hugetlb: support larger than MAX_ORDER
[linux-2.6.git] / mm / hugetlb.c
1 /*
2  * Generic hugetlb support.
3  * (C) William Irwin, April 2004
4  */
5 #include <linux/gfp.h>
6 #include <linux/list.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/cpuset.h>
16 #include <linux/mutex.h>
17 #include <linux/bootmem.h>
18 #include <linux/sysfs.h>
19
20 #include <asm/page.h>
21 #include <asm/pgtable.h>
22
23 #include <linux/hugetlb.h>
24 #include "internal.h"
25
26 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
27 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
28 unsigned long hugepages_treat_as_movable;
29
30 static int max_hstate;
31 unsigned int default_hstate_idx;
32 struct hstate hstates[HUGE_MAX_HSTATE];
33
34 /* for command line parsing */
35 static struct hstate * __initdata parsed_hstate;
36 static unsigned long __initdata default_hstate_max_huge_pages;
37
38 #define for_each_hstate(h) \
39         for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
40
41 /*
42  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
43  */
44 static DEFINE_SPINLOCK(hugetlb_lock);
45
46 /*
47  * Region tracking -- allows tracking of reservations and instantiated pages
48  *                    across the pages in a mapping.
49  *
50  * The region data structures are protected by a combination of the mmap_sem
51  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
52  * must either hold the mmap_sem for write, or the mmap_sem for read and
53  * the hugetlb_instantiation mutex:
54  *
55  *      down_write(&mm->mmap_sem);
56  * or
57  *      down_read(&mm->mmap_sem);
58  *      mutex_lock(&hugetlb_instantiation_mutex);
59  */
60 struct file_region {
61         struct list_head link;
62         long from;
63         long to;
64 };
65
66 static long region_add(struct list_head *head, long f, long t)
67 {
68         struct file_region *rg, *nrg, *trg;
69
70         /* Locate the region we are either in or before. */
71         list_for_each_entry(rg, head, link)
72                 if (f <= rg->to)
73                         break;
74
75         /* Round our left edge to the current segment if it encloses us. */
76         if (f > rg->from)
77                 f = rg->from;
78
79         /* Check for and consume any regions we now overlap with. */
80         nrg = rg;
81         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
82                 if (&rg->link == head)
83                         break;
84                 if (rg->from > t)
85                         break;
86
87                 /* If this area reaches higher then extend our area to
88                  * include it completely.  If this is not the first area
89                  * which we intend to reuse, free it. */
90                 if (rg->to > t)
91                         t = rg->to;
92                 if (rg != nrg) {
93                         list_del(&rg->link);
94                         kfree(rg);
95                 }
96         }
97         nrg->from = f;
98         nrg->to = t;
99         return 0;
100 }
101
102 static long region_chg(struct list_head *head, long f, long t)
103 {
104         struct file_region *rg, *nrg;
105         long chg = 0;
106
107         /* Locate the region we are before or in. */
108         list_for_each_entry(rg, head, link)
109                 if (f <= rg->to)
110                         break;
111
112         /* If we are below the current region then a new region is required.
113          * Subtle, allocate a new region at the position but make it zero
114          * size such that we can guarantee to record the reservation. */
115         if (&rg->link == head || t < rg->from) {
116                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
117                 if (!nrg)
118                         return -ENOMEM;
119                 nrg->from = f;
120                 nrg->to   = f;
121                 INIT_LIST_HEAD(&nrg->link);
122                 list_add(&nrg->link, rg->link.prev);
123
124                 return t - f;
125         }
126
127         /* Round our left edge to the current segment if it encloses us. */
128         if (f > rg->from)
129                 f = rg->from;
130         chg = t - f;
131
132         /* Check for and consume any regions we now overlap with. */
133         list_for_each_entry(rg, rg->link.prev, link) {
134                 if (&rg->link == head)
135                         break;
136                 if (rg->from > t)
137                         return chg;
138
139                 /* We overlap with this area, if it extends futher than
140                  * us then we must extend ourselves.  Account for its
141                  * existing reservation. */
142                 if (rg->to > t) {
143                         chg += rg->to - t;
144                         t = rg->to;
145                 }
146                 chg -= rg->to - rg->from;
147         }
148         return chg;
149 }
150
151 static long region_truncate(struct list_head *head, long end)
152 {
153         struct file_region *rg, *trg;
154         long chg = 0;
155
156         /* Locate the region we are either in or before. */
157         list_for_each_entry(rg, head, link)
158                 if (end <= rg->to)
159                         break;
160         if (&rg->link == head)
161                 return 0;
162
163         /* If we are in the middle of a region then adjust it. */
164         if (end > rg->from) {
165                 chg = rg->to - end;
166                 rg->to = end;
167                 rg = list_entry(rg->link.next, typeof(*rg), link);
168         }
169
170         /* Drop any remaining regions. */
171         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
172                 if (&rg->link == head)
173                         break;
174                 chg += rg->to - rg->from;
175                 list_del(&rg->link);
176                 kfree(rg);
177         }
178         return chg;
179 }
180
181 static long region_count(struct list_head *head, long f, long t)
182 {
183         struct file_region *rg;
184         long chg = 0;
185
186         /* Locate each segment we overlap with, and count that overlap. */
187         list_for_each_entry(rg, head, link) {
188                 int seg_from;
189                 int seg_to;
190
191                 if (rg->to <= f)
192                         continue;
193                 if (rg->from >= t)
194                         break;
195
196                 seg_from = max(rg->from, f);
197                 seg_to = min(rg->to, t);
198
199                 chg += seg_to - seg_from;
200         }
201
202         return chg;
203 }
204
205 /*
206  * Convert the address within this vma to the page offset within
207  * the mapping, in pagecache page units; huge pages here.
208  */
209 static pgoff_t vma_hugecache_offset(struct hstate *h,
210                         struct vm_area_struct *vma, unsigned long address)
211 {
212         return ((address - vma->vm_start) >> huge_page_shift(h)) +
213                         (vma->vm_pgoff >> huge_page_order(h));
214 }
215
216 /*
217  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
218  * bits of the reservation map pointer, which are always clear due to
219  * alignment.
220  */
221 #define HPAGE_RESV_OWNER    (1UL << 0)
222 #define HPAGE_RESV_UNMAPPED (1UL << 1)
223 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
224
225 /*
226  * These helpers are used to track how many pages are reserved for
227  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
228  * is guaranteed to have their future faults succeed.
229  *
230  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
231  * the reserve counters are updated with the hugetlb_lock held. It is safe
232  * to reset the VMA at fork() time as it is not in use yet and there is no
233  * chance of the global counters getting corrupted as a result of the values.
234  *
235  * The private mapping reservation is represented in a subtly different
236  * manner to a shared mapping.  A shared mapping has a region map associated
237  * with the underlying file, this region map represents the backing file
238  * pages which have ever had a reservation assigned which this persists even
239  * after the page is instantiated.  A private mapping has a region map
240  * associated with the original mmap which is attached to all VMAs which
241  * reference it, this region map represents those offsets which have consumed
242  * reservation ie. where pages have been instantiated.
243  */
244 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
245 {
246         return (unsigned long)vma->vm_private_data;
247 }
248
249 static void set_vma_private_data(struct vm_area_struct *vma,
250                                                         unsigned long value)
251 {
252         vma->vm_private_data = (void *)value;
253 }
254
255 struct resv_map {
256         struct kref refs;
257         struct list_head regions;
258 };
259
260 struct resv_map *resv_map_alloc(void)
261 {
262         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
263         if (!resv_map)
264                 return NULL;
265
266         kref_init(&resv_map->refs);
267         INIT_LIST_HEAD(&resv_map->regions);
268
269         return resv_map;
270 }
271
272 void resv_map_release(struct kref *ref)
273 {
274         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
275
276         /* Clear out any active regions before we release the map. */
277         region_truncate(&resv_map->regions, 0);
278         kfree(resv_map);
279 }
280
281 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
282 {
283         VM_BUG_ON(!is_vm_hugetlb_page(vma));
284         if (!(vma->vm_flags & VM_SHARED))
285                 return (struct resv_map *)(get_vma_private_data(vma) &
286                                                         ~HPAGE_RESV_MASK);
287         return 0;
288 }
289
290 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
291 {
292         VM_BUG_ON(!is_vm_hugetlb_page(vma));
293         VM_BUG_ON(vma->vm_flags & VM_SHARED);
294
295         set_vma_private_data(vma, (get_vma_private_data(vma) &
296                                 HPAGE_RESV_MASK) | (unsigned long)map);
297 }
298
299 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
300 {
301         VM_BUG_ON(!is_vm_hugetlb_page(vma));
302         VM_BUG_ON(vma->vm_flags & VM_SHARED);
303
304         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
305 }
306
307 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
308 {
309         VM_BUG_ON(!is_vm_hugetlb_page(vma));
310
311         return (get_vma_private_data(vma) & flag) != 0;
312 }
313
314 /* Decrement the reserved pages in the hugepage pool by one */
315 static void decrement_hugepage_resv_vma(struct hstate *h,
316                         struct vm_area_struct *vma)
317 {
318         if (vma->vm_flags & VM_NORESERVE)
319                 return;
320
321         if (vma->vm_flags & VM_SHARED) {
322                 /* Shared mappings always use reserves */
323                 h->resv_huge_pages--;
324         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
325                 /*
326                  * Only the process that called mmap() has reserves for
327                  * private mappings.
328                  */
329                 h->resv_huge_pages--;
330         }
331 }
332
333 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
334 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
335 {
336         VM_BUG_ON(!is_vm_hugetlb_page(vma));
337         if (!(vma->vm_flags & VM_SHARED))
338                 vma->vm_private_data = (void *)0;
339 }
340
341 /* Returns true if the VMA has associated reserve pages */
342 static int vma_has_private_reserves(struct vm_area_struct *vma)
343 {
344         if (vma->vm_flags & VM_SHARED)
345                 return 0;
346         if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER))
347                 return 0;
348         return 1;
349 }
350
351 static void clear_huge_page(struct page *page,
352                         unsigned long addr, unsigned long sz)
353 {
354         int i;
355
356         might_sleep();
357         for (i = 0; i < sz/PAGE_SIZE; i++) {
358                 cond_resched();
359                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
360         }
361 }
362
363 static void copy_huge_page(struct page *dst, struct page *src,
364                            unsigned long addr, struct vm_area_struct *vma)
365 {
366         int i;
367         struct hstate *h = hstate_vma(vma);
368
369         might_sleep();
370         for (i = 0; i < pages_per_huge_page(h); i++) {
371                 cond_resched();
372                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
373         }
374 }
375
376 static void enqueue_huge_page(struct hstate *h, struct page *page)
377 {
378         int nid = page_to_nid(page);
379         list_add(&page->lru, &h->hugepage_freelists[nid]);
380         h->free_huge_pages++;
381         h->free_huge_pages_node[nid]++;
382 }
383
384 static struct page *dequeue_huge_page(struct hstate *h)
385 {
386         int nid;
387         struct page *page = NULL;
388
389         for (nid = 0; nid < MAX_NUMNODES; ++nid) {
390                 if (!list_empty(&h->hugepage_freelists[nid])) {
391                         page = list_entry(h->hugepage_freelists[nid].next,
392                                           struct page, lru);
393                         list_del(&page->lru);
394                         h->free_huge_pages--;
395                         h->free_huge_pages_node[nid]--;
396                         break;
397                 }
398         }
399         return page;
400 }
401
402 static struct page *dequeue_huge_page_vma(struct hstate *h,
403                                 struct vm_area_struct *vma,
404                                 unsigned long address, int avoid_reserve)
405 {
406         int nid;
407         struct page *page = NULL;
408         struct mempolicy *mpol;
409         nodemask_t *nodemask;
410         struct zonelist *zonelist = huge_zonelist(vma, address,
411                                         htlb_alloc_mask, &mpol, &nodemask);
412         struct zone *zone;
413         struct zoneref *z;
414
415         /*
416          * A child process with MAP_PRIVATE mappings created by their parent
417          * have no page reserves. This check ensures that reservations are
418          * not "stolen". The child may still get SIGKILLed
419          */
420         if (!vma_has_private_reserves(vma) &&
421                         h->free_huge_pages - h->resv_huge_pages == 0)
422                 return NULL;
423
424         /* If reserves cannot be used, ensure enough pages are in the pool */
425         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
426                 return NULL;
427
428         for_each_zone_zonelist_nodemask(zone, z, zonelist,
429                                                 MAX_NR_ZONES - 1, nodemask) {
430                 nid = zone_to_nid(zone);
431                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
432                     !list_empty(&h->hugepage_freelists[nid])) {
433                         page = list_entry(h->hugepage_freelists[nid].next,
434                                           struct page, lru);
435                         list_del(&page->lru);
436                         h->free_huge_pages--;
437                         h->free_huge_pages_node[nid]--;
438
439                         if (!avoid_reserve)
440                                 decrement_hugepage_resv_vma(h, vma);
441
442                         break;
443                 }
444         }
445         mpol_cond_put(mpol);
446         return page;
447 }
448
449 static void update_and_free_page(struct hstate *h, struct page *page)
450 {
451         int i;
452
453         h->nr_huge_pages--;
454         h->nr_huge_pages_node[page_to_nid(page)]--;
455         for (i = 0; i < pages_per_huge_page(h); i++) {
456                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
457                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
458                                 1 << PG_private | 1<< PG_writeback);
459         }
460         set_compound_page_dtor(page, NULL);
461         set_page_refcounted(page);
462         arch_release_hugepage(page);
463         __free_pages(page, huge_page_order(h));
464 }
465
466 struct hstate *size_to_hstate(unsigned long size)
467 {
468         struct hstate *h;
469
470         for_each_hstate(h) {
471                 if (huge_page_size(h) == size)
472                         return h;
473         }
474         return NULL;
475 }
476
477 static void free_huge_page(struct page *page)
478 {
479         /*
480          * Can't pass hstate in here because it is called from the
481          * compound page destructor.
482          */
483         struct hstate *h = page_hstate(page);
484         int nid = page_to_nid(page);
485         struct address_space *mapping;
486
487         mapping = (struct address_space *) page_private(page);
488         set_page_private(page, 0);
489         BUG_ON(page_count(page));
490         INIT_LIST_HEAD(&page->lru);
491
492         spin_lock(&hugetlb_lock);
493         if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
494                 update_and_free_page(h, page);
495                 h->surplus_huge_pages--;
496                 h->surplus_huge_pages_node[nid]--;
497         } else {
498                 enqueue_huge_page(h, page);
499         }
500         spin_unlock(&hugetlb_lock);
501         if (mapping)
502                 hugetlb_put_quota(mapping, 1);
503 }
504
505 /*
506  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
507  * balanced by operating on them in a round-robin fashion.
508  * Returns 1 if an adjustment was made.
509  */
510 static int adjust_pool_surplus(struct hstate *h, int delta)
511 {
512         static int prev_nid;
513         int nid = prev_nid;
514         int ret = 0;
515
516         VM_BUG_ON(delta != -1 && delta != 1);
517         do {
518                 nid = next_node(nid, node_online_map);
519                 if (nid == MAX_NUMNODES)
520                         nid = first_node(node_online_map);
521
522                 /* To shrink on this node, there must be a surplus page */
523                 if (delta < 0 && !h->surplus_huge_pages_node[nid])
524                         continue;
525                 /* Surplus cannot exceed the total number of pages */
526                 if (delta > 0 && h->surplus_huge_pages_node[nid] >=
527                                                 h->nr_huge_pages_node[nid])
528                         continue;
529
530                 h->surplus_huge_pages += delta;
531                 h->surplus_huge_pages_node[nid] += delta;
532                 ret = 1;
533                 break;
534         } while (nid != prev_nid);
535
536         prev_nid = nid;
537         return ret;
538 }
539
540 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
541 {
542         set_compound_page_dtor(page, free_huge_page);
543         spin_lock(&hugetlb_lock);
544         h->nr_huge_pages++;
545         h->nr_huge_pages_node[nid]++;
546         spin_unlock(&hugetlb_lock);
547         put_page(page); /* free it into the hugepage allocator */
548 }
549
550 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
551 {
552         struct page *page;
553
554         if (h->order >= MAX_ORDER)
555                 return NULL;
556
557         page = alloc_pages_node(nid,
558                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
559                                                 __GFP_REPEAT|__GFP_NOWARN,
560                 huge_page_order(h));
561         if (page) {
562                 if (arch_prepare_hugepage(page)) {
563                         __free_pages(page, HUGETLB_PAGE_ORDER);
564                         return NULL;
565                 }
566                 prep_new_huge_page(h, page, nid);
567         }
568
569         return page;
570 }
571
572 /*
573  * Use a helper variable to find the next node and then
574  * copy it back to hugetlb_next_nid afterwards:
575  * otherwise there's a window in which a racer might
576  * pass invalid nid MAX_NUMNODES to alloc_pages_node.
577  * But we don't need to use a spin_lock here: it really
578  * doesn't matter if occasionally a racer chooses the
579  * same nid as we do.  Move nid forward in the mask even
580  * if we just successfully allocated a hugepage so that
581  * the next caller gets hugepages on the next node.
582  */
583 static int hstate_next_node(struct hstate *h)
584 {
585         int next_nid;
586         next_nid = next_node(h->hugetlb_next_nid, node_online_map);
587         if (next_nid == MAX_NUMNODES)
588                 next_nid = first_node(node_online_map);
589         h->hugetlb_next_nid = next_nid;
590         return next_nid;
591 }
592
593 static int alloc_fresh_huge_page(struct hstate *h)
594 {
595         struct page *page;
596         int start_nid;
597         int next_nid;
598         int ret = 0;
599
600         start_nid = h->hugetlb_next_nid;
601
602         do {
603                 page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
604                 if (page)
605                         ret = 1;
606                 next_nid = hstate_next_node(h);
607         } while (!page && h->hugetlb_next_nid != start_nid);
608
609         if (ret)
610                 count_vm_event(HTLB_BUDDY_PGALLOC);
611         else
612                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
613
614         return ret;
615 }
616
617 static struct page *alloc_buddy_huge_page(struct hstate *h,
618                         struct vm_area_struct *vma, unsigned long address)
619 {
620         struct page *page;
621         unsigned int nid;
622
623         if (h->order >= MAX_ORDER)
624                 return NULL;
625
626         /*
627          * Assume we will successfully allocate the surplus page to
628          * prevent racing processes from causing the surplus to exceed
629          * overcommit
630          *
631          * This however introduces a different race, where a process B
632          * tries to grow the static hugepage pool while alloc_pages() is
633          * called by process A. B will only examine the per-node
634          * counters in determining if surplus huge pages can be
635          * converted to normal huge pages in adjust_pool_surplus(). A
636          * won't be able to increment the per-node counter, until the
637          * lock is dropped by B, but B doesn't drop hugetlb_lock until
638          * no more huge pages can be converted from surplus to normal
639          * state (and doesn't try to convert again). Thus, we have a
640          * case where a surplus huge page exists, the pool is grown, and
641          * the surplus huge page still exists after, even though it
642          * should just have been converted to a normal huge page. This
643          * does not leak memory, though, as the hugepage will be freed
644          * once it is out of use. It also does not allow the counters to
645          * go out of whack in adjust_pool_surplus() as we don't modify
646          * the node values until we've gotten the hugepage and only the
647          * per-node value is checked there.
648          */
649         spin_lock(&hugetlb_lock);
650         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
651                 spin_unlock(&hugetlb_lock);
652                 return NULL;
653         } else {
654                 h->nr_huge_pages++;
655                 h->surplus_huge_pages++;
656         }
657         spin_unlock(&hugetlb_lock);
658
659         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
660                                         __GFP_REPEAT|__GFP_NOWARN,
661                                         huge_page_order(h));
662
663         spin_lock(&hugetlb_lock);
664         if (page) {
665                 /*
666                  * This page is now managed by the hugetlb allocator and has
667                  * no users -- drop the buddy allocator's reference.
668                  */
669                 put_page_testzero(page);
670                 VM_BUG_ON(page_count(page));
671                 nid = page_to_nid(page);
672                 set_compound_page_dtor(page, free_huge_page);
673                 /*
674                  * We incremented the global counters already
675                  */
676                 h->nr_huge_pages_node[nid]++;
677                 h->surplus_huge_pages_node[nid]++;
678                 __count_vm_event(HTLB_BUDDY_PGALLOC);
679         } else {
680                 h->nr_huge_pages--;
681                 h->surplus_huge_pages--;
682                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
683         }
684         spin_unlock(&hugetlb_lock);
685
686         return page;
687 }
688
689 /*
690  * Increase the hugetlb pool such that it can accomodate a reservation
691  * of size 'delta'.
692  */
693 static int gather_surplus_pages(struct hstate *h, int delta)
694 {
695         struct list_head surplus_list;
696         struct page *page, *tmp;
697         int ret, i;
698         int needed, allocated;
699
700         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
701         if (needed <= 0) {
702                 h->resv_huge_pages += delta;
703                 return 0;
704         }
705
706         allocated = 0;
707         INIT_LIST_HEAD(&surplus_list);
708
709         ret = -ENOMEM;
710 retry:
711         spin_unlock(&hugetlb_lock);
712         for (i = 0; i < needed; i++) {
713                 page = alloc_buddy_huge_page(h, NULL, 0);
714                 if (!page) {
715                         /*
716                          * We were not able to allocate enough pages to
717                          * satisfy the entire reservation so we free what
718                          * we've allocated so far.
719                          */
720                         spin_lock(&hugetlb_lock);
721                         needed = 0;
722                         goto free;
723                 }
724
725                 list_add(&page->lru, &surplus_list);
726         }
727         allocated += needed;
728
729         /*
730          * After retaking hugetlb_lock, we need to recalculate 'needed'
731          * because either resv_huge_pages or free_huge_pages may have changed.
732          */
733         spin_lock(&hugetlb_lock);
734         needed = (h->resv_huge_pages + delta) -
735                         (h->free_huge_pages + allocated);
736         if (needed > 0)
737                 goto retry;
738
739         /*
740          * The surplus_list now contains _at_least_ the number of extra pages
741          * needed to accomodate the reservation.  Add the appropriate number
742          * of pages to the hugetlb pool and free the extras back to the buddy
743          * allocator.  Commit the entire reservation here to prevent another
744          * process from stealing the pages as they are added to the pool but
745          * before they are reserved.
746          */
747         needed += allocated;
748         h->resv_huge_pages += delta;
749         ret = 0;
750 free:
751         /* Free the needed pages to the hugetlb pool */
752         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
753                 if ((--needed) < 0)
754                         break;
755                 list_del(&page->lru);
756                 enqueue_huge_page(h, page);
757         }
758
759         /* Free unnecessary surplus pages to the buddy allocator */
760         if (!list_empty(&surplus_list)) {
761                 spin_unlock(&hugetlb_lock);
762                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
763                         list_del(&page->lru);
764                         /*
765                          * The page has a reference count of zero already, so
766                          * call free_huge_page directly instead of using
767                          * put_page.  This must be done with hugetlb_lock
768                          * unlocked which is safe because free_huge_page takes
769                          * hugetlb_lock before deciding how to free the page.
770                          */
771                         free_huge_page(page);
772                 }
773                 spin_lock(&hugetlb_lock);
774         }
775
776         return ret;
777 }
778
779 /*
780  * When releasing a hugetlb pool reservation, any surplus pages that were
781  * allocated to satisfy the reservation must be explicitly freed if they were
782  * never used.
783  */
784 static void return_unused_surplus_pages(struct hstate *h,
785                                         unsigned long unused_resv_pages)
786 {
787         static int nid = -1;
788         struct page *page;
789         unsigned long nr_pages;
790
791         /*
792          * We want to release as many surplus pages as possible, spread
793          * evenly across all nodes. Iterate across all nodes until we
794          * can no longer free unreserved surplus pages. This occurs when
795          * the nodes with surplus pages have no free pages.
796          */
797         unsigned long remaining_iterations = num_online_nodes();
798
799         /* Uncommit the reservation */
800         h->resv_huge_pages -= unused_resv_pages;
801
802         /* Cannot return gigantic pages currently */
803         if (h->order >= MAX_ORDER)
804                 return;
805
806         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
807
808         while (remaining_iterations-- && nr_pages) {
809                 nid = next_node(nid, node_online_map);
810                 if (nid == MAX_NUMNODES)
811                         nid = first_node(node_online_map);
812
813                 if (!h->surplus_huge_pages_node[nid])
814                         continue;
815
816                 if (!list_empty(&h->hugepage_freelists[nid])) {
817                         page = list_entry(h->hugepage_freelists[nid].next,
818                                           struct page, lru);
819                         list_del(&page->lru);
820                         update_and_free_page(h, page);
821                         h->free_huge_pages--;
822                         h->free_huge_pages_node[nid]--;
823                         h->surplus_huge_pages--;
824                         h->surplus_huge_pages_node[nid]--;
825                         nr_pages--;
826                         remaining_iterations = num_online_nodes();
827                 }
828         }
829 }
830
831 /*
832  * Determine if the huge page at addr within the vma has an associated
833  * reservation.  Where it does not we will need to logically increase
834  * reservation and actually increase quota before an allocation can occur.
835  * Where any new reservation would be required the reservation change is
836  * prepared, but not committed.  Once the page has been quota'd allocated
837  * an instantiated the change should be committed via vma_commit_reservation.
838  * No action is required on failure.
839  */
840 static int vma_needs_reservation(struct hstate *h,
841                         struct vm_area_struct *vma, unsigned long addr)
842 {
843         struct address_space *mapping = vma->vm_file->f_mapping;
844         struct inode *inode = mapping->host;
845
846         if (vma->vm_flags & VM_SHARED) {
847                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
848                 return region_chg(&inode->i_mapping->private_list,
849                                                         idx, idx + 1);
850
851         } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
852                 return 1;
853
854         } else  {
855                 int err;
856                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
857                 struct resv_map *reservations = vma_resv_map(vma);
858
859                 err = region_chg(&reservations->regions, idx, idx + 1);
860                 if (err < 0)
861                         return err;
862                 return 0;
863         }
864 }
865 static void vma_commit_reservation(struct hstate *h,
866                         struct vm_area_struct *vma, unsigned long addr)
867 {
868         struct address_space *mapping = vma->vm_file->f_mapping;
869         struct inode *inode = mapping->host;
870
871         if (vma->vm_flags & VM_SHARED) {
872                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
873                 region_add(&inode->i_mapping->private_list, idx, idx + 1);
874
875         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
876                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
877                 struct resv_map *reservations = vma_resv_map(vma);
878
879                 /* Mark this page used in the map. */
880                 region_add(&reservations->regions, idx, idx + 1);
881         }
882 }
883
884 static struct page *alloc_huge_page(struct vm_area_struct *vma,
885                                     unsigned long addr, int avoid_reserve)
886 {
887         struct hstate *h = hstate_vma(vma);
888         struct page *page;
889         struct address_space *mapping = vma->vm_file->f_mapping;
890         struct inode *inode = mapping->host;
891         unsigned int chg;
892
893         /*
894          * Processes that did not create the mapping will have no reserves and
895          * will not have accounted against quota. Check that the quota can be
896          * made before satisfying the allocation
897          * MAP_NORESERVE mappings may also need pages and quota allocated
898          * if no reserve mapping overlaps.
899          */
900         chg = vma_needs_reservation(h, vma, addr);
901         if (chg < 0)
902                 return ERR_PTR(chg);
903         if (chg)
904                 if (hugetlb_get_quota(inode->i_mapping, chg))
905                         return ERR_PTR(-ENOSPC);
906
907         spin_lock(&hugetlb_lock);
908         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
909         spin_unlock(&hugetlb_lock);
910
911         if (!page) {
912                 page = alloc_buddy_huge_page(h, vma, addr);
913                 if (!page) {
914                         hugetlb_put_quota(inode->i_mapping, chg);
915                         return ERR_PTR(-VM_FAULT_OOM);
916                 }
917         }
918
919         set_page_refcounted(page);
920         set_page_private(page, (unsigned long) mapping);
921
922         vma_commit_reservation(h, vma, addr);
923
924         return page;
925 }
926
927 static __initdata LIST_HEAD(huge_boot_pages);
928
929 struct huge_bootmem_page {
930         struct list_head list;
931         struct hstate *hstate;
932 };
933
934 static int __init alloc_bootmem_huge_page(struct hstate *h)
935 {
936         struct huge_bootmem_page *m;
937         int nr_nodes = nodes_weight(node_online_map);
938
939         while (nr_nodes) {
940                 void *addr;
941
942                 addr = __alloc_bootmem_node_nopanic(
943                                 NODE_DATA(h->hugetlb_next_nid),
944                                 huge_page_size(h), huge_page_size(h), 0);
945
946                 if (addr) {
947                         /*
948                          * Use the beginning of the huge page to store the
949                          * huge_bootmem_page struct (until gather_bootmem
950                          * puts them into the mem_map).
951                          */
952                         m = addr;
953                         if (m)
954                                 goto found;
955                 }
956                 hstate_next_node(h);
957                 nr_nodes--;
958         }
959         return 0;
960
961 found:
962         BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
963         /* Put them into a private list first because mem_map is not up yet */
964         list_add(&m->list, &huge_boot_pages);
965         m->hstate = h;
966         return 1;
967 }
968
969 /* Put bootmem huge pages into the standard lists after mem_map is up */
970 static void __init gather_bootmem_prealloc(void)
971 {
972         struct huge_bootmem_page *m;
973
974         list_for_each_entry(m, &huge_boot_pages, list) {
975                 struct page *page = virt_to_page(m);
976                 struct hstate *h = m->hstate;
977                 __ClearPageReserved(page);
978                 WARN_ON(page_count(page) != 1);
979                 prep_compound_page(page, h->order);
980                 prep_new_huge_page(h, page, page_to_nid(page));
981         }
982 }
983
984 static void __init hugetlb_init_one_hstate(struct hstate *h)
985 {
986         unsigned long i;
987
988         for (i = 0; i < MAX_NUMNODES; ++i)
989                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
990
991         h->hugetlb_next_nid = first_node(node_online_map);
992
993         for (i = 0; i < h->max_huge_pages; ++i) {
994                 if (h->order >= MAX_ORDER) {
995                         if (!alloc_bootmem_huge_page(h))
996                                 break;
997                 } else if (!alloc_fresh_huge_page(h))
998                         break;
999         }
1000         h->max_huge_pages = h->free_huge_pages = h->nr_huge_pages = i;
1001 }
1002
1003 static void __init hugetlb_init_hstates(void)
1004 {
1005         struct hstate *h;
1006
1007         for_each_hstate(h) {
1008                 hugetlb_init_one_hstate(h);
1009         }
1010 }
1011
1012 static void __init report_hugepages(void)
1013 {
1014         struct hstate *h;
1015
1016         for_each_hstate(h) {
1017                 printk(KERN_INFO "Total HugeTLB memory allocated, "
1018                                 "%ld %dMB pages\n",
1019                                 h->free_huge_pages,
1020                                 1 << (h->order + PAGE_SHIFT - 20));
1021         }
1022 }
1023
1024 #ifdef CONFIG_SYSCTL
1025 #ifdef CONFIG_HIGHMEM
1026 static void try_to_free_low(struct hstate *h, unsigned long count)
1027 {
1028         int i;
1029
1030         if (h->order >= MAX_ORDER)
1031                 return;
1032
1033         for (i = 0; i < MAX_NUMNODES; ++i) {
1034                 struct page *page, *next;
1035                 struct list_head *freel = &h->hugepage_freelists[i];
1036                 list_for_each_entry_safe(page, next, freel, lru) {
1037                         if (count >= h->nr_huge_pages)
1038                                 return;
1039                         if (PageHighMem(page))
1040                                 continue;
1041                         list_del(&page->lru);
1042                         update_and_free_page(h, page);
1043                         h->free_huge_pages--;
1044                         h->free_huge_pages_node[page_to_nid(page)]--;
1045                 }
1046         }
1047 }
1048 #else
1049 static inline void try_to_free_low(struct hstate *h, unsigned long count)
1050 {
1051 }
1052 #endif
1053
1054 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1055 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
1056 {
1057         unsigned long min_count, ret;
1058
1059         if (h->order >= MAX_ORDER)
1060                 return h->max_huge_pages;
1061
1062         /*
1063          * Increase the pool size
1064          * First take pages out of surplus state.  Then make up the
1065          * remaining difference by allocating fresh huge pages.
1066          *
1067          * We might race with alloc_buddy_huge_page() here and be unable
1068          * to convert a surplus huge page to a normal huge page. That is
1069          * not critical, though, it just means the overall size of the
1070          * pool might be one hugepage larger than it needs to be, but
1071          * within all the constraints specified by the sysctls.
1072          */
1073         spin_lock(&hugetlb_lock);
1074         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1075                 if (!adjust_pool_surplus(h, -1))
1076                         break;
1077         }
1078
1079         while (count > persistent_huge_pages(h)) {
1080                 /*
1081                  * If this allocation races such that we no longer need the
1082                  * page, free_huge_page will handle it by freeing the page
1083                  * and reducing the surplus.
1084                  */
1085                 spin_unlock(&hugetlb_lock);
1086                 ret = alloc_fresh_huge_page(h);
1087                 spin_lock(&hugetlb_lock);
1088                 if (!ret)
1089                         goto out;
1090
1091         }
1092
1093         /*
1094          * Decrease the pool size
1095          * First return free pages to the buddy allocator (being careful
1096          * to keep enough around to satisfy reservations).  Then place
1097          * pages into surplus state as needed so the pool will shrink
1098          * to the desired size as pages become free.
1099          *
1100          * By placing pages into the surplus state independent of the
1101          * overcommit value, we are allowing the surplus pool size to
1102          * exceed overcommit. There are few sane options here. Since
1103          * alloc_buddy_huge_page() is checking the global counter,
1104          * though, we'll note that we're not allowed to exceed surplus
1105          * and won't grow the pool anywhere else. Not until one of the
1106          * sysctls are changed, or the surplus pages go out of use.
1107          */
1108         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1109         min_count = max(count, min_count);
1110         try_to_free_low(h, min_count);
1111         while (min_count < persistent_huge_pages(h)) {
1112                 struct page *page = dequeue_huge_page(h);
1113                 if (!page)
1114                         break;
1115                 update_and_free_page(h, page);
1116         }
1117         while (count < persistent_huge_pages(h)) {
1118                 if (!adjust_pool_surplus(h, 1))
1119                         break;
1120         }
1121 out:
1122         ret = persistent_huge_pages(h);
1123         spin_unlock(&hugetlb_lock);
1124         return ret;
1125 }
1126
1127 #define HSTATE_ATTR_RO(_name) \
1128         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1129
1130 #define HSTATE_ATTR(_name) \
1131         static struct kobj_attribute _name##_attr = \
1132                 __ATTR(_name, 0644, _name##_show, _name##_store)
1133
1134 static struct kobject *hugepages_kobj;
1135 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1136
1137 static struct hstate *kobj_to_hstate(struct kobject *kobj)
1138 {
1139         int i;
1140         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1141                 if (hstate_kobjs[i] == kobj)
1142                         return &hstates[i];
1143         BUG();
1144         return NULL;
1145 }
1146
1147 static ssize_t nr_hugepages_show(struct kobject *kobj,
1148                                         struct kobj_attribute *attr, char *buf)
1149 {
1150         struct hstate *h = kobj_to_hstate(kobj);
1151         return sprintf(buf, "%lu\n", h->nr_huge_pages);
1152 }
1153 static ssize_t nr_hugepages_store(struct kobject *kobj,
1154                 struct kobj_attribute *attr, const char *buf, size_t count)
1155 {
1156         int err;
1157         unsigned long input;
1158         struct hstate *h = kobj_to_hstate(kobj);
1159
1160         err = strict_strtoul(buf, 10, &input);
1161         if (err)
1162                 return 0;
1163
1164         h->max_huge_pages = set_max_huge_pages(h, input);
1165
1166         return count;
1167 }
1168 HSTATE_ATTR(nr_hugepages);
1169
1170 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1171                                         struct kobj_attribute *attr, char *buf)
1172 {
1173         struct hstate *h = kobj_to_hstate(kobj);
1174         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1175 }
1176 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1177                 struct kobj_attribute *attr, const char *buf, size_t count)
1178 {
1179         int err;
1180         unsigned long input;
1181         struct hstate *h = kobj_to_hstate(kobj);
1182
1183         err = strict_strtoul(buf, 10, &input);
1184         if (err)
1185                 return 0;
1186
1187         spin_lock(&hugetlb_lock);
1188         h->nr_overcommit_huge_pages = input;
1189         spin_unlock(&hugetlb_lock);
1190
1191         return count;
1192 }
1193 HSTATE_ATTR(nr_overcommit_hugepages);
1194
1195 static ssize_t free_hugepages_show(struct kobject *kobj,
1196                                         struct kobj_attribute *attr, char *buf)
1197 {
1198         struct hstate *h = kobj_to_hstate(kobj);
1199         return sprintf(buf, "%lu\n", h->free_huge_pages);
1200 }
1201 HSTATE_ATTR_RO(free_hugepages);
1202
1203 static ssize_t resv_hugepages_show(struct kobject *kobj,
1204                                         struct kobj_attribute *attr, char *buf)
1205 {
1206         struct hstate *h = kobj_to_hstate(kobj);
1207         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1208 }
1209 HSTATE_ATTR_RO(resv_hugepages);
1210
1211 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1212                                         struct kobj_attribute *attr, char *buf)
1213 {
1214         struct hstate *h = kobj_to_hstate(kobj);
1215         return sprintf(buf, "%lu\n", h->surplus_huge_pages);
1216 }
1217 HSTATE_ATTR_RO(surplus_hugepages);
1218
1219 static struct attribute *hstate_attrs[] = {
1220         &nr_hugepages_attr.attr,
1221         &nr_overcommit_hugepages_attr.attr,
1222         &free_hugepages_attr.attr,
1223         &resv_hugepages_attr.attr,
1224         &surplus_hugepages_attr.attr,
1225         NULL,
1226 };
1227
1228 static struct attribute_group hstate_attr_group = {
1229         .attrs = hstate_attrs,
1230 };
1231
1232 static int __init hugetlb_sysfs_add_hstate(struct hstate *h)
1233 {
1234         int retval;
1235
1236         hstate_kobjs[h - hstates] = kobject_create_and_add(h->name,
1237                                                         hugepages_kobj);
1238         if (!hstate_kobjs[h - hstates])
1239                 return -ENOMEM;
1240
1241         retval = sysfs_create_group(hstate_kobjs[h - hstates],
1242                                                         &hstate_attr_group);
1243         if (retval)
1244                 kobject_put(hstate_kobjs[h - hstates]);
1245
1246         return retval;
1247 }
1248
1249 static void __init hugetlb_sysfs_init(void)
1250 {
1251         struct hstate *h;
1252         int err;
1253
1254         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1255         if (!hugepages_kobj)
1256                 return;
1257
1258         for_each_hstate(h) {
1259                 err = hugetlb_sysfs_add_hstate(h);
1260                 if (err)
1261                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1262                                                                 h->name);
1263         }
1264 }
1265
1266 static void __exit hugetlb_exit(void)
1267 {
1268         struct hstate *h;
1269
1270         for_each_hstate(h) {
1271                 kobject_put(hstate_kobjs[h - hstates]);
1272         }
1273
1274         kobject_put(hugepages_kobj);
1275 }
1276 module_exit(hugetlb_exit);
1277
1278 static int __init hugetlb_init(void)
1279 {
1280         BUILD_BUG_ON(HPAGE_SHIFT == 0);
1281
1282         if (!size_to_hstate(HPAGE_SIZE)) {
1283                 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1284                 parsed_hstate->max_huge_pages = default_hstate_max_huge_pages;
1285         }
1286         default_hstate_idx = size_to_hstate(HPAGE_SIZE) - hstates;
1287
1288         hugetlb_init_hstates();
1289
1290         gather_bootmem_prealloc();
1291
1292         report_hugepages();
1293
1294         hugetlb_sysfs_init();
1295
1296         return 0;
1297 }
1298 module_init(hugetlb_init);
1299
1300 /* Should be called on processing a hugepagesz=... option */
1301 void __init hugetlb_add_hstate(unsigned order)
1302 {
1303         struct hstate *h;
1304         if (size_to_hstate(PAGE_SIZE << order)) {
1305                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1306                 return;
1307         }
1308         BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1309         BUG_ON(order == 0);
1310         h = &hstates[max_hstate++];
1311         h->order = order;
1312         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1313         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1314                                         huge_page_size(h)/1024);
1315         hugetlb_init_one_hstate(h);
1316         parsed_hstate = h;
1317 }
1318
1319 static int __init hugetlb_setup(char *s)
1320 {
1321         unsigned long *mhp;
1322
1323         /*
1324          * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1325          * so this hugepages= parameter goes to the "default hstate".
1326          */
1327         if (!max_hstate)
1328                 mhp = &default_hstate_max_huge_pages;
1329         else
1330                 mhp = &parsed_hstate->max_huge_pages;
1331
1332         if (sscanf(s, "%lu", mhp) <= 0)
1333                 *mhp = 0;
1334
1335         return 1;
1336 }
1337 __setup("hugepages=", hugetlb_setup);
1338
1339 static unsigned int cpuset_mems_nr(unsigned int *array)
1340 {
1341         int node;
1342         unsigned int nr = 0;
1343
1344         for_each_node_mask(node, cpuset_current_mems_allowed)
1345                 nr += array[node];
1346
1347         return nr;
1348 }
1349
1350 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1351                            struct file *file, void __user *buffer,
1352                            size_t *length, loff_t *ppos)
1353 {
1354         struct hstate *h = &default_hstate;
1355         unsigned long tmp;
1356
1357         if (!write)
1358                 tmp = h->max_huge_pages;
1359
1360         table->data = &tmp;
1361         table->maxlen = sizeof(unsigned long);
1362         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1363
1364         if (write)
1365                 h->max_huge_pages = set_max_huge_pages(h, tmp);
1366
1367         return 0;
1368 }
1369
1370 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1371                         struct file *file, void __user *buffer,
1372                         size_t *length, loff_t *ppos)
1373 {
1374         proc_dointvec(table, write, file, buffer, length, ppos);
1375         if (hugepages_treat_as_movable)
1376                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1377         else
1378                 htlb_alloc_mask = GFP_HIGHUSER;
1379         return 0;
1380 }
1381
1382 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1383                         struct file *file, void __user *buffer,
1384                         size_t *length, loff_t *ppos)
1385 {
1386         struct hstate *h = &default_hstate;
1387         unsigned long tmp;
1388
1389         if (!write)
1390                 tmp = h->nr_overcommit_huge_pages;
1391
1392         table->data = &tmp;
1393         table->maxlen = sizeof(unsigned long);
1394         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1395
1396         if (write) {
1397                 spin_lock(&hugetlb_lock);
1398                 h->nr_overcommit_huge_pages = tmp;
1399                 spin_unlock(&hugetlb_lock);
1400         }
1401
1402         return 0;
1403 }
1404
1405 #endif /* CONFIG_SYSCTL */
1406
1407 int hugetlb_report_meminfo(char *buf)
1408 {
1409         struct hstate *h = &default_hstate;
1410         return sprintf(buf,
1411                         "HugePages_Total: %5lu\n"
1412                         "HugePages_Free:  %5lu\n"
1413                         "HugePages_Rsvd:  %5lu\n"
1414                         "HugePages_Surp:  %5lu\n"
1415                         "Hugepagesize:    %5lu kB\n",
1416                         h->nr_huge_pages,
1417                         h->free_huge_pages,
1418                         h->resv_huge_pages,
1419                         h->surplus_huge_pages,
1420                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1421 }
1422
1423 int hugetlb_report_node_meminfo(int nid, char *buf)
1424 {
1425         struct hstate *h = &default_hstate;
1426         return sprintf(buf,
1427                 "Node %d HugePages_Total: %5u\n"
1428                 "Node %d HugePages_Free:  %5u\n"
1429                 "Node %d HugePages_Surp:  %5u\n",
1430                 nid, h->nr_huge_pages_node[nid],
1431                 nid, h->free_huge_pages_node[nid],
1432                 nid, h->surplus_huge_pages_node[nid]);
1433 }
1434
1435 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1436 unsigned long hugetlb_total_pages(void)
1437 {
1438         struct hstate *h = &default_hstate;
1439         return h->nr_huge_pages * pages_per_huge_page(h);
1440 }
1441
1442 static int hugetlb_acct_memory(struct hstate *h, long delta)
1443 {
1444         int ret = -ENOMEM;
1445
1446         spin_lock(&hugetlb_lock);
1447         /*
1448          * When cpuset is configured, it breaks the strict hugetlb page
1449          * reservation as the accounting is done on a global variable. Such
1450          * reservation is completely rubbish in the presence of cpuset because
1451          * the reservation is not checked against page availability for the
1452          * current cpuset. Application can still potentially OOM'ed by kernel
1453          * with lack of free htlb page in cpuset that the task is in.
1454          * Attempt to enforce strict accounting with cpuset is almost
1455          * impossible (or too ugly) because cpuset is too fluid that
1456          * task or memory node can be dynamically moved between cpusets.
1457          *
1458          * The change of semantics for shared hugetlb mapping with cpuset is
1459          * undesirable. However, in order to preserve some of the semantics,
1460          * we fall back to check against current free page availability as
1461          * a best attempt and hopefully to minimize the impact of changing
1462          * semantics that cpuset has.
1463          */
1464         if (delta > 0) {
1465                 if (gather_surplus_pages(h, delta) < 0)
1466                         goto out;
1467
1468                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1469                         return_unused_surplus_pages(h, delta);
1470                         goto out;
1471                 }
1472         }
1473
1474         ret = 0;
1475         if (delta < 0)
1476                 return_unused_surplus_pages(h, (unsigned long) -delta);
1477
1478 out:
1479         spin_unlock(&hugetlb_lock);
1480         return ret;
1481 }
1482
1483 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
1484 {
1485         struct resv_map *reservations = vma_resv_map(vma);
1486
1487         /*
1488          * This new VMA should share its siblings reservation map if present.
1489          * The VMA will only ever have a valid reservation map pointer where
1490          * it is being copied for another still existing VMA.  As that VMA
1491          * has a reference to the reservation map it cannot dissappear until
1492          * after this open call completes.  It is therefore safe to take a
1493          * new reference here without additional locking.
1494          */
1495         if (reservations)
1496                 kref_get(&reservations->refs);
1497 }
1498
1499 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
1500 {
1501         struct hstate *h = hstate_vma(vma);
1502         struct resv_map *reservations = vma_resv_map(vma);
1503         unsigned long reserve;
1504         unsigned long start;
1505         unsigned long end;
1506
1507         if (reservations) {
1508                 start = vma_hugecache_offset(h, vma, vma->vm_start);
1509                 end = vma_hugecache_offset(h, vma, vma->vm_end);
1510
1511                 reserve = (end - start) -
1512                         region_count(&reservations->regions, start, end);
1513
1514                 kref_put(&reservations->refs, resv_map_release);
1515
1516                 if (reserve)
1517                         hugetlb_acct_memory(h, -reserve);
1518         }
1519 }
1520
1521 /*
1522  * We cannot handle pagefaults against hugetlb pages at all.  They cause
1523  * handle_mm_fault() to try to instantiate regular-sized pages in the
1524  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
1525  * this far.
1526  */
1527 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1528 {
1529         BUG();
1530         return 0;
1531 }
1532
1533 struct vm_operations_struct hugetlb_vm_ops = {
1534         .fault = hugetlb_vm_op_fault,
1535         .open = hugetlb_vm_op_open,
1536         .close = hugetlb_vm_op_close,
1537 };
1538
1539 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
1540                                 int writable)
1541 {
1542         pte_t entry;
1543
1544         if (writable) {
1545                 entry =
1546                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
1547         } else {
1548                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
1549         }
1550         entry = pte_mkyoung(entry);
1551         entry = pte_mkhuge(entry);
1552
1553         return entry;
1554 }
1555
1556 static void set_huge_ptep_writable(struct vm_area_struct *vma,
1557                                    unsigned long address, pte_t *ptep)
1558 {
1559         pte_t entry;
1560
1561         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
1562         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
1563                 update_mmu_cache(vma, address, entry);
1564         }
1565 }
1566
1567
1568 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
1569                             struct vm_area_struct *vma)
1570 {
1571         pte_t *src_pte, *dst_pte, entry;
1572         struct page *ptepage;
1573         unsigned long addr;
1574         int cow;
1575         struct hstate *h = hstate_vma(vma);
1576         unsigned long sz = huge_page_size(h);
1577
1578         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
1579
1580         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
1581                 src_pte = huge_pte_offset(src, addr);
1582                 if (!src_pte)
1583                         continue;
1584                 dst_pte = huge_pte_alloc(dst, addr, sz);
1585                 if (!dst_pte)
1586                         goto nomem;
1587
1588                 /* If the pagetables are shared don't copy or take references */
1589                 if (dst_pte == src_pte)
1590                         continue;
1591
1592                 spin_lock(&dst->page_table_lock);
1593                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
1594                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
1595                         if (cow)
1596                                 huge_ptep_set_wrprotect(src, addr, src_pte);
1597                         entry = huge_ptep_get(src_pte);
1598                         ptepage = pte_page(entry);
1599                         get_page(ptepage);
1600                         set_huge_pte_at(dst, addr, dst_pte, entry);
1601                 }
1602                 spin_unlock(&src->page_table_lock);
1603                 spin_unlock(&dst->page_table_lock);
1604         }
1605         return 0;
1606
1607 nomem:
1608         return -ENOMEM;
1609 }
1610
1611 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1612                             unsigned long end, struct page *ref_page)
1613 {
1614         struct mm_struct *mm = vma->vm_mm;
1615         unsigned long address;
1616         pte_t *ptep;
1617         pte_t pte;
1618         struct page *page;
1619         struct page *tmp;
1620         struct hstate *h = hstate_vma(vma);
1621         unsigned long sz = huge_page_size(h);
1622
1623         /*
1624          * A page gathering list, protected by per file i_mmap_lock. The
1625          * lock is used to avoid list corruption from multiple unmapping
1626          * of the same page since we are using page->lru.
1627          */
1628         LIST_HEAD(page_list);
1629
1630         WARN_ON(!is_vm_hugetlb_page(vma));
1631         BUG_ON(start & ~huge_page_mask(h));
1632         BUG_ON(end & ~huge_page_mask(h));
1633
1634         spin_lock(&mm->page_table_lock);
1635         for (address = start; address < end; address += sz) {
1636                 ptep = huge_pte_offset(mm, address);
1637                 if (!ptep)
1638                         continue;
1639
1640                 if (huge_pmd_unshare(mm, &address, ptep))
1641                         continue;
1642
1643                 /*
1644                  * If a reference page is supplied, it is because a specific
1645                  * page is being unmapped, not a range. Ensure the page we
1646                  * are about to unmap is the actual page of interest.
1647                  */
1648                 if (ref_page) {
1649                         pte = huge_ptep_get(ptep);
1650                         if (huge_pte_none(pte))
1651                                 continue;
1652                         page = pte_page(pte);
1653                         if (page != ref_page)
1654                                 continue;
1655
1656                         /*
1657                          * Mark the VMA as having unmapped its page so that
1658                          * future faults in this VMA will fail rather than
1659                          * looking like data was lost
1660                          */
1661                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
1662                 }
1663
1664                 pte = huge_ptep_get_and_clear(mm, address, ptep);
1665                 if (huge_pte_none(pte))
1666                         continue;
1667
1668                 page = pte_page(pte);
1669                 if (pte_dirty(pte))
1670                         set_page_dirty(page);
1671                 list_add(&page->lru, &page_list);
1672         }
1673         spin_unlock(&mm->page_table_lock);
1674         flush_tlb_range(vma, start, end);
1675         list_for_each_entry_safe(page, tmp, &page_list, lru) {
1676                 list_del(&page->lru);
1677                 put_page(page);
1678         }
1679 }
1680
1681 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1682                           unsigned long end, struct page *ref_page)
1683 {
1684         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1685         __unmap_hugepage_range(vma, start, end, ref_page);
1686         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1687 }
1688
1689 /*
1690  * This is called when the original mapper is failing to COW a MAP_PRIVATE
1691  * mappping it owns the reserve page for. The intention is to unmap the page
1692  * from other VMAs and let the children be SIGKILLed if they are faulting the
1693  * same region.
1694  */
1695 int unmap_ref_private(struct mm_struct *mm,
1696                                         struct vm_area_struct *vma,
1697                                         struct page *page,
1698                                         unsigned long address)
1699 {
1700         struct vm_area_struct *iter_vma;
1701         struct address_space *mapping;
1702         struct prio_tree_iter iter;
1703         pgoff_t pgoff;
1704
1705         /*
1706          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1707          * from page cache lookup which is in HPAGE_SIZE units.
1708          */
1709         address = address & huge_page_mask(hstate_vma(vma));
1710         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1711                 + (vma->vm_pgoff >> PAGE_SHIFT);
1712         mapping = (struct address_space *)page_private(page);
1713
1714         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1715                 /* Do not unmap the current VMA */
1716                 if (iter_vma == vma)
1717                         continue;
1718
1719                 /*
1720                  * Unmap the page from other VMAs without their own reserves.
1721                  * They get marked to be SIGKILLed if they fault in these
1722                  * areas. This is because a future no-page fault on this VMA
1723                  * could insert a zeroed page instead of the data existing
1724                  * from the time of fork. This would look like data corruption
1725                  */
1726                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1727                         unmap_hugepage_range(iter_vma,
1728                                 address, address + HPAGE_SIZE,
1729                                 page);
1730         }
1731
1732         return 1;
1733 }
1734
1735 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1736                         unsigned long address, pte_t *ptep, pte_t pte,
1737                         struct page *pagecache_page)
1738 {
1739         struct hstate *h = hstate_vma(vma);
1740         struct page *old_page, *new_page;
1741         int avoidcopy;
1742         int outside_reserve = 0;
1743
1744         old_page = pte_page(pte);
1745
1746 retry_avoidcopy:
1747         /* If no-one else is actually using this page, avoid the copy
1748          * and just make the page writable */
1749         avoidcopy = (page_count(old_page) == 1);
1750         if (avoidcopy) {
1751                 set_huge_ptep_writable(vma, address, ptep);
1752                 return 0;
1753         }
1754
1755         /*
1756          * If the process that created a MAP_PRIVATE mapping is about to
1757          * perform a COW due to a shared page count, attempt to satisfy
1758          * the allocation without using the existing reserves. The pagecache
1759          * page is used to determine if the reserve at this address was
1760          * consumed or not. If reserves were used, a partial faulted mapping
1761          * at the time of fork() could consume its reserves on COW instead
1762          * of the full address range.
1763          */
1764         if (!(vma->vm_flags & VM_SHARED) &&
1765                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1766                         old_page != pagecache_page)
1767                 outside_reserve = 1;
1768
1769         page_cache_get(old_page);
1770         new_page = alloc_huge_page(vma, address, outside_reserve);
1771
1772         if (IS_ERR(new_page)) {
1773                 page_cache_release(old_page);
1774
1775                 /*
1776                  * If a process owning a MAP_PRIVATE mapping fails to COW,
1777                  * it is due to references held by a child and an insufficient
1778                  * huge page pool. To guarantee the original mappers
1779                  * reliability, unmap the page from child processes. The child
1780                  * may get SIGKILLed if it later faults.
1781                  */
1782                 if (outside_reserve) {
1783                         BUG_ON(huge_pte_none(pte));
1784                         if (unmap_ref_private(mm, vma, old_page, address)) {
1785                                 BUG_ON(page_count(old_page) != 1);
1786                                 BUG_ON(huge_pte_none(pte));
1787                                 goto retry_avoidcopy;
1788                         }
1789                         WARN_ON_ONCE(1);
1790                 }
1791
1792                 return -PTR_ERR(new_page);
1793         }
1794
1795         spin_unlock(&mm->page_table_lock);
1796         copy_huge_page(new_page, old_page, address, vma);
1797         __SetPageUptodate(new_page);
1798         spin_lock(&mm->page_table_lock);
1799
1800         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
1801         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1802                 /* Break COW */
1803                 huge_ptep_clear_flush(vma, address, ptep);
1804                 set_huge_pte_at(mm, address, ptep,
1805                                 make_huge_pte(vma, new_page, 1));
1806                 /* Make the old page be freed below */
1807                 new_page = old_page;
1808         }
1809         page_cache_release(new_page);
1810         page_cache_release(old_page);
1811         return 0;
1812 }
1813
1814 /* Return the pagecache page at a given address within a VMA */
1815 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
1816                         struct vm_area_struct *vma, unsigned long address)
1817 {
1818         struct address_space *mapping;
1819         pgoff_t idx;
1820
1821         mapping = vma->vm_file->f_mapping;
1822         idx = vma_hugecache_offset(h, vma, address);
1823
1824         return find_lock_page(mapping, idx);
1825 }
1826
1827 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1828                         unsigned long address, pte_t *ptep, int write_access)
1829 {
1830         struct hstate *h = hstate_vma(vma);
1831         int ret = VM_FAULT_SIGBUS;
1832         pgoff_t idx;
1833         unsigned long size;
1834         struct page *page;
1835         struct address_space *mapping;
1836         pte_t new_pte;
1837
1838         /*
1839          * Currently, we are forced to kill the process in the event the
1840          * original mapper has unmapped pages from the child due to a failed
1841          * COW. Warn that such a situation has occured as it may not be obvious
1842          */
1843         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
1844                 printk(KERN_WARNING
1845                         "PID %d killed due to inadequate hugepage pool\n",
1846                         current->pid);
1847                 return ret;
1848         }
1849
1850         mapping = vma->vm_file->f_mapping;
1851         idx = vma_hugecache_offset(h, vma, address);
1852
1853         /*
1854          * Use page lock to guard against racing truncation
1855          * before we get page_table_lock.
1856          */
1857 retry:
1858         page = find_lock_page(mapping, idx);
1859         if (!page) {
1860                 size = i_size_read(mapping->host) >> huge_page_shift(h);
1861                 if (idx >= size)
1862                         goto out;
1863                 page = alloc_huge_page(vma, address, 0);
1864                 if (IS_ERR(page)) {
1865                         ret = -PTR_ERR(page);
1866                         goto out;
1867                 }
1868                 clear_huge_page(page, address, huge_page_size(h));
1869                 __SetPageUptodate(page);
1870
1871                 if (vma->vm_flags & VM_SHARED) {
1872                         int err;
1873                         struct inode *inode = mapping->host;
1874
1875                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
1876                         if (err) {
1877                                 put_page(page);
1878                                 if (err == -EEXIST)
1879                                         goto retry;
1880                                 goto out;
1881                         }
1882
1883                         spin_lock(&inode->i_lock);
1884                         inode->i_blocks += blocks_per_huge_page(h);
1885                         spin_unlock(&inode->i_lock);
1886                 } else
1887                         lock_page(page);
1888         }
1889
1890         spin_lock(&mm->page_table_lock);
1891         size = i_size_read(mapping->host) >> huge_page_shift(h);
1892         if (idx >= size)
1893                 goto backout;
1894
1895         ret = 0;
1896         if (!huge_pte_none(huge_ptep_get(ptep)))
1897                 goto backout;
1898
1899         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
1900                                 && (vma->vm_flags & VM_SHARED)));
1901         set_huge_pte_at(mm, address, ptep, new_pte);
1902
1903         if (write_access && !(vma->vm_flags & VM_SHARED)) {
1904                 /* Optimization, do the COW without a second fault */
1905                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
1906         }
1907
1908         spin_unlock(&mm->page_table_lock);
1909         unlock_page(page);
1910 out:
1911         return ret;
1912
1913 backout:
1914         spin_unlock(&mm->page_table_lock);
1915         unlock_page(page);
1916         put_page(page);
1917         goto out;
1918 }
1919
1920 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
1921                         unsigned long address, int write_access)
1922 {
1923         pte_t *ptep;
1924         pte_t entry;
1925         int ret;
1926         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
1927         struct hstate *h = hstate_vma(vma);
1928
1929         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
1930         if (!ptep)
1931                 return VM_FAULT_OOM;
1932
1933         /*
1934          * Serialize hugepage allocation and instantiation, so that we don't
1935          * get spurious allocation failures if two CPUs race to instantiate
1936          * the same page in the page cache.
1937          */
1938         mutex_lock(&hugetlb_instantiation_mutex);
1939         entry = huge_ptep_get(ptep);
1940         if (huge_pte_none(entry)) {
1941                 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1942                 mutex_unlock(&hugetlb_instantiation_mutex);
1943                 return ret;
1944         }
1945
1946         ret = 0;
1947
1948         spin_lock(&mm->page_table_lock);
1949         /* Check for a racing update before calling hugetlb_cow */
1950         if (likely(pte_same(entry, huge_ptep_get(ptep))))
1951                 if (write_access && !pte_write(entry)) {
1952                         struct page *page;
1953                         page = hugetlbfs_pagecache_page(h, vma, address);
1954                         ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
1955                         if (page) {
1956                                 unlock_page(page);
1957                                 put_page(page);
1958                         }
1959                 }
1960         spin_unlock(&mm->page_table_lock);
1961         mutex_unlock(&hugetlb_instantiation_mutex);
1962
1963         return ret;
1964 }
1965
1966 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1967                         struct page **pages, struct vm_area_struct **vmas,
1968                         unsigned long *position, int *length, int i,
1969                         int write)
1970 {
1971         unsigned long pfn_offset;
1972         unsigned long vaddr = *position;
1973         int remainder = *length;
1974         struct hstate *h = hstate_vma(vma);
1975
1976         spin_lock(&mm->page_table_lock);
1977         while (vaddr < vma->vm_end && remainder) {
1978                 pte_t *pte;
1979                 struct page *page;
1980
1981                 /*
1982                  * Some archs (sparc64, sh*) have multiple pte_ts to
1983                  * each hugepage.  We have to make * sure we get the
1984                  * first, for the page indexing below to work.
1985                  */
1986                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
1987
1988                 if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
1989                     (write && !pte_write(huge_ptep_get(pte)))) {
1990                         int ret;
1991
1992                         spin_unlock(&mm->page_table_lock);
1993                         ret = hugetlb_fault(mm, vma, vaddr, write);
1994                         spin_lock(&mm->page_table_lock);
1995                         if (!(ret & VM_FAULT_ERROR))
1996                                 continue;
1997
1998                         remainder = 0;
1999                         if (!i)
2000                                 i = -EFAULT;
2001                         break;
2002                 }
2003
2004                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2005                 page = pte_page(huge_ptep_get(pte));
2006 same_page:
2007                 if (pages) {
2008                         get_page(page);
2009                         pages[i] = page + pfn_offset;
2010                 }
2011
2012                 if (vmas)
2013                         vmas[i] = vma;
2014
2015                 vaddr += PAGE_SIZE;
2016                 ++pfn_offset;
2017                 --remainder;
2018                 ++i;
2019                 if (vaddr < vma->vm_end && remainder &&
2020                                 pfn_offset < pages_per_huge_page(h)) {
2021                         /*
2022                          * We use pfn_offset to avoid touching the pageframes
2023                          * of this compound page.
2024                          */
2025                         goto same_page;
2026                 }
2027         }
2028         spin_unlock(&mm->page_table_lock);
2029         *length = remainder;
2030         *position = vaddr;
2031
2032         return i;
2033 }
2034
2035 void hugetlb_change_protection(struct vm_area_struct *vma,
2036                 unsigned long address, unsigned long end, pgprot_t newprot)
2037 {
2038         struct mm_struct *mm = vma->vm_mm;
2039         unsigned long start = address;
2040         pte_t *ptep;
2041         pte_t pte;
2042         struct hstate *h = hstate_vma(vma);
2043
2044         BUG_ON(address >= end);
2045         flush_cache_range(vma, address, end);
2046
2047         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2048         spin_lock(&mm->page_table_lock);
2049         for (; address < end; address += huge_page_size(h)) {
2050                 ptep = huge_pte_offset(mm, address);
2051                 if (!ptep)
2052                         continue;
2053                 if (huge_pmd_unshare(mm, &address, ptep))
2054                         continue;
2055                 if (!huge_pte_none(huge_ptep_get(ptep))) {
2056                         pte = huge_ptep_get_and_clear(mm, address, ptep);
2057                         pte = pte_mkhuge(pte_modify(pte, newprot));
2058                         set_huge_pte_at(mm, address, ptep, pte);
2059                 }
2060         }
2061         spin_unlock(&mm->page_table_lock);
2062         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2063
2064         flush_tlb_range(vma, start, end);
2065 }
2066
2067 int hugetlb_reserve_pages(struct inode *inode,
2068                                         long from, long to,
2069                                         struct vm_area_struct *vma)
2070 {
2071         long ret, chg;
2072         struct hstate *h = hstate_inode(inode);
2073
2074         if (vma && vma->vm_flags & VM_NORESERVE)
2075                 return 0;
2076
2077         /*
2078          * Shared mappings base their reservation on the number of pages that
2079          * are already allocated on behalf of the file. Private mappings need
2080          * to reserve the full area even if read-only as mprotect() may be
2081          * called to make the mapping read-write. Assume !vma is a shm mapping
2082          */
2083         if (!vma || vma->vm_flags & VM_SHARED)
2084                 chg = region_chg(&inode->i_mapping->private_list, from, to);
2085         else {
2086                 struct resv_map *resv_map = resv_map_alloc();
2087                 if (!resv_map)
2088                         return -ENOMEM;
2089
2090                 chg = to - from;
2091
2092                 set_vma_resv_map(vma, resv_map);
2093                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2094         }
2095
2096         if (chg < 0)
2097                 return chg;
2098
2099         if (hugetlb_get_quota(inode->i_mapping, chg))
2100                 return -ENOSPC;
2101         ret = hugetlb_acct_memory(h, chg);
2102         if (ret < 0) {
2103                 hugetlb_put_quota(inode->i_mapping, chg);
2104                 return ret;
2105         }
2106         if (!vma || vma->vm_flags & VM_SHARED)
2107                 region_add(&inode->i_mapping->private_list, from, to);
2108         return 0;
2109 }
2110
2111 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2112 {
2113         struct hstate *h = hstate_inode(inode);
2114         long chg = region_truncate(&inode->i_mapping->private_list, offset);
2115
2116         spin_lock(&inode->i_lock);
2117         inode->i_blocks -= blocks_per_huge_page(h);
2118         spin_unlock(&inode->i_lock);
2119
2120         hugetlb_put_quota(inode->i_mapping, (chg - freed));
2121         hugetlb_acct_memory(h, -(chg - freed));
2122 }