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