hugetlb: acquire the i_mmap_lock before walking the prio_tree to unmap a page
[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 > 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         }
1282
1283         /*
1284          * Decrease the pool size
1285          * First return free pages to the buddy allocator (being careful
1286          * to keep enough around to satisfy reservations).  Then place
1287          * pages into surplus state as needed so the pool will shrink
1288          * to the desired size as pages become free.
1289          *
1290          * By placing pages into the surplus state independent of the
1291          * overcommit value, we are allowing the surplus pool size to
1292          * exceed overcommit. There are few sane options here. Since
1293          * alloc_buddy_huge_page() is checking the global counter,
1294          * though, we'll note that we're not allowed to exceed surplus
1295          * and won't grow the pool anywhere else. Not until one of the
1296          * sysctls are changed, or the surplus pages go out of use.
1297          */
1298         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1299         min_count = max(count, min_count);
1300         try_to_free_low(h, min_count, nodes_allowed);
1301         while (min_count < persistent_huge_pages(h)) {
1302                 if (!free_pool_huge_page(h, nodes_allowed, 0))
1303                         break;
1304         }
1305         while (count < persistent_huge_pages(h)) {
1306                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
1307                         break;
1308         }
1309 out:
1310         ret = persistent_huge_pages(h);
1311         spin_unlock(&hugetlb_lock);
1312         return ret;
1313 }
1314
1315 #define HSTATE_ATTR_RO(_name) \
1316         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1317
1318 #define HSTATE_ATTR(_name) \
1319         static struct kobj_attribute _name##_attr = \
1320                 __ATTR(_name, 0644, _name##_show, _name##_store)
1321
1322 static struct kobject *hugepages_kobj;
1323 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1324
1325 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1326
1327 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1328 {
1329         int i;
1330
1331         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1332                 if (hstate_kobjs[i] == kobj) {
1333                         if (nidp)
1334                                 *nidp = NUMA_NO_NODE;
1335                         return &hstates[i];
1336                 }
1337
1338         return kobj_to_node_hstate(kobj, nidp);
1339 }
1340
1341 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1342                                         struct kobj_attribute *attr, char *buf)
1343 {
1344         struct hstate *h;
1345         unsigned long nr_huge_pages;
1346         int nid;
1347
1348         h = kobj_to_hstate(kobj, &nid);
1349         if (nid == NUMA_NO_NODE)
1350                 nr_huge_pages = h->nr_huge_pages;
1351         else
1352                 nr_huge_pages = h->nr_huge_pages_node[nid];
1353
1354         return sprintf(buf, "%lu\n", nr_huge_pages);
1355 }
1356 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1357                         struct kobject *kobj, struct kobj_attribute *attr,
1358                         const char *buf, size_t len)
1359 {
1360         int err;
1361         int nid;
1362         unsigned long count;
1363         struct hstate *h;
1364         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1365
1366         err = strict_strtoul(buf, 10, &count);
1367         if (err)
1368                 return 0;
1369
1370         h = kobj_to_hstate(kobj, &nid);
1371         if (nid == NUMA_NO_NODE) {
1372                 /*
1373                  * global hstate attribute
1374                  */
1375                 if (!(obey_mempolicy &&
1376                                 init_nodemask_of_mempolicy(nodes_allowed))) {
1377                         NODEMASK_FREE(nodes_allowed);
1378                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1379                 }
1380         } else if (nodes_allowed) {
1381                 /*
1382                  * per node hstate attribute: adjust count to global,
1383                  * but restrict alloc/free to the specified node.
1384                  */
1385                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1386                 init_nodemask_of_node(nodes_allowed, nid);
1387         } else
1388                 nodes_allowed = &node_states[N_HIGH_MEMORY];
1389
1390         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1391
1392         if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1393                 NODEMASK_FREE(nodes_allowed);
1394
1395         return len;
1396 }
1397
1398 static ssize_t nr_hugepages_show(struct kobject *kobj,
1399                                        struct kobj_attribute *attr, char *buf)
1400 {
1401         return nr_hugepages_show_common(kobj, attr, buf);
1402 }
1403
1404 static ssize_t nr_hugepages_store(struct kobject *kobj,
1405                struct kobj_attribute *attr, const char *buf, size_t len)
1406 {
1407         return nr_hugepages_store_common(false, kobj, attr, buf, len);
1408 }
1409 HSTATE_ATTR(nr_hugepages);
1410
1411 #ifdef CONFIG_NUMA
1412
1413 /*
1414  * hstate attribute for optionally mempolicy-based constraint on persistent
1415  * huge page alloc/free.
1416  */
1417 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1418                                        struct kobj_attribute *attr, char *buf)
1419 {
1420         return nr_hugepages_show_common(kobj, attr, buf);
1421 }
1422
1423 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1424                struct kobj_attribute *attr, const char *buf, size_t len)
1425 {
1426         return nr_hugepages_store_common(true, kobj, attr, buf, len);
1427 }
1428 HSTATE_ATTR(nr_hugepages_mempolicy);
1429 #endif
1430
1431
1432 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1433                                         struct kobj_attribute *attr, char *buf)
1434 {
1435         struct hstate *h = kobj_to_hstate(kobj, NULL);
1436         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1437 }
1438 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1439                 struct kobj_attribute *attr, const char *buf, size_t count)
1440 {
1441         int err;
1442         unsigned long input;
1443         struct hstate *h = kobj_to_hstate(kobj, NULL);
1444
1445         err = strict_strtoul(buf, 10, &input);
1446         if (err)
1447                 return 0;
1448
1449         spin_lock(&hugetlb_lock);
1450         h->nr_overcommit_huge_pages = input;
1451         spin_unlock(&hugetlb_lock);
1452
1453         return count;
1454 }
1455 HSTATE_ATTR(nr_overcommit_hugepages);
1456
1457 static ssize_t free_hugepages_show(struct kobject *kobj,
1458                                         struct kobj_attribute *attr, char *buf)
1459 {
1460         struct hstate *h;
1461         unsigned long free_huge_pages;
1462         int nid;
1463
1464         h = kobj_to_hstate(kobj, &nid);
1465         if (nid == NUMA_NO_NODE)
1466                 free_huge_pages = h->free_huge_pages;
1467         else
1468                 free_huge_pages = h->free_huge_pages_node[nid];
1469
1470         return sprintf(buf, "%lu\n", free_huge_pages);
1471 }
1472 HSTATE_ATTR_RO(free_hugepages);
1473
1474 static ssize_t resv_hugepages_show(struct kobject *kobj,
1475                                         struct kobj_attribute *attr, char *buf)
1476 {
1477         struct hstate *h = kobj_to_hstate(kobj, NULL);
1478         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1479 }
1480 HSTATE_ATTR_RO(resv_hugepages);
1481
1482 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1483                                         struct kobj_attribute *attr, char *buf)
1484 {
1485         struct hstate *h;
1486         unsigned long surplus_huge_pages;
1487         int nid;
1488
1489         h = kobj_to_hstate(kobj, &nid);
1490         if (nid == NUMA_NO_NODE)
1491                 surplus_huge_pages = h->surplus_huge_pages;
1492         else
1493                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
1494
1495         return sprintf(buf, "%lu\n", surplus_huge_pages);
1496 }
1497 HSTATE_ATTR_RO(surplus_hugepages);
1498
1499 static struct attribute *hstate_attrs[] = {
1500         &nr_hugepages_attr.attr,
1501         &nr_overcommit_hugepages_attr.attr,
1502         &free_hugepages_attr.attr,
1503         &resv_hugepages_attr.attr,
1504         &surplus_hugepages_attr.attr,
1505 #ifdef CONFIG_NUMA
1506         &nr_hugepages_mempolicy_attr.attr,
1507 #endif
1508         NULL,
1509 };
1510
1511 static struct attribute_group hstate_attr_group = {
1512         .attrs = hstate_attrs,
1513 };
1514
1515 static int __init hugetlb_sysfs_add_hstate(struct hstate *h,
1516                                 struct kobject *parent,
1517                                 struct kobject **hstate_kobjs,
1518                                 struct attribute_group *hstate_attr_group)
1519 {
1520         int retval;
1521         int hi = h - hstates;
1522
1523         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1524         if (!hstate_kobjs[hi])
1525                 return -ENOMEM;
1526
1527         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1528         if (retval)
1529                 kobject_put(hstate_kobjs[hi]);
1530
1531         return retval;
1532 }
1533
1534 static void __init hugetlb_sysfs_init(void)
1535 {
1536         struct hstate *h;
1537         int err;
1538
1539         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1540         if (!hugepages_kobj)
1541                 return;
1542
1543         for_each_hstate(h) {
1544                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1545                                          hstate_kobjs, &hstate_attr_group);
1546                 if (err)
1547                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1548                                                                 h->name);
1549         }
1550 }
1551
1552 #ifdef CONFIG_NUMA
1553
1554 /*
1555  * node_hstate/s - associate per node hstate attributes, via their kobjects,
1556  * with node sysdevs in node_devices[] using a parallel array.  The array
1557  * index of a node sysdev or _hstate == node id.
1558  * This is here to avoid any static dependency of the node sysdev driver, in
1559  * the base kernel, on the hugetlb module.
1560  */
1561 struct node_hstate {
1562         struct kobject          *hugepages_kobj;
1563         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1564 };
1565 struct node_hstate node_hstates[MAX_NUMNODES];
1566
1567 /*
1568  * A subset of global hstate attributes for node sysdevs
1569  */
1570 static struct attribute *per_node_hstate_attrs[] = {
1571         &nr_hugepages_attr.attr,
1572         &free_hugepages_attr.attr,
1573         &surplus_hugepages_attr.attr,
1574         NULL,
1575 };
1576
1577 static struct attribute_group per_node_hstate_attr_group = {
1578         .attrs = per_node_hstate_attrs,
1579 };
1580
1581 /*
1582  * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj.
1583  * Returns node id via non-NULL nidp.
1584  */
1585 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1586 {
1587         int nid;
1588
1589         for (nid = 0; nid < nr_node_ids; nid++) {
1590                 struct node_hstate *nhs = &node_hstates[nid];
1591                 int i;
1592                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1593                         if (nhs->hstate_kobjs[i] == kobj) {
1594                                 if (nidp)
1595                                         *nidp = nid;
1596                                 return &hstates[i];
1597                         }
1598         }
1599
1600         BUG();
1601         return NULL;
1602 }
1603
1604 /*
1605  * Unregister hstate attributes from a single node sysdev.
1606  * No-op if no hstate attributes attached.
1607  */
1608 void hugetlb_unregister_node(struct node *node)
1609 {
1610         struct hstate *h;
1611         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1612
1613         if (!nhs->hugepages_kobj)
1614                 return;         /* no hstate attributes */
1615
1616         for_each_hstate(h)
1617                 if (nhs->hstate_kobjs[h - hstates]) {
1618                         kobject_put(nhs->hstate_kobjs[h - hstates]);
1619                         nhs->hstate_kobjs[h - hstates] = NULL;
1620                 }
1621
1622         kobject_put(nhs->hugepages_kobj);
1623         nhs->hugepages_kobj = NULL;
1624 }
1625
1626 /*
1627  * hugetlb module exit:  unregister hstate attributes from node sysdevs
1628  * that have them.
1629  */
1630 static void hugetlb_unregister_all_nodes(void)
1631 {
1632         int nid;
1633
1634         /*
1635          * disable node sysdev registrations.
1636          */
1637         register_hugetlbfs_with_node(NULL, NULL);
1638
1639         /*
1640          * remove hstate attributes from any nodes that have them.
1641          */
1642         for (nid = 0; nid < nr_node_ids; nid++)
1643                 hugetlb_unregister_node(&node_devices[nid]);
1644 }
1645
1646 /*
1647  * Register hstate attributes for a single node sysdev.
1648  * No-op if attributes already registered.
1649  */
1650 void hugetlb_register_node(struct node *node)
1651 {
1652         struct hstate *h;
1653         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1654         int err;
1655
1656         if (nhs->hugepages_kobj)
1657                 return;         /* already allocated */
1658
1659         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1660                                                         &node->sysdev.kobj);
1661         if (!nhs->hugepages_kobj)
1662                 return;
1663
1664         for_each_hstate(h) {
1665                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1666                                                 nhs->hstate_kobjs,
1667                                                 &per_node_hstate_attr_group);
1668                 if (err) {
1669                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1670                                         " for node %d\n",
1671                                                 h->name, node->sysdev.id);
1672                         hugetlb_unregister_node(node);
1673                         break;
1674                 }
1675         }
1676 }
1677
1678 /*
1679  * hugetlb init time:  register hstate attributes for all registered node
1680  * sysdevs of nodes that have memory.  All on-line nodes should have
1681  * registered their associated sysdev by this time.
1682  */
1683 static void hugetlb_register_all_nodes(void)
1684 {
1685         int nid;
1686
1687         for_each_node_state(nid, N_HIGH_MEMORY) {
1688                 struct node *node = &node_devices[nid];
1689                 if (node->sysdev.id == nid)
1690                         hugetlb_register_node(node);
1691         }
1692
1693         /*
1694          * Let the node sysdev driver know we're here so it can
1695          * [un]register hstate attributes on node hotplug.
1696          */
1697         register_hugetlbfs_with_node(hugetlb_register_node,
1698                                      hugetlb_unregister_node);
1699 }
1700 #else   /* !CONFIG_NUMA */
1701
1702 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1703 {
1704         BUG();
1705         if (nidp)
1706                 *nidp = -1;
1707         return NULL;
1708 }
1709
1710 static void hugetlb_unregister_all_nodes(void) { }
1711
1712 static void hugetlb_register_all_nodes(void) { }
1713
1714 #endif
1715
1716 static void __exit hugetlb_exit(void)
1717 {
1718         struct hstate *h;
1719
1720         hugetlb_unregister_all_nodes();
1721
1722         for_each_hstate(h) {
1723                 kobject_put(hstate_kobjs[h - hstates]);
1724         }
1725
1726         kobject_put(hugepages_kobj);
1727 }
1728 module_exit(hugetlb_exit);
1729
1730 static int __init hugetlb_init(void)
1731 {
1732         /* Some platform decide whether they support huge pages at boot
1733          * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1734          * there is no such support
1735          */
1736         if (HPAGE_SHIFT == 0)
1737                 return 0;
1738
1739         if (!size_to_hstate(default_hstate_size)) {
1740                 default_hstate_size = HPAGE_SIZE;
1741                 if (!size_to_hstate(default_hstate_size))
1742                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1743         }
1744         default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1745         if (default_hstate_max_huge_pages)
1746                 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1747
1748         hugetlb_init_hstates();
1749
1750         gather_bootmem_prealloc();
1751
1752         report_hugepages();
1753
1754         hugetlb_sysfs_init();
1755
1756         hugetlb_register_all_nodes();
1757
1758         return 0;
1759 }
1760 module_init(hugetlb_init);
1761
1762 /* Should be called on processing a hugepagesz=... option */
1763 void __init hugetlb_add_hstate(unsigned order)
1764 {
1765         struct hstate *h;
1766         unsigned long i;
1767
1768         if (size_to_hstate(PAGE_SIZE << order)) {
1769                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1770                 return;
1771         }
1772         BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1773         BUG_ON(order == 0);
1774         h = &hstates[max_hstate++];
1775         h->order = order;
1776         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1777         h->nr_huge_pages = 0;
1778         h->free_huge_pages = 0;
1779         for (i = 0; i < MAX_NUMNODES; ++i)
1780                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1781         h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
1782         h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
1783         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1784                                         huge_page_size(h)/1024);
1785
1786         parsed_hstate = h;
1787 }
1788
1789 static int __init hugetlb_nrpages_setup(char *s)
1790 {
1791         unsigned long *mhp;
1792         static unsigned long *last_mhp;
1793
1794         /*
1795          * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1796          * so this hugepages= parameter goes to the "default hstate".
1797          */
1798         if (!max_hstate)
1799                 mhp = &default_hstate_max_huge_pages;
1800         else
1801                 mhp = &parsed_hstate->max_huge_pages;
1802
1803         if (mhp == last_mhp) {
1804                 printk(KERN_WARNING "hugepages= specified twice without "
1805                         "interleaving hugepagesz=, ignoring\n");
1806                 return 1;
1807         }
1808
1809         if (sscanf(s, "%lu", mhp) <= 0)
1810                 *mhp = 0;
1811
1812         /*
1813          * Global state is always initialized later in hugetlb_init.
1814          * But we need to allocate >= MAX_ORDER hstates here early to still
1815          * use the bootmem allocator.
1816          */
1817         if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1818                 hugetlb_hstate_alloc_pages(parsed_hstate);
1819
1820         last_mhp = mhp;
1821
1822         return 1;
1823 }
1824 __setup("hugepages=", hugetlb_nrpages_setup);
1825
1826 static int __init hugetlb_default_setup(char *s)
1827 {
1828         default_hstate_size = memparse(s, &s);
1829         return 1;
1830 }
1831 __setup("default_hugepagesz=", hugetlb_default_setup);
1832
1833 static unsigned int cpuset_mems_nr(unsigned int *array)
1834 {
1835         int node;
1836         unsigned int nr = 0;
1837
1838         for_each_node_mask(node, cpuset_current_mems_allowed)
1839                 nr += array[node];
1840
1841         return nr;
1842 }
1843
1844 #ifdef CONFIG_SYSCTL
1845 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
1846                          struct ctl_table *table, int write,
1847                          void __user *buffer, size_t *length, loff_t *ppos)
1848 {
1849         struct hstate *h = &default_hstate;
1850         unsigned long tmp;
1851
1852         if (!write)
1853                 tmp = h->max_huge_pages;
1854
1855         table->data = &tmp;
1856         table->maxlen = sizeof(unsigned long);
1857         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1858
1859         if (write) {
1860                 NODEMASK_ALLOC(nodemask_t, nodes_allowed,
1861                                                 GFP_KERNEL | __GFP_NORETRY);
1862                 if (!(obey_mempolicy &&
1863                                init_nodemask_of_mempolicy(nodes_allowed))) {
1864                         NODEMASK_FREE(nodes_allowed);
1865                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1866                 }
1867                 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
1868
1869                 if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1870                         NODEMASK_FREE(nodes_allowed);
1871         }
1872
1873         return 0;
1874 }
1875
1876 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1877                           void __user *buffer, size_t *length, loff_t *ppos)
1878 {
1879
1880         return hugetlb_sysctl_handler_common(false, table, write,
1881                                                         buffer, length, ppos);
1882 }
1883
1884 #ifdef CONFIG_NUMA
1885 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
1886                           void __user *buffer, size_t *length, loff_t *ppos)
1887 {
1888         return hugetlb_sysctl_handler_common(true, table, write,
1889                                                         buffer, length, ppos);
1890 }
1891 #endif /* CONFIG_NUMA */
1892
1893 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1894                         void __user *buffer,
1895                         size_t *length, loff_t *ppos)
1896 {
1897         proc_dointvec(table, write, buffer, length, ppos);
1898         if (hugepages_treat_as_movable)
1899                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1900         else
1901                 htlb_alloc_mask = GFP_HIGHUSER;
1902         return 0;
1903 }
1904
1905 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1906                         void __user *buffer,
1907                         size_t *length, loff_t *ppos)
1908 {
1909         struct hstate *h = &default_hstate;
1910         unsigned long tmp;
1911
1912         if (!write)
1913                 tmp = h->nr_overcommit_huge_pages;
1914
1915         table->data = &tmp;
1916         table->maxlen = sizeof(unsigned long);
1917         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1918
1919         if (write) {
1920                 spin_lock(&hugetlb_lock);
1921                 h->nr_overcommit_huge_pages = tmp;
1922                 spin_unlock(&hugetlb_lock);
1923         }
1924
1925         return 0;
1926 }
1927
1928 #endif /* CONFIG_SYSCTL */
1929
1930 void hugetlb_report_meminfo(struct seq_file *m)
1931 {
1932         struct hstate *h = &default_hstate;
1933         seq_printf(m,
1934                         "HugePages_Total:   %5lu\n"
1935                         "HugePages_Free:    %5lu\n"
1936                         "HugePages_Rsvd:    %5lu\n"
1937                         "HugePages_Surp:    %5lu\n"
1938                         "Hugepagesize:   %8lu kB\n",
1939                         h->nr_huge_pages,
1940                         h->free_huge_pages,
1941                         h->resv_huge_pages,
1942                         h->surplus_huge_pages,
1943                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1944 }
1945
1946 int hugetlb_report_node_meminfo(int nid, char *buf)
1947 {
1948         struct hstate *h = &default_hstate;
1949         return sprintf(buf,
1950                 "Node %d HugePages_Total: %5u\n"
1951                 "Node %d HugePages_Free:  %5u\n"
1952                 "Node %d HugePages_Surp:  %5u\n",
1953                 nid, h->nr_huge_pages_node[nid],
1954                 nid, h->free_huge_pages_node[nid],
1955                 nid, h->surplus_huge_pages_node[nid]);
1956 }
1957
1958 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1959 unsigned long hugetlb_total_pages(void)
1960 {
1961         struct hstate *h = &default_hstate;
1962         return h->nr_huge_pages * pages_per_huge_page(h);
1963 }
1964
1965 static int hugetlb_acct_memory(struct hstate *h, long delta)
1966 {
1967         int ret = -ENOMEM;
1968
1969         spin_lock(&hugetlb_lock);
1970         /*
1971          * When cpuset is configured, it breaks the strict hugetlb page
1972          * reservation as the accounting is done on a global variable. Such
1973          * reservation is completely rubbish in the presence of cpuset because
1974          * the reservation is not checked against page availability for the
1975          * current cpuset. Application can still potentially OOM'ed by kernel
1976          * with lack of free htlb page in cpuset that the task is in.
1977          * Attempt to enforce strict accounting with cpuset is almost
1978          * impossible (or too ugly) because cpuset is too fluid that
1979          * task or memory node can be dynamically moved between cpusets.
1980          *
1981          * The change of semantics for shared hugetlb mapping with cpuset is
1982          * undesirable. However, in order to preserve some of the semantics,
1983          * we fall back to check against current free page availability as
1984          * a best attempt and hopefully to minimize the impact of changing
1985          * semantics that cpuset has.
1986          */
1987         if (delta > 0) {
1988                 if (gather_surplus_pages(h, delta) < 0)
1989                         goto out;
1990
1991                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1992                         return_unused_surplus_pages(h, delta);
1993                         goto out;
1994                 }
1995         }
1996
1997         ret = 0;
1998         if (delta < 0)
1999                 return_unused_surplus_pages(h, (unsigned long) -delta);
2000
2001 out:
2002         spin_unlock(&hugetlb_lock);
2003         return ret;
2004 }
2005
2006 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2007 {
2008         struct resv_map *reservations = vma_resv_map(vma);
2009
2010         /*
2011          * This new VMA should share its siblings reservation map if present.
2012          * The VMA will only ever have a valid reservation map pointer where
2013          * it is being copied for another still existing VMA.  As that VMA
2014          * has a reference to the reservation map it cannot dissappear until
2015          * after this open call completes.  It is therefore safe to take a
2016          * new reference here without additional locking.
2017          */
2018         if (reservations)
2019                 kref_get(&reservations->refs);
2020 }
2021
2022 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2023 {
2024         struct hstate *h = hstate_vma(vma);
2025         struct resv_map *reservations = vma_resv_map(vma);
2026         unsigned long reserve;
2027         unsigned long start;
2028         unsigned long end;
2029
2030         if (reservations) {
2031                 start = vma_hugecache_offset(h, vma, vma->vm_start);
2032                 end = vma_hugecache_offset(h, vma, vma->vm_end);
2033
2034                 reserve = (end - start) -
2035                         region_count(&reservations->regions, start, end);
2036
2037                 kref_put(&reservations->refs, resv_map_release);
2038
2039                 if (reserve) {
2040                         hugetlb_acct_memory(h, -reserve);
2041                         hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
2042                 }
2043         }
2044 }
2045
2046 /*
2047  * We cannot handle pagefaults against hugetlb pages at all.  They cause
2048  * handle_mm_fault() to try to instantiate regular-sized pages in the
2049  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2050  * this far.
2051  */
2052 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2053 {
2054         BUG();
2055         return 0;
2056 }
2057
2058 const struct vm_operations_struct hugetlb_vm_ops = {
2059         .fault = hugetlb_vm_op_fault,
2060         .open = hugetlb_vm_op_open,
2061         .close = hugetlb_vm_op_close,
2062 };
2063
2064 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2065                                 int writable)
2066 {
2067         pte_t entry;
2068
2069         if (writable) {
2070                 entry =
2071                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2072         } else {
2073                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2074         }
2075         entry = pte_mkyoung(entry);
2076         entry = pte_mkhuge(entry);
2077
2078         return entry;
2079 }
2080
2081 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2082                                    unsigned long address, pte_t *ptep)
2083 {
2084         pte_t entry;
2085
2086         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2087         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
2088                 update_mmu_cache(vma, address, entry);
2089         }
2090 }
2091
2092
2093 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2094                             struct vm_area_struct *vma)
2095 {
2096         pte_t *src_pte, *dst_pte, entry;
2097         struct page *ptepage;
2098         unsigned long addr;
2099         int cow;
2100         struct hstate *h = hstate_vma(vma);
2101         unsigned long sz = huge_page_size(h);
2102
2103         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2104
2105         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2106                 src_pte = huge_pte_offset(src, addr);
2107                 if (!src_pte)
2108                         continue;
2109                 dst_pte = huge_pte_alloc(dst, addr, sz);
2110                 if (!dst_pte)
2111                         goto nomem;
2112
2113                 /* If the pagetables are shared don't copy or take references */
2114                 if (dst_pte == src_pte)
2115                         continue;
2116
2117                 spin_lock(&dst->page_table_lock);
2118                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2119                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
2120                         if (cow)
2121                                 huge_ptep_set_wrprotect(src, addr, src_pte);
2122                         entry = huge_ptep_get(src_pte);
2123                         ptepage = pte_page(entry);
2124                         get_page(ptepage);
2125                         set_huge_pte_at(dst, addr, dst_pte, entry);
2126                 }
2127                 spin_unlock(&src->page_table_lock);
2128                 spin_unlock(&dst->page_table_lock);
2129         }
2130         return 0;
2131
2132 nomem:
2133         return -ENOMEM;
2134 }
2135
2136 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2137                             unsigned long end, struct page *ref_page)
2138 {
2139         struct mm_struct *mm = vma->vm_mm;
2140         unsigned long address;
2141         pte_t *ptep;
2142         pte_t pte;
2143         struct page *page;
2144         struct page *tmp;
2145         struct hstate *h = hstate_vma(vma);
2146         unsigned long sz = huge_page_size(h);
2147
2148         /*
2149          * A page gathering list, protected by per file i_mmap_lock. The
2150          * lock is used to avoid list corruption from multiple unmapping
2151          * of the same page since we are using page->lru.
2152          */
2153         LIST_HEAD(page_list);
2154
2155         WARN_ON(!is_vm_hugetlb_page(vma));
2156         BUG_ON(start & ~huge_page_mask(h));
2157         BUG_ON(end & ~huge_page_mask(h));
2158
2159         mmu_notifier_invalidate_range_start(mm, start, end);
2160         spin_lock(&mm->page_table_lock);
2161         for (address = start; address < end; address += sz) {
2162                 ptep = huge_pte_offset(mm, address);
2163                 if (!ptep)
2164                         continue;
2165
2166                 if (huge_pmd_unshare(mm, &address, ptep))
2167                         continue;
2168
2169                 /*
2170                  * If a reference page is supplied, it is because a specific
2171                  * page is being unmapped, not a range. Ensure the page we
2172                  * are about to unmap is the actual page of interest.
2173                  */
2174                 if (ref_page) {
2175                         pte = huge_ptep_get(ptep);
2176                         if (huge_pte_none(pte))
2177                                 continue;
2178                         page = pte_page(pte);
2179                         if (page != ref_page)
2180                                 continue;
2181
2182                         /*
2183                          * Mark the VMA as having unmapped its page so that
2184                          * future faults in this VMA will fail rather than
2185                          * looking like data was lost
2186                          */
2187                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2188                 }
2189
2190                 pte = huge_ptep_get_and_clear(mm, address, ptep);
2191                 if (huge_pte_none(pte))
2192                         continue;
2193
2194                 page = pte_page(pte);
2195                 if (pte_dirty(pte))
2196                         set_page_dirty(page);
2197                 list_add(&page->lru, &page_list);
2198         }
2199         spin_unlock(&mm->page_table_lock);
2200         flush_tlb_range(vma, start, end);
2201         mmu_notifier_invalidate_range_end(mm, start, end);
2202         list_for_each_entry_safe(page, tmp, &page_list, lru) {
2203                 list_del(&page->lru);
2204                 put_page(page);
2205         }
2206 }
2207
2208 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2209                           unsigned long end, struct page *ref_page)
2210 {
2211         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2212         __unmap_hugepage_range(vma, start, end, ref_page);
2213         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2214 }
2215
2216 /*
2217  * This is called when the original mapper is failing to COW a MAP_PRIVATE
2218  * mappping it owns the reserve page for. The intention is to unmap the page
2219  * from other VMAs and let the children be SIGKILLed if they are faulting the
2220  * same region.
2221  */
2222 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2223                                 struct page *page, unsigned long address)
2224 {
2225         struct hstate *h = hstate_vma(vma);
2226         struct vm_area_struct *iter_vma;
2227         struct address_space *mapping;
2228         struct prio_tree_iter iter;
2229         pgoff_t pgoff;
2230
2231         /*
2232          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2233          * from page cache lookup which is in HPAGE_SIZE units.
2234          */
2235         address = address & huge_page_mask(h);
2236         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
2237                 + (vma->vm_pgoff >> PAGE_SHIFT);
2238         mapping = (struct address_space *)page_private(page);
2239
2240         /*
2241          * Take the mapping lock for the duration of the table walk. As
2242          * this mapping should be shared between all the VMAs,
2243          * __unmap_hugepage_range() is called as the lock is already held
2244          */
2245         spin_lock(&mapping->i_mmap_lock);
2246         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2247                 /* Do not unmap the current VMA */
2248                 if (iter_vma == vma)
2249                         continue;
2250
2251                 /*
2252                  * Unmap the page from other VMAs without their own reserves.
2253                  * They get marked to be SIGKILLed if they fault in these
2254                  * areas. This is because a future no-page fault on this VMA
2255                  * could insert a zeroed page instead of the data existing
2256                  * from the time of fork. This would look like data corruption
2257                  */
2258                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2259                         __unmap_hugepage_range(iter_vma,
2260                                 address, address + huge_page_size(h),
2261                                 page);
2262         }
2263         spin_unlock(&mapping->i_mmap_lock);
2264
2265         return 1;
2266 }
2267
2268 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2269                         unsigned long address, pte_t *ptep, pte_t pte,
2270                         struct page *pagecache_page)
2271 {
2272         struct hstate *h = hstate_vma(vma);
2273         struct page *old_page, *new_page;
2274         int avoidcopy;
2275         int outside_reserve = 0;
2276
2277         old_page = pte_page(pte);
2278
2279 retry_avoidcopy:
2280         /* If no-one else is actually using this page, avoid the copy
2281          * and just make the page writable */
2282         avoidcopy = (page_count(old_page) == 1);
2283         if (avoidcopy) {
2284                 set_huge_ptep_writable(vma, address, ptep);
2285                 return 0;
2286         }
2287
2288         /*
2289          * If the process that created a MAP_PRIVATE mapping is about to
2290          * perform a COW due to a shared page count, attempt to satisfy
2291          * the allocation without using the existing reserves. The pagecache
2292          * page is used to determine if the reserve at this address was
2293          * consumed or not. If reserves were used, a partial faulted mapping
2294          * at the time of fork() could consume its reserves on COW instead
2295          * of the full address range.
2296          */
2297         if (!(vma->vm_flags & VM_MAYSHARE) &&
2298                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2299                         old_page != pagecache_page)
2300                 outside_reserve = 1;
2301
2302         page_cache_get(old_page);
2303
2304         /* Drop page_table_lock as buddy allocator may be called */
2305         spin_unlock(&mm->page_table_lock);
2306         new_page = alloc_huge_page(vma, address, outside_reserve);
2307
2308         if (IS_ERR(new_page)) {
2309                 page_cache_release(old_page);
2310
2311                 /*
2312                  * If a process owning a MAP_PRIVATE mapping fails to COW,
2313                  * it is due to references held by a child and an insufficient
2314                  * huge page pool. To guarantee the original mappers
2315                  * reliability, unmap the page from child processes. The child
2316                  * may get SIGKILLed if it later faults.
2317                  */
2318                 if (outside_reserve) {
2319                         BUG_ON(huge_pte_none(pte));
2320                         if (unmap_ref_private(mm, vma, old_page, address)) {
2321                                 BUG_ON(page_count(old_page) != 1);
2322                                 BUG_ON(huge_pte_none(pte));
2323                                 spin_lock(&mm->page_table_lock);
2324                                 goto retry_avoidcopy;
2325                         }
2326                         WARN_ON_ONCE(1);
2327                 }
2328
2329                 /* Caller expects lock to be held */
2330                 spin_lock(&mm->page_table_lock);
2331                 return -PTR_ERR(new_page);
2332         }
2333
2334         copy_huge_page(new_page, old_page, address, vma);
2335         __SetPageUptodate(new_page);
2336
2337         /*
2338          * Retake the page_table_lock to check for racing updates
2339          * before the page tables are altered
2340          */
2341         spin_lock(&mm->page_table_lock);
2342         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2343         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2344                 /* Break COW */
2345                 huge_ptep_clear_flush(vma, address, ptep);
2346                 set_huge_pte_at(mm, address, ptep,
2347                                 make_huge_pte(vma, new_page, 1));
2348                 /* Make the old page be freed below */
2349                 new_page = old_page;
2350         }
2351         page_cache_release(new_page);
2352         page_cache_release(old_page);
2353         return 0;
2354 }
2355
2356 /* Return the pagecache page at a given address within a VMA */
2357 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2358                         struct vm_area_struct *vma, unsigned long address)
2359 {
2360         struct address_space *mapping;
2361         pgoff_t idx;
2362
2363         mapping = vma->vm_file->f_mapping;
2364         idx = vma_hugecache_offset(h, vma, address);
2365
2366         return find_lock_page(mapping, idx);
2367 }
2368
2369 /*
2370  * Return whether there is a pagecache page to back given address within VMA.
2371  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2372  */
2373 static bool hugetlbfs_pagecache_present(struct hstate *h,
2374                         struct vm_area_struct *vma, unsigned long address)
2375 {
2376         struct address_space *mapping;
2377         pgoff_t idx;
2378         struct page *page;
2379
2380         mapping = vma->vm_file->f_mapping;
2381         idx = vma_hugecache_offset(h, vma, address);
2382
2383         page = find_get_page(mapping, idx);
2384         if (page)
2385                 put_page(page);
2386         return page != NULL;
2387 }
2388
2389 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2390                         unsigned long address, pte_t *ptep, unsigned int flags)
2391 {
2392         struct hstate *h = hstate_vma(vma);
2393         int ret = VM_FAULT_SIGBUS;
2394         pgoff_t idx;
2395         unsigned long size;
2396         struct page *page;
2397         struct address_space *mapping;
2398         pte_t new_pte;
2399
2400         /*
2401          * Currently, we are forced to kill the process in the event the
2402          * original mapper has unmapped pages from the child due to a failed
2403          * COW. Warn that such a situation has occured as it may not be obvious
2404          */
2405         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2406                 printk(KERN_WARNING
2407                         "PID %d killed due to inadequate hugepage pool\n",
2408                         current->pid);
2409                 return ret;
2410         }
2411
2412         mapping = vma->vm_file->f_mapping;
2413         idx = vma_hugecache_offset(h, vma, address);
2414
2415         /*
2416          * Use page lock to guard against racing truncation
2417          * before we get page_table_lock.
2418          */
2419 retry:
2420         page = find_lock_page(mapping, idx);
2421         if (!page) {
2422                 size = i_size_read(mapping->host) >> huge_page_shift(h);
2423                 if (idx >= size)
2424                         goto out;
2425                 page = alloc_huge_page(vma, address, 0);
2426                 if (IS_ERR(page)) {
2427                         ret = -PTR_ERR(page);
2428                         goto out;
2429                 }
2430                 clear_huge_page(page, address, huge_page_size(h));
2431                 __SetPageUptodate(page);
2432
2433                 if (vma->vm_flags & VM_MAYSHARE) {
2434                         int err;
2435                         struct inode *inode = mapping->host;
2436
2437                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2438                         if (err) {
2439                                 put_page(page);
2440                                 if (err == -EEXIST)
2441                                         goto retry;
2442                                 goto out;
2443                         }
2444
2445                         spin_lock(&inode->i_lock);
2446                         inode->i_blocks += blocks_per_huge_page(h);
2447                         spin_unlock(&inode->i_lock);
2448                 } else
2449                         lock_page(page);
2450         }
2451
2452         /*
2453          * If we are going to COW a private mapping later, we examine the
2454          * pending reservations for this page now. This will ensure that
2455          * any allocations necessary to record that reservation occur outside
2456          * the spinlock.
2457          */
2458         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2459                 if (vma_needs_reservation(h, vma, address) < 0) {
2460                         ret = VM_FAULT_OOM;
2461                         goto backout_unlocked;
2462                 }
2463
2464         spin_lock(&mm->page_table_lock);
2465         size = i_size_read(mapping->host) >> huge_page_shift(h);
2466         if (idx >= size)
2467                 goto backout;
2468
2469         ret = 0;
2470         if (!huge_pte_none(huge_ptep_get(ptep)))
2471                 goto backout;
2472
2473         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2474                                 && (vma->vm_flags & VM_SHARED)));
2475         set_huge_pte_at(mm, address, ptep, new_pte);
2476
2477         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2478                 /* Optimization, do the COW without a second fault */
2479                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2480         }
2481
2482         spin_unlock(&mm->page_table_lock);
2483         unlock_page(page);
2484 out:
2485         return ret;
2486
2487 backout:
2488         spin_unlock(&mm->page_table_lock);
2489 backout_unlocked:
2490         unlock_page(page);
2491         put_page(page);
2492         goto out;
2493 }
2494
2495 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2496                         unsigned long address, unsigned int flags)
2497 {
2498         pte_t *ptep;
2499         pte_t entry;
2500         int ret;
2501         struct page *pagecache_page = NULL;
2502         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2503         struct hstate *h = hstate_vma(vma);
2504
2505         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2506         if (!ptep)
2507                 return VM_FAULT_OOM;
2508
2509         /*
2510          * Serialize hugepage allocation and instantiation, so that we don't
2511          * get spurious allocation failures if two CPUs race to instantiate
2512          * the same page in the page cache.
2513          */
2514         mutex_lock(&hugetlb_instantiation_mutex);
2515         entry = huge_ptep_get(ptep);
2516         if (huge_pte_none(entry)) {
2517                 ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2518                 goto out_mutex;
2519         }
2520
2521         ret = 0;
2522
2523         /*
2524          * If we are going to COW the mapping later, we examine the pending
2525          * reservations for this page now. This will ensure that any
2526          * allocations necessary to record that reservation occur outside the
2527          * spinlock. For private mappings, we also lookup the pagecache
2528          * page now as it is used to determine if a reservation has been
2529          * consumed.
2530          */
2531         if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2532                 if (vma_needs_reservation(h, vma, address) < 0) {
2533                         ret = VM_FAULT_OOM;
2534                         goto out_mutex;
2535                 }
2536
2537                 if (!(vma->vm_flags & VM_MAYSHARE))
2538                         pagecache_page = hugetlbfs_pagecache_page(h,
2539                                                                 vma, address);
2540         }
2541
2542         spin_lock(&mm->page_table_lock);
2543         /* Check for a racing update before calling hugetlb_cow */
2544         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2545                 goto out_page_table_lock;
2546
2547
2548         if (flags & FAULT_FLAG_WRITE) {
2549                 if (!pte_write(entry)) {
2550                         ret = hugetlb_cow(mm, vma, address, ptep, entry,
2551                                                         pagecache_page);
2552                         goto out_page_table_lock;
2553                 }
2554                 entry = pte_mkdirty(entry);
2555         }
2556         entry = pte_mkyoung(entry);
2557         if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2558                                                 flags & FAULT_FLAG_WRITE))
2559                 update_mmu_cache(vma, address, entry);
2560
2561 out_page_table_lock:
2562         spin_unlock(&mm->page_table_lock);
2563
2564         if (pagecache_page) {
2565                 unlock_page(pagecache_page);
2566                 put_page(pagecache_page);
2567         }
2568
2569 out_mutex:
2570         mutex_unlock(&hugetlb_instantiation_mutex);
2571
2572         return ret;
2573 }
2574
2575 /* Can be overriden by architectures */
2576 __attribute__((weak)) struct page *
2577 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2578                pud_t *pud, int write)
2579 {
2580         BUG();
2581         return NULL;
2582 }
2583
2584 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2585                         struct page **pages, struct vm_area_struct **vmas,
2586                         unsigned long *position, int *length, int i,
2587                         unsigned int flags)
2588 {
2589         unsigned long pfn_offset;
2590         unsigned long vaddr = *position;
2591         int remainder = *length;
2592         struct hstate *h = hstate_vma(vma);
2593
2594         spin_lock(&mm->page_table_lock);
2595         while (vaddr < vma->vm_end && remainder) {
2596                 pte_t *pte;
2597                 int absent;
2598                 struct page *page;
2599
2600                 /*
2601                  * Some archs (sparc64, sh*) have multiple pte_ts to
2602                  * each hugepage.  We have to make sure we get the
2603                  * first, for the page indexing below to work.
2604                  */
2605                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2606                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
2607
2608                 /*
2609                  * When coredumping, it suits get_dump_page if we just return
2610                  * an error where there's an empty slot with no huge pagecache
2611                  * to back it.  This way, we avoid allocating a hugepage, and
2612                  * the sparse dumpfile avoids allocating disk blocks, but its
2613                  * huge holes still show up with zeroes where they need to be.
2614                  */
2615                 if (absent && (flags & FOLL_DUMP) &&
2616                     !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2617                         remainder = 0;
2618                         break;
2619                 }
2620
2621                 if (absent ||
2622                     ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2623                         int ret;
2624
2625                         spin_unlock(&mm->page_table_lock);
2626                         ret = hugetlb_fault(mm, vma, vaddr,
2627                                 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2628                         spin_lock(&mm->page_table_lock);
2629                         if (!(ret & VM_FAULT_ERROR))
2630                                 continue;
2631
2632                         remainder = 0;
2633                         break;
2634                 }
2635
2636                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2637                 page = pte_page(huge_ptep_get(pte));
2638 same_page:
2639                 if (pages) {
2640                         pages[i] = mem_map_offset(page, pfn_offset);
2641                         get_page(pages[i]);
2642                 }
2643
2644                 if (vmas)
2645                         vmas[i] = vma;
2646
2647                 vaddr += PAGE_SIZE;
2648                 ++pfn_offset;
2649                 --remainder;
2650                 ++i;
2651                 if (vaddr < vma->vm_end && remainder &&
2652                                 pfn_offset < pages_per_huge_page(h)) {
2653                         /*
2654                          * We use pfn_offset to avoid touching the pageframes
2655                          * of this compound page.
2656                          */
2657                         goto same_page;
2658                 }
2659         }
2660         spin_unlock(&mm->page_table_lock);
2661         *length = remainder;
2662         *position = vaddr;
2663
2664         return i ? i : -EFAULT;
2665 }
2666
2667 void hugetlb_change_protection(struct vm_area_struct *vma,
2668                 unsigned long address, unsigned long end, pgprot_t newprot)
2669 {
2670         struct mm_struct *mm = vma->vm_mm;
2671         unsigned long start = address;
2672         pte_t *ptep;
2673         pte_t pte;
2674         struct hstate *h = hstate_vma(vma);
2675
2676         BUG_ON(address >= end);
2677         flush_cache_range(vma, address, end);
2678
2679         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2680         spin_lock(&mm->page_table_lock);
2681         for (; address < end; address += huge_page_size(h)) {
2682                 ptep = huge_pte_offset(mm, address);
2683                 if (!ptep)
2684                         continue;
2685                 if (huge_pmd_unshare(mm, &address, ptep))
2686                         continue;
2687                 if (!huge_pte_none(huge_ptep_get(ptep))) {
2688                         pte = huge_ptep_get_and_clear(mm, address, ptep);
2689                         pte = pte_mkhuge(pte_modify(pte, newprot));
2690                         set_huge_pte_at(mm, address, ptep, pte);
2691                 }
2692         }
2693         spin_unlock(&mm->page_table_lock);
2694         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2695
2696         flush_tlb_range(vma, start, end);
2697 }
2698
2699 int hugetlb_reserve_pages(struct inode *inode,
2700                                         long from, long to,
2701                                         struct vm_area_struct *vma,
2702                                         int acctflag)
2703 {
2704         long ret, chg;
2705         struct hstate *h = hstate_inode(inode);
2706
2707         /*
2708          * Only apply hugepage reservation if asked. At fault time, an
2709          * attempt will be made for VM_NORESERVE to allocate a page
2710          * and filesystem quota without using reserves
2711          */
2712         if (acctflag & VM_NORESERVE)
2713                 return 0;
2714
2715         /*
2716          * Shared mappings base their reservation on the number of pages that
2717          * are already allocated on behalf of the file. Private mappings need
2718          * to reserve the full area even if read-only as mprotect() may be
2719          * called to make the mapping read-write. Assume !vma is a shm mapping
2720          */
2721         if (!vma || vma->vm_flags & VM_MAYSHARE)
2722                 chg = region_chg(&inode->i_mapping->private_list, from, to);
2723         else {
2724                 struct resv_map *resv_map = resv_map_alloc();
2725                 if (!resv_map)
2726                         return -ENOMEM;
2727
2728                 chg = to - from;
2729
2730                 set_vma_resv_map(vma, resv_map);
2731                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2732         }
2733
2734         if (chg < 0)
2735                 return chg;
2736
2737         /* There must be enough filesystem quota for the mapping */
2738         if (hugetlb_get_quota(inode->i_mapping, chg))
2739                 return -ENOSPC;
2740
2741         /*
2742          * Check enough hugepages are available for the reservation.
2743          * Hand back the quota if there are not
2744          */
2745         ret = hugetlb_acct_memory(h, chg);
2746         if (ret < 0) {
2747                 hugetlb_put_quota(inode->i_mapping, chg);
2748                 return ret;
2749         }
2750
2751         /*
2752          * Account for the reservations made. Shared mappings record regions
2753          * that have reservations as they are shared by multiple VMAs.
2754          * When the last VMA disappears, the region map says how much
2755          * the reservation was and the page cache tells how much of
2756          * the reservation was consumed. Private mappings are per-VMA and
2757          * only the consumed reservations are tracked. When the VMA
2758          * disappears, the original reservation is the VMA size and the
2759          * consumed reservations are stored in the map. Hence, nothing
2760          * else has to be done for private mappings here
2761          */
2762         if (!vma || vma->vm_flags & VM_MAYSHARE)
2763                 region_add(&inode->i_mapping->private_list, from, to);
2764         return 0;
2765 }
2766
2767 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2768 {
2769         struct hstate *h = hstate_inode(inode);
2770         long chg = region_truncate(&inode->i_mapping->private_list, offset);
2771
2772         spin_lock(&inode->i_lock);
2773         inode->i_blocks -= (blocks_per_huge_page(h) * freed);
2774         spin_unlock(&inode->i_lock);
2775
2776         hugetlb_put_quota(inode->i_mapping, (chg - freed));
2777         hugetlb_acct_memory(h, -(chg - freed));
2778 }