hugetlb: fix infinite loop in get_futex_key() when backed by huge pages
[linux-2.6.git] / mm / hugetlb.c
1 /*
2  * Generic hugetlb support.
3  * (C) William Irwin, April 2004
4  */
5 #include <linux/list.h>
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/mm.h>
9 #include <linux/seq_file.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/nodemask.h>
14 #include <linux/pagemap.h>
15 #include <linux/mempolicy.h>
16 #include <linux/cpuset.h>
17 #include <linux/mutex.h>
18 #include <linux/bootmem.h>
19 #include <linux/sysfs.h>
20 #include <linux/slab.h>
21
22 #include <asm/page.h>
23 #include <asm/pgtable.h>
24 #include <asm/io.h>
25
26 #include <linux/hugetlb.h>
27 #include <linux/node.h>
28 #include "internal.h"
29
30 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
31 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
32 unsigned long hugepages_treat_as_movable;
33
34 static int max_hstate;
35 unsigned int default_hstate_idx;
36 struct hstate hstates[HUGE_MAX_HSTATE];
37
38 __initdata LIST_HEAD(huge_boot_pages);
39
40 /* for command line parsing */
41 static struct hstate * __initdata parsed_hstate;
42 static unsigned long __initdata default_hstate_max_huge_pages;
43 static unsigned long __initdata default_hstate_size;
44
45 #define for_each_hstate(h) \
46         for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
47
48 /*
49  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
50  */
51 static DEFINE_SPINLOCK(hugetlb_lock);
52
53 /*
54  * Region tracking -- allows tracking of reservations and instantiated pages
55  *                    across the pages in a mapping.
56  *
57  * The region data structures are protected by a combination of the mmap_sem
58  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
59  * must either hold the mmap_sem for write, or the mmap_sem for read and
60  * the hugetlb_instantiation mutex:
61  *
62  *      down_write(&mm->mmap_sem);
63  * or
64  *      down_read(&mm->mmap_sem);
65  *      mutex_lock(&hugetlb_instantiation_mutex);
66  */
67 struct file_region {
68         struct list_head link;
69         long from;
70         long to;
71 };
72
73 static long region_add(struct list_head *head, long f, long t)
74 {
75         struct file_region *rg, *nrg, *trg;
76
77         /* Locate the region we are either in or before. */
78         list_for_each_entry(rg, head, link)
79                 if (f <= rg->to)
80                         break;
81
82         /* Round our left edge to the current segment if it encloses us. */
83         if (f > rg->from)
84                 f = rg->from;
85
86         /* Check for and consume any regions we now overlap with. */
87         nrg = rg;
88         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
89                 if (&rg->link == head)
90                         break;
91                 if (rg->from > t)
92                         break;
93
94                 /* If this area reaches higher then extend our area to
95                  * include it completely.  If this is not the first area
96                  * which we intend to reuse, free it. */
97                 if (rg->to > t)
98                         t = rg->to;
99                 if (rg != nrg) {
100                         list_del(&rg->link);
101                         kfree(rg);
102                 }
103         }
104         nrg->from = f;
105         nrg->to = t;
106         return 0;
107 }
108
109 static long region_chg(struct list_head *head, long f, long t)
110 {
111         struct file_region *rg, *nrg;
112         long chg = 0;
113
114         /* Locate the region we are before or in. */
115         list_for_each_entry(rg, head, link)
116                 if (f <= rg->to)
117                         break;
118
119         /* If we are below the current region then a new region is required.
120          * Subtle, allocate a new region at the position but make it zero
121          * size such that we can guarantee to record the reservation. */
122         if (&rg->link == head || t < rg->from) {
123                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
124                 if (!nrg)
125                         return -ENOMEM;
126                 nrg->from = f;
127                 nrg->to   = f;
128                 INIT_LIST_HEAD(&nrg->link);
129                 list_add(&nrg->link, rg->link.prev);
130
131                 return t - f;
132         }
133
134         /* Round our left edge to the current segment if it encloses us. */
135         if (f > rg->from)
136                 f = rg->from;
137         chg = t - f;
138
139         /* Check for and consume any regions we now overlap with. */
140         list_for_each_entry(rg, rg->link.prev, link) {
141                 if (&rg->link == head)
142                         break;
143                 if (rg->from > t)
144                         return chg;
145
146                 /* We overlap with this area, if it extends futher than
147                  * us then we must extend ourselves.  Account for its
148                  * existing reservation. */
149                 if (rg->to > t) {
150                         chg += rg->to - t;
151                         t = rg->to;
152                 }
153                 chg -= rg->to - rg->from;
154         }
155         return chg;
156 }
157
158 static long region_truncate(struct list_head *head, long end)
159 {
160         struct file_region *rg, *trg;
161         long chg = 0;
162
163         /* Locate the region we are either in or before. */
164         list_for_each_entry(rg, head, link)
165                 if (end <= rg->to)
166                         break;
167         if (&rg->link == head)
168                 return 0;
169
170         /* If we are in the middle of a region then adjust it. */
171         if (end > rg->from) {
172                 chg = rg->to - end;
173                 rg->to = end;
174                 rg = list_entry(rg->link.next, typeof(*rg), link);
175         }
176
177         /* Drop any remaining regions. */
178         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
179                 if (&rg->link == head)
180                         break;
181                 chg += rg->to - rg->from;
182                 list_del(&rg->link);
183                 kfree(rg);
184         }
185         return chg;
186 }
187
188 static long region_count(struct list_head *head, long f, long t)
189 {
190         struct file_region *rg;
191         long chg = 0;
192
193         /* Locate each segment we overlap with, and count that overlap. */
194         list_for_each_entry(rg, head, link) {
195                 int seg_from;
196                 int seg_to;
197
198                 if (rg->to <= f)
199                         continue;
200                 if (rg->from >= t)
201                         break;
202
203                 seg_from = max(rg->from, f);
204                 seg_to = min(rg->to, t);
205
206                 chg += seg_to - seg_from;
207         }
208
209         return chg;
210 }
211
212 /*
213  * Convert the address within this vma to the page offset within
214  * the mapping, in pagecache page units; huge pages here.
215  */
216 static pgoff_t vma_hugecache_offset(struct hstate *h,
217                         struct vm_area_struct *vma, unsigned long address)
218 {
219         return ((address - vma->vm_start) >> huge_page_shift(h)) +
220                         (vma->vm_pgoff >> huge_page_order(h));
221 }
222
223 /*
224  * Return the size of the pages allocated when backing a VMA. In the majority
225  * cases this will be same size as used by the page table entries.
226  */
227 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
228 {
229         struct hstate *hstate;
230
231         if (!is_vm_hugetlb_page(vma))
232                 return PAGE_SIZE;
233
234         hstate = hstate_vma(vma);
235
236         return 1UL << (hstate->order + PAGE_SHIFT);
237 }
238 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
239
240 /*
241  * Return the page size being used by the MMU to back a VMA. In the majority
242  * of cases, the page size used by the kernel matches the MMU size. On
243  * architectures where it differs, an architecture-specific version of this
244  * function is required.
245  */
246 #ifndef vma_mmu_pagesize
247 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
248 {
249         return vma_kernel_pagesize(vma);
250 }
251 #endif
252
253 /*
254  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
255  * bits of the reservation map pointer, which are always clear due to
256  * alignment.
257  */
258 #define HPAGE_RESV_OWNER    (1UL << 0)
259 #define HPAGE_RESV_UNMAPPED (1UL << 1)
260 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
261
262 /*
263  * These helpers are used to track how many pages are reserved for
264  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
265  * is guaranteed to have their future faults succeed.
266  *
267  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
268  * the reserve counters are updated with the hugetlb_lock held. It is safe
269  * to reset the VMA at fork() time as it is not in use yet and there is no
270  * chance of the global counters getting corrupted as a result of the values.
271  *
272  * The private mapping reservation is represented in a subtly different
273  * manner to a shared mapping.  A shared mapping has a region map associated
274  * with the underlying file, this region map represents the backing file
275  * pages which have ever had a reservation assigned which this persists even
276  * after the page is instantiated.  A private mapping has a region map
277  * associated with the original mmap which is attached to all VMAs which
278  * reference it, this region map represents those offsets which have consumed
279  * reservation ie. where pages have been instantiated.
280  */
281 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
282 {
283         return (unsigned long)vma->vm_private_data;
284 }
285
286 static void set_vma_private_data(struct vm_area_struct *vma,
287                                                         unsigned long value)
288 {
289         vma->vm_private_data = (void *)value;
290 }
291
292 struct resv_map {
293         struct kref refs;
294         struct list_head regions;
295 };
296
297 static struct resv_map *resv_map_alloc(void)
298 {
299         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
300         if (!resv_map)
301                 return NULL;
302
303         kref_init(&resv_map->refs);
304         INIT_LIST_HEAD(&resv_map->regions);
305
306         return resv_map;
307 }
308
309 static void resv_map_release(struct kref *ref)
310 {
311         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
312
313         /* Clear out any active regions before we release the map. */
314         region_truncate(&resv_map->regions, 0);
315         kfree(resv_map);
316 }
317
318 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
319 {
320         VM_BUG_ON(!is_vm_hugetlb_page(vma));
321         if (!(vma->vm_flags & VM_MAYSHARE))
322                 return (struct resv_map *)(get_vma_private_data(vma) &
323                                                         ~HPAGE_RESV_MASK);
324         return NULL;
325 }
326
327 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
328 {
329         VM_BUG_ON(!is_vm_hugetlb_page(vma));
330         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
331
332         set_vma_private_data(vma, (get_vma_private_data(vma) &
333                                 HPAGE_RESV_MASK) | (unsigned long)map);
334 }
335
336 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
337 {
338         VM_BUG_ON(!is_vm_hugetlb_page(vma));
339         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
340
341         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
342 }
343
344 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
345 {
346         VM_BUG_ON(!is_vm_hugetlb_page(vma));
347
348         return (get_vma_private_data(vma) & flag) != 0;
349 }
350
351 /* Decrement the reserved pages in the hugepage pool by one */
352 static void decrement_hugepage_resv_vma(struct hstate *h,
353                         struct vm_area_struct *vma)
354 {
355         if (vma->vm_flags & VM_NORESERVE)
356                 return;
357
358         if (vma->vm_flags & VM_MAYSHARE) {
359                 /* Shared mappings always use reserves */
360                 h->resv_huge_pages--;
361         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
362                 /*
363                  * Only the process that called mmap() has reserves for
364                  * private mappings.
365                  */
366                 h->resv_huge_pages--;
367         }
368 }
369
370 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
371 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
372 {
373         VM_BUG_ON(!is_vm_hugetlb_page(vma));
374         if (!(vma->vm_flags & VM_MAYSHARE))
375                 vma->vm_private_data = (void *)0;
376 }
377
378 /* Returns true if the VMA has associated reserve pages */
379 static int vma_has_reserves(struct vm_area_struct *vma)
380 {
381         if (vma->vm_flags & VM_MAYSHARE)
382                 return 1;
383         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
384                 return 1;
385         return 0;
386 }
387
388 static void clear_gigantic_page(struct page *page,
389                         unsigned long addr, unsigned long sz)
390 {
391         int i;
392         struct page *p = page;
393
394         might_sleep();
395         for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
396                 cond_resched();
397                 clear_user_highpage(p, addr + i * PAGE_SIZE);
398         }
399 }
400 static void clear_huge_page(struct page *page,
401                         unsigned long addr, unsigned long sz)
402 {
403         int i;
404
405         if (unlikely(sz/PAGE_SIZE > MAX_ORDER_NR_PAGES)) {
406                 clear_gigantic_page(page, addr, sz);
407                 return;
408         }
409
410         might_sleep();
411         for (i = 0; i < sz/PAGE_SIZE; i++) {
412                 cond_resched();
413                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
414         }
415 }
416
417 static void copy_gigantic_page(struct page *dst, struct page *src,
418                            unsigned long addr, struct vm_area_struct *vma)
419 {
420         int i;
421         struct hstate *h = hstate_vma(vma);
422         struct page *dst_base = dst;
423         struct page *src_base = src;
424         might_sleep();
425         for (i = 0; i < pages_per_huge_page(h); ) {
426                 cond_resched();
427                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
428
429                 i++;
430                 dst = mem_map_next(dst, dst_base, i);
431                 src = mem_map_next(src, src_base, i);
432         }
433 }
434 static void copy_huge_page(struct page *dst, struct page *src,
435                            unsigned long addr, struct vm_area_struct *vma)
436 {
437         int i;
438         struct hstate *h = hstate_vma(vma);
439
440         if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
441                 copy_gigantic_page(dst, src, addr, vma);
442                 return;
443         }
444
445         might_sleep();
446         for (i = 0; i < pages_per_huge_page(h); i++) {
447                 cond_resched();
448                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
449         }
450 }
451
452 static void enqueue_huge_page(struct hstate *h, struct page *page)
453 {
454         int nid = page_to_nid(page);
455         list_add(&page->lru, &h->hugepage_freelists[nid]);
456         h->free_huge_pages++;
457         h->free_huge_pages_node[nid]++;
458 }
459
460 static struct page *dequeue_huge_page_vma(struct hstate *h,
461                                 struct vm_area_struct *vma,
462                                 unsigned long address, int avoid_reserve)
463 {
464         int nid;
465         struct page *page = NULL;
466         struct mempolicy *mpol;
467         nodemask_t *nodemask;
468         struct zonelist *zonelist = huge_zonelist(vma, address,
469                                         htlb_alloc_mask, &mpol, &nodemask);
470         struct zone *zone;
471         struct zoneref *z;
472
473         /*
474          * A child process with MAP_PRIVATE mappings created by their parent
475          * have no page reserves. This check ensures that reservations are
476          * not "stolen". The child may still get SIGKILLed
477          */
478         if (!vma_has_reserves(vma) &&
479                         h->free_huge_pages - h->resv_huge_pages == 0)
480                 return NULL;
481
482         /* If reserves cannot be used, ensure enough pages are in the pool */
483         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
484                 return NULL;
485
486         for_each_zone_zonelist_nodemask(zone, z, zonelist,
487                                                 MAX_NR_ZONES - 1, nodemask) {
488                 nid = zone_to_nid(zone);
489                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
490                     !list_empty(&h->hugepage_freelists[nid])) {
491                         page = list_entry(h->hugepage_freelists[nid].next,
492                                           struct page, lru);
493                         list_del(&page->lru);
494                         h->free_huge_pages--;
495                         h->free_huge_pages_node[nid]--;
496
497                         if (!avoid_reserve)
498                                 decrement_hugepage_resv_vma(h, vma);
499
500                         break;
501                 }
502         }
503         mpol_cond_put(mpol);
504         return page;
505 }
506
507 static void update_and_free_page(struct hstate *h, struct page *page)
508 {
509         int i;
510
511         VM_BUG_ON(h->order >= MAX_ORDER);
512
513         h->nr_huge_pages--;
514         h->nr_huge_pages_node[page_to_nid(page)]--;
515         for (i = 0; i < pages_per_huge_page(h); i++) {
516                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
517                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
518                                 1 << PG_private | 1<< PG_writeback);
519         }
520         set_compound_page_dtor(page, NULL);
521         set_page_refcounted(page);
522         arch_release_hugepage(page);
523         __free_pages(page, huge_page_order(h));
524 }
525
526 struct hstate *size_to_hstate(unsigned long size)
527 {
528         struct hstate *h;
529
530         for_each_hstate(h) {
531                 if (huge_page_size(h) == size)
532                         return h;
533         }
534         return NULL;
535 }
536
537 static void free_huge_page(struct page *page)
538 {
539         /*
540          * Can't pass hstate in here because it is called from the
541          * compound page destructor.
542          */
543         struct hstate *h = page_hstate(page);
544         int nid = page_to_nid(page);
545         struct address_space *mapping;
546
547         mapping = (struct address_space *) page_private(page);
548         set_page_private(page, 0);
549         page->mapping = NULL;
550         BUG_ON(page_count(page));
551         INIT_LIST_HEAD(&page->lru);
552
553         spin_lock(&hugetlb_lock);
554         if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
555                 update_and_free_page(h, page);
556                 h->surplus_huge_pages--;
557                 h->surplus_huge_pages_node[nid]--;
558         } else {
559                 enqueue_huge_page(h, page);
560         }
561         spin_unlock(&hugetlb_lock);
562         if (mapping)
563                 hugetlb_put_quota(mapping, 1);
564 }
565
566 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
567 {
568         set_compound_page_dtor(page, free_huge_page);
569         spin_lock(&hugetlb_lock);
570         h->nr_huge_pages++;
571         h->nr_huge_pages_node[nid]++;
572         spin_unlock(&hugetlb_lock);
573         put_page(page); /* free it into the hugepage allocator */
574 }
575
576 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
577 {
578         int i;
579         int nr_pages = 1 << order;
580         struct page *p = page + 1;
581
582         /* we rely on prep_new_huge_page to set the destructor */
583         set_compound_order(page, order);
584         __SetPageHead(page);
585         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
586                 __SetPageTail(p);
587                 p->first_page = page;
588         }
589 }
590
591 int PageHuge(struct page *page)
592 {
593         compound_page_dtor *dtor;
594
595         if (!PageCompound(page))
596                 return 0;
597
598         page = compound_head(page);
599         dtor = get_compound_page_dtor(page);
600
601         return dtor == free_huge_page;
602 }
603
604 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
605 {
606         struct page *page;
607
608         if (h->order >= MAX_ORDER)
609                 return NULL;
610
611         page = alloc_pages_exact_node(nid,
612                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
613                                                 __GFP_REPEAT|__GFP_NOWARN,
614                 huge_page_order(h));
615         if (page) {
616                 if (arch_prepare_hugepage(page)) {
617                         __free_pages(page, huge_page_order(h));
618                         return NULL;
619                 }
620                 prep_new_huge_page(h, page, nid);
621         }
622
623         return page;
624 }
625
626 /*
627  * common helper functions for hstate_next_node_to_{alloc|free}.
628  * We may have allocated or freed a huge page based on a different
629  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
630  * be outside of *nodes_allowed.  Ensure that we use an allowed
631  * node for alloc or free.
632  */
633 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
634 {
635         nid = next_node(nid, *nodes_allowed);
636         if (nid == MAX_NUMNODES)
637                 nid = first_node(*nodes_allowed);
638         VM_BUG_ON(nid >= MAX_NUMNODES);
639
640         return nid;
641 }
642
643 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
644 {
645         if (!node_isset(nid, *nodes_allowed))
646                 nid = next_node_allowed(nid, nodes_allowed);
647         return nid;
648 }
649
650 /*
651  * returns the previously saved node ["this node"] from which to
652  * allocate a persistent huge page for the pool and advance the
653  * next node from which to allocate, handling wrap at end of node
654  * mask.
655  */
656 static int hstate_next_node_to_alloc(struct hstate *h,
657                                         nodemask_t *nodes_allowed)
658 {
659         int nid;
660
661         VM_BUG_ON(!nodes_allowed);
662
663         nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
664         h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
665
666         return nid;
667 }
668
669 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
670 {
671         struct page *page;
672         int start_nid;
673         int next_nid;
674         int ret = 0;
675
676         start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
677         next_nid = start_nid;
678
679         do {
680                 page = alloc_fresh_huge_page_node(h, next_nid);
681                 if (page) {
682                         ret = 1;
683                         break;
684                 }
685                 next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
686         } while (next_nid != start_nid);
687
688         if (ret)
689                 count_vm_event(HTLB_BUDDY_PGALLOC);
690         else
691                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
692
693         return ret;
694 }
695
696 /*
697  * helper for free_pool_huge_page() - return the previously saved
698  * node ["this node"] from which to free a huge page.  Advance the
699  * next node id whether or not we find a free huge page to free so
700  * that the next attempt to free addresses the next node.
701  */
702 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
703 {
704         int nid;
705
706         VM_BUG_ON(!nodes_allowed);
707
708         nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
709         h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
710
711         return nid;
712 }
713
714 /*
715  * Free huge page from pool from next node to free.
716  * Attempt to keep persistent huge pages more or less
717  * balanced over allowed nodes.
718  * Called with hugetlb_lock locked.
719  */
720 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
721                                                          bool acct_surplus)
722 {
723         int start_nid;
724         int next_nid;
725         int ret = 0;
726
727         start_nid = hstate_next_node_to_free(h, nodes_allowed);
728         next_nid = start_nid;
729
730         do {
731                 /*
732                  * If we're returning unused surplus pages, only examine
733                  * nodes with surplus pages.
734                  */
735                 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
736                     !list_empty(&h->hugepage_freelists[next_nid])) {
737                         struct page *page =
738                                 list_entry(h->hugepage_freelists[next_nid].next,
739                                           struct page, lru);
740                         list_del(&page->lru);
741                         h->free_huge_pages--;
742                         h->free_huge_pages_node[next_nid]--;
743                         if (acct_surplus) {
744                                 h->surplus_huge_pages--;
745                                 h->surplus_huge_pages_node[next_nid]--;
746                         }
747                         update_and_free_page(h, page);
748                         ret = 1;
749                         break;
750                 }
751                 next_nid = hstate_next_node_to_free(h, nodes_allowed);
752         } while (next_nid != start_nid);
753
754         return ret;
755 }
756
757 static struct page *alloc_buddy_huge_page(struct hstate *h,
758                         struct vm_area_struct *vma, unsigned long address)
759 {
760         struct page *page;
761         unsigned int nid;
762
763         if (h->order >= MAX_ORDER)
764                 return NULL;
765
766         /*
767          * Assume we will successfully allocate the surplus page to
768          * prevent racing processes from causing the surplus to exceed
769          * overcommit
770          *
771          * This however introduces a different race, where a process B
772          * tries to grow the static hugepage pool while alloc_pages() is
773          * called by process A. B will only examine the per-node
774          * counters in determining if surplus huge pages can be
775          * converted to normal huge pages in adjust_pool_surplus(). A
776          * won't be able to increment the per-node counter, until the
777          * lock is dropped by B, but B doesn't drop hugetlb_lock until
778          * no more huge pages can be converted from surplus to normal
779          * state (and doesn't try to convert again). Thus, we have a
780          * case where a surplus huge page exists, the pool is grown, and
781          * the surplus huge page still exists after, even though it
782          * should just have been converted to a normal huge page. This
783          * does not leak memory, though, as the hugepage will be freed
784          * once it is out of use. It also does not allow the counters to
785          * go out of whack in adjust_pool_surplus() as we don't modify
786          * the node values until we've gotten the hugepage and only the
787          * per-node value is checked there.
788          */
789         spin_lock(&hugetlb_lock);
790         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
791                 spin_unlock(&hugetlb_lock);
792                 return NULL;
793         } else {
794                 h->nr_huge_pages++;
795                 h->surplus_huge_pages++;
796         }
797         spin_unlock(&hugetlb_lock);
798
799         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
800                                         __GFP_REPEAT|__GFP_NOWARN,
801                                         huge_page_order(h));
802
803         if (page && arch_prepare_hugepage(page)) {
804                 __free_pages(page, huge_page_order(h));
805                 return NULL;
806         }
807
808         spin_lock(&hugetlb_lock);
809         if (page) {
810                 /*
811                  * This page is now managed by the hugetlb allocator and has
812                  * no users -- drop the buddy allocator's reference.
813                  */
814                 put_page_testzero(page);
815                 VM_BUG_ON(page_count(page));
816                 nid = page_to_nid(page);
817                 set_compound_page_dtor(page, free_huge_page);
818                 /*
819                  * We incremented the global counters already
820                  */
821                 h->nr_huge_pages_node[nid]++;
822                 h->surplus_huge_pages_node[nid]++;
823                 __count_vm_event(HTLB_BUDDY_PGALLOC);
824         } else {
825                 h->nr_huge_pages--;
826                 h->surplus_huge_pages--;
827                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
828         }
829         spin_unlock(&hugetlb_lock);
830
831         return page;
832 }
833
834 /*
835  * Increase the hugetlb pool such that it can accomodate a reservation
836  * of size 'delta'.
837  */
838 static int gather_surplus_pages(struct hstate *h, int delta)
839 {
840         struct list_head surplus_list;
841         struct page *page, *tmp;
842         int ret, i;
843         int needed, allocated;
844
845         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
846         if (needed <= 0) {
847                 h->resv_huge_pages += delta;
848                 return 0;
849         }
850
851         allocated = 0;
852         INIT_LIST_HEAD(&surplus_list);
853
854         ret = -ENOMEM;
855 retry:
856         spin_unlock(&hugetlb_lock);
857         for (i = 0; i < needed; i++) {
858                 page = alloc_buddy_huge_page(h, NULL, 0);
859                 if (!page) {
860                         /*
861                          * We were not able to allocate enough pages to
862                          * satisfy the entire reservation so we free what
863                          * we've allocated so far.
864                          */
865                         spin_lock(&hugetlb_lock);
866                         needed = 0;
867                         goto free;
868                 }
869
870                 list_add(&page->lru, &surplus_list);
871         }
872         allocated += needed;
873
874         /*
875          * After retaking hugetlb_lock, we need to recalculate 'needed'
876          * because either resv_huge_pages or free_huge_pages may have changed.
877          */
878         spin_lock(&hugetlb_lock);
879         needed = (h->resv_huge_pages + delta) -
880                         (h->free_huge_pages + allocated);
881         if (needed > 0)
882                 goto retry;
883
884         /*
885          * The surplus_list now contains _at_least_ the number of extra pages
886          * needed to accomodate the reservation.  Add the appropriate number
887          * of pages to the hugetlb pool and free the extras back to the buddy
888          * allocator.  Commit the entire reservation here to prevent another
889          * process from stealing the pages as they are added to the pool but
890          * before they are reserved.
891          */
892         needed += allocated;
893         h->resv_huge_pages += delta;
894         ret = 0;
895 free:
896         /* Free the needed pages to the hugetlb pool */
897         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
898                 if ((--needed) < 0)
899                         break;
900                 list_del(&page->lru);
901                 enqueue_huge_page(h, page);
902         }
903
904         /* Free unnecessary surplus pages to the buddy allocator */
905         if (!list_empty(&surplus_list)) {
906                 spin_unlock(&hugetlb_lock);
907                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
908                         list_del(&page->lru);
909                         /*
910                          * The page has a reference count of zero already, so
911                          * call free_huge_page directly instead of using
912                          * put_page.  This must be done with hugetlb_lock
913                          * unlocked which is safe because free_huge_page takes
914                          * hugetlb_lock before deciding how to free the page.
915                          */
916                         free_huge_page(page);
917                 }
918                 spin_lock(&hugetlb_lock);
919         }
920
921         return ret;
922 }
923
924 /*
925  * When releasing a hugetlb pool reservation, any surplus pages that were
926  * allocated to satisfy the reservation must be explicitly freed if they were
927  * never used.
928  * Called with hugetlb_lock held.
929  */
930 static void return_unused_surplus_pages(struct hstate *h,
931                                         unsigned long unused_resv_pages)
932 {
933         unsigned long nr_pages;
934
935         /* Uncommit the reservation */
936         h->resv_huge_pages -= unused_resv_pages;
937
938         /* Cannot return gigantic pages currently */
939         if (h->order >= MAX_ORDER)
940                 return;
941
942         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
943
944         /*
945          * We want to release as many surplus pages as possible, spread
946          * evenly across all nodes with memory. Iterate across these nodes
947          * until we can no longer free unreserved surplus pages. This occurs
948          * when the nodes with surplus pages have no free pages.
949          * free_pool_huge_page() will balance the the freed pages across the
950          * on-line nodes with memory and will handle the hstate accounting.
951          */
952         while (nr_pages--) {
953                 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
954                         break;
955         }
956 }
957
958 /*
959  * Determine if the huge page at addr within the vma has an associated
960  * reservation.  Where it does not we will need to logically increase
961  * reservation and actually increase quota before an allocation can occur.
962  * Where any new reservation would be required the reservation change is
963  * prepared, but not committed.  Once the page has been quota'd allocated
964  * an instantiated the change should be committed via vma_commit_reservation.
965  * No action is required on failure.
966  */
967 static long vma_needs_reservation(struct hstate *h,
968                         struct vm_area_struct *vma, unsigned long addr)
969 {
970         struct address_space *mapping = vma->vm_file->f_mapping;
971         struct inode *inode = mapping->host;
972
973         if (vma->vm_flags & VM_MAYSHARE) {
974                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
975                 return region_chg(&inode->i_mapping->private_list,
976                                                         idx, idx + 1);
977
978         } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
979                 return 1;
980
981         } else  {
982                 long err;
983                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
984                 struct resv_map *reservations = vma_resv_map(vma);
985
986                 err = region_chg(&reservations->regions, idx, idx + 1);
987                 if (err < 0)
988                         return err;
989                 return 0;
990         }
991 }
992 static void vma_commit_reservation(struct hstate *h,
993                         struct vm_area_struct *vma, unsigned long addr)
994 {
995         struct address_space *mapping = vma->vm_file->f_mapping;
996         struct inode *inode = mapping->host;
997
998         if (vma->vm_flags & VM_MAYSHARE) {
999                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1000                 region_add(&inode->i_mapping->private_list, idx, idx + 1);
1001
1002         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1003                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1004                 struct resv_map *reservations = vma_resv_map(vma);
1005
1006                 /* Mark this page used in the map. */
1007                 region_add(&reservations->regions, idx, idx + 1);
1008         }
1009 }
1010
1011 static struct page *alloc_huge_page(struct vm_area_struct *vma,
1012                                     unsigned long addr, int avoid_reserve)
1013 {
1014         struct hstate *h = hstate_vma(vma);
1015         struct page *page;
1016         struct address_space *mapping = vma->vm_file->f_mapping;
1017         struct inode *inode = mapping->host;
1018         long chg;
1019
1020         /*
1021          * Processes that did not create the mapping will have no reserves and
1022          * will not have accounted against quota. Check that the quota can be
1023          * made before satisfying the allocation
1024          * MAP_NORESERVE mappings may also need pages and quota allocated
1025          * if no reserve mapping overlaps.
1026          */
1027         chg = vma_needs_reservation(h, vma, addr);
1028         if (chg < 0)
1029                 return ERR_PTR(chg);
1030         if (chg)
1031                 if (hugetlb_get_quota(inode->i_mapping, chg))
1032                         return ERR_PTR(-ENOSPC);
1033
1034         spin_lock(&hugetlb_lock);
1035         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
1036         spin_unlock(&hugetlb_lock);
1037
1038         if (!page) {
1039                 page = alloc_buddy_huge_page(h, vma, addr);
1040                 if (!page) {
1041                         hugetlb_put_quota(inode->i_mapping, chg);
1042                         return ERR_PTR(-VM_FAULT_OOM);
1043                 }
1044         }
1045
1046         set_page_refcounted(page);
1047         set_page_private(page, (unsigned long) mapping);
1048
1049         vma_commit_reservation(h, vma, addr);
1050
1051         return page;
1052 }
1053
1054 int __weak alloc_bootmem_huge_page(struct hstate *h)
1055 {
1056         struct huge_bootmem_page *m;
1057         int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
1058
1059         while (nr_nodes) {
1060                 void *addr;
1061
1062                 addr = __alloc_bootmem_node_nopanic(
1063                                 NODE_DATA(hstate_next_node_to_alloc(h,
1064                                                 &node_states[N_HIGH_MEMORY])),
1065                                 huge_page_size(h), huge_page_size(h), 0);
1066
1067                 if (addr) {
1068                         /*
1069                          * Use the beginning of the huge page to store the
1070                          * huge_bootmem_page struct (until gather_bootmem
1071                          * puts them into the mem_map).
1072                          */
1073                         m = addr;
1074                         goto found;
1075                 }
1076                 nr_nodes--;
1077         }
1078         return 0;
1079
1080 found:
1081         BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1082         /* Put them into a private list first because mem_map is not up yet */
1083         list_add(&m->list, &huge_boot_pages);
1084         m->hstate = h;
1085         return 1;
1086 }
1087
1088 static void prep_compound_huge_page(struct page *page, int order)
1089 {
1090         if (unlikely(order > (MAX_ORDER - 1)))
1091                 prep_compound_gigantic_page(page, order);
1092         else
1093                 prep_compound_page(page, order);
1094 }
1095
1096 /* Put bootmem huge pages into the standard lists after mem_map is up */
1097 static void __init gather_bootmem_prealloc(void)
1098 {
1099         struct huge_bootmem_page *m;
1100
1101         list_for_each_entry(m, &huge_boot_pages, list) {
1102                 struct page *page = virt_to_page(m);
1103                 struct hstate *h = m->hstate;
1104                 __ClearPageReserved(page);
1105                 WARN_ON(page_count(page) != 1);
1106                 prep_compound_huge_page(page, h->order);
1107                 prep_new_huge_page(h, page, page_to_nid(page));
1108         }
1109 }
1110
1111 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1112 {
1113         unsigned long i;
1114
1115         for (i = 0; i < h->max_huge_pages; ++i) {
1116                 if (h->order >= MAX_ORDER) {
1117                         if (!alloc_bootmem_huge_page(h))
1118                                 break;
1119                 } else if (!alloc_fresh_huge_page(h,
1120                                          &node_states[N_HIGH_MEMORY]))
1121                         break;
1122         }
1123         h->max_huge_pages = i;
1124 }
1125
1126 static void __init hugetlb_init_hstates(void)
1127 {
1128         struct hstate *h;
1129
1130         for_each_hstate(h) {
1131                 /* oversize hugepages were init'ed in early boot */
1132                 if (h->order < MAX_ORDER)
1133                         hugetlb_hstate_alloc_pages(h);
1134         }
1135 }
1136
1137 static char * __init memfmt(char *buf, unsigned long n)
1138 {
1139         if (n >= (1UL << 30))
1140                 sprintf(buf, "%lu GB", n >> 30);
1141         else if (n >= (1UL << 20))
1142                 sprintf(buf, "%lu MB", n >> 20);
1143         else
1144                 sprintf(buf, "%lu KB", n >> 10);
1145         return buf;
1146 }
1147
1148 static void __init report_hugepages(void)
1149 {
1150         struct hstate *h;
1151
1152         for_each_hstate(h) {
1153                 char buf[32];
1154                 printk(KERN_INFO "HugeTLB registered %s page size, "
1155                                  "pre-allocated %ld pages\n",
1156                         memfmt(buf, huge_page_size(h)),
1157                         h->free_huge_pages);
1158         }
1159 }
1160
1161 #ifdef CONFIG_HIGHMEM
1162 static void try_to_free_low(struct hstate *h, unsigned long count,
1163                                                 nodemask_t *nodes_allowed)
1164 {
1165         int i;
1166
1167         if (h->order >= MAX_ORDER)
1168                 return;
1169
1170         for_each_node_mask(i, *nodes_allowed) {
1171                 struct page *page, *next;
1172                 struct list_head *freel = &h->hugepage_freelists[i];
1173                 list_for_each_entry_safe(page, next, freel, lru) {
1174                         if (count >= h->nr_huge_pages)
1175                                 return;
1176                         if (PageHighMem(page))
1177                                 continue;
1178                         list_del(&page->lru);
1179                         update_and_free_page(h, page);
1180                         h->free_huge_pages--;
1181                         h->free_huge_pages_node[page_to_nid(page)]--;
1182                 }
1183         }
1184 }
1185 #else
1186 static inline void try_to_free_low(struct hstate *h, unsigned long count,
1187                                                 nodemask_t *nodes_allowed)
1188 {
1189 }
1190 #endif
1191
1192 /*
1193  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1194  * balanced by operating on them in a round-robin fashion.
1195  * Returns 1 if an adjustment was made.
1196  */
1197 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1198                                 int delta)
1199 {
1200         int start_nid, next_nid;
1201         int ret = 0;
1202
1203         VM_BUG_ON(delta != -1 && delta != 1);
1204
1205         if (delta < 0)
1206                 start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1207         else
1208                 start_nid = hstate_next_node_to_free(h, nodes_allowed);
1209         next_nid = start_nid;
1210
1211         do {
1212                 int nid = next_nid;
1213                 if (delta < 0)  {
1214                         /*
1215                          * To shrink on this node, there must be a surplus page
1216                          */
1217                         if (!h->surplus_huge_pages_node[nid]) {
1218                                 next_nid = hstate_next_node_to_alloc(h,
1219                                                                 nodes_allowed);
1220                                 continue;
1221                         }
1222                 }
1223                 if (delta > 0) {
1224                         /*
1225                          * Surplus cannot exceed the total number of pages
1226                          */
1227                         if (h->surplus_huge_pages_node[nid] >=
1228                                                 h->nr_huge_pages_node[nid]) {
1229                                 next_nid = hstate_next_node_to_free(h,
1230                                                                 nodes_allowed);
1231                                 continue;
1232                         }
1233                 }
1234
1235                 h->surplus_huge_pages += delta;
1236                 h->surplus_huge_pages_node[nid] += delta;
1237                 ret = 1;
1238                 break;
1239         } while (next_nid != start_nid);
1240
1241         return ret;
1242 }
1243
1244 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1245 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1246                                                 nodemask_t *nodes_allowed)
1247 {
1248         unsigned long min_count, ret;
1249
1250         if (h->order >= MAX_ORDER)
1251                 return h->max_huge_pages;
1252
1253         /*
1254          * Increase the pool size
1255          * First take pages out of surplus state.  Then make up the
1256          * remaining difference by allocating fresh huge pages.
1257          *
1258          * We might race with alloc_buddy_huge_page() here and be unable
1259          * to convert a surplus huge page to a normal huge page. That is
1260          * not critical, though, it just means the overall size of the
1261          * pool might be one hugepage larger than it needs to be, but
1262          * within all the constraints specified by the sysctls.
1263          */
1264         spin_lock(&hugetlb_lock);
1265         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1266                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
1267                         break;
1268         }
1269
1270         while (count > persistent_huge_pages(h)) {
1271                 /*
1272                  * If this allocation races such that we no longer need the
1273                  * page, free_huge_page will handle it by freeing the page
1274                  * and reducing the surplus.
1275                  */
1276                 spin_unlock(&hugetlb_lock);
1277                 ret = alloc_fresh_huge_page(h, nodes_allowed);
1278                 spin_lock(&hugetlb_lock);
1279                 if (!ret)
1280                         goto out;
1281
1282                 /* Bail for signals. Probably ctrl-c from user */
1283                 if (signal_pending(current))
1284                         goto out;
1285         }
1286
1287         /*
1288          * Decrease the pool size
1289          * First return free pages to the buddy allocator (being careful
1290          * to keep enough around to satisfy reservations).  Then place
1291          * pages into surplus state as needed so the pool will shrink
1292          * to the desired size as pages become free.
1293          *
1294          * By placing pages into the surplus state independent of the
1295          * overcommit value, we are allowing the surplus pool size to
1296          * exceed overcommit. There are few sane options here. Since
1297          * alloc_buddy_huge_page() is checking the global counter,
1298          * though, we'll note that we're not allowed to exceed surplus
1299          * and won't grow the pool anywhere else. Not until one of the
1300          * sysctls are changed, or the surplus pages go out of use.
1301          */
1302         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1303         min_count = max(count, min_count);
1304         try_to_free_low(h, min_count, nodes_allowed);
1305         while (min_count < persistent_huge_pages(h)) {
1306                 if (!free_pool_huge_page(h, nodes_allowed, 0))
1307                         break;
1308         }
1309         while (count < persistent_huge_pages(h)) {
1310                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
1311                         break;
1312         }
1313 out:
1314         ret = persistent_huge_pages(h);
1315         spin_unlock(&hugetlb_lock);
1316         return ret;
1317 }
1318
1319 #define HSTATE_ATTR_RO(_name) \
1320         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1321
1322 #define HSTATE_ATTR(_name) \
1323         static struct kobj_attribute _name##_attr = \
1324                 __ATTR(_name, 0644, _name##_show, _name##_store)
1325
1326 static struct kobject *hugepages_kobj;
1327 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1328
1329 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1330
1331 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1332 {
1333         int i;
1334
1335         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1336                 if (hstate_kobjs[i] == kobj) {
1337                         if (nidp)
1338                                 *nidp = NUMA_NO_NODE;
1339                         return &hstates[i];
1340                 }
1341
1342         return kobj_to_node_hstate(kobj, nidp);
1343 }
1344
1345 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1346                                         struct kobj_attribute *attr, char *buf)
1347 {
1348         struct hstate *h;
1349         unsigned long nr_huge_pages;
1350         int nid;
1351
1352         h = kobj_to_hstate(kobj, &nid);
1353         if (nid == NUMA_NO_NODE)
1354                 nr_huge_pages = h->nr_huge_pages;
1355         else
1356                 nr_huge_pages = h->nr_huge_pages_node[nid];
1357
1358         return sprintf(buf, "%lu\n", nr_huge_pages);
1359 }
1360 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1361                         struct kobject *kobj, struct kobj_attribute *attr,
1362                         const char *buf, size_t len)
1363 {
1364         int err;
1365         int nid;
1366         unsigned long count;
1367         struct hstate *h;
1368         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1369
1370         err = strict_strtoul(buf, 10, &count);
1371         if (err)
1372                 return 0;
1373
1374         h = kobj_to_hstate(kobj, &nid);
1375         if (nid == NUMA_NO_NODE) {
1376                 /*
1377                  * global hstate attribute
1378                  */
1379                 if (!(obey_mempolicy &&
1380                                 init_nodemask_of_mempolicy(nodes_allowed))) {
1381                         NODEMASK_FREE(nodes_allowed);
1382                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1383                 }
1384         } else if (nodes_allowed) {
1385                 /*
1386                  * per node hstate attribute: adjust count to global,
1387                  * but restrict alloc/free to the specified node.
1388                  */
1389                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1390                 init_nodemask_of_node(nodes_allowed, nid);
1391         } else
1392                 nodes_allowed = &node_states[N_HIGH_MEMORY];
1393
1394         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1395
1396         if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1397                 NODEMASK_FREE(nodes_allowed);
1398
1399         return len;
1400 }
1401
1402 static ssize_t nr_hugepages_show(struct kobject *kobj,
1403                                        struct kobj_attribute *attr, char *buf)
1404 {
1405         return nr_hugepages_show_common(kobj, attr, buf);
1406 }
1407
1408 static ssize_t nr_hugepages_store(struct kobject *kobj,
1409                struct kobj_attribute *attr, const char *buf, size_t len)
1410 {
1411         return nr_hugepages_store_common(false, kobj, attr, buf, len);
1412 }
1413 HSTATE_ATTR(nr_hugepages);
1414
1415 #ifdef CONFIG_NUMA
1416
1417 /*
1418  * hstate attribute for optionally mempolicy-based constraint on persistent
1419  * huge page alloc/free.
1420  */
1421 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1422                                        struct kobj_attribute *attr, char *buf)
1423 {
1424         return nr_hugepages_show_common(kobj, attr, buf);
1425 }
1426
1427 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1428                struct kobj_attribute *attr, const char *buf, size_t len)
1429 {
1430         return nr_hugepages_store_common(true, kobj, attr, buf, len);
1431 }
1432 HSTATE_ATTR(nr_hugepages_mempolicy);
1433 #endif
1434
1435
1436 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1437                                         struct kobj_attribute *attr, char *buf)
1438 {
1439         struct hstate *h = kobj_to_hstate(kobj, NULL);
1440         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1441 }
1442 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1443                 struct kobj_attribute *attr, const char *buf, size_t count)
1444 {
1445         int err;
1446         unsigned long input;
1447         struct hstate *h = kobj_to_hstate(kobj, NULL);
1448
1449         err = strict_strtoul(buf, 10, &input);
1450         if (err)
1451                 return 0;
1452
1453         spin_lock(&hugetlb_lock);
1454         h->nr_overcommit_huge_pages = input;
1455         spin_unlock(&hugetlb_lock);
1456
1457         return count;
1458 }
1459 HSTATE_ATTR(nr_overcommit_hugepages);
1460
1461 static ssize_t free_hugepages_show(struct kobject *kobj,
1462                                         struct kobj_attribute *attr, char *buf)
1463 {
1464         struct hstate *h;
1465         unsigned long free_huge_pages;
1466         int nid;
1467
1468         h = kobj_to_hstate(kobj, &nid);
1469         if (nid == NUMA_NO_NODE)
1470                 free_huge_pages = h->free_huge_pages;
1471         else
1472                 free_huge_pages = h->free_huge_pages_node[nid];
1473
1474         return sprintf(buf, "%lu\n", free_huge_pages);
1475 }
1476 HSTATE_ATTR_RO(free_hugepages);
1477
1478 static ssize_t resv_hugepages_show(struct kobject *kobj,
1479                                         struct kobj_attribute *attr, char *buf)
1480 {
1481         struct hstate *h = kobj_to_hstate(kobj, NULL);
1482         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1483 }
1484 HSTATE_ATTR_RO(resv_hugepages);
1485
1486 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1487                                         struct kobj_attribute *attr, char *buf)
1488 {
1489         struct hstate *h;
1490         unsigned long surplus_huge_pages;
1491         int nid;
1492
1493         h = kobj_to_hstate(kobj, &nid);
1494         if (nid == NUMA_NO_NODE)
1495                 surplus_huge_pages = h->surplus_huge_pages;
1496         else
1497                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
1498
1499         return sprintf(buf, "%lu\n", surplus_huge_pages);
1500 }
1501 HSTATE_ATTR_RO(surplus_hugepages);
1502
1503 static struct attribute *hstate_attrs[] = {
1504         &nr_hugepages_attr.attr,
1505         &nr_overcommit_hugepages_attr.attr,
1506         &free_hugepages_attr.attr,
1507         &resv_hugepages_attr.attr,
1508         &surplus_hugepages_attr.attr,
1509 #ifdef CONFIG_NUMA
1510         &nr_hugepages_mempolicy_attr.attr,
1511 #endif
1512         NULL,
1513 };
1514
1515 static struct attribute_group hstate_attr_group = {
1516         .attrs = hstate_attrs,
1517 };
1518
1519 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1520                                     struct kobject **hstate_kobjs,
1521                                     struct attribute_group *hstate_attr_group)
1522 {
1523         int retval;
1524         int hi = h - hstates;
1525
1526         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1527         if (!hstate_kobjs[hi])
1528                 return -ENOMEM;
1529
1530         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1531         if (retval)
1532                 kobject_put(hstate_kobjs[hi]);
1533
1534         return retval;
1535 }
1536
1537 static void __init hugetlb_sysfs_init(void)
1538 {
1539         struct hstate *h;
1540         int err;
1541
1542         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1543         if (!hugepages_kobj)
1544                 return;
1545
1546         for_each_hstate(h) {
1547                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1548                                          hstate_kobjs, &hstate_attr_group);
1549                 if (err)
1550                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1551                                                                 h->name);
1552         }
1553 }
1554
1555 #ifdef CONFIG_NUMA
1556
1557 /*
1558  * node_hstate/s - associate per node hstate attributes, via their kobjects,
1559  * with node sysdevs in node_devices[] using a parallel array.  The array
1560  * index of a node sysdev or _hstate == node id.
1561  * This is here to avoid any static dependency of the node sysdev driver, in
1562  * the base kernel, on the hugetlb module.
1563  */
1564 struct node_hstate {
1565         struct kobject          *hugepages_kobj;
1566         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1567 };
1568 struct node_hstate node_hstates[MAX_NUMNODES];
1569
1570 /*
1571  * A subset of global hstate attributes for node sysdevs
1572  */
1573 static struct attribute *per_node_hstate_attrs[] = {
1574         &nr_hugepages_attr.attr,
1575         &free_hugepages_attr.attr,
1576         &surplus_hugepages_attr.attr,
1577         NULL,
1578 };
1579
1580 static struct attribute_group per_node_hstate_attr_group = {
1581         .attrs = per_node_hstate_attrs,
1582 };
1583
1584 /*
1585  * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj.
1586  * Returns node id via non-NULL nidp.
1587  */
1588 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1589 {
1590         int nid;
1591
1592         for (nid = 0; nid < nr_node_ids; nid++) {
1593                 struct node_hstate *nhs = &node_hstates[nid];
1594                 int i;
1595                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1596                         if (nhs->hstate_kobjs[i] == kobj) {
1597                                 if (nidp)
1598                                         *nidp = nid;
1599                                 return &hstates[i];
1600                         }
1601         }
1602
1603         BUG();
1604         return NULL;
1605 }
1606
1607 /*
1608  * Unregister hstate attributes from a single node sysdev.
1609  * No-op if no hstate attributes attached.
1610  */
1611 void hugetlb_unregister_node(struct node *node)
1612 {
1613         struct hstate *h;
1614         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1615
1616         if (!nhs->hugepages_kobj)
1617                 return;         /* no hstate attributes */
1618
1619         for_each_hstate(h)
1620                 if (nhs->hstate_kobjs[h - hstates]) {
1621                         kobject_put(nhs->hstate_kobjs[h - hstates]);
1622                         nhs->hstate_kobjs[h - hstates] = NULL;
1623                 }
1624
1625         kobject_put(nhs->hugepages_kobj);
1626         nhs->hugepages_kobj = NULL;
1627 }
1628
1629 /*
1630  * hugetlb module exit:  unregister hstate attributes from node sysdevs
1631  * that have them.
1632  */
1633 static void hugetlb_unregister_all_nodes(void)
1634 {
1635         int nid;
1636
1637         /*
1638          * disable node sysdev registrations.
1639          */
1640         register_hugetlbfs_with_node(NULL, NULL);
1641
1642         /*
1643          * remove hstate attributes from any nodes that have them.
1644          */
1645         for (nid = 0; nid < nr_node_ids; nid++)
1646                 hugetlb_unregister_node(&node_devices[nid]);
1647 }
1648
1649 /*
1650  * Register hstate attributes for a single node sysdev.
1651  * No-op if attributes already registered.
1652  */
1653 void hugetlb_register_node(struct node *node)
1654 {
1655         struct hstate *h;
1656         struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1657         int err;
1658
1659         if (nhs->hugepages_kobj)
1660                 return;         /* already allocated */
1661
1662         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1663                                                         &node->sysdev.kobj);
1664         if (!nhs->hugepages_kobj)
1665                 return;
1666
1667         for_each_hstate(h) {
1668                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1669                                                 nhs->hstate_kobjs,
1670                                                 &per_node_hstate_attr_group);
1671                 if (err) {
1672                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1673                                         " for node %d\n",
1674                                                 h->name, node->sysdev.id);
1675                         hugetlb_unregister_node(node);
1676                         break;
1677                 }
1678         }
1679 }
1680
1681 /*
1682  * hugetlb init time:  register hstate attributes for all registered node
1683  * sysdevs of nodes that have memory.  All on-line nodes should have
1684  * registered their associated sysdev by this time.
1685  */
1686 static void hugetlb_register_all_nodes(void)
1687 {
1688         int nid;
1689
1690         for_each_node_state(nid, N_HIGH_MEMORY) {
1691                 struct node *node = &node_devices[nid];
1692                 if (node->sysdev.id == nid)
1693                         hugetlb_register_node(node);
1694         }
1695
1696         /*
1697          * Let the node sysdev driver know we're here so it can
1698          * [un]register hstate attributes on node hotplug.
1699          */
1700         register_hugetlbfs_with_node(hugetlb_register_node,
1701                                      hugetlb_unregister_node);
1702 }
1703 #else   /* !CONFIG_NUMA */
1704
1705 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1706 {
1707         BUG();
1708         if (nidp)
1709                 *nidp = -1;
1710         return NULL;
1711 }
1712
1713 static void hugetlb_unregister_all_nodes(void) { }
1714
1715 static void hugetlb_register_all_nodes(void) { }
1716
1717 #endif
1718
1719 static void __exit hugetlb_exit(void)
1720 {
1721         struct hstate *h;
1722
1723         hugetlb_unregister_all_nodes();
1724
1725         for_each_hstate(h) {
1726                 kobject_put(hstate_kobjs[h - hstates]);
1727         }
1728
1729         kobject_put(hugepages_kobj);
1730 }
1731 module_exit(hugetlb_exit);
1732
1733 static int __init hugetlb_init(void)
1734 {
1735         /* Some platform decide whether they support huge pages at boot
1736          * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1737          * there is no such support
1738          */
1739         if (HPAGE_SHIFT == 0)
1740                 return 0;
1741
1742         if (!size_to_hstate(default_hstate_size)) {
1743                 default_hstate_size = HPAGE_SIZE;
1744                 if (!size_to_hstate(default_hstate_size))
1745                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1746         }
1747         default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1748         if (default_hstate_max_huge_pages)
1749                 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1750
1751         hugetlb_init_hstates();
1752
1753         gather_bootmem_prealloc();
1754
1755         report_hugepages();
1756
1757         hugetlb_sysfs_init();
1758
1759         hugetlb_register_all_nodes();
1760
1761         return 0;
1762 }
1763 module_init(hugetlb_init);
1764
1765 /* Should be called on processing a hugepagesz=... option */
1766 void __init hugetlb_add_hstate(unsigned order)
1767 {
1768         struct hstate *h;
1769         unsigned long i;
1770
1771         if (size_to_hstate(PAGE_SIZE << order)) {
1772                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1773                 return;
1774         }
1775         BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1776         BUG_ON(order == 0);
1777         h = &hstates[max_hstate++];
1778         h->order = order;
1779         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1780         h->nr_huge_pages = 0;
1781         h->free_huge_pages = 0;
1782         for (i = 0; i < MAX_NUMNODES; ++i)
1783                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1784         h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
1785         h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
1786         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1787                                         huge_page_size(h)/1024);
1788
1789         parsed_hstate = h;
1790 }
1791
1792 static int __init hugetlb_nrpages_setup(char *s)
1793 {
1794         unsigned long *mhp;
1795         static unsigned long *last_mhp;
1796
1797         /*
1798          * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1799          * so this hugepages= parameter goes to the "default hstate".
1800          */
1801         if (!max_hstate)
1802                 mhp = &default_hstate_max_huge_pages;
1803         else
1804                 mhp = &parsed_hstate->max_huge_pages;
1805
1806         if (mhp == last_mhp) {
1807                 printk(KERN_WARNING "hugepages= specified twice without "
1808                         "interleaving hugepagesz=, ignoring\n");
1809                 return 1;
1810         }
1811
1812         if (sscanf(s, "%lu", mhp) <= 0)
1813                 *mhp = 0;
1814
1815         /*
1816          * Global state is always initialized later in hugetlb_init.
1817          * But we need to allocate >= MAX_ORDER hstates here early to still
1818          * use the bootmem allocator.
1819          */
1820         if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1821                 hugetlb_hstate_alloc_pages(parsed_hstate);
1822
1823         last_mhp = mhp;
1824
1825         return 1;
1826 }
1827 __setup("hugepages=", hugetlb_nrpages_setup);
1828
1829 static int __init hugetlb_default_setup(char *s)
1830 {
1831         default_hstate_size = memparse(s, &s);
1832         return 1;
1833 }
1834 __setup("default_hugepagesz=", hugetlb_default_setup);
1835
1836 static unsigned int cpuset_mems_nr(unsigned int *array)
1837 {
1838         int node;
1839         unsigned int nr = 0;
1840
1841         for_each_node_mask(node, cpuset_current_mems_allowed)
1842                 nr += array[node];
1843
1844         return nr;
1845 }
1846
1847 #ifdef CONFIG_SYSCTL
1848 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
1849                          struct ctl_table *table, int write,
1850                          void __user *buffer, size_t *length, loff_t *ppos)
1851 {
1852         struct hstate *h = &default_hstate;
1853         unsigned long tmp;
1854
1855         if (!write)
1856                 tmp = h->max_huge_pages;
1857
1858         table->data = &tmp;
1859         table->maxlen = sizeof(unsigned long);
1860         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1861
1862         if (write) {
1863                 NODEMASK_ALLOC(nodemask_t, nodes_allowed,
1864                                                 GFP_KERNEL | __GFP_NORETRY);
1865                 if (!(obey_mempolicy &&
1866                                init_nodemask_of_mempolicy(nodes_allowed))) {
1867                         NODEMASK_FREE(nodes_allowed);
1868                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1869                 }
1870                 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
1871
1872                 if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1873                         NODEMASK_FREE(nodes_allowed);
1874         }
1875
1876         return 0;
1877 }
1878
1879 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1880                           void __user *buffer, size_t *length, loff_t *ppos)
1881 {
1882
1883         return hugetlb_sysctl_handler_common(false, table, write,
1884                                                         buffer, length, ppos);
1885 }
1886
1887 #ifdef CONFIG_NUMA
1888 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
1889                           void __user *buffer, size_t *length, loff_t *ppos)
1890 {
1891         return hugetlb_sysctl_handler_common(true, table, write,
1892                                                         buffer, length, ppos);
1893 }
1894 #endif /* CONFIG_NUMA */
1895
1896 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1897                         void __user *buffer,
1898                         size_t *length, loff_t *ppos)
1899 {
1900         proc_dointvec(table, write, buffer, length, ppos);
1901         if (hugepages_treat_as_movable)
1902                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1903         else
1904                 htlb_alloc_mask = GFP_HIGHUSER;
1905         return 0;
1906 }
1907
1908 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1909                         void __user *buffer,
1910                         size_t *length, loff_t *ppos)
1911 {
1912         struct hstate *h = &default_hstate;
1913         unsigned long tmp;
1914
1915         if (!write)
1916                 tmp = h->nr_overcommit_huge_pages;
1917
1918         table->data = &tmp;
1919         table->maxlen = sizeof(unsigned long);
1920         proc_doulongvec_minmax(table, write, buffer, length, ppos);
1921
1922         if (write) {
1923                 spin_lock(&hugetlb_lock);
1924                 h->nr_overcommit_huge_pages = tmp;
1925                 spin_unlock(&hugetlb_lock);
1926         }
1927
1928         return 0;
1929 }
1930
1931 #endif /* CONFIG_SYSCTL */
1932
1933 void hugetlb_report_meminfo(struct seq_file *m)
1934 {
1935         struct hstate *h = &default_hstate;
1936         seq_printf(m,
1937                         "HugePages_Total:   %5lu\n"
1938                         "HugePages_Free:    %5lu\n"
1939                         "HugePages_Rsvd:    %5lu\n"
1940                         "HugePages_Surp:    %5lu\n"
1941                         "Hugepagesize:   %8lu kB\n",
1942                         h->nr_huge_pages,
1943                         h->free_huge_pages,
1944                         h->resv_huge_pages,
1945                         h->surplus_huge_pages,
1946                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1947 }
1948
1949 int hugetlb_report_node_meminfo(int nid, char *buf)
1950 {
1951         struct hstate *h = &default_hstate;
1952         return sprintf(buf,
1953                 "Node %d HugePages_Total: %5u\n"
1954                 "Node %d HugePages_Free:  %5u\n"
1955                 "Node %d HugePages_Surp:  %5u\n",
1956                 nid, h->nr_huge_pages_node[nid],
1957                 nid, h->free_huge_pages_node[nid],
1958                 nid, h->surplus_huge_pages_node[nid]);
1959 }
1960
1961 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1962 unsigned long hugetlb_total_pages(void)
1963 {
1964         struct hstate *h = &default_hstate;
1965         return h->nr_huge_pages * pages_per_huge_page(h);
1966 }
1967
1968 static int hugetlb_acct_memory(struct hstate *h, long delta)
1969 {
1970         int ret = -ENOMEM;
1971
1972         spin_lock(&hugetlb_lock);
1973         /*
1974          * When cpuset is configured, it breaks the strict hugetlb page
1975          * reservation as the accounting is done on a global variable. Such
1976          * reservation is completely rubbish in the presence of cpuset because
1977          * the reservation is not checked against page availability for the
1978          * current cpuset. Application can still potentially OOM'ed by kernel
1979          * with lack of free htlb page in cpuset that the task is in.
1980          * Attempt to enforce strict accounting with cpuset is almost
1981          * impossible (or too ugly) because cpuset is too fluid that
1982          * task or memory node can be dynamically moved between cpusets.
1983          *
1984          * The change of semantics for shared hugetlb mapping with cpuset is
1985          * undesirable. However, in order to preserve some of the semantics,
1986          * we fall back to check against current free page availability as
1987          * a best attempt and hopefully to minimize the impact of changing
1988          * semantics that cpuset has.
1989          */
1990         if (delta > 0) {
1991                 if (gather_surplus_pages(h, delta) < 0)
1992                         goto out;
1993
1994                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1995                         return_unused_surplus_pages(h, delta);
1996                         goto out;
1997                 }
1998         }
1999
2000         ret = 0;
2001         if (delta < 0)
2002                 return_unused_surplus_pages(h, (unsigned long) -delta);
2003
2004 out:
2005         spin_unlock(&hugetlb_lock);
2006         return ret;
2007 }
2008
2009 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2010 {
2011         struct resv_map *reservations = vma_resv_map(vma);
2012
2013         /*
2014          * This new VMA should share its siblings reservation map if present.
2015          * The VMA will only ever have a valid reservation map pointer where
2016          * it is being copied for another still existing VMA.  As that VMA
2017          * has a reference to the reservation map it cannot dissappear until
2018          * after this open call completes.  It is therefore safe to take a
2019          * new reference here without additional locking.
2020          */
2021         if (reservations)
2022                 kref_get(&reservations->refs);
2023 }
2024
2025 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2026 {
2027         struct hstate *h = hstate_vma(vma);
2028         struct resv_map *reservations = vma_resv_map(vma);
2029         unsigned long reserve;
2030         unsigned long start;
2031         unsigned long end;
2032
2033         if (reservations) {
2034                 start = vma_hugecache_offset(h, vma, vma->vm_start);
2035                 end = vma_hugecache_offset(h, vma, vma->vm_end);
2036
2037                 reserve = (end - start) -
2038                         region_count(&reservations->regions, start, end);
2039
2040                 kref_put(&reservations->refs, resv_map_release);
2041
2042                 if (reserve) {
2043                         hugetlb_acct_memory(h, -reserve);
2044                         hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
2045                 }
2046         }
2047 }
2048
2049 /*
2050  * We cannot handle pagefaults against hugetlb pages at all.  They cause
2051  * handle_mm_fault() to try to instantiate regular-sized pages in the
2052  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2053  * this far.
2054  */
2055 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2056 {
2057         BUG();
2058         return 0;
2059 }
2060
2061 const struct vm_operations_struct hugetlb_vm_ops = {
2062         .fault = hugetlb_vm_op_fault,
2063         .open = hugetlb_vm_op_open,
2064         .close = hugetlb_vm_op_close,
2065 };
2066
2067 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2068                                 int writable)
2069 {
2070         pte_t entry;
2071
2072         if (writable) {
2073                 entry =
2074                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2075         } else {
2076                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2077         }
2078         entry = pte_mkyoung(entry);
2079         entry = pte_mkhuge(entry);
2080
2081         return entry;
2082 }
2083
2084 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2085                                    unsigned long address, pte_t *ptep)
2086 {
2087         pte_t entry;
2088
2089         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2090         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
2091                 update_mmu_cache(vma, address, ptep);
2092         }
2093 }
2094
2095
2096 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2097                             struct vm_area_struct *vma)
2098 {
2099         pte_t *src_pte, *dst_pte, entry;
2100         struct page *ptepage;
2101         unsigned long addr;
2102         int cow;
2103         struct hstate *h = hstate_vma(vma);
2104         unsigned long sz = huge_page_size(h);
2105
2106         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2107
2108         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2109                 src_pte = huge_pte_offset(src, addr);
2110                 if (!src_pte)
2111                         continue;
2112                 dst_pte = huge_pte_alloc(dst, addr, sz);
2113                 if (!dst_pte)
2114                         goto nomem;
2115
2116                 /* If the pagetables are shared don't copy or take references */
2117                 if (dst_pte == src_pte)
2118                         continue;
2119
2120                 spin_lock(&dst->page_table_lock);
2121                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2122                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
2123                         if (cow)
2124                                 huge_ptep_set_wrprotect(src, addr, src_pte);
2125                         entry = huge_ptep_get(src_pte);
2126                         ptepage = pte_page(entry);
2127                         get_page(ptepage);
2128                         set_huge_pte_at(dst, addr, dst_pte, entry);
2129                 }
2130                 spin_unlock(&src->page_table_lock);
2131                 spin_unlock(&dst->page_table_lock);
2132         }
2133         return 0;
2134
2135 nomem:
2136         return -ENOMEM;
2137 }
2138
2139 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2140                             unsigned long end, struct page *ref_page)
2141 {
2142         struct mm_struct *mm = vma->vm_mm;
2143         unsigned long address;
2144         pte_t *ptep;
2145         pte_t pte;
2146         struct page *page;
2147         struct page *tmp;
2148         struct hstate *h = hstate_vma(vma);
2149         unsigned long sz = huge_page_size(h);
2150
2151         /*
2152          * A page gathering list, protected by per file i_mmap_lock. The
2153          * lock is used to avoid list corruption from multiple unmapping
2154          * of the same page since we are using page->lru.
2155          */
2156         LIST_HEAD(page_list);
2157
2158         WARN_ON(!is_vm_hugetlb_page(vma));
2159         BUG_ON(start & ~huge_page_mask(h));
2160         BUG_ON(end & ~huge_page_mask(h));
2161
2162         mmu_notifier_invalidate_range_start(mm, start, end);
2163         spin_lock(&mm->page_table_lock);
2164         for (address = start; address < end; address += sz) {
2165                 ptep = huge_pte_offset(mm, address);
2166                 if (!ptep)
2167                         continue;
2168
2169                 if (huge_pmd_unshare(mm, &address, ptep))
2170                         continue;
2171
2172                 /*
2173                  * If a reference page is supplied, it is because a specific
2174                  * page is being unmapped, not a range. Ensure the page we
2175                  * are about to unmap is the actual page of interest.
2176                  */
2177                 if (ref_page) {
2178                         pte = huge_ptep_get(ptep);
2179                         if (huge_pte_none(pte))
2180                                 continue;
2181                         page = pte_page(pte);
2182                         if (page != ref_page)
2183                                 continue;
2184
2185                         /*
2186                          * Mark the VMA as having unmapped its page so that
2187                          * future faults in this VMA will fail rather than
2188                          * looking like data was lost
2189                          */
2190                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2191                 }
2192
2193                 pte = huge_ptep_get_and_clear(mm, address, ptep);
2194                 if (huge_pte_none(pte))
2195                         continue;
2196
2197                 page = pte_page(pte);
2198                 if (pte_dirty(pte))
2199                         set_page_dirty(page);
2200                 list_add(&page->lru, &page_list);
2201         }
2202         spin_unlock(&mm->page_table_lock);
2203         flush_tlb_range(vma, start, end);
2204         mmu_notifier_invalidate_range_end(mm, start, end);
2205         list_for_each_entry_safe(page, tmp, &page_list, lru) {
2206                 list_del(&page->lru);
2207                 put_page(page);
2208         }
2209 }
2210
2211 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2212                           unsigned long end, struct page *ref_page)
2213 {
2214         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2215         __unmap_hugepage_range(vma, start, end, ref_page);
2216         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2217 }
2218
2219 /*
2220  * This is called when the original mapper is failing to COW a MAP_PRIVATE
2221  * mappping it owns the reserve page for. The intention is to unmap the page
2222  * from other VMAs and let the children be SIGKILLed if they are faulting the
2223  * same region.
2224  */
2225 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2226                                 struct page *page, unsigned long address)
2227 {
2228         struct hstate *h = hstate_vma(vma);
2229         struct vm_area_struct *iter_vma;
2230         struct address_space *mapping;
2231         struct prio_tree_iter iter;
2232         pgoff_t pgoff;
2233
2234         /*
2235          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2236          * from page cache lookup which is in HPAGE_SIZE units.
2237          */
2238         address = address & huge_page_mask(h);
2239         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
2240                 + (vma->vm_pgoff >> PAGE_SHIFT);
2241         mapping = (struct address_space *)page_private(page);
2242
2243         /*
2244          * Take the mapping lock for the duration of the table walk. As
2245          * this mapping should be shared between all the VMAs,
2246          * __unmap_hugepage_range() is called as the lock is already held
2247          */
2248         spin_lock(&mapping->i_mmap_lock);
2249         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2250                 /* Do not unmap the current VMA */
2251                 if (iter_vma == vma)
2252                         continue;
2253
2254                 /*
2255                  * Unmap the page from other VMAs without their own reserves.
2256                  * They get marked to be SIGKILLed if they fault in these
2257                  * areas. This is because a future no-page fault on this VMA
2258                  * could insert a zeroed page instead of the data existing
2259                  * from the time of fork. This would look like data corruption
2260                  */
2261                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2262                         __unmap_hugepage_range(iter_vma,
2263                                 address, address + huge_page_size(h),
2264                                 page);
2265         }
2266         spin_unlock(&mapping->i_mmap_lock);
2267
2268         return 1;
2269 }
2270
2271 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2272                         unsigned long address, pte_t *ptep, pte_t pte,
2273                         struct page *pagecache_page)
2274 {
2275         struct hstate *h = hstate_vma(vma);
2276         struct page *old_page, *new_page;
2277         int avoidcopy;
2278         int outside_reserve = 0;
2279
2280         old_page = pte_page(pte);
2281
2282 retry_avoidcopy:
2283         /* If no-one else is actually using this page, avoid the copy
2284          * and just make the page writable */
2285         avoidcopy = (page_count(old_page) == 1);
2286         if (avoidcopy) {
2287                 set_huge_ptep_writable(vma, address, ptep);
2288                 return 0;
2289         }
2290
2291         /*
2292          * If the process that created a MAP_PRIVATE mapping is about to
2293          * perform a COW due to a shared page count, attempt to satisfy
2294          * the allocation without using the existing reserves. The pagecache
2295          * page is used to determine if the reserve at this address was
2296          * consumed or not. If reserves were used, a partial faulted mapping
2297          * at the time of fork() could consume its reserves on COW instead
2298          * of the full address range.
2299          */
2300         if (!(vma->vm_flags & VM_MAYSHARE) &&
2301                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2302                         old_page != pagecache_page)
2303                 outside_reserve = 1;
2304
2305         page_cache_get(old_page);
2306
2307         /* Drop page_table_lock as buddy allocator may be called */
2308         spin_unlock(&mm->page_table_lock);
2309         new_page = alloc_huge_page(vma, address, outside_reserve);
2310
2311         if (IS_ERR(new_page)) {
2312                 page_cache_release(old_page);
2313
2314                 /*
2315                  * If a process owning a MAP_PRIVATE mapping fails to COW,
2316                  * it is due to references held by a child and an insufficient
2317                  * huge page pool. To guarantee the original mappers
2318                  * reliability, unmap the page from child processes. The child
2319                  * may get SIGKILLed if it later faults.
2320                  */
2321                 if (outside_reserve) {
2322                         BUG_ON(huge_pte_none(pte));
2323                         if (unmap_ref_private(mm, vma, old_page, address)) {
2324                                 BUG_ON(page_count(old_page) != 1);
2325                                 BUG_ON(huge_pte_none(pte));
2326                                 spin_lock(&mm->page_table_lock);
2327                                 goto retry_avoidcopy;
2328                         }
2329                         WARN_ON_ONCE(1);
2330                 }
2331
2332                 /* Caller expects lock to be held */
2333                 spin_lock(&mm->page_table_lock);
2334                 return -PTR_ERR(new_page);
2335         }
2336
2337         copy_huge_page(new_page, old_page, address, vma);
2338         __SetPageUptodate(new_page);
2339
2340         /*
2341          * Retake the page_table_lock to check for racing updates
2342          * before the page tables are altered
2343          */
2344         spin_lock(&mm->page_table_lock);
2345         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2346         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2347                 /* Break COW */
2348                 huge_ptep_clear_flush(vma, address, ptep);
2349                 set_huge_pte_at(mm, address, ptep,
2350                                 make_huge_pte(vma, new_page, 1));
2351                 /* Make the old page be freed below */
2352                 new_page = old_page;
2353         }
2354         page_cache_release(new_page);
2355         page_cache_release(old_page);
2356         return 0;
2357 }
2358
2359 /* Return the pagecache page at a given address within a VMA */
2360 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2361                         struct vm_area_struct *vma, unsigned long address)
2362 {
2363         struct address_space *mapping;
2364         pgoff_t idx;
2365
2366         mapping = vma->vm_file->f_mapping;
2367         idx = vma_hugecache_offset(h, vma, address);
2368
2369         return find_lock_page(mapping, idx);
2370 }
2371
2372 /*
2373  * Return whether there is a pagecache page to back given address within VMA.
2374  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2375  */
2376 static bool hugetlbfs_pagecache_present(struct hstate *h,
2377                         struct vm_area_struct *vma, unsigned long address)
2378 {
2379         struct address_space *mapping;
2380         pgoff_t idx;
2381         struct page *page;
2382
2383         mapping = vma->vm_file->f_mapping;
2384         idx = vma_hugecache_offset(h, vma, address);
2385
2386         page = find_get_page(mapping, idx);
2387         if (page)
2388                 put_page(page);
2389         return page != NULL;
2390 }
2391
2392 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2393                         unsigned long address, pte_t *ptep, unsigned int flags)
2394 {
2395         struct hstate *h = hstate_vma(vma);
2396         int ret = VM_FAULT_SIGBUS;
2397         pgoff_t idx;
2398         unsigned long size;
2399         struct page *page;
2400         struct address_space *mapping;
2401         pte_t new_pte;
2402
2403         /*
2404          * Currently, we are forced to kill the process in the event the
2405          * original mapper has unmapped pages from the child due to a failed
2406          * COW. Warn that such a situation has occured as it may not be obvious
2407          */
2408         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2409                 printk(KERN_WARNING
2410                         "PID %d killed due to inadequate hugepage pool\n",
2411                         current->pid);
2412                 return ret;
2413         }
2414
2415         mapping = vma->vm_file->f_mapping;
2416         idx = vma_hugecache_offset(h, vma, address);
2417
2418         /*
2419          * Use page lock to guard against racing truncation
2420          * before we get page_table_lock.
2421          */
2422 retry:
2423         page = find_lock_page(mapping, idx);
2424         if (!page) {
2425                 size = i_size_read(mapping->host) >> huge_page_shift(h);
2426                 if (idx >= size)
2427                         goto out;
2428                 page = alloc_huge_page(vma, address, 0);
2429                 if (IS_ERR(page)) {
2430                         ret = -PTR_ERR(page);
2431                         goto out;
2432                 }
2433                 clear_huge_page(page, address, huge_page_size(h));
2434                 __SetPageUptodate(page);
2435
2436                 if (vma->vm_flags & VM_MAYSHARE) {
2437                         int err;
2438                         struct inode *inode = mapping->host;
2439
2440                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2441                         if (err) {
2442                                 put_page(page);
2443                                 if (err == -EEXIST)
2444                                         goto retry;
2445                                 goto out;
2446                         }
2447
2448                         spin_lock(&inode->i_lock);
2449                         inode->i_blocks += blocks_per_huge_page(h);
2450                         spin_unlock(&inode->i_lock);
2451                 } else {
2452                         lock_page(page);
2453                         page->mapping = HUGETLB_POISON;
2454                 }
2455         }
2456
2457         /*
2458          * If we are going to COW a private mapping later, we examine the
2459          * pending reservations for this page now. This will ensure that
2460          * any allocations necessary to record that reservation occur outside
2461          * the spinlock.
2462          */
2463         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2464                 if (vma_needs_reservation(h, vma, address) < 0) {
2465                         ret = VM_FAULT_OOM;
2466                         goto backout_unlocked;
2467                 }
2468
2469         spin_lock(&mm->page_table_lock);
2470         size = i_size_read(mapping->host) >> huge_page_shift(h);
2471         if (idx >= size)
2472                 goto backout;
2473
2474         ret = 0;
2475         if (!huge_pte_none(huge_ptep_get(ptep)))
2476                 goto backout;
2477
2478         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2479                                 && (vma->vm_flags & VM_SHARED)));
2480         set_huge_pte_at(mm, address, ptep, new_pte);
2481
2482         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2483                 /* Optimization, do the COW without a second fault */
2484                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2485         }
2486
2487         spin_unlock(&mm->page_table_lock);
2488         unlock_page(page);
2489 out:
2490         return ret;
2491
2492 backout:
2493         spin_unlock(&mm->page_table_lock);
2494 backout_unlocked:
2495         unlock_page(page);
2496         put_page(page);
2497         goto out;
2498 }
2499
2500 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2501                         unsigned long address, unsigned int flags)
2502 {
2503         pte_t *ptep;
2504         pte_t entry;
2505         int ret;
2506         struct page *pagecache_page = NULL;
2507         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2508         struct hstate *h = hstate_vma(vma);
2509
2510         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2511         if (!ptep)
2512                 return VM_FAULT_OOM;
2513
2514         /*
2515          * Serialize hugepage allocation and instantiation, so that we don't
2516          * get spurious allocation failures if two CPUs race to instantiate
2517          * the same page in the page cache.
2518          */
2519         mutex_lock(&hugetlb_instantiation_mutex);
2520         entry = huge_ptep_get(ptep);
2521         if (huge_pte_none(entry)) {
2522                 ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2523                 goto out_mutex;
2524         }
2525
2526         ret = 0;
2527
2528         /*
2529          * If we are going to COW the mapping later, we examine the pending
2530          * reservations for this page now. This will ensure that any
2531          * allocations necessary to record that reservation occur outside the
2532          * spinlock. For private mappings, we also lookup the pagecache
2533          * page now as it is used to determine if a reservation has been
2534          * consumed.
2535          */
2536         if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2537                 if (vma_needs_reservation(h, vma, address) < 0) {
2538                         ret = VM_FAULT_OOM;
2539                         goto out_mutex;
2540                 }
2541
2542                 if (!(vma->vm_flags & VM_MAYSHARE))
2543                         pagecache_page = hugetlbfs_pagecache_page(h,
2544                                                                 vma, address);
2545         }
2546
2547         spin_lock(&mm->page_table_lock);
2548         /* Check for a racing update before calling hugetlb_cow */
2549         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2550                 goto out_page_table_lock;
2551
2552
2553         if (flags & FAULT_FLAG_WRITE) {
2554                 if (!pte_write(entry)) {
2555                         ret = hugetlb_cow(mm, vma, address, ptep, entry,
2556                                                         pagecache_page);
2557                         goto out_page_table_lock;
2558                 }
2559                 entry = pte_mkdirty(entry);
2560         }
2561         entry = pte_mkyoung(entry);
2562         if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2563                                                 flags & FAULT_FLAG_WRITE))
2564                 update_mmu_cache(vma, address, ptep);
2565
2566 out_page_table_lock:
2567         spin_unlock(&mm->page_table_lock);
2568
2569         if (pagecache_page) {
2570                 unlock_page(pagecache_page);
2571                 put_page(pagecache_page);
2572         }
2573
2574 out_mutex:
2575         mutex_unlock(&hugetlb_instantiation_mutex);
2576
2577         return ret;
2578 }
2579
2580 /* Can be overriden by architectures */
2581 __attribute__((weak)) struct page *
2582 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2583                pud_t *pud, int write)
2584 {
2585         BUG();
2586         return NULL;
2587 }
2588
2589 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2590                         struct page **pages, struct vm_area_struct **vmas,
2591                         unsigned long *position, int *length, int i,
2592                         unsigned int flags)
2593 {
2594         unsigned long pfn_offset;
2595         unsigned long vaddr = *position;
2596         int remainder = *length;
2597         struct hstate *h = hstate_vma(vma);
2598
2599         spin_lock(&mm->page_table_lock);
2600         while (vaddr < vma->vm_end && remainder) {
2601                 pte_t *pte;
2602                 int absent;
2603                 struct page *page;
2604
2605                 /*
2606                  * Some archs (sparc64, sh*) have multiple pte_ts to
2607                  * each hugepage.  We have to make sure we get the
2608                  * first, for the page indexing below to work.
2609                  */
2610                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2611                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
2612
2613                 /*
2614                  * When coredumping, it suits get_dump_page if we just return
2615                  * an error where there's an empty slot with no huge pagecache
2616                  * to back it.  This way, we avoid allocating a hugepage, and
2617                  * the sparse dumpfile avoids allocating disk blocks, but its
2618                  * huge holes still show up with zeroes where they need to be.
2619                  */
2620                 if (absent && (flags & FOLL_DUMP) &&
2621                     !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2622                         remainder = 0;
2623                         break;
2624                 }
2625
2626                 if (absent ||
2627                     ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2628                         int ret;
2629
2630                         spin_unlock(&mm->page_table_lock);
2631                         ret = hugetlb_fault(mm, vma, vaddr,
2632                                 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2633                         spin_lock(&mm->page_table_lock);
2634                         if (!(ret & VM_FAULT_ERROR))
2635                                 continue;
2636
2637                         remainder = 0;
2638                         break;
2639                 }
2640
2641                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2642                 page = pte_page(huge_ptep_get(pte));
2643 same_page:
2644                 if (pages) {
2645                         pages[i] = mem_map_offset(page, pfn_offset);
2646                         get_page(pages[i]);
2647                 }
2648
2649                 if (vmas)
2650                         vmas[i] = vma;
2651
2652                 vaddr += PAGE_SIZE;
2653                 ++pfn_offset;
2654                 --remainder;
2655                 ++i;
2656                 if (vaddr < vma->vm_end && remainder &&
2657                                 pfn_offset < pages_per_huge_page(h)) {
2658                         /*
2659                          * We use pfn_offset to avoid touching the pageframes
2660                          * of this compound page.
2661                          */
2662                         goto same_page;
2663                 }
2664         }
2665         spin_unlock(&mm->page_table_lock);
2666         *length = remainder;
2667         *position = vaddr;
2668
2669         return i ? i : -EFAULT;
2670 }
2671
2672 void hugetlb_change_protection(struct vm_area_struct *vma,
2673                 unsigned long address, unsigned long end, pgprot_t newprot)
2674 {
2675         struct mm_struct *mm = vma->vm_mm;
2676         unsigned long start = address;
2677         pte_t *ptep;
2678         pte_t pte;
2679         struct hstate *h = hstate_vma(vma);
2680
2681         BUG_ON(address >= end);
2682         flush_cache_range(vma, address, end);
2683
2684         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2685         spin_lock(&mm->page_table_lock);
2686         for (; address < end; address += huge_page_size(h)) {
2687                 ptep = huge_pte_offset(mm, address);
2688                 if (!ptep)
2689                         continue;
2690                 if (huge_pmd_unshare(mm, &address, ptep))
2691                         continue;
2692                 if (!huge_pte_none(huge_ptep_get(ptep))) {
2693                         pte = huge_ptep_get_and_clear(mm, address, ptep);
2694                         pte = pte_mkhuge(pte_modify(pte, newprot));
2695                         set_huge_pte_at(mm, address, ptep, pte);
2696                 }
2697         }
2698         spin_unlock(&mm->page_table_lock);
2699         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2700
2701         flush_tlb_range(vma, start, end);
2702 }
2703
2704 int hugetlb_reserve_pages(struct inode *inode,
2705                                         long from, long to,
2706                                         struct vm_area_struct *vma,
2707                                         int acctflag)
2708 {
2709         long ret, chg;
2710         struct hstate *h = hstate_inode(inode);
2711
2712         /*
2713          * Only apply hugepage reservation if asked. At fault time, an
2714          * attempt will be made for VM_NORESERVE to allocate a page
2715          * and filesystem quota without using reserves
2716          */
2717         if (acctflag & VM_NORESERVE)
2718                 return 0;
2719
2720         /*
2721          * Shared mappings base their reservation on the number of pages that
2722          * are already allocated on behalf of the file. Private mappings need
2723          * to reserve the full area even if read-only as mprotect() may be
2724          * called to make the mapping read-write. Assume !vma is a shm mapping
2725          */
2726         if (!vma || vma->vm_flags & VM_MAYSHARE)
2727                 chg = region_chg(&inode->i_mapping->private_list, from, to);
2728         else {
2729                 struct resv_map *resv_map = resv_map_alloc();
2730                 if (!resv_map)
2731                         return -ENOMEM;
2732
2733                 chg = to - from;
2734
2735                 set_vma_resv_map(vma, resv_map);
2736                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2737         }
2738
2739         if (chg < 0)
2740                 return chg;
2741
2742         /* There must be enough filesystem quota for the mapping */
2743         if (hugetlb_get_quota(inode->i_mapping, chg))
2744                 return -ENOSPC;
2745
2746         /*
2747          * Check enough hugepages are available for the reservation.
2748          * Hand back the quota if there are not
2749          */
2750         ret = hugetlb_acct_memory(h, chg);
2751         if (ret < 0) {
2752                 hugetlb_put_quota(inode->i_mapping, chg);
2753                 return ret;
2754         }
2755
2756         /*
2757          * Account for the reservations made. Shared mappings record regions
2758          * that have reservations as they are shared by multiple VMAs.
2759          * When the last VMA disappears, the region map says how much
2760          * the reservation was and the page cache tells how much of
2761          * the reservation was consumed. Private mappings are per-VMA and
2762          * only the consumed reservations are tracked. When the VMA
2763          * disappears, the original reservation is the VMA size and the
2764          * consumed reservations are stored in the map. Hence, nothing
2765          * else has to be done for private mappings here
2766          */
2767         if (!vma || vma->vm_flags & VM_MAYSHARE)
2768                 region_add(&inode->i_mapping->private_list, from, to);
2769         return 0;
2770 }
2771
2772 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2773 {
2774         struct hstate *h = hstate_inode(inode);
2775         long chg = region_truncate(&inode->i_mapping->private_list, offset);
2776
2777         spin_lock(&inode->i_lock);
2778         inode->i_blocks -= (blocks_per_huge_page(h) * freed);
2779         spin_unlock(&inode->i_lock);
2780
2781         hugetlb_put_quota(inode->i_mapping, (chg - freed));
2782         hugetlb_acct_memory(h, -(chg - freed));
2783 }