HugeTLB registered %s page size, "
1154                                  "pre-allocated %ld pages\n",
1155                         memfmt(buf, huge_page_size(h)),
1156                         h->free_huge_pages);
1157         }
1158 }
1159
1160 #ifdef CONFIG_HIGHMEM
1161 static void try_to_free_low(struct hstate *h, unsigned long count,
1162                                                 nodemask_t *nodes_allowed)
1163 {
1164         int i;
1165
1166         if (h->order >= MAX_ORDER)
1167                 return;
1168
1169         for_each_node_mask(i, *nodes_allowed) {
1170                 struct page *page, *next;
1171                 struct list_head *freel = &h->hugepage_freelists[i];
1172                 list_for_each_entry_safe(page, next, freel, lru) {
1173                         if (count >= h->nr_huge_pages)
1174                                 return;
1175                         if (PageHighMem(page))
1176                                 continue;
1177                         list_del(&page->lru);
1178                         update_and_free_page(h, page);
1179                         h->free_huge_pages--;
1180                         h->free_huge_pages_node[page_to_nid(page)]--;
1181                 }
1182         }
1183 }
1184 #else
1185 static inline void try_to_free_low(struct hstate *h, unsigned long count,
1186                                                 nodemask_t *nodes_allowed)
1187 {
1188 }
1189 #endif
1190
1191 /*
1192  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1193  * balanced by operating on them in a round-robin fashion.
1194  * Returns 1 if an adjustment was made.
1195  */
1196 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1197                                 int delta)
1198 {
1199         int start_nid, next_nid;
1200         int ret = 0;
1201
1202         VM_BUG_ON(delta != -1 && delta != 1);
1203
1204         if (delta < 0)
1205                 start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1206         else
1207                 start_nid = hstate_next_node_to_free(h, nodes_allowed);
1208         next_nid = start_nid;
1209
1210         do {
1211                 int nid = next_nid;
1212                 if (delta < 0)  {
1213                         /*
1214                          * To shrink on this node, there must be a surplus page
1215                          */
1216                         if (!h->surplus_huge_pages_node[nid]) {
1217                                 next_nid = hstate_next_node_to_alloc(h,
1218                                                                 nodes_allowed);
1219                                 continue;
1220                         }
1221                 }
1222                 if (delta > 0) {
1223                         /*
1224                          * Surplus cannot exceed the total number of pages
1225                          */
1226                         if (h->surplus_huge_pages_node[nid] >=
1227                                                 h->nr_huge_pages_node[nid]) {
1228                                 next_nid = hstate_next_node_to_free(h,
1229                                                                 nodes_allowed);
1230                                 continue;
1231                         }
1232                 }
1233
1234                 h->surplus_huge_pages += delta;
1235                 h->surplus_huge_pages_node[nid] += delta;
1236                 ret = 1;
1237                 break;
1238         } while (next_nid != start_nid);
1239
1240         return ret;
1241 }
1242
1243 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1244 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1245                                                 nodemask_t *nodes_allowed)
1246 {
1247         unsigned long min_count, ret;
1248
1249         if (h->order >= MAX_ORDER)
1250                 return h->max_huge_pages;
1251
1252         /*
1253          * Increase the pool size
1254          * First take pages out of surplus state.  Then make up the
1255          * remaining difference by allocating fresh huge pages.
1256          *
1257          * We might race with alloc_buddy_huge_page() here and be unable
1258          * to convert a surplus huge page to a normal huge page. That is
1259          * not critical, though, it just means the overall size of the
1260          * pool might be one hugepage larger than it needs to be, but
1261          * within all the constraints specified by the sysctls.
1262          */
1263         spin_lock(&hugetlb_lock);
1264         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1265                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
1266                         break;
1267         }
1268
1269         while (count > persistent_huge_pages(h)) {
1270                 /*
1271                  * If this allocation races such that we no longer need the
1272                  * page, free_huge_page will handle it by freeing the page
1273                  * and reducing the surplus.
1274                  */
1275                 spin_unlock(&hugetlb_lock);
1276                 ret = alloc_fresh_huge_page(h, nodes_allowed);
1277                 spin_lock(&hugetlb_lock);
1278                 if (!ret)
1279                         goto out;
1280
1281                 /* Bail for signals. Probably ctrl-c from user */
1282                 if (signal_pending(current))
1283                         goto out;
1284         }
1285
1286         /*
1287          * Decrease the pool size
1288          * First return free pages to the buddy allocator (being careful
1289          * to keep enough around to satisfy reservations).  Then place
1290          * pages into surplus state as needed so the pool will shrink
1291          * to the desired size as pages become free.
1292          *
1293          * By placing pages into the surplus state independent of the
1294          * overcommit value, we are allowing the surplus pool size to
1295          * exceed overcommit. There are few sane options here. Since
1296          * alloc_buddy_huge_page() is checking the global counter,
1297          * though, we'll note that we're not allowed to exceed surplus
1298          * and won't grow the pool anywhere else. Not until one of the
1299          * sysctls are changed, or the surplus pages go out of use.
1300          */
1301         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1302         min_count = max(count, min_count);
1303         try_to_free_low(h, min_count, nodes_allowed);
1304         while (min_count < persistent_huge_pages(h)) {
1305                 if (!free_pool_huge_page(h, nodes_allowed, 0))
1306                         break;
1307         }
1308         while (count < persistent_huge_pages(h)) {
1309                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
1310                         break;
1311         }
1312 out:
1313         ret = persistent_huge_pages(h);
1314         spin_unlock(&hugetlb_lock);
1315         return ret;
1316 }
1317
1318 #define HSTATE_ATTR_RO(_name) \
1319         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1320
1321 #define HSTATE_ATTR(_name) \
1322         static struct kobj_attribute _name##_attr = \
1323                 __ATTR(_name, 0644, _name##_show, _name##_store)
1324
1325 static struct kobject *hugepages_kobj;
1326 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1327
1328 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1329
1330 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1331 {
1332         int i;
1333
1334         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1335                 if (hstate_kobjs[i] == kobj) {
1336                         if (nidp)
1337                                 *nidp = NUMA_NO_NODE;
1338                         return &hstates[i];
1339                 }
1340
1341         return kobj_to_node_hstate(kobj, nidp);
1342 }
1343
1344 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1345                                         struct kobj_attribute *attr, char *buf)
1346 {
1347         struct hstate *h;
1348         unsigned long nr_huge_pages;
1349         int nid;
1350
1351         h = kobj_to_hstate(kobj, &nid);
1352         if (nid == NUMA_NO_NODE)
1353                 nr_huge_pages = h->nr_huge_pages;
1354         else
1355                 nr_huge_pages = h->nr_huge_pages_node[nid];
1356
1357         return sprintf(buf, "%lu\n", nr_huge_pages);
1358 }
1359 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1360                         struct kobject *kobj, struct kobj_attribute *attr,
1361                         const char *buf, size_t len)
1362 {
1363         int err;
1364         int nid;
1365         unsigned long count;
1366         struct hstate *h;
1367         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1368
1369         err = strict_strtoul(buf, 10, &count);
1370         if (err)
1371                 return 0;
1372
1373         h = kobj_to_hstate(kobj, &nid);
1374         if (nid == NUMA_NO_NODE) {
1375                 /*
1376                  * global hstate attribute
1377                  */
1378                 if (!(obey_mempolicy &&
1379                                 init_nodemask_of_mempolicy(nodes_allowed))) {
1380                         NODEMASK_FREE(nodes_allowed);
1381                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1382                 }
1383         } else if (nodes_allowed) {
1384                 /*
1385                  * per node hstate attribute: adjust count to global,
1386                  * but restrict alloc/free to the specified node.
1387                  */
1388                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1389                 init_nodemask_of_node(nodes_allowed, nid);
1390         } else
1391                 nodes_allowed = &node_states[N_HIGH_MEMORY];
1392
1393         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1394
1395         if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1396                 NODEMASK_FREE(nodes_allowed);
1397
1398         return len;
1399 }
1400
1401 static ssize_t nr_hugepages_show(struct kobject *kobj,
1402                                        struct kobj_attribute *attr, char *buf)
1403 {
1404         return nr_hugepages_show_common(kobj, attr, buf);
1405 }
1406
1407 static ssize_t nr_hugepages_store(struct kobject *kobj,
1408                struct kobj_attribute *attr, const char *buf, size_t len)
1409 {
1410         return nr_hugepages_store_common(false, kobj, attr, buf, len);
1411 }
1412 HSTATE_ATTR(nr_hugepages);
1413
1414 #ifdef CONFIG_NUMA
1415
1416 /*
1417  * hstate attribute for optionally mempolicy-based constraint on persistent
1418  * huge page alloc/free.
1419  */
1420 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1421                                        struct kobj_attribute *attr, char *buf)
1422 {
1423         return nr_hugepages_show_common(kobj, attr, buf);
1424 }
1425
1426 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1427                struct kobj_attribute *attr, const char *buf, size_t len)
1428 {
1429         return nr_hugepages_store_common(true, kobj, attr, buf, len);
1430 }
1431 HSTATE_ATTR(nr_hugepages_mempolicy);
1432 #endif
1433
1434
1435 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1436                                         struct kobj_attribute *attr, char *buf)
1437 {
1438         struct hstate *h = kobj_to_hstate(kobj, NULL);
1439         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1440 }
1441 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1442                 struct kobj_attribute *attr, const char *buf, size_t count)
1443 {
1444         int err;
1445         unsigned long input;
1446         struct hstate *h = kobj_to_hstate(kobj, NULL);
1447
1448         err = strict_strtoul(buf, 10, &input);
1449         if (err)
1450                 return 0;
1451
1452         spin_lock(&hugetlb_lock);
1453         h->nr_overcommit_huge_pages = input;
1454         spin_unlock(&hugetlb_lock);
1455
1456         return count;
1457 }
1458 HSTATE_ATTR(nr_overcommit_hugepages);
1459
1460 static ssize_t free_hugepages_show(struct kobject *kobj,
1461                                         struct kobj_attribute *attr, char *buf)
1462 {
1463         struct hstate *h;
1464         unsigned long free_huge_pages;
1465         int nid;
1466
1467         h = kobj_to_hstate(kobj, &nid);
1468         if (nid == NUMA_NO_NODE)
1469                 free_huge_pages = h->free_huge_pages;
1470         else
1471                 free_huge_pages = h->free_huge_pages_node[nid];
1472
1473         return sprintf(buf, "%lu\n", free_huge_pages);
1474 }
1475 HSTATE_ATTR_RO(free_hugepages);
1476
1477 static ssize_t resv_hugepages_show(struct kobject *kobj,
1478                                         struct kobj_attribute *attr, char *buf)
1479 {
1480         struct hstate *h = kobj_to_hstate(kobj, NULL);
1481         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1482 }
1483 HSTATE_ATTR_RO(resv_hugepages);
1484
1485 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1486                                         struct kobj_attribute *attr, char *buf)
1487 {
1488         struct hstate *h;
1489         unsigned long surplus_huge_pages;
1490         int nid;
1491
1492         h = kobj_to_hstate(kobj, &nid);
1493         if (nid == NUMA_NO_NODE)
1494                 surplus_huge_pages = h->surplus_huge_pages;
1495         else
1496                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
1497
1498         return sprintf(buf, "%lu\n", surplus_huge_pages);
1499 }
1500 HSTATE_ATTR_RO(surplus_hugepages);
1501
1502 static struct attribute *hstate_attrs[] = {
1503         &nr_hugepages_attr.attr,
1504         &nr_overcommit_hugepages_attr.attr,
1505         &free_hugepages_attr.attr,
1506         &resv_hugepages_attr.attr,
1507         &surplus_hugepages_attr.attr,
1508 #ifdef CONFIG_NUMA
1509         &nr_hugepages_mempolicy_attr.attr,
1510 #endif
1511         NULL,
1512 };
1513
1514 static struct attribute_group hstate_attr_group = {
1515         .attrs = hstate_attrs,
1516 };
1517
1518 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1519                                     struct kobject **hstate_kobjs,
1520                                     struct attribute_group *hstate_attr_group)
1521 {
1522         int retval;
1523         int hi = h - hstates;
1524
1525         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1526         if (!hstate_kobjs[hi])
1527                 return -ENOMEM;
1528
1529         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1530         if (retval)
1531                 kobject_put(hstate_kobjs[hi]);
1532
1533         return retval;
1534 }
1535
1536 static void __init hugetlb_sysfs_init(void)
1537 {
1538         struct hstate *h;
1539         int err;
1540
1541         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1542         if (!hugepages_kobj)
1543                 return;
1544
1545         for_each_hstate(h) {
1546                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1547                                          hstate_kobjs, &hstate_attr_group);
1548                 if (err)
1549                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1550                                                                 h->name);
1551         }
1552 }
1553
1554 #ifdef CONFIG_NUMA
1555
1556 /*
1557  * node_hstate/s - associate per node hstate attributes, via their kobjects,
1558  * with node sysdevs in node_devices[] using a parallel array.  The array
1559  * index of a node sysdev or _hstate == node id.
1560  * This is here to avoid any static dependency of the node sysdev driver, in
1561  * the base kernel, on the hugetlb module.
1562  */
1563 struct node_hstate {
1564         struct kobject          *hugepages_kobj;
1565         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1566 };
1567 struct node_hstate node_hstates[MAX_NUMNODES];
1568
1569 /*
1570  * A subset of global hstate attributes for node sysdevs
1571  */
1572 static struct attribute *per_node_hstate_attrs[] = {
1573         &nr_hugepages_attr.attr,
1574         &free_hugepages_attr.attr,
1575         &surplus_hugepages_attr.attr,
1576         NULL,
1577 };
1578
1579 static struct attribute_group per_node_hstate_attr_group = {
1580         .attrs = per_node_hstate_attrs,
1581 };
1582
1583 /*
1584  * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj.
1585  * Returns node id via non-NULL nidp.
1586  */
1587 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1588 {
1589         int nid;
1590
1591         for (nid = 0; nid < nr_node_ids; nid++) {
1592                 struct node_hstate *nhs = &node_hstates[nid];
1593                 int i;
1594                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1595                         if (nhs->hstate_kobjs[i] == kobj) {
1596                                 if (nidp)
1597                                         *nidp = nid;
1598                                 return &hstates[i];
1599                         }
1600         }
1601
1602         BUG();
1603         return NULL;
1604 }
1605
1606 /*
1607  * Unregister hstate attributes from a single node sysdev.
1608  * No-op if no hstate attributes attached.
1609  */
1610 void hugetlb_unregister_node(struct node *node)
1611 {
1612         struct hstate *h;
1613         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1614
1615         if (!nhs->hugepages_kobj)
1616                 return;         /* no hstate attributes */
1617
1618         for_each_hstate(h)
1619                 if (nhs->hstate_kobjs[h - hstates]) {
1620                         kobject_put(nhs->hstate_kobjs[h - hstates]);
1621                         nhs->hstate_kobjs[h - hstates] = NULL;
1622                 }
1623
1624         kobject_put(nhs->hugepages_kobj);
1625         nhs->hugepages_kobj = NULL;
1626 }
1627
1628 /*
1629  * hugetlb module exit:  unregister hstate attributes from node sysdevs
1630  * that have them.
1631  */
1632 static void hugetlb_unregister_all_nodes(void)
1633 {
1634         int nid;
1635
1636         /*
1637          * disable node sysdev registrations.
1638          */
1639         register_hugetlbfs_with_node(NULL, NULL);
1640
1641         /*
1642          * remove hstate attributes from any nodes that have them.
1643          */
1644         for (nid = 0; nid < nr_node_ids; nid++)
1645                 hugetlb_unregister_node(&node_devices[nid]);
1646 }
1647
1648 /*
1649  * Register hstate attributes for a single node sysdev.
1650  * No-op if attributes already registered.
1651  */
1652 void hugetlb_register_node(struct node *node)
1653 {
1654         struct hstate *h;
1655         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1656         int err;
1657
1658         if (nhs->hugepages_kobj)
1659                 return;         /* already allocated */
1660
1661         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1662                                                         &node->sysdev.kobj);
1663         if (!nhs->hugepages_kobj)
1664                 return;
1665
1666         for_each_hstate(h) {
1667                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1668                                                 nhs->hstate_kobjs,
1669                                                 &per_node_hstate_attr_group);
1670                 if (err) {
1671                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1672                                         " for node %d\n",
1673                                                 h->name, node->sysdev.id);
1674                         hugetlb_unregister_node(node);
1675                         break;
1676                 }
1677         }
1678 }
1679
1680 /*
1681  * hugetlb init time:  register hstate attributes for all registered node
1682  * sysdevs of nodes that have memory.  All on-line nodes should have
1683  * registered their associated sysdev by this time.
1684  */
1685 static void hugetlb_register_all_nodes(void)
1686 {
1687         int nid;
1688
1689         for_each_node_state(nid, N_HIGH_MEMORY) {
1690                 struct node *node = &node_devices[nid];
1691                 if (node->sysdev.id == nid)
1692                         hugetlb_register_node(node);
1693         }
1694
1695         /*
1696          * Let the node sysdev driver know we're here so it can
1697          * [un]register hstate attributes on node hotplug.
1698          */
1699         register_hugetlbfs_with_node(hugetlb_register_node,
1700                                      hugetlb_unregister_node);
1701 }
1702 #else   /* !CONFIG_NUMA */
1703
1704 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1705 {
1706         BUG();
1707         if (nidp)
1708                 *nidp = -1;
1709         return NULL;
1710 }
1711
1712 static void hugetlb_unregister_all_nodes(void) { }
1713
1714 static void hugetlb_register_all_nodes(void) { }
1715
1716 #endif
1717
1718 static void __exit hugetlb_exit(void)
1719 {
1720         struct hstate *h;
1721
1722         hugetlb_unregister_all_nodes();
1723
1724         for_each_hstate(h) {
1725                 kobject_put(hstate_kobjs[h - hstates]);
1726         }
1727
1728         kobject_put(hugepages_kobj);
1729 }
1730 module_exit(hugetlb_exit);
1731
1732 static int __init hugetlb_init(void)
1733 {
1734         /* Some platform decide whether they support huge pages at boot
1735          * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1736          * there is no such support
1737          */
1738         if (HPAGE_SHIFT == 0)
1739                 return 0;
1740
1741         if (!size_to_hstate(default_hstate_size)) {
1742                 default_hstate_size = HPAGE_SIZE;
1743                 if (!size_to_hstate(default_hstate_size))
1744                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1745         }
1746         default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1747         if (default_hstate_max_huge_pages)
1748                 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1749
1750         hugetlb_init_hstates();
1751
1752         gather_bootmem_prealloc();
1753
1754         report_hugepages();
1755
1756         hugetlb_sysfs_init();
1757
1758         hugetlb_register_all_nodes();
1759
1760         return 0;
1761 }
1762 module_init(hugetlb_init);
1763
1764 /* Should be called on processing a hugepagesz=... option */
1765 void __init hugetlb_add_hstate(unsigned order)
1766 {
1767         struct hstate *h;
1768         unsigned long i;
1769
1770         if (size_to_hstate(PAGE_SIZE << order)) {
1771                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1772                 return;
1773         }
1774         BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1775         BUG_ON(order == 0);
1776         h = &hstates[max_hstate++];
1777         h->order = order;
1778         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1779         h->nr_huge_pages = 0;
1780         h->free_huge_pages = 0;
1781         for (i = 0; i < MAX_NUMNODES; ++i)
1782                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1783         h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
1784         h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
1785         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1786                                         huge_page_size(h)/1024);
1787
1788         parsed_hstate = h;
1789 }
1790
1791 static int __init hugetlb_nrpages_setup(char *s)
1792 {
1793         unsigned long *mhp;
1794         static unsigned long *last_mhp;
1795
1796         /*
1797          * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1798          * so this hugepages= parameter goes to the "default hstate".
1799          */
1800         if (!max_hstate)
1801                 mhp = &default_hstate_max_huge_pages;
1802         else
1803                 mhp = &parsed_hstate->max_huge_pages;
1804
1805         if (mhp == last_mhp) {
1806                 printk(KERN_WARNING "hugepages= specified twice without "
1807                         "interleaving hugepagesz=, ignoring\n");
1808                 return 1;
1809         }
1810
1811         if (sscanf(s, "%lu", mhp) <= 0)
1812                 *mhp = 0;
1813
1814         /*
1815          * Global state is always initialized later in hugetlb_init.
1816          * But we need to allocate >= MAX_ORDER hstates here early to still
1817          * use the bootmem allocator.
1818          */
1819         if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1820                 hugetlb_hstate_alloc_pages(parsed_hstate);
1821
1822         last_mhp = mhp;
1823
1824         return 1;
1825 }
1826 __setup("hugepages=", hugetlb_nrpages_setup);
1827
1828 static int __init hugetlb_default_setup(char *s)
1829 {
1830         default_hstate_size = memparse(s, &s);
1831         return 1;
1832 }
1833 __setup("default_hugepagesz=", hugetlb_default_setup);
1834
1835 static unsigned int cpuset_mems_nr(unsigned int *array)
1836 {
1837         int node;
1838         unsigned int nr = 0;
1839
1840         for_each_node_mask(node, cpuset_current_mems_allowed)
1841                 nr += array[node];
1842
1843         return nr;
1844 }
1845
1846 #ifdef CONFIG_SYSCTL
1847 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
1848                          struct ctl_table *table, int write,
1849                          void __user *buffer, size_t *length, loff_t *ppos)
1850 {
1851         struct hstate *h = &default_hstate;
1852         unsigned long tmp;
1853
1854         if (!write)
1855                 tmp = h->max_huge_pages;
1856
1857         table->data = &tmp;
1858         table->maxlen = sizeof(unsigned long);
1859         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1860
1861         if (write) {
1862                 NODEMASK_ALLOC(nodemask_t, nodes_allowed,
1863                                                 GFP_KERNEL | __GFP_NORETRY);
1864                 if (!(obey_mempolicy &&
1865                                init_nodemask_of_mempolicy(nodes_allowed))) {
1866                         NODEMASK_FREE(nodes_allowed);
1867                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1868                 }
1869                 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
1870
1871                 if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1872                         NODEMASK_FREE(nodes_allowed);
1873         }
1874
1875         return 0;
1876 }
1877
1878 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1879                           void __user *buffer, size_t *length, loff_t *ppos)
1880 {
1881
1882         return hugetlb_sysctl_handler_common(false, table, write,
1883                                                         buffer, length, ppos);
1884 }
1885
1886 #ifdef CONFIG_NUMA
1887 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
1888                           void __user *buffer, size_t *length, loff_t *ppos)
1889 {
1890         return hugetlb_sysctl_handler_common(true, table, write,
1891                                                         buffer, length, ppos);
1892 }
1893 #endif /* CONFIG_NUMA */
1894
1895 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1896                         void __user *buffer,
1897                         size_t *length, loff_t *ppos)
1898 {
1899         proc_dointvec(table, write, buffer, length, ppos);
1900         if (hugepages_treat_as_movable)
1901                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1902         else
1903                 htlb_alloc_mask = GFP_HIGHUSER;
1904         return 0;
1905 }
1906
1907 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1908                         void __user *buffer,
1909                         size_t *length, loff_t *ppos)
1910 {
1911         struct hstate *h = &default_hstate;
1912         unsigned long tmp;
1913
1914         if (!write)
1915                 tmp = h->nr_overcommit_huge_pages;
1916
1917         table->data = &tmp;
1918         table->maxlen = sizeof(unsigned long);
1919         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1920
1921         if (write) {
1922                 spin_lock(&hugetlb_lock);
1923                 h->nr_overcommit_huge_pages = tmp;
1924                 spin_unlock(&hugetlb_lock);
1925         }
1926
1927         return 0;
1928 }
1929
1930 #endif /* CONFIG_SYSCTL */
1931
1932 void hugetlb_report_meminfo(struct seq_file *m)
1933 {
1934         struct hstate *h = &default_hstate;
1935         seq_printf(m,
1936                         "HugePages_Total:   %5lu\n"
1937                         "HugePages_Free:    %5lu\n"
1938                         "HugePages_Rsvd:    %5lu\n"
1939                         "HugePages_Surp:    %5lu\n"
1940                         "Hugepagesize:   %8lu kB\n",
1941                         h->nr_huge_pages,
1942                         h->free_huge_pages,
1943                         h->resv_huge_pages,
1944                         h->surplus_huge_pages,
1945                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1946 }
1947
1948 int hugetlb_report_node_meminfo(int nid, char *buf)
1949 {
1950         struct hstate *h = &default_hstate;
1951         return sprintf(buf,
1952                 "Node %d HugePages_Total: %5u\n"
1953                 "Node %d HugePages_Free:  %5u\n"
1954                 "Node %d HugePages_Surp:  %5u\n",
1955                 nid, h->nr_huge_pages_node[nid],
1956                 nid, h->free_huge_pages_node[nid],
1957                 nid, h->surplus_huge_pages_node[nid]);
1958 }
1959
1960 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1961 unsigned long hugetlb_total_pages(void)
1962 {
1963         struct hstate *h = &default_hstate;
1964         return h->nr_huge_pages * pages_per_huge_page(h);
1965 }
1966
1967 static int hugetlb_acct_memory(struct hstate *h, long delta)
1968 {
1969         int ret = -ENOMEM;
1970
1971         spin_lock(&hugetlb_lock);
1972         /*
1973          * When cpuset is configured, it breaks the strict hugetlb page
1974          * reservation as the accounting is done on a global variable. Such
1975          * reservation is completely rubbish in the presence of cpuset because
1976          * the reservation is not checked against page availability for the
1977          * current cpuset. Application can still potentially OOM'ed by kernel
1978          * with lack of free htlb page in cpuset that the task is in.
1979          * Attempt to enforce strict accounting with cpuset is almost
1980          * impossible (or too ugly) because cpuset is too fluid that
1981          * task or memory node can be dynamically moved between cpusets.
1982          *
1983          * The change of semantics for shared hugetlb mapping with cpuset is
1984          * undesirable. However, in order to preserve some of the semantics,
1985          * we fall back to check against current free page availability as
1986          * a best attempt and hopefully to minimize the impact of changing
1987          * semantics that cpuset has.
1988          */
1989         if (delta > 0) {
1990                 if (gather_surplus_pages(h, delta) < 0)
1991                         goto out;
1992
1993                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1994                         return_unused_surplus_pages(h, delta);
1995                         goto out;
1996                 }
1997         }
1998
1999         ret = 0;
2000         if (delta < 0)
2001                 return_unused_surplus_pages(h, (unsigned long) -delta);
2002
2003 out:
2004         spin_unlock(&hugetlb_lock);
2005         return ret;
2006 }
2007
2008 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2009 {
2010         struct resv_map *reservations = vma_resv_map(vma);
2011
2012         /*
2013          * This new VMA should share its siblings reservation map if present.
2014          * The VMA will only ever have a valid reservation map pointer where
2015          * it is being copied for another still existing VMA.  As that VMA
2016          * has a reference to the reservation map it cannot dissappear until
2017          * after this open call completes.  It is therefore safe to take a
2018          * new reference here without additional locking.
2019          */
2020         if (reservations)
2021                 kref_get(&reservations->refs);
2022 }
2023
2024 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2025 {
2026         struct hstate *h = hstate_vma(vma);
2027         struct resv_map *reservations = vma_resv_map(vma);
2028         unsigned long reserve;
2029         unsigned long start;
2030         unsigned long end;
2031
2032         if (reservations) {
2033                 start = vma_hugecache_offset(h, vma, vma->vm_start);
2034                 end = vma_hugecache_offset(h, vma, vma->vm_end);
2035
2036                 reserve = (end - start) -
2037                         region_count(&reservations->regions, start, end);
2038
2039                 kref_put(&reservations->refs, resv_map_release);
2040
2041                 if (reserve) {
2042                         hugetlb_acct_memory(h, -reserve);
2043                         hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
2044                 }
2045         }
2046 }
2047
2048 /*
2049  * We cannot handle pagefaults against hugetlb pages at all.  They cause
2050  * handle_mm_fault() to try to instantiate regular-sized pages in the
2051  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2052  * this far.
2053  */
2054 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2055 {
2056         BUG();
2057         return 0;
2058 }
2059
2060 const struct vm_operations_struct hugetlb_vm_ops = {
2061         .fault = hugetlb_vm_op_fault,
2062         .open = hugetlb_vm_op_open,
2063         .close = hugetlb_vm_op_close,
2064 };
2065
2066 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2067                                 int writable)
2068 {
2069         pte_t entry;
2070
2071         if (writable) {
2072                 entry =
2073                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2074         } else {
2075                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2076         }
2077         entry = pte_mkyoung(entry);
2078         entry = pte_mkhuge(entry);
2079
2080         return entry;
2081 }
2082
2083 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2084                                    unsigned long address, pte_t *ptep)
2085 {
2086         pte_t entry;
2087
2088         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2089         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
2090                 update_mmu_cache(vma, address, ptep);
2091         }
2092 }
2093
2094
2095 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2096                             struct vm_area_struct *vma)
2097 {
2098         pte_t *src_pte, *dst_pte, entry;
2099         struct page *ptepage;
2100         unsigned long addr;
2101         int cow;
2102         struct hstate *h = hstate_vma(vma);
2103         unsigned long sz = huge_page_size(h);
2104
2105         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2106
2107         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2108                 src_pte = huge_pte_offset(src, addr);
2109                 if (!src_pte)
2110                         continue;
2111                 dst_pte = huge_pte_alloc(dst, addr, sz);
2112                 if (!dst_pte)
2113                         goto nomem;
2114
2115                 /* If the pagetables are shared don't copy or take references */
2116                 if (dst_pte == src_pte)
2117                         continue;
2118
2119                 spin_lock(&dst->page_table_lock);
2120                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2121                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
2122                         if (cow)
2123                                 huge_ptep_set_wrprotect(src, addr, src_pte);
2124                         entry = huge_ptep_get(src_pte);
2125                         ptepage = pte_page(entry);
2126                         get_page(ptepage);
2127                         set_huge_pte_at(dst, addr, dst_pte, entry);
2128                 }
2129                 spin_unlock(&src->page_table_lock);
2130                 spin_unlock(&dst->page_table_lock);
2131         }
2132         return 0;
2133
2134 nomem:
2135         return -ENOMEM;
2136 }
2137
2138 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2139                             unsigned long end, struct page *ref_page)
2140 {
2141         struct mm_struct *mm = vma->vm_mm;
2142         unsigned long address;
2143         pte_t *ptep;
2144         pte_t pte;
2145         struct page *page;
2146         struct page *tmp;
2147         struct hstate *h = hstate_vma(vma);
2148         unsigned long sz = huge_page_size(h);
2149
2150         /*
2151          * A page gathering list, protected by per file i_mmap_lock. The
2152          * lock is used to avoid list corruption from multiple unmapping
2153          * of the same page since we are using page->lru.
2154          */
2155         LIST_HEAD(page_list);
2156
2157         WARN_ON(!is_vm_hugetlb_page(vma));
2158         BUG_ON(start & ~huge_page_mask(h));
2159         BUG_ON(end & ~huge_page_mask(h));
2160
2161         mmu_notifier_invalidate_range_start(mm, start, end);
2162         spin_lock(&mm->page_table_lock);
2163         for (address = start; address < end; address += sz) {
2164                 ptep = huge_pte_offset(mm, address);
2165                 if (!ptep)
2166                         continue;
2167
2168                 if (huge_pmd_unshare(mm, &address, ptep))
2169                         continue;
2170
2171                 /*
2172                  * If a reference page is supplied, it is because a specific
2173                  * page is being unmapped, not a range. Ensure the page we
2174                  * are about to unmap is the actual page of interest.
2175                  */
2176                 if (ref_page) {
2177                         pte = huge_ptep_get(ptep);
2178                         if (huge_pte_none(pte))
2179                                 continue;
2180                         page = pte_page(pte);
2181                         if (page != ref_page)
2182                                 continue;
2183
2184                         /*
2185                          * Mark the VMA as having unmapped its page so that
2186                          * future faults in this VMA will fail rather than
2187                          * looking like data was lost
2188                          */
2189                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2190                 }
2191
2192                 pte = huge_ptep_get_and_clear(mm, address, ptep);
2193                 if (huge_pte_none(pte))
2194                         continue;
2195
2196                 page = pte_page(pte);
2197                 if (pte_dirty(pte))
2198                         set_page_dirty(page);
2199                 list_add(&page->lru, &page_list);
2200         }
2201         spin_unlock(&mm->page_table_lock);
2202         flush_tlb_range(vma, start, end);
2203         mmu_notifier_invalidate_range_end(mm, start, end);
2204         list_for_each_entry_safe(page, tmp, &page_list, lru) {
2205                 list_del(&page->lru);
2206                 put_page(page);
2207         }
2208 }
2209
2210 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2211                           unsigned long end, struct page *ref_page)
2212 {
2213         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2214         __unmap_hugepage_range(vma, start, end, ref_page);
2215         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2216 }
2217
2218 /*
2219  * This is called when the original mapper is failing to COW a MAP_PRIVATE
2220  * mappping it owns the reserve page for. The intention is to unmap the page
2221  * from other VMAs and let the children be SIGKILLed if they are faulting the
2222  * same region.
2223  */
2224 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2225                                 struct page *page, unsigned long address)
2226 {
2227         struct hstate *h = hstate_vma(vma);
2228         struct vm_area_struct *iter_vma;
2229         struct address_space *mapping;
2230         struct prio_tree_iter iter;
2231         pgoff_t pgoff;
2232
2233         /*
2234          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2235          * from page cache lookup which is in HPAGE_SIZE units.
2236          */
2237         address = address & huge_page_mask(h);
2238         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
2239                 + (vma->vm_pgoff >> PAGE_SHIFT);
2240         mapping = (struct address_space *)page_private(page);
2241
2242         /*
2243          * Take the mapping lock for the duration of the table walk. As
2244          * this mapping should be shared between all the VMAs,
2245          * __unmap_hugepage_range() is called as the lock is already held
2246          */
2247         spin_lock(&mapping->i_mmap_lock);
2248         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2249                 /* Do not unmap the current VMA */
2250                 if (iter_vma == vma)
2251                         continue;
2252
2253                 /*
2254                  * Unmap the page from other VMAs without their own reserves.
2255                  * They get marked to be SIGKILLed if they fault in these
2256                  * areas. This is because a future no-page fault on this VMA
2257                  * could insert a zeroed page instead of the data existing
2258                  * from the time of fork. This would look like data corruption
2259                  */
2260                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2261                         __unmap_hugepage_range(iter_vma,
2262                                 address, address + huge_page_size(h),
2263                                 page);
2264         }
2265         spin_unlock(&mapping->i_mmap_lock);
2266
2267         return 1;
2268 }
2269
2270 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2271                         unsigned long address, pte_t *ptep, pte_t pte,
2272                         struct page *pagecache_page)
2273 {
2274         struct hstate *h = hstate_vma(vma);
2275         struct page *old_page, *new_page;
2276         int avoidcopy;
2277         int outside_reserve = 0;
2278
2279         old_page = pte_page(pte);
2280
2281 retry_avoidcopy:
2282         /* If no-one else is actually using this page, avoid the copy
2283          * and just make the page writable */
2284         avoidcopy = (page_count(old_page) == 1);
2285         if (avoidcopy) {
2286                 set_huge_ptep_writable(vma, address, ptep);
2287                 return 0;
2288         }
2289
2290         /*
2291          * If the process that created a MAP_PRIVATE mapping is about to
2292          * perform a COW due to a shared page count, attempt to satisfy
2293          * the allocation without using the existing reserves. The pagecache
2294          * page is used to determine if the reserve at this address was
2295          * consumed or not. If reserves were used, a partial faulted mapping
2296          * at the time of fork() could consume its reserves on COW instead
2297          * of the full address range.
2298          */
2299         if (!(vma->vm_flags & VM_MAYSHARE) &&
2300                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2301                         old_page != pagecache_page)
2302                 outside_reserve = 1;
2303
2304         page_cache_get(old_page);
2305
2306         /* Drop page_table_lock as buddy allocator may be called */
2307         spin_unlock(&mm->page_table_lock);
2308         new_page = alloc_huge_page(vma, address, outside_reserve);
2309
2310         if (IS_ERR(new_page)) {
2311                 page_cache_release(old_page);
2312
2313                 /*
2314                  * If a process owning a MAP_PRIVATE mapping fails to COW,
2315                  * it is due to references held by a child and an insufficient
2316                  * huge page pool. To guarantee the original mappers
2317                  * reliability, unmap the page from child processes. The child
2318                  * may get SIGKILLed if it later faults.
2319                  */
2320                 if (outside_reserve) {
2321                         BUG_ON(huge_pte_none(pte));
2322                         if (unmap_ref_private(mm, vma, old_page, address)) {
2323                                 BUG_ON(page_count(old_page) != 1);
2324                                 BUG_ON(huge_pte_none(pte));
2325                                 spin_lock(&mm->page_table_lock);
2326                                 goto retry_avoidcopy;
2327                         }
2328                         WARN_ON_ONCE(1);
2329                 }
2330
2331                 /* Caller expects lock to be held */
2332                 spin_lock(&mm->page_table_lock);
2333                 return -PTR_ERR(new_page);
2334         }
2335
2336         copy_huge_page(new_page, old_page, address, vma);
2337         __SetPageUptodate(new_page);
2338
2339         /*
2340          * Retake the page_table_lock to check for racing updates
2341          * before the page tables are altered
2342          */
2343         spin_lock(&mm->page_table_lock);
2344         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2345         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2346                 /* Break COW */
2347                 huge_ptep_clear_flush(vma, address, ptep);
2348                 set_huge_pte_at(mm, address, ptep,
2349                                 make_huge_pte(vma, new_page, 1));
2350                 /* Make the old page be freed below */
2351                 new_page = old_page;
2352         }
2353         page_cache_release(new_page);
2354         page_cache_release(old_page);
2355         return 0;
2356 }
2357
2358 /* Return the pagecache page at a given address within a VMA */
2359 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2360                         struct vm_area_struct *vma, unsigned long address)
2361 {
2362         struct address_space *mapping;
2363         pgoff_t idx;
2364
2365         mapping = vma->vm_file->f_mapping;
2366         idx = vma_hugecache_offset(h, vma, address);
2367
2368         return find_lock_page(mapping, idx);
2369 }
2370
2371 /*
2372  * Return whether there is a pagecache page to back given address within VMA.
2373  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2374  */
2375 static bool hugetlbfs_pagecache_present(struct hstate *h,
2376                         struct vm_area_struct *vma, unsigned long address)
2377 {
2378         struct address_space *mapping;
2379         pgoff_t idx;
2380         struct page *page;
2381
2382         mapping = vma->vm_file->f_mapping;
2383         idx = vma_hugecache_offset(h, vma, address);
2384
2385         page = find_get_page(mapping, idx);
2386         if (page)
2387                 put_page(page);
2388         return page != NULL;
2389 }
2390
2391 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2392                         unsigned long address, pte_t *ptep, unsigned int flags)
2393 {
2394         struct hstate *h = hstate_vma(vma);
2395         int ret = VM_FAULT_SIGBUS;
2396         pgoff_t idx;
2397         unsigned long size;
2398         struct page *page;
2399         struct address_space *mapping;
2400         pte_t new_pte;
2401
2402         /*
2403          * Currently, we are forced to kill the process in the event the
2404          * original mapper has unmapped pages from the child due to a failed
2405          * COW. Warn that such a situation has occured as it may not be obvious
2406          */
2407         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2408                 printk(KERN_WARNING
2409                         "PID %d killed due to inadequate hugepage pool\n",
2410                         current->pid);
2411                 return ret;
2412         }
2413
2414         mapping = vma->vm_file->f_mapping;
2415         idx = vma_hugecache_offset(h, vma, address);
2416
2417         /*
2418          * Use page lock to guard against racing truncation
2419          * before we get page_table_lock.
2420          */
2421 retry:
2422         page = find_lock_page(mapping, idx);
2423         if (!page) {
2424                 size = i_size_read(mapping->host) >> huge_page_shift(h);
2425                 if (idx >= size)
2426                         goto out;
2427                 page = alloc_huge_page(vma, address, 0);
2428                 if (IS_ERR(page)) {
2429                         ret = -PTR_ERR(page);
2430                         goto out;
2431                 }
2432                 clear_huge_page(page, address, huge_page_size(h));
2433                 __SetPageUptodate(page);
2434
2435                 if (vma->vm_flags & VM_MAYSHARE) {
2436                         int err;
2437                         struct inode *inode = mapping->host;
2438
2439                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2440                         if (err) {
2441                                 put_page(page);
2442                                 if (err == -EEXIST)
2443                                         goto retry;
2444                                 goto out;
2445                         }
2446
2447                         spin_lock(&inode->i_lock);
2448                         inode->i_blocks += blocks_per_huge_page(h);
2449                         spin_unlock(&inode->i_lock);
2450                 } else
2451                         lock_page(page);
2452         }
2453
2454         /*
2455          * If we are going to COW a private mapping later, we examine the
2456          * pending reservations for this page now. This will ensure that
2457          * any allocations necessary to record that reservation occur outside
2458          * the spinlock.
2459          */
2460         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2461                 if (vma_needs_reservation(h, vma, address) < 0) {
2462                         ret = VM_FAULT_OOM;
2463                         goto backout_unlocked;
2464                 }
2465
2466         spin_lock(&mm->page_table_lock);
2467         size = i_size_read(mapping->host) >> huge_page_shift(h);
2468         if (idx >= size)
2469                 goto backout;
2470
2471         ret = 0;
2472         if (!huge_pte_none(huge_ptep_get(ptep)))
2473                 goto backout;
2474
2475         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2476                                 && (vma->vm_flags & VM_SHARED)));
2477         set_huge_pte_at(mm, address, ptep, new_pte);
2478
2479         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2480                 /* Optimization, do the COW without a second fault */
2481                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2482         }
2483
2484         spin_unlock(&mm->page_table_lock);
2485         unlock_page(page);
2486 out:
2487         return ret;
2488
2489 backout:
2490         spin_unlock(&mm->page_table_lock);
2491 backout_unlocked:
2492         unlock_page(page);
2493         put_page(page);
2494         goto out;
2495 }
2496
2497 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2498                         unsigned long address, unsigned int flags)
2499 {
2500         pte_t *ptep;
2501         pte_t entry;
2502         int ret;
2503         struct page *pagecache_page = NULL;
2504         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2505         struct hstate *h = hstate_vma(vma);
2506
2507         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2508         if (!ptep)
2509                 return VM_FAULT_OOM;
2510
2511         /*
2512          * Serialize hugepage allocation and instantiation, so that we don't
2513          * get spurious allocation failures if two CPUs race to instantiate
2514          * the same page in the page cache.
2515          */
2516         mutex_lock(&hugetlb_instantiation_mutex);
2517         entry = huge_ptep_get(ptep);
2518         if (huge_pte_none(entry)) {
2519                 ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2520                 goto out_mutex;
2521         }
2522
2523         ret = 0;
2524
2525         /*
2526          * If we are going to COW the mapping later, we examine the pending
2527          * reservations for this page now. This will ensure that any
2528          * allocations necessary to record that reservation occur outside the
2529          * spinlock. For private mappings, we also lookup the pagecache
2530          * page now as it is used to determine if a reservation has been
2531          * consumed.
2532          */
2533         if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2534                 if (vma_needs_reservation(h, vma, address) < 0) {
2535                         ret = VM_FAULT_OOM;
2536                         goto out_mutex;
2537                 }
2538
2539                 if (!(vma->vm_flags & VM_MAYSHARE))
2540                         pagecache_page = hugetlbfs_pagecache_page(h,
2541                                                                 vma, address);
2542         }
2543
2544         spin_lock(&mm->page_table_lock);
2545         /* Check for a racing update before calling hugetlb_cow */
2546         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2547                 goto out_page_table_lock;
2548
2549
2550         if (flags & FAULT_FLAG_WRITE) {
2551                 if (!pte_write(entry)) {
2552                         ret = hugetlb_cow(mm, vma, address, ptep, entry,
2553                                                         pagecache_page);
2554                         goto out_page_table_lock;
2555                 }
2556                 entry = pte_mkdirty(entry);
2557         }
2558         entry = pte_mkyoung(entry);
2559         if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2560                                                 flags & FAULT_FLAG_WRITE))
2561                 update_mmu_cache(vma, address, ptep);
2562
2563 out_page_table_lock:
2564         spin_unlock(&mm->page_table_lock);
2565
2566         if (pagecache_page) {
2567                 unlock_page(pagecache_page);
2568                 put_page(pagecache_page);
2569         }
2570
2571 out_mutex:
2572         mutex_unlock(&hugetlb_instantiation_mutex);
2573
2574         return ret;
2575 }
2576
2577 /* Can be overriden by architectures */
2578 __attribute__((weak)) struct page *
2579 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2580                pud_t *pud, int write)
2581 {
2582         BUG();
2583         return NULL;
2584 }
2585
2586 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2587                         struct page **pages, struct vm_area_struct **vmas,
2588                         unsigned long *position, int *length, int i,
2589                         unsigned int flags)
2590 {
2591         unsigned long pfn_offset;
2592         unsigned long vaddr = *position;
2593         int remainder = *length;
2594         struct hstate *h = hstate_vma(vma);
2595
2596         spin_lock(&mm->page_table_lock);
2597         while (vaddr < vma->vm_end && remainder) {
2598                 pte_t *pte;
2599                 int absent;
2600                 struct page *page;
2601
2602                 /*
2603                  * Some archs (sparc64, sh*) have multiple pte_ts to
2604                  * each hugepage.  We have to make sure we get the
2605                  * first, for the page indexing below to work.
2606                  */
2607                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2608                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
2609
2610                 /*
2611                  * When coredumping, it suits get_dump_page if we just return
2612                  * an error where there's an empty slot with no huge pagecache
2613                  * to back it.  This way, we avoid allocating a hugepage, and
2614                  * the sparse dumpfile avoids allocating disk blocks, but its
2615                  * huge holes still show up with zeroes where they need to be.
2616                  */
2617                 if (absent && (flags & FOLL_DUMP) &&
2618                     !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2619                         remainder = 0;
2620                         break;
2621                 }
2622
2623                 if (absent ||
2624                     ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2625                         int ret;
2626
2627                         spin_unlock(&mm->page_table_lock);
2628                         ret = hugetlb_fault(mm, vma, vaddr,
2629                                 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2630                         spin_lock(&mm->page_table_lock);
2631                         if (!(ret & VM_FAULT_ERROR))
2632                                 continue;
2633
2634                         remainder = 0;
2635                         break;
2636                 }
2637
2638                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2639                 page = pte_page(huge_ptep_get(pte));
2640 same_page:
2641                 if (pages) {
2642                         pages[i] = mem_map_offset(page, pfn_offset);
2643                         get_page(pages[i]);
2644                 }
2645
2646                 if (vmas)
2647                         vmas[i] = vma;
2648
2649                 vaddr += PAGE_SIZE;
2650                 ++pfn_offset;
2651                 --remainder;
2652                 ++i;
2653                 if (vaddr < vma->vm_end && remainder &&
2654                                 pfn_offset < pages_per_huge_page(h)) {
2655                         /*
2656                          * We use pfn_offset to avoid touching the pageframes
2657                          * of this compound page.
2658                          */
2659                         goto same_page;
2660                 }
2661         }
2662         spin_unlock(&mm->page_table_lock);
2663         *length = remainder;
2664         *position = vaddr;
2665
2666         return i ? i : -EFAULT;
2667 }
2668
2669 void hugetlb_change_protection(struct vm_area_struct *vma,
2670                 unsigned long address, unsigned long end, pgprot_t newprot)
2671 {
2672         struct mm_struct *mm = vma->vm_mm;
2673         unsigned long start = address;
2674         pte_t *ptep;
2675         pte_t pte;
2676         struct hstate *h = hstate_vma(vma);
2677
2678         BUG_ON(address >= end);
2679         flush_cache_range(vma, address, end);
2680
2681         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2682         spin_lock(&mm->page_table_lock);
2683         for (; address < end; address += huge_page_size(h)) {
2684                 ptep = huge_pte_offset(mm, address);
2685                 if (!ptep)
2686                         continue;
2687                 if (huge_pmd_unshare(mm, &address, ptep))
2688                         continue;
2689                 if (!huge_pte_none(huge_ptep_get(ptep))) {
2690                         pte = huge_ptep_get_and_clear(mm, address, ptep);
2691                         pte = pte_mkhuge(pte_modify(pte, newprot));
2692                         set_huge_pte_at(mm, address, ptep, pte);
2693                 }
2694         }
2695         spin_unlock(&mm->page_table_lock);
2696         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2697
2698         flush_tlb_range(vma, start, end);
2699 }
2700
2701 int hugetlb_reserve_pages(struct inode *inode,
2702                                         long from, long to,
2703                                         struct vm_area_struct *vma,
2704                                         int acctflag)
2705 {
2706         long ret, chg;
2707         struct hstate *h = hstate_inode(inode);
2708
2709         /*
2710          * Only apply hugepage reservation if asked. At fault time, an
2711          * attempt will be made for VM_NORESERVE to allocate a page
2712          * and filesystem quota without using reserves
2713          */
2714         if (acctflag & VM_NORESERVE)
2715                 return 0;
2716
2717         /*
2718          * Shared mappings base their reservation on the number of pages that
2719          * are already allocated on behalf of the file. Private mappings need
2720          * to reserve the full area even if read-only as mprotect() may be
2721          * called to make the mapping read-write. Assume !vma is a shm mapping
2722          */
2723         if (!vma || vma->vm_flags & VM_MAYSHARE)
2724                 chg = region_chg(&inode->i_mapping->private_list, from, to);
2725         else {
2726                 struct resv_map *resv_map = resv_map_alloc();
2727                 if (!resv_map)
2728                         return -ENOMEM;
2729
2730                 chg = to - from;
2731
2732                 set_vma_resv_map(vma, resv_map);
2733                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2734         }
2735
2736         if (chg < 0)
2737                 return chg;
2738
2739         /* There must be enough filesystem quota for the mapping */
2740         if (hugetlb_get_quota(inode->i_mapping, chg))
2741                 return -ENOSPC;
2742
2743         /*
2744          * Check enough hugepages are available for the reservation.
2745          * Hand back the quota if there are not
2746          */
2747         ret = hugetlb_acct_memory(h, chg);
2748         if (ret < 0) {
2749                 hugetlb_put_quota(inode->i_mapping, chg);
2750                 return ret;
2751         }
2752
2753         /*
2754          * Account for the reservations made. Shared mappings record regions
2755          * that have reservations as they are shared by multiple VMAs.
2756          * When the last VMA disappears, the region map says how much
2757          * the reservation was and the page cache tells how much of
2758          * the reservation was consumed. Private mappings are per-VMA and
2759          * only the consumed reservations are tracked. When the VMA
2760          * disappears, the original reservation is the VMA size and the
2761          * consumed reservations are stored in the map. Hence, nothing
2762          * else has to be done for private mappings here
2763          */
2764         if (!vma || vma->vm_flags & VM_MAYSHARE)
2765                 region_add(&inode->i_mapping->private_list, from, to);
2766         return 0;
2767 }
2768
2769 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2770 {
2771         struct hstate *h = hstate_inode(inode);
2772         long chg = region_truncate(&inode->i_mapping->private_list, offset);
2773
2774         spin_lock(&inode->i_lock);
2775         inode->i_blocks -= (blocks_per_huge_page(h) * freed);
2776         spin_unlock(&inode->i_lock);
2777
2778         hugetlb_put_quota(inode->i_mapping, (chg - freed));
2779         hugetlb_acct_memory(h, -(chg - freed));
2780 }