mm: swap: implement generic handler for swap_activate
[linux-3.10.git] / mm / hugetlb.c
1 /*
2  * Generic hugetlb support.
3  * (C) William Irwin, April 2004
4  */
5 #include <linux/list.h>
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/mm.h>
9 #include <linux/seq_file.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/nodemask.h>
14 #include <linux/pagemap.h>
15 #include <linux/mempolicy.h>
16 #include <linux/cpuset.h>
17 #include <linux/mutex.h>
18 #include <linux/bootmem.h>
19 #include <linux/sysfs.h>
20 #include <linux/slab.h>
21 #include <linux/rmap.h>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24
25 #include <asm/page.h>
26 #include <asm/pgtable.h>
27 #include <asm/tlb.h>
28
29 #include <linux/io.h>
30 #include <linux/hugetlb.h>
31 #include <linux/hugetlb_cgroup.h>
32 #include <linux/node.h>
33 #include <linux/hugetlb_cgroup.h>
34 #include "internal.h"
35
36 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
37 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
38 unsigned long hugepages_treat_as_movable;
39
40 int hugetlb_max_hstate __read_mostly;
41 unsigned int default_hstate_idx;
42 struct hstate hstates[HUGE_MAX_HSTATE];
43
44 __initdata LIST_HEAD(huge_boot_pages);
45
46 /* for command line parsing */
47 static struct hstate * __initdata parsed_hstate;
48 static unsigned long __initdata default_hstate_max_huge_pages;
49 static unsigned long __initdata default_hstate_size;
50
51 /*
52  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
53  */
54 DEFINE_SPINLOCK(hugetlb_lock);
55
56 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
57 {
58         bool free = (spool->count == 0) && (spool->used_hpages == 0);
59
60         spin_unlock(&spool->lock);
61
62         /* If no pages are used, and no other handles to the subpool
63          * remain, free the subpool the subpool remain */
64         if (free)
65                 kfree(spool);
66 }
67
68 struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
69 {
70         struct hugepage_subpool *spool;
71
72         spool = kmalloc(sizeof(*spool), GFP_KERNEL);
73         if (!spool)
74                 return NULL;
75
76         spin_lock_init(&spool->lock);
77         spool->count = 1;
78         spool->max_hpages = nr_blocks;
79         spool->used_hpages = 0;
80
81         return spool;
82 }
83
84 void hugepage_put_subpool(struct hugepage_subpool *spool)
85 {
86         spin_lock(&spool->lock);
87         BUG_ON(!spool->count);
88         spool->count--;
89         unlock_or_release_subpool(spool);
90 }
91
92 static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
93                                       long delta)
94 {
95         int ret = 0;
96
97         if (!spool)
98                 return 0;
99
100         spin_lock(&spool->lock);
101         if ((spool->used_hpages + delta) <= spool->max_hpages) {
102                 spool->used_hpages += delta;
103         } else {
104                 ret = -ENOMEM;
105         }
106         spin_unlock(&spool->lock);
107
108         return ret;
109 }
110
111 static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
112                                        long delta)
113 {
114         if (!spool)
115                 return;
116
117         spin_lock(&spool->lock);
118         spool->used_hpages -= delta;
119         /* If hugetlbfs_put_super couldn't free spool due to
120         * an outstanding quota reference, free it now. */
121         unlock_or_release_subpool(spool);
122 }
123
124 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
125 {
126         return HUGETLBFS_SB(inode->i_sb)->spool;
127 }
128
129 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
130 {
131         return subpool_inode(vma->vm_file->f_dentry->d_inode);
132 }
133
134 /*
135  * Region tracking -- allows tracking of reservations and instantiated pages
136  *                    across the pages in a mapping.
137  *
138  * The region data structures are protected by a combination of the mmap_sem
139  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
140  * must either hold the mmap_sem for write, or the mmap_sem for read and
141  * the hugetlb_instantiation mutex:
142  *
143  *      down_write(&mm->mmap_sem);
144  * or
145  *      down_read(&mm->mmap_sem);
146  *      mutex_lock(&hugetlb_instantiation_mutex);
147  */
148 struct file_region {
149         struct list_head link;
150         long from;
151         long to;
152 };
153
154 static long region_add(struct list_head *head, long f, long t)
155 {
156         struct file_region *rg, *nrg, *trg;
157
158         /* Locate the region we are either in or before. */
159         list_for_each_entry(rg, head, link)
160                 if (f <= rg->to)
161                         break;
162
163         /* Round our left edge to the current segment if it encloses us. */
164         if (f > rg->from)
165                 f = rg->from;
166
167         /* Check for and consume any regions we now overlap with. */
168         nrg = rg;
169         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
170                 if (&rg->link == head)
171                         break;
172                 if (rg->from > t)
173                         break;
174
175                 /* If this area reaches higher then extend our area to
176                  * include it completely.  If this is not the first area
177                  * which we intend to reuse, free it. */
178                 if (rg->to > t)
179                         t = rg->to;
180                 if (rg != nrg) {
181                         list_del(&rg->link);
182                         kfree(rg);
183                 }
184         }
185         nrg->from = f;
186         nrg->to = t;
187         return 0;
188 }
189
190 static long region_chg(struct list_head *head, long f, long t)
191 {
192         struct file_region *rg, *nrg;
193         long chg = 0;
194
195         /* Locate the region we are before or in. */
196         list_for_each_entry(rg, head, link)
197                 if (f <= rg->to)
198                         break;
199
200         /* If we are below the current region then a new region is required.
201          * Subtle, allocate a new region at the position but make it zero
202          * size such that we can guarantee to record the reservation. */
203         if (&rg->link == head || t < rg->from) {
204                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
205                 if (!nrg)
206                         return -ENOMEM;
207                 nrg->from = f;
208                 nrg->to   = f;
209                 INIT_LIST_HEAD(&nrg->link);
210                 list_add(&nrg->link, rg->link.prev);
211
212                 return t - f;
213         }
214
215         /* Round our left edge to the current segment if it encloses us. */
216         if (f > rg->from)
217                 f = rg->from;
218         chg = t - f;
219
220         /* Check for and consume any regions we now overlap with. */
221         list_for_each_entry(rg, rg->link.prev, link) {
222                 if (&rg->link == head)
223                         break;
224                 if (rg->from > t)
225                         return chg;
226
227                 /* We overlap with this area, if it extends further than
228                  * us then we must extend ourselves.  Account for its
229                  * existing reservation. */
230                 if (rg->to > t) {
231                         chg += rg->to - t;
232                         t = rg->to;
233                 }
234                 chg -= rg->to - rg->from;
235         }
236         return chg;
237 }
238
239 static long region_truncate(struct list_head *head, long end)
240 {
241         struct file_region *rg, *trg;
242         long chg = 0;
243
244         /* Locate the region we are either in or before. */
245         list_for_each_entry(rg, head, link)
246                 if (end <= rg->to)
247                         break;
248         if (&rg->link == head)
249                 return 0;
250
251         /* If we are in the middle of a region then adjust it. */
252         if (end > rg->from) {
253                 chg = rg->to - end;
254                 rg->to = end;
255                 rg = list_entry(rg->link.next, typeof(*rg), link);
256         }
257
258         /* Drop any remaining regions. */
259         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
260                 if (&rg->link == head)
261                         break;
262                 chg += rg->to - rg->from;
263                 list_del(&rg->link);
264                 kfree(rg);
265         }
266         return chg;
267 }
268
269 static long region_count(struct list_head *head, long f, long t)
270 {
271         struct file_region *rg;
272         long chg = 0;
273
274         /* Locate each segment we overlap with, and count that overlap. */
275         list_for_each_entry(rg, head, link) {
276                 long seg_from;
277                 long seg_to;
278
279                 if (rg->to <= f)
280                         continue;
281                 if (rg->from >= t)
282                         break;
283
284                 seg_from = max(rg->from, f);
285                 seg_to = min(rg->to, t);
286
287                 chg += seg_to - seg_from;
288         }
289
290         return chg;
291 }
292
293 /*
294  * Convert the address within this vma to the page offset within
295  * the mapping, in pagecache page units; huge pages here.
296  */
297 static pgoff_t vma_hugecache_offset(struct hstate *h,
298                         struct vm_area_struct *vma, unsigned long address)
299 {
300         return ((address - vma->vm_start) >> huge_page_shift(h)) +
301                         (vma->vm_pgoff >> huge_page_order(h));
302 }
303
304 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
305                                      unsigned long address)
306 {
307         return vma_hugecache_offset(hstate_vma(vma), vma, address);
308 }
309
310 /*
311  * Return the size of the pages allocated when backing a VMA. In the majority
312  * cases this will be same size as used by the page table entries.
313  */
314 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
315 {
316         struct hstate *hstate;
317
318         if (!is_vm_hugetlb_page(vma))
319                 return PAGE_SIZE;
320
321         hstate = hstate_vma(vma);
322
323         return 1UL << (hstate->order + PAGE_SHIFT);
324 }
325 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
326
327 /*
328  * Return the page size being used by the MMU to back a VMA. In the majority
329  * of cases, the page size used by the kernel matches the MMU size. On
330  * architectures where it differs, an architecture-specific version of this
331  * function is required.
332  */
333 #ifndef vma_mmu_pagesize
334 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
335 {
336         return vma_kernel_pagesize(vma);
337 }
338 #endif
339
340 /*
341  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
342  * bits of the reservation map pointer, which are always clear due to
343  * alignment.
344  */
345 #define HPAGE_RESV_OWNER    (1UL << 0)
346 #define HPAGE_RESV_UNMAPPED (1UL << 1)
347 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
348
349 /*
350  * These helpers are used to track how many pages are reserved for
351  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
352  * is guaranteed to have their future faults succeed.
353  *
354  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
355  * the reserve counters are updated with the hugetlb_lock held. It is safe
356  * to reset the VMA at fork() time as it is not in use yet and there is no
357  * chance of the global counters getting corrupted as a result of the values.
358  *
359  * The private mapping reservation is represented in a subtly different
360  * manner to a shared mapping.  A shared mapping has a region map associated
361  * with the underlying file, this region map represents the backing file
362  * pages which have ever had a reservation assigned which this persists even
363  * after the page is instantiated.  A private mapping has a region map
364  * associated with the original mmap which is attached to all VMAs which
365  * reference it, this region map represents those offsets which have consumed
366  * reservation ie. where pages have been instantiated.
367  */
368 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
369 {
370         return (unsigned long)vma->vm_private_data;
371 }
372
373 static void set_vma_private_data(struct vm_area_struct *vma,
374                                                         unsigned long value)
375 {
376         vma->vm_private_data = (void *)value;
377 }
378
379 struct resv_map {
380         struct kref refs;
381         struct list_head regions;
382 };
383
384 static struct resv_map *resv_map_alloc(void)
385 {
386         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
387         if (!resv_map)
388                 return NULL;
389
390         kref_init(&resv_map->refs);
391         INIT_LIST_HEAD(&resv_map->regions);
392
393         return resv_map;
394 }
395
396 static void resv_map_release(struct kref *ref)
397 {
398         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
399
400         /* Clear out any active regions before we release the map. */
401         region_truncate(&resv_map->regions, 0);
402         kfree(resv_map);
403 }
404
405 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
406 {
407         VM_BUG_ON(!is_vm_hugetlb_page(vma));
408         if (!(vma->vm_flags & VM_MAYSHARE))
409                 return (struct resv_map *)(get_vma_private_data(vma) &
410                                                         ~HPAGE_RESV_MASK);
411         return NULL;
412 }
413
414 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
415 {
416         VM_BUG_ON(!is_vm_hugetlb_page(vma));
417         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
418
419         set_vma_private_data(vma, (get_vma_private_data(vma) &
420                                 HPAGE_RESV_MASK) | (unsigned long)map);
421 }
422
423 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
424 {
425         VM_BUG_ON(!is_vm_hugetlb_page(vma));
426         VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
427
428         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
429 }
430
431 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
432 {
433         VM_BUG_ON(!is_vm_hugetlb_page(vma));
434
435         return (get_vma_private_data(vma) & flag) != 0;
436 }
437
438 /* Decrement the reserved pages in the hugepage pool by one */
439 static void decrement_hugepage_resv_vma(struct hstate *h,
440                         struct vm_area_struct *vma)
441 {
442         if (vma->vm_flags & VM_NORESERVE)
443                 return;
444
445         if (vma->vm_flags & VM_MAYSHARE) {
446                 /* Shared mappings always use reserves */
447                 h->resv_huge_pages--;
448         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
449                 /*
450                  * Only the process that called mmap() has reserves for
451                  * private mappings.
452                  */
453                 h->resv_huge_pages--;
454         }
455 }
456
457 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
458 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
459 {
460         VM_BUG_ON(!is_vm_hugetlb_page(vma));
461         if (!(vma->vm_flags & VM_MAYSHARE))
462                 vma->vm_private_data = (void *)0;
463 }
464
465 /* Returns true if the VMA has associated reserve pages */
466 static int vma_has_reserves(struct vm_area_struct *vma)
467 {
468         if (vma->vm_flags & VM_MAYSHARE)
469                 return 1;
470         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
471                 return 1;
472         return 0;
473 }
474
475 static void copy_gigantic_page(struct page *dst, struct page *src)
476 {
477         int i;
478         struct hstate *h = page_hstate(src);
479         struct page *dst_base = dst;
480         struct page *src_base = src;
481
482         for (i = 0; i < pages_per_huge_page(h); ) {
483                 cond_resched();
484                 copy_highpage(dst, src);
485
486                 i++;
487                 dst = mem_map_next(dst, dst_base, i);
488                 src = mem_map_next(src, src_base, i);
489         }
490 }
491
492 void copy_huge_page(struct page *dst, struct page *src)
493 {
494         int i;
495         struct hstate *h = page_hstate(src);
496
497         if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
498                 copy_gigantic_page(dst, src);
499                 return;
500         }
501
502         might_sleep();
503         for (i = 0; i < pages_per_huge_page(h); i++) {
504                 cond_resched();
505                 copy_highpage(dst + i, src + i);
506         }
507 }
508
509 static void enqueue_huge_page(struct hstate *h, struct page *page)
510 {
511         int nid = page_to_nid(page);
512         list_move(&page->lru, &h->hugepage_freelists[nid]);
513         h->free_huge_pages++;
514         h->free_huge_pages_node[nid]++;
515 }
516
517 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
518 {
519         struct page *page;
520
521         if (list_empty(&h->hugepage_freelists[nid]))
522                 return NULL;
523         page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
524         list_move(&page->lru, &h->hugepage_activelist);
525         set_page_refcounted(page);
526         h->free_huge_pages--;
527         h->free_huge_pages_node[nid]--;
528         return page;
529 }
530
531 static struct page *dequeue_huge_page_vma(struct hstate *h,
532                                 struct vm_area_struct *vma,
533                                 unsigned long address, int avoid_reserve)
534 {
535         struct page *page = NULL;
536         struct mempolicy *mpol;
537         nodemask_t *nodemask;
538         struct zonelist *zonelist;
539         struct zone *zone;
540         struct zoneref *z;
541         unsigned int cpuset_mems_cookie;
542
543 retry_cpuset:
544         cpuset_mems_cookie = get_mems_allowed();
545         zonelist = huge_zonelist(vma, address,
546                                         htlb_alloc_mask, &mpol, &nodemask);
547         /*
548          * A child process with MAP_PRIVATE mappings created by their parent
549          * have no page reserves. This check ensures that reservations are
550          * not "stolen". The child may still get SIGKILLed
551          */
552         if (!vma_has_reserves(vma) &&
553                         h->free_huge_pages - h->resv_huge_pages == 0)
554                 goto err;
555
556         /* If reserves cannot be used, ensure enough pages are in the pool */
557         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
558                 goto err;
559
560         for_each_zone_zonelist_nodemask(zone, z, zonelist,
561                                                 MAX_NR_ZONES - 1, nodemask) {
562                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
563                         page = dequeue_huge_page_node(h, zone_to_nid(zone));
564                         if (page) {
565                                 if (!avoid_reserve)
566                                         decrement_hugepage_resv_vma(h, vma);
567                                 break;
568                         }
569                 }
570         }
571
572         mpol_cond_put(mpol);
573         if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
574                 goto retry_cpuset;
575         return page;
576
577 err:
578         mpol_cond_put(mpol);
579         return NULL;
580 }
581
582 static void update_and_free_page(struct hstate *h, struct page *page)
583 {
584         int i;
585
586         VM_BUG_ON(h->order >= MAX_ORDER);
587
588         h->nr_huge_pages--;
589         h->nr_huge_pages_node[page_to_nid(page)]--;
590         for (i = 0; i < pages_per_huge_page(h); i++) {
591                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
592                                 1 << PG_referenced | 1 << PG_dirty |
593                                 1 << PG_active | 1 << PG_reserved |
594                                 1 << PG_private | 1 << PG_writeback);
595         }
596         VM_BUG_ON(hugetlb_cgroup_from_page(page));
597         set_compound_page_dtor(page, NULL);
598         set_page_refcounted(page);
599         arch_release_hugepage(page);
600         __free_pages(page, huge_page_order(h));
601 }
602
603 struct hstate *size_to_hstate(unsigned long size)
604 {
605         struct hstate *h;
606
607         for_each_hstate(h) {
608                 if (huge_page_size(h) == size)
609                         return h;
610         }
611         return NULL;
612 }
613
614 static void free_huge_page(struct page *page)
615 {
616         /*
617          * Can't pass hstate in here because it is called from the
618          * compound page destructor.
619          */
620         struct hstate *h = page_hstate(page);
621         int nid = page_to_nid(page);
622         struct hugepage_subpool *spool =
623                 (struct hugepage_subpool *)page_private(page);
624
625         set_page_private(page, 0);
626         page->mapping = NULL;
627         BUG_ON(page_count(page));
628         BUG_ON(page_mapcount(page));
629
630         spin_lock(&hugetlb_lock);
631         hugetlb_cgroup_uncharge_page(hstate_index(h),
632                                      pages_per_huge_page(h), page);
633         if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
634                 /* remove the page from active list */
635                 list_del(&page->lru);
636                 update_and_free_page(h, page);
637                 h->surplus_huge_pages--;
638                 h->surplus_huge_pages_node[nid]--;
639         } else {
640                 enqueue_huge_page(h, page);
641         }
642         spin_unlock(&hugetlb_lock);
643         hugepage_subpool_put_pages(spool, 1);
644 }
645
646 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
647 {
648         INIT_LIST_HEAD(&page->lru);
649         set_compound_page_dtor(page, free_huge_page);
650         spin_lock(&hugetlb_lock);
651         set_hugetlb_cgroup(page, NULL);
652         h->nr_huge_pages++;
653         h->nr_huge_pages_node[nid]++;
654         spin_unlock(&hugetlb_lock);
655         put_page(page); /* free it into the hugepage allocator */
656 }
657
658 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
659 {
660         int i;
661         int nr_pages = 1 << order;
662         struct page *p = page + 1;
663
664         /* we rely on prep_new_huge_page to set the destructor */
665         set_compound_order(page, order);
666         __SetPageHead(page);
667         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
668                 __SetPageTail(p);
669                 set_page_count(p, 0);
670                 p->first_page = page;
671         }
672 }
673
674 int PageHuge(struct page *page)
675 {
676         compound_page_dtor *dtor;
677
678         if (!PageCompound(page))
679                 return 0;
680
681         page = compound_head(page);
682         dtor = get_compound_page_dtor(page);
683
684         return dtor == free_huge_page;
685 }
686 EXPORT_SYMBOL_GPL(PageHuge);
687
688 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
689 {
690         struct page *page;
691
692         if (h->order >= MAX_ORDER)
693                 return NULL;
694
695         page = alloc_pages_exact_node(nid,
696                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
697                                                 __GFP_REPEAT|__GFP_NOWARN,
698                 huge_page_order(h));
699         if (page) {
700                 if (arch_prepare_hugepage(page)) {
701                         __free_pages(page, huge_page_order(h));
702                         return NULL;
703                 }
704                 prep_new_huge_page(h, page, nid);
705         }
706
707         return page;
708 }
709
710 /*
711  * common helper functions for hstate_next_node_to_{alloc|free}.
712  * We may have allocated or freed a huge page based on a different
713  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
714  * be outside of *nodes_allowed.  Ensure that we use an allowed
715  * node for alloc or free.
716  */
717 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
718 {
719         nid = next_node(nid, *nodes_allowed);
720         if (nid == MAX_NUMNODES)
721                 nid = first_node(*nodes_allowed);
722         VM_BUG_ON(nid >= MAX_NUMNODES);
723
724         return nid;
725 }
726
727 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
728 {
729         if (!node_isset(nid, *nodes_allowed))
730                 nid = next_node_allowed(nid, nodes_allowed);
731         return nid;
732 }
733
734 /*
735  * returns the previously saved node ["this node"] from which to
736  * allocate a persistent huge page for the pool and advance the
737  * next node from which to allocate, handling wrap at end of node
738  * mask.
739  */
740 static int hstate_next_node_to_alloc(struct hstate *h,
741                                         nodemask_t *nodes_allowed)
742 {
743         int nid;
744
745         VM_BUG_ON(!nodes_allowed);
746
747         nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
748         h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
749
750         return nid;
751 }
752
753 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
754 {
755         struct page *page;
756         int start_nid;
757         int next_nid;
758         int ret = 0;
759
760         start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
761         next_nid = start_nid;
762
763         do {
764                 page = alloc_fresh_huge_page_node(h, next_nid);
765                 if (page) {
766                         ret = 1;
767                         break;
768                 }
769                 next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
770         } while (next_nid != start_nid);
771
772         if (ret)
773                 count_vm_event(HTLB_BUDDY_PGALLOC);
774         else
775                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
776
777         return ret;
778 }
779
780 /*
781  * helper for free_pool_huge_page() - return the previously saved
782  * node ["this node"] from which to free a huge page.  Advance the
783  * next node id whether or not we find a free huge page to free so
784  * that the next attempt to free addresses the next node.
785  */
786 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
787 {
788         int nid;
789
790         VM_BUG_ON(!nodes_allowed);
791
792         nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
793         h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
794
795         return nid;
796 }
797
798 /*
799  * Free huge page from pool from next node to free.
800  * Attempt to keep persistent huge pages more or less
801  * balanced over allowed nodes.
802  * Called with hugetlb_lock locked.
803  */
804 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
805                                                          bool acct_surplus)
806 {
807         int start_nid;
808         int next_nid;
809         int ret = 0;
810
811         start_nid = hstate_next_node_to_free(h, nodes_allowed);
812         next_nid = start_nid;
813
814         do {
815                 /*
816                  * If we're returning unused surplus pages, only examine
817                  * nodes with surplus pages.
818                  */
819                 if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
820                     !list_empty(&h->hugepage_freelists[next_nid])) {
821                         struct page *page =
822                                 list_entry(h->hugepage_freelists[next_nid].next,
823                                           struct page, lru);
824                         list_del(&page->lru);
825                         h->free_huge_pages--;
826                         h->free_huge_pages_node[next_nid]--;
827                         if (acct_surplus) {
828                                 h->surplus_huge_pages--;
829                                 h->surplus_huge_pages_node[next_nid]--;
830                         }
831                         update_and_free_page(h, page);
832                         ret = 1;
833                         break;
834                 }
835                 next_nid = hstate_next_node_to_free(h, nodes_allowed);
836         } while (next_nid != start_nid);
837
838         return ret;
839 }
840
841 static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
842 {
843         struct page *page;
844         unsigned int r_nid;
845
846         if (h->order >= MAX_ORDER)
847                 return NULL;
848
849         /*
850          * Assume we will successfully allocate the surplus page to
851          * prevent racing processes from causing the surplus to exceed
852          * overcommit
853          *
854          * This however introduces a different race, where a process B
855          * tries to grow the static hugepage pool while alloc_pages() is
856          * called by process A. B will only examine the per-node
857          * counters in determining if surplus huge pages can be
858          * converted to normal huge pages in adjust_pool_surplus(). A
859          * won't be able to increment the per-node counter, until the
860          * lock is dropped by B, but B doesn't drop hugetlb_lock until
861          * no more huge pages can be converted from surplus to normal
862          * state (and doesn't try to convert again). Thus, we have a
863          * case where a surplus huge page exists, the pool is grown, and
864          * the surplus huge page still exists after, even though it
865          * should just have been converted to a normal huge page. This
866          * does not leak memory, though, as the hugepage will be freed
867          * once it is out of use. It also does not allow the counters to
868          * go out of whack in adjust_pool_surplus() as we don't modify
869          * the node values until we've gotten the hugepage and only the
870          * per-node value is checked there.
871          */
872         spin_lock(&hugetlb_lock);
873         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
874                 spin_unlock(&hugetlb_lock);
875                 return NULL;
876         } else {
877                 h->nr_huge_pages++;
878                 h->surplus_huge_pages++;
879         }
880         spin_unlock(&hugetlb_lock);
881
882         if (nid == NUMA_NO_NODE)
883                 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
884                                    __GFP_REPEAT|__GFP_NOWARN,
885                                    huge_page_order(h));
886         else
887                 page = alloc_pages_exact_node(nid,
888                         htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
889                         __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
890
891         if (page && arch_prepare_hugepage(page)) {
892                 __free_pages(page, huge_page_order(h));
893                 page = NULL;
894         }
895
896         spin_lock(&hugetlb_lock);
897         if (page) {
898                 INIT_LIST_HEAD(&page->lru);
899                 r_nid = page_to_nid(page);
900                 set_compound_page_dtor(page, free_huge_page);
901                 set_hugetlb_cgroup(page, NULL);
902                 /*
903                  * We incremented the global counters already
904                  */
905                 h->nr_huge_pages_node[r_nid]++;
906                 h->surplus_huge_pages_node[r_nid]++;
907                 __count_vm_event(HTLB_BUDDY_PGALLOC);
908         } else {
909                 h->nr_huge_pages--;
910                 h->surplus_huge_pages--;
911                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
912         }
913         spin_unlock(&hugetlb_lock);
914
915         return page;
916 }
917
918 /*
919  * This allocation function is useful in the context where vma is irrelevant.
920  * E.g. soft-offlining uses this function because it only cares physical
921  * address of error page.
922  */
923 struct page *alloc_huge_page_node(struct hstate *h, int nid)
924 {
925         struct page *page;
926
927         spin_lock(&hugetlb_lock);
928         page = dequeue_huge_page_node(h, nid);
929         spin_unlock(&hugetlb_lock);
930
931         if (!page)
932                 page = alloc_buddy_huge_page(h, nid);
933
934         return page;
935 }
936
937 /*
938  * Increase the hugetlb pool such that it can accommodate a reservation
939  * of size 'delta'.
940  */
941 static int gather_surplus_pages(struct hstate *h, int delta)
942 {
943         struct list_head surplus_list;
944         struct page *page, *tmp;
945         int ret, i;
946         int needed, allocated;
947         bool alloc_ok = true;
948
949         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
950         if (needed <= 0) {
951                 h->resv_huge_pages += delta;
952                 return 0;
953         }
954
955         allocated = 0;
956         INIT_LIST_HEAD(&surplus_list);
957
958         ret = -ENOMEM;
959 retry:
960         spin_unlock(&hugetlb_lock);
961         for (i = 0; i < needed; i++) {
962                 page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
963                 if (!page) {
964                         alloc_ok = false;
965                         break;
966                 }
967                 list_add(&page->lru, &surplus_list);
968         }
969         allocated += i;
970
971         /*
972          * After retaking hugetlb_lock, we need to recalculate 'needed'
973          * because either resv_huge_pages or free_huge_pages may have changed.
974          */
975         spin_lock(&hugetlb_lock);
976         needed = (h->resv_huge_pages + delta) -
977                         (h->free_huge_pages + allocated);
978         if (needed > 0) {
979                 if (alloc_ok)
980                         goto retry;
981                 /*
982                  * We were not able to allocate enough pages to
983                  * satisfy the entire reservation so we free what
984                  * we've allocated so far.
985                  */
986                 goto free;
987         }
988         /*
989          * The surplus_list now contains _at_least_ the number of extra pages
990          * needed to accommodate the reservation.  Add the appropriate number
991          * of pages to the hugetlb pool and free the extras back to the buddy
992          * allocator.  Commit the entire reservation here to prevent another
993          * process from stealing the pages as they are added to the pool but
994          * before they are reserved.
995          */
996         needed += allocated;
997         h->resv_huge_pages += delta;
998         ret = 0;
999
1000         /* Free the needed pages to the hugetlb pool */
1001         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1002                 if ((--needed) < 0)
1003                         break;
1004                 /*
1005                  * This page is now managed by the hugetlb allocator and has
1006                  * no users -- drop the buddy allocator's reference.
1007                  */
1008                 put_page_testzero(page);
1009                 VM_BUG_ON(page_count(page));
1010                 enqueue_huge_page(h, page);
1011         }
1012 free:
1013         spin_unlock(&hugetlb_lock);
1014
1015         /* Free unnecessary surplus pages to the buddy allocator */
1016         if (!list_empty(&surplus_list)) {
1017                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1018                         put_page(page);
1019                 }
1020         }
1021         spin_lock(&hugetlb_lock);
1022
1023         return ret;
1024 }
1025
1026 /*
1027  * When releasing a hugetlb pool reservation, any surplus pages that were
1028  * allocated to satisfy the reservation must be explicitly freed if they were
1029  * never used.
1030  * Called with hugetlb_lock held.
1031  */
1032 static void return_unused_surplus_pages(struct hstate *h,
1033                                         unsigned long unused_resv_pages)
1034 {
1035         unsigned long nr_pages;
1036
1037         /* Uncommit the reservation */
1038         h->resv_huge_pages -= unused_resv_pages;
1039
1040         /* Cannot return gigantic pages currently */
1041         if (h->order >= MAX_ORDER)
1042                 return;
1043
1044         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1045
1046         /*
1047          * We want to release as many surplus pages as possible, spread
1048          * evenly across all nodes with memory. Iterate across these nodes
1049          * until we can no longer free unreserved surplus pages. This occurs
1050          * when the nodes with surplus pages have no free pages.
1051          * free_pool_huge_page() will balance the the freed pages across the
1052          * on-line nodes with memory and will handle the hstate accounting.
1053          */
1054         while (nr_pages--) {
1055                 if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
1056                         break;
1057         }
1058 }
1059
1060 /*
1061  * Determine if the huge page at addr within the vma has an associated
1062  * reservation.  Where it does not we will need to logically increase
1063  * reservation and actually increase subpool usage before an allocation
1064  * can occur.  Where any new reservation would be required the
1065  * reservation change is prepared, but not committed.  Once the page
1066  * has been allocated from the subpool and instantiated the change should
1067  * be committed via vma_commit_reservation.  No action is required on
1068  * failure.
1069  */
1070 static long vma_needs_reservation(struct hstate *h,
1071                         struct vm_area_struct *vma, unsigned long addr)
1072 {
1073         struct address_space *mapping = vma->vm_file->f_mapping;
1074         struct inode *inode = mapping->host;
1075
1076         if (vma->vm_flags & VM_MAYSHARE) {
1077                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1078                 return region_chg(&inode->i_mapping->private_list,
1079                                                         idx, idx + 1);
1080
1081         } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1082                 return 1;
1083
1084         } else  {
1085                 long err;
1086                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1087                 struct resv_map *reservations = vma_resv_map(vma);
1088
1089                 err = region_chg(&reservations->regions, idx, idx + 1);
1090                 if (err < 0)
1091                         return err;
1092                 return 0;
1093         }
1094 }
1095 static void vma_commit_reservation(struct hstate *h,
1096                         struct vm_area_struct *vma, unsigned long addr)
1097 {
1098         struct address_space *mapping = vma->vm_file->f_mapping;
1099         struct inode *inode = mapping->host;
1100
1101         if (vma->vm_flags & VM_MAYSHARE) {
1102                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1103                 region_add(&inode->i_mapping->private_list, idx, idx + 1);
1104
1105         } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1106                 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1107                 struct resv_map *reservations = vma_resv_map(vma);
1108
1109                 /* Mark this page used in the map. */
1110                 region_add(&reservations->regions, idx, idx + 1);
1111         }
1112 }
1113
1114 static struct page *alloc_huge_page(struct vm_area_struct *vma,
1115                                     unsigned long addr, int avoid_reserve)
1116 {
1117         struct hugepage_subpool *spool = subpool_vma(vma);
1118         struct hstate *h = hstate_vma(vma);
1119         struct page *page;
1120         long chg;
1121         int ret, idx;
1122         struct hugetlb_cgroup *h_cg;
1123
1124         idx = hstate_index(h);
1125         /*
1126          * Processes that did not create the mapping will have no
1127          * reserves and will not have accounted against subpool
1128          * limit. Check that the subpool limit can be made before
1129          * satisfying the allocation MAP_NORESERVE mappings may also
1130          * need pages and subpool limit allocated allocated if no reserve
1131          * mapping overlaps.
1132          */
1133         chg = vma_needs_reservation(h, vma, addr);
1134         if (chg < 0)
1135                 return ERR_PTR(-ENOMEM);
1136         if (chg)
1137                 if (hugepage_subpool_get_pages(spool, chg))
1138                         return ERR_PTR(-ENOSPC);
1139
1140         ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1141         if (ret) {
1142                 hugepage_subpool_put_pages(spool, chg);
1143                 return ERR_PTR(-ENOSPC);
1144         }
1145         spin_lock(&hugetlb_lock);
1146         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
1147         if (page) {
1148                 /* update page cgroup details */
1149                 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
1150                                              h_cg, page);
1151                 spin_unlock(&hugetlb_lock);
1152         } else {
1153                 spin_unlock(&hugetlb_lock);
1154                 page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
1155                 if (!page) {
1156                         hugetlb_cgroup_uncharge_cgroup(idx,
1157                                                        pages_per_huge_page(h),
1158                                                        h_cg);
1159                         hugepage_subpool_put_pages(spool, chg);
1160                         return ERR_PTR(-ENOSPC);
1161                 }
1162                 spin_lock(&hugetlb_lock);
1163                 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
1164                                              h_cg, page);
1165                 list_move(&page->lru, &h->hugepage_activelist);
1166                 spin_unlock(&hugetlb_lock);
1167         }
1168
1169         set_page_private(page, (unsigned long)spool);
1170
1171         vma_commit_reservation(h, vma, addr);
1172         return page;
1173 }
1174
1175 int __weak alloc_bootmem_huge_page(struct hstate *h)
1176 {
1177         struct huge_bootmem_page *m;
1178         int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
1179
1180         while (nr_nodes) {
1181                 void *addr;
1182
1183                 addr = __alloc_bootmem_node_nopanic(
1184                                 NODE_DATA(hstate_next_node_to_alloc(h,
1185                                                 &node_states[N_HIGH_MEMORY])),
1186                                 huge_page_size(h), huge_page_size(h), 0);
1187
1188                 if (addr) {
1189                         /*
1190                          * Use the beginning of the huge page to store the
1191                          * huge_bootmem_page struct (until gather_bootmem
1192                          * puts them into the mem_map).
1193                          */
1194                         m = addr;
1195                         goto found;
1196                 }
1197                 nr_nodes--;
1198         }
1199         return 0;
1200
1201 found:
1202         BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1203         /* Put them into a private list first because mem_map is not up yet */
1204         list_add(&m->list, &huge_boot_pages);
1205         m->hstate = h;
1206         return 1;
1207 }
1208
1209 static void prep_compound_huge_page(struct page *page, int order)
1210 {
1211         if (unlikely(order > (MAX_ORDER - 1)))
1212                 prep_compound_gigantic_page(page, order);
1213         else
1214                 prep_compound_page(page, order);
1215 }
1216
1217 /* Put bootmem huge pages into the standard lists after mem_map is up */
1218 static void __init gather_bootmem_prealloc(void)
1219 {
1220         struct huge_bootmem_page *m;
1221
1222         list_for_each_entry(m, &huge_boot_pages, list) {
1223                 struct hstate *h = m->hstate;
1224                 struct page *page;
1225
1226 #ifdef CONFIG_HIGHMEM
1227                 page = pfn_to_page(m->phys >> PAGE_SHIFT);
1228                 free_bootmem_late((unsigned long)m,
1229                                   sizeof(struct huge_bootmem_page));
1230 #else
1231                 page = virt_to_page(m);
1232 #endif
1233                 __ClearPageReserved(page);
1234                 WARN_ON(page_count(page) != 1);
1235                 prep_compound_huge_page(page, h->order);
1236                 prep_new_huge_page(h, page, page_to_nid(page));
1237                 /*
1238                  * If we had gigantic hugepages allocated at boot time, we need
1239                  * to restore the 'stolen' pages to totalram_pages in order to
1240                  * fix confusing memory reports from free(1) and another
1241                  * side-effects, like CommitLimit going negative.
1242                  */
1243                 if (h->order > (MAX_ORDER - 1))
1244                         totalram_pages += 1 << h->order;
1245         }
1246 }
1247
1248 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1249 {
1250         unsigned long i;
1251
1252         for (i = 0; i < h->max_huge_pages; ++i) {
1253                 if (h->order >= MAX_ORDER) {
1254                         if (!alloc_bootmem_huge_page(h))
1255                                 break;
1256                 } else if (!alloc_fresh_huge_page(h,
1257                                          &node_states[N_HIGH_MEMORY]))
1258                         break;
1259         }
1260         h->max_huge_pages = i;
1261 }
1262
1263 static void __init hugetlb_init_hstates(void)
1264 {
1265         struct hstate *h;
1266
1267         for_each_hstate(h) {
1268                 /* oversize hugepages were init'ed in early boot */
1269                 if (h->order < MAX_ORDER)
1270                         hugetlb_hstate_alloc_pages(h);
1271         }
1272 }
1273
1274 static char * __init memfmt(char *buf, unsigned long n)
1275 {
1276         if (n >= (1UL << 30))
1277                 sprintf(buf, "%lu GB", n >> 30);
1278         else if (n >= (1UL << 20))
1279                 sprintf(buf, "%lu MB", n >> 20);
1280         else
1281                 sprintf(buf, "%lu KB", n >> 10);
1282         return buf;
1283 }
1284
1285 static void __init report_hugepages(void)
1286 {
1287         struct hstate *h;
1288
1289         for_each_hstate(h) {
1290                 char buf[32];
1291                 printk(KERN_INFO "HugeTLB registered %s page size, "
1292                                  "pre-allocated %ld pages\n",
1293                         memfmt(buf, huge_page_size(h)),
1294                         h->free_huge_pages);
1295         }
1296 }
1297
1298 #ifdef CONFIG_HIGHMEM
1299 static void try_to_free_low(struct hstate *h, unsigned long count,
1300                                                 nodemask_t *nodes_allowed)
1301 {
1302         int i;
1303
1304         if (h->order >= MAX_ORDER)
1305                 return;
1306
1307         for_each_node_mask(i, *nodes_allowed) {
1308                 struct page *page, *next;
1309                 struct list_head *freel = &h->hugepage_freelists[i];
1310                 list_for_each_entry_safe(page, next, freel, lru) {
1311                         if (count >= h->nr_huge_pages)
1312                                 return;
1313                         if (PageHighMem(page))
1314                                 continue;
1315                         list_del(&page->lru);
1316                         update_and_free_page(h, page);
1317                         h->free_huge_pages--;
1318                         h->free_huge_pages_node[page_to_nid(page)]--;
1319                 }
1320         }
1321 }
1322 #else
1323 static inline void try_to_free_low(struct hstate *h, unsigned long count,
1324                                                 nodemask_t *nodes_allowed)
1325 {
1326 }
1327 #endif
1328
1329 /*
1330  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1331  * balanced by operating on them in a round-robin fashion.
1332  * Returns 1 if an adjustment was made.
1333  */
1334 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1335                                 int delta)
1336 {
1337         int start_nid, next_nid;
1338         int ret = 0;
1339
1340         VM_BUG_ON(delta != -1 && delta != 1);
1341
1342         if (delta < 0)
1343                 start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1344         else
1345                 start_nid = hstate_next_node_to_free(h, nodes_allowed);
1346         next_nid = start_nid;
1347
1348         do {
1349                 int nid = next_nid;
1350                 if (delta < 0)  {
1351                         /*
1352                          * To shrink on this node, there must be a surplus page
1353                          */
1354                         if (!h->surplus_huge_pages_node[nid]) {
1355                                 next_nid = hstate_next_node_to_alloc(h,
1356                                                                 nodes_allowed);
1357                                 continue;
1358                         }
1359                 }
1360                 if (delta > 0) {
1361                         /*
1362                          * Surplus cannot exceed the total number of pages
1363                          */
1364                         if (h->surplus_huge_pages_node[nid] >=
1365                                                 h->nr_huge_pages_node[nid]) {
1366                                 next_nid = hstate_next_node_to_free(h,
1367                                                                 nodes_allowed);
1368                                 continue;
1369                         }
1370                 }
1371
1372                 h->surplus_huge_pages += delta;
1373                 h->surplus_huge_pages_node[nid] += delta;
1374                 ret = 1;
1375                 break;
1376         } while (next_nid != start_nid);
1377
1378         return ret;
1379 }
1380
1381 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1382 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1383                                                 nodemask_t *nodes_allowed)
1384 {
1385         unsigned long min_count, ret;
1386
1387         if (h->order >= MAX_ORDER)
1388                 return h->max_huge_pages;
1389
1390         /*
1391          * Increase the pool size
1392          * First take pages out of surplus state.  Then make up the
1393          * remaining difference by allocating fresh huge pages.
1394          *
1395          * We might race with alloc_buddy_huge_page() here and be unable
1396          * to convert a surplus huge page to a normal huge page. That is
1397          * not critical, though, it just means the overall size of the
1398          * pool might be one hugepage larger than it needs to be, but
1399          * within all the constraints specified by the sysctls.
1400          */
1401         spin_lock(&hugetlb_lock);
1402         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1403                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
1404                         break;
1405         }
1406
1407         while (count > persistent_huge_pages(h)) {
1408                 /*
1409                  * If this allocation races such that we no longer need the
1410                  * page, free_huge_page will handle it by freeing the page
1411                  * and reducing the surplus.
1412                  */
1413                 spin_unlock(&hugetlb_lock);
1414                 ret = alloc_fresh_huge_page(h, nodes_allowed);
1415                 spin_lock(&hugetlb_lock);
1416                 if (!ret)
1417                         goto out;
1418
1419                 /* Bail for signals. Probably ctrl-c from user */
1420                 if (signal_pending(current))
1421                         goto out;
1422         }
1423
1424         /*
1425          * Decrease the pool size
1426          * First return free pages to the buddy allocator (being careful
1427          * to keep enough around to satisfy reservations).  Then place
1428          * pages into surplus state as needed so the pool will shrink
1429          * to the desired size as pages become free.
1430          *
1431          * By placing pages into the surplus state independent of the
1432          * overcommit value, we are allowing the surplus pool size to
1433          * exceed overcommit. There are few sane options here. Since
1434          * alloc_buddy_huge_page() is checking the global counter,
1435          * though, we'll note that we're not allowed to exceed surplus
1436          * and won't grow the pool anywhere else. Not until one of the
1437          * sysctls are changed, or the surplus pages go out of use.
1438          */
1439         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1440         min_count = max(count, min_count);
1441         try_to_free_low(h, min_count, nodes_allowed);
1442         while (min_count < persistent_huge_pages(h)) {
1443                 if (!free_pool_huge_page(h, nodes_allowed, 0))
1444                         break;
1445         }
1446         while (count < persistent_huge_pages(h)) {
1447                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
1448                         break;
1449         }
1450 out:
1451         ret = persistent_huge_pages(h);
1452         spin_unlock(&hugetlb_lock);
1453         return ret;
1454 }
1455
1456 #define HSTATE_ATTR_RO(_name) \
1457         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1458
1459 #define HSTATE_ATTR(_name) \
1460         static struct kobj_attribute _name##_attr = \
1461                 __ATTR(_name, 0644, _name##_show, _name##_store)
1462
1463 static struct kobject *hugepages_kobj;
1464 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1465
1466 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1467
1468 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1469 {
1470         int i;
1471
1472         for (i = 0; i < HUGE_MAX_HSTATE; i++)
1473                 if (hstate_kobjs[i] == kobj) {
1474                         if (nidp)
1475                                 *nidp = NUMA_NO_NODE;
1476                         return &hstates[i];
1477                 }
1478
1479         return kobj_to_node_hstate(kobj, nidp);
1480 }
1481
1482 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1483                                         struct kobj_attribute *attr, char *buf)
1484 {
1485         struct hstate *h;
1486         unsigned long nr_huge_pages;
1487         int nid;
1488
1489         h = kobj_to_hstate(kobj, &nid);
1490         if (nid == NUMA_NO_NODE)
1491                 nr_huge_pages = h->nr_huge_pages;
1492         else
1493                 nr_huge_pages = h->nr_huge_pages_node[nid];
1494
1495         return sprintf(buf, "%lu\n", nr_huge_pages);
1496 }
1497
1498 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1499                         struct kobject *kobj, struct kobj_attribute *attr,
1500                         const char *buf, size_t len)
1501 {
1502         int err;
1503         int nid;
1504         unsigned long count;
1505         struct hstate *h;
1506         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1507
1508         err = strict_strtoul(buf, 10, &count);
1509         if (err)
1510                 goto out;
1511
1512         h = kobj_to_hstate(kobj, &nid);
1513         if (h->order >= MAX_ORDER) {
1514                 err = -EINVAL;
1515                 goto out;
1516         }
1517
1518         if (nid == NUMA_NO_NODE) {
1519                 /*
1520                  * global hstate attribute
1521                  */
1522                 if (!(obey_mempolicy &&
1523                                 init_nodemask_of_mempolicy(nodes_allowed))) {
1524                         NODEMASK_FREE(nodes_allowed);
1525                         nodes_allowed = &node_states[N_HIGH_MEMORY];
1526                 }
1527         } else if (nodes_allowed) {
1528                 /*
1529                  * per node hstate attribute: adjust count to global,
1530                  * but restrict alloc/free to the specified node.
1531                  */
1532                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1533                 init_nodemask_of_node(nodes_allowed, nid);
1534         } else
1535                 nodes_allowed = &node_states[N_HIGH_MEMORY];
1536
1537         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1538
1539         if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1540                 NODEMASK_FREE(nodes_allowed);
1541
1542         return len;
1543 out:
1544         NODEMASK_FREE(nodes_allowed);
1545         return err;
1546 }
1547
1548 static ssize_t nr_hugepages_show(struct kobject *kobj,
1549                                        struct kobj_attribute *attr, char *buf)
1550 {
1551         return nr_hugepages_show_common(kobj, attr, buf);
1552 }
1553
1554 static ssize_t nr_hugepages_store(struct kobject *kobj,
1555                struct kobj_attribute *attr, const char *buf, size_t len)
1556 {
1557         return nr_hugepages_store_common(false, kobj, attr, buf, len);
1558 }
1559 HSTATE_ATTR(nr_hugepages);
1560
1561 #ifdef CONFIG_NUMA
1562
1563 /*
1564  * hstate attribute for optionally mempolicy-based constraint on persistent
1565  * huge page alloc/free.
1566  */
1567 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1568                                        struct kobj_attribute *attr, char *buf)
1569 {
1570         return nr_hugepages_show_common(kobj, attr, buf);
1571 }
1572
1573 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1574                struct kobj_attribute *attr, const char *buf, size_t len)
1575 {
1576         return nr_hugepages_store_common(true, kobj, attr, buf, len);
1577 }
1578 HSTATE_ATTR(nr_hugepages_mempolicy);
1579 #endif
1580
1581
1582 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1583                                         struct kobj_attribute *attr, char *buf)
1584 {
1585         struct hstate *h = kobj_to_hstate(kobj, NULL);
1586         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1587 }
1588
1589 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1590                 struct kobj_attribute *attr, const char *buf, size_t count)
1591 {
1592         int err;
1593         unsigned long input;
1594         struct hstate *h = kobj_to_hstate(kobj, NULL);
1595
1596         if (h->order >= MAX_ORDER)
1597                 return -EINVAL;
1598
1599         err = strict_strtoul(buf, 10, &input);
1600         if (err)
1601                 return err;
1602
1603         spin_lock(&hugetlb_lock);
1604         h->nr_overcommit_huge_pages = input;
1605         spin_unlock(&hugetlb_lock);
1606
1607         return count;
1608 }
1609 HSTATE_ATTR(nr_overcommit_hugepages);
1610
1611 static ssize_t free_hugepages_show(struct kobject *kobj,
1612                                         struct kobj_attribute *attr, char *buf)
1613 {
1614         struct hstate *h;
1615         unsigned long free_huge_pages;
1616         int nid;
1617
1618         h = kobj_to_hstate(kobj, &nid);
1619         if (nid == NUMA_NO_NODE)
1620                 free_huge_pages = h->free_huge_pages;
1621         else
1622                 free_huge_pages = h->free_huge_pages_node[nid];
1623
1624         return sprintf(buf, "%lu\n", free_huge_pages);
1625 }
1626 HSTATE_ATTR_RO(free_hugepages);
1627
1628 static ssize_t resv_hugepages_show(struct kobject *kobj,
1629                                         struct kobj_attribute *attr, char *buf)
1630 {
1631         struct hstate *h = kobj_to_hstate(kobj, NULL);
1632         return sprintf(buf, "%lu\n", h->resv_huge_pages);
1633 }
1634 HSTATE_ATTR_RO(resv_hugepages);
1635
1636 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1637                                         struct kobj_attribute *attr, char *buf)
1638 {
1639         struct hstate *h;
1640         unsigned long surplus_huge_pages;
1641         int nid;
1642
1643         h = kobj_to_hstate(kobj, &nid);
1644         if (nid == NUMA_NO_NODE)
1645                 surplus_huge_pages = h->surplus_huge_pages;
1646         else
1647                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
1648
1649         return sprintf(buf, "%lu\n", surplus_huge_pages);
1650 }
1651 HSTATE_ATTR_RO(surplus_hugepages);
1652
1653 static struct attribute *hstate_attrs[] = {
1654         &nr_hugepages_attr.attr,
1655         &nr_overcommit_hugepages_attr.attr,
1656         &free_hugepages_attr.attr,
1657         &resv_hugepages_attr.attr,
1658         &surplus_hugepages_attr.attr,
1659 #ifdef CONFIG_NUMA
1660         &nr_hugepages_mempolicy_attr.attr,
1661 #endif
1662         NULL,
1663 };
1664
1665 static struct attribute_group hstate_attr_group = {
1666         .attrs = hstate_attrs,
1667 };
1668
1669 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1670                                     struct kobject **hstate_kobjs,
1671                                     struct attribute_group *hstate_attr_group)
1672 {
1673         int retval;
1674         int hi = hstate_index(h);
1675
1676         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1677         if (!hstate_kobjs[hi])
1678                 return -ENOMEM;
1679
1680         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1681         if (retval)
1682                 kobject_put(hstate_kobjs[hi]);
1683
1684         return retval;
1685 }
1686
1687 static void __init hugetlb_sysfs_init(void)
1688 {
1689         struct hstate *h;
1690         int err;
1691
1692         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1693         if (!hugepages_kobj)
1694                 return;
1695
1696         for_each_hstate(h) {
1697                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1698                                          hstate_kobjs, &hstate_attr_group);
1699                 if (err)
1700                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1701                                                                 h->name);
1702         }
1703 }
1704
1705 #ifdef CONFIG_NUMA
1706
1707 /*
1708  * node_hstate/s - associate per node hstate attributes, via their kobjects,
1709  * with node devices in node_devices[] using a parallel array.  The array
1710  * index of a node device or _hstate == node id.
1711  * This is here to avoid any static dependency of the node device driver, in
1712  * the base kernel, on the hugetlb module.
1713  */
1714 struct node_hstate {
1715         struct kobject          *hugepages_kobj;
1716         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
1717 };
1718 struct node_hstate node_hstates[MAX_NUMNODES];
1719
1720 /*
1721  * A subset of global hstate attributes for node devices
1722  */
1723 static struct attribute *per_node_hstate_attrs[] = {
1724         &nr_hugepages_attr.attr,
1725         &free_hugepages_attr.attr,
1726         &surplus_hugepages_attr.attr,
1727         NULL,
1728 };
1729
1730 static struct attribute_group per_node_hstate_attr_group = {
1731         .attrs = per_node_hstate_attrs,
1732 };
1733
1734 /*
1735  * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
1736  * Returns node id via non-NULL nidp.
1737  */
1738 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1739 {
1740         int nid;
1741
1742         for (nid = 0; nid < nr_node_ids; nid++) {
1743                 struct node_hstate *nhs = &node_hstates[nid];
1744                 int i;
1745                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1746                         if (nhs->hstate_kobjs[i] == kobj) {
1747                                 if (nidp)
1748                                         *nidp = nid;
1749                                 return &hstates[i];
1750                         }
1751         }
1752
1753         BUG();
1754         return NULL;
1755 }
1756
1757 /*
1758  * Unregister hstate attributes from a single node device.
1759  * No-op if no hstate attributes attached.
1760  */
1761 void hugetlb_unregister_node(struct node *node)
1762 {
1763         struct hstate *h;
1764         struct node_hstate *nhs = &node_hstates[node->dev.id];
1765
1766         if (!nhs->hugepages_kobj)
1767                 return;         /* no hstate attributes */
1768
1769         for_each_hstate(h) {
1770                 int idx = hstate_index(h);
1771                 if (nhs->hstate_kobjs[idx]) {
1772                         kobject_put(nhs->hstate_kobjs[idx]);
1773                         nhs->hstate_kobjs[idx] = NULL;
1774                 }
1775         }
1776
1777         kobject_put(nhs->hugepages_kobj);
1778         nhs->hugepages_kobj = NULL;
1779 }
1780
1781 /*
1782  * hugetlb module exit:  unregister hstate attributes from node devices
1783  * that have them.
1784  */
1785 static void hugetlb_unregister_all_nodes(void)
1786 {
1787         int nid;
1788
1789         /*
1790          * disable node device registrations.
1791          */
1792         register_hugetlbfs_with_node(NULL, NULL);
1793
1794         /*
1795          * remove hstate attributes from any nodes that have them.
1796          */
1797         for (nid = 0; nid < nr_node_ids; nid++)
1798                 hugetlb_unregister_node(&node_devices[nid]);
1799 }
1800
1801 /*
1802  * Register hstate attributes for a single node device.
1803  * No-op if attributes already registered.
1804  */
1805 void hugetlb_register_node(struct node *node)
1806 {
1807         struct hstate *h;
1808         struct node_hstate *nhs = &node_hstates[node->dev.id];
1809         int err;
1810
1811         if (nhs->hugepages_kobj)
1812                 return;         /* already allocated */
1813
1814         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1815                                                         &node->dev.kobj);
1816         if (!nhs->hugepages_kobj)
1817                 return;
1818
1819         for_each_hstate(h) {
1820                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1821                                                 nhs->hstate_kobjs,
1822                                                 &per_node_hstate_attr_group);
1823                 if (err) {
1824                         printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1825                                         " for node %d\n",
1826                                                 h->name, node->dev.id);
1827                         hugetlb_unregister_node(node);
1828                         break;
1829                 }
1830         }
1831 }
1832
1833 /*
1834  * hugetlb init time:  register hstate attributes for all registered node
1835  * devices of nodes that have memory.  All on-line nodes should have
1836  * registered their associated device by this time.
1837  */
1838 static void hugetlb_register_all_nodes(void)
1839 {
1840         int nid;
1841
1842         for_each_node_state(nid, N_HIGH_MEMORY) {
1843                 struct node *node = &node_devices[nid];
1844                 if (node->dev.id == nid)
1845                         hugetlb_register_node(node);
1846         }
1847
1848         /*
1849          * Let the node device driver know we're here so it can
1850          * [un]register hstate attributes on node hotplug.
1851          */
1852         register_hugetlbfs_with_node(hugetlb_register_node,
1853                                      hugetlb_unregister_node);
1854 }
1855 #else   /* !CONFIG_NUMA */
1856
1857 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1858 {
1859         BUG();
1860         if (nidp)
1861                 *nidp = -1;
1862         return NULL;
1863 }
1864
1865 static void hugetlb_unregister_all_nodes(void) { }
1866
1867 static void hugetlb_register_all_nodes(void) { }
1868
1869 #endif
1870
1871 static void __exit hugetlb_exit(void)
1872 {
1873         struct hstate *h;
1874
1875         hugetlb_unregister_all_nodes();
1876
1877         for_each_hstate(h) {
1878                 kobject_put(hstate_kobjs[hstate_index(h)]);
1879         }
1880
1881         kobject_put(hugepages_kobj);
1882 }
1883 module_exit(hugetlb_exit);
1884
1885 static int __init hugetlb_init(void)
1886 {
1887         /* Some platform decide whether they support huge pages at boot
1888          * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1889          * there is no such support
1890          */
1891         if (HPAGE_SHIFT == 0)
1892                 return 0;
1893
1894         if (!size_to_hstate(default_hstate_size)) {
1895                 default_hstate_size = HPAGE_SIZE;
1896                 if (!size_to_hstate(default_hstate_size))
1897                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1898         }
1899         default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
1900         if (default_hstate_max_huge_pages)
1901                 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1902
1903         hugetlb_init_hstates();
1904
1905         gather_bootmem_prealloc();
1906
1907         report_hugepages();
1908
1909         hugetlb_sysfs_init();
1910
1911         hugetlb_register_all_nodes();
1912
1913         return 0;
1914 }
1915 module_init(hugetlb_init);
1916
1917 /* Should be called on processing a hugepagesz=... option */
1918 void __init hugetlb_add_hstate(unsigned order)
1919 {
1920         struct hstate *h;
1921         unsigned long i;
1922
1923         if (size_to_hstate(PAGE_SIZE << order)) {
1924                 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1925                 return;
1926         }
1927         BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
1928         BUG_ON(order == 0);
1929         h = &hstates[hugetlb_max_hstate++];
1930         h->order = order;
1931         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1932         h->nr_huge_pages = 0;
1933         h->free_huge_pages = 0;
1934         for (i = 0; i < MAX_NUMNODES; ++i)
1935                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1936         INIT_LIST_HEAD(&h->hugepage_activelist);
1937         h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
1938         h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
1939         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1940                                         huge_page_size(h)/1024);
1941         /*
1942          * Add cgroup control files only if the huge page consists
1943          * of more than two normal pages. This is because we use
1944          * page[2].lru.next for storing cgoup details.
1945          */
1946         if (order >= HUGETLB_CGROUP_MIN_ORDER)
1947                 hugetlb_cgroup_file_init(hugetlb_max_hstate - 1);
1948
1949         parsed_hstate = h;
1950 }
1951
1952 static int __init hugetlb_nrpages_setup(char *s)
1953 {
1954         unsigned long *mhp;
1955         static unsigned long *last_mhp;
1956
1957         /*
1958          * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
1959          * so this hugepages= parameter goes to the "default hstate".
1960          */
1961         if (!hugetlb_max_hstate)
1962                 mhp = &default_hstate_max_huge_pages;
1963         else
1964                 mhp = &parsed_hstate->max_huge_pages;
1965
1966         if (mhp == last_mhp) {
1967                 printk(KERN_WARNING "hugepages= specified twice without "
1968                         "interleaving hugepagesz=, ignoring\n");
1969                 return 1;
1970         }
1971
1972         if (sscanf(s, "%lu", mhp) <= 0)
1973                 *mhp = 0;
1974
1975         /*
1976          * Global state is always initialized later in hugetlb_init.
1977          * But we need to allocate >= MAX_ORDER hstates here early to still
1978          * use the bootmem allocator.
1979          */
1980         if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
1981                 hugetlb_hstate_alloc_pages(parsed_hstate);
1982
1983         last_mhp = mhp;
1984
1985         return 1;
1986 }
1987 __setup("hugepages=", hugetlb_nrpages_setup);
1988
1989 static int __init hugetlb_default_setup(char *s)
1990 {
1991         default_hstate_size = memparse(s, &s);
1992         return 1;
1993 }
1994 __setup("default_hugepagesz=", hugetlb_default_setup);
1995
1996 static unsigned int cpuset_mems_nr(unsigned int *array)
1997 {
1998         int node;
1999         unsigned int nr = 0;
2000
2001         for_each_node_mask(node, cpuset_current_mems_allowed)
2002                 nr += array[node];
2003
2004         return nr;
2005 }
2006
2007 #ifdef CONFIG_SYSCTL
2008 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2009                          struct ctl_table *table, int write,
2010                          void __user *buffer, size_t *length, loff_t *ppos)
2011 {
2012         struct hstate *h = &default_hstate;
2013         unsigned long tmp;
2014         int ret;
2015
2016         tmp = h->max_huge_pages;
2017
2018         if (write && h->order >= MAX_ORDER)
2019                 return -EINVAL;
2020
2021         table->data = &tmp;
2022         table->maxlen = sizeof(unsigned long);
2023         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2024         if (ret)
2025                 goto out;
2026
2027         if (write) {
2028                 NODEMASK_ALLOC(nodemask_t, nodes_allowed,
2029                                                 GFP_KERNEL | __GFP_NORETRY);
2030                 if (!(obey_mempolicy &&
2031                                init_nodemask_of_mempolicy(nodes_allowed))) {
2032                         NODEMASK_FREE(nodes_allowed);
2033                         nodes_allowed = &node_states[N_HIGH_MEMORY];
2034                 }
2035                 h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
2036
2037                 if (nodes_allowed != &node_states[N_HIGH_MEMORY])
2038                         NODEMASK_FREE(nodes_allowed);
2039         }
2040 out:
2041         return ret;
2042 }
2043
2044 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2045                           void __user *buffer, size_t *length, loff_t *ppos)
2046 {
2047
2048         return hugetlb_sysctl_handler_common(false, table, write,
2049                                                         buffer, length, ppos);
2050 }
2051
2052 #ifdef CONFIG_NUMA
2053 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2054                           void __user *buffer, size_t *length, loff_t *ppos)
2055 {
2056         return hugetlb_sysctl_handler_common(true, table, write,
2057                                                         buffer, length, ppos);
2058 }
2059 #endif /* CONFIG_NUMA */
2060
2061 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
2062                         void __user *buffer,
2063                         size_t *length, loff_t *ppos)
2064 {
2065         proc_dointvec(table, write, buffer, length, ppos);
2066         if (hugepages_treat_as_movable)
2067                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
2068         else
2069                 htlb_alloc_mask = GFP_HIGHUSER;
2070         return 0;
2071 }
2072
2073 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2074                         void __user *buffer,
2075                         size_t *length, loff_t *ppos)
2076 {
2077         struct hstate *h = &default_hstate;
2078         unsigned long tmp;
2079         int ret;
2080
2081         tmp = h->nr_overcommit_huge_pages;
2082
2083         if (write && h->order >= MAX_ORDER)
2084                 return -EINVAL;
2085
2086         table->data = &tmp;
2087         table->maxlen = sizeof(unsigned long);
2088         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2089         if (ret)
2090                 goto out;
2091
2092         if (write) {
2093                 spin_lock(&hugetlb_lock);
2094                 h->nr_overcommit_huge_pages = tmp;
2095                 spin_unlock(&hugetlb_lock);
2096         }
2097 out:
2098         return ret;
2099 }
2100
2101 #endif /* CONFIG_SYSCTL */
2102
2103 void hugetlb_report_meminfo(struct seq_file *m)
2104 {
2105         struct hstate *h = &default_hstate;
2106         seq_printf(m,
2107                         "HugePages_Total:   %5lu\n"
2108                         "HugePages_Free:    %5lu\n"
2109                         "HugePages_Rsvd:    %5lu\n"
2110                         "HugePages_Surp:    %5lu\n"
2111                         "Hugepagesize:   %8lu kB\n",
2112                         h->nr_huge_pages,
2113                         h->free_huge_pages,
2114                         h->resv_huge_pages,
2115                         h->surplus_huge_pages,
2116                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2117 }
2118
2119 int hugetlb_report_node_meminfo(int nid, char *buf)
2120 {
2121         struct hstate *h = &default_hstate;
2122         return sprintf(buf,
2123                 "Node %d HugePages_Total: %5u\n"
2124                 "Node %d HugePages_Free:  %5u\n"
2125                 "Node %d HugePages_Surp:  %5u\n",
2126                 nid, h->nr_huge_pages_node[nid],
2127                 nid, h->free_huge_pages_node[nid],
2128                 nid, h->surplus_huge_pages_node[nid]);
2129 }
2130
2131 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2132 unsigned long hugetlb_total_pages(void)
2133 {
2134         struct hstate *h = &default_hstate;
2135         return h->nr_huge_pages * pages_per_huge_page(h);
2136 }
2137
2138 static int hugetlb_acct_memory(struct hstate *h, long delta)
2139 {
2140         int ret = -ENOMEM;
2141
2142         spin_lock(&hugetlb_lock);
2143         /*
2144          * When cpuset is configured, it breaks the strict hugetlb page
2145          * reservation as the accounting is done on a global variable. Such
2146          * reservation is completely rubbish in the presence of cpuset because
2147          * the reservation is not checked against page availability for the
2148          * current cpuset. Application can still potentially OOM'ed by kernel
2149          * with lack of free htlb page in cpuset that the task is in.
2150          * Attempt to enforce strict accounting with cpuset is almost
2151          * impossible (or too ugly) because cpuset is too fluid that
2152          * task or memory node can be dynamically moved between cpusets.
2153          *
2154          * The change of semantics for shared hugetlb mapping with cpuset is
2155          * undesirable. However, in order to preserve some of the semantics,
2156          * we fall back to check against current free page availability as
2157          * a best attempt and hopefully to minimize the impact of changing
2158          * semantics that cpuset has.
2159          */
2160         if (delta > 0) {
2161                 if (gather_surplus_pages(h, delta) < 0)
2162                         goto out;
2163
2164                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2165                         return_unused_surplus_pages(h, delta);
2166                         goto out;
2167                 }
2168         }
2169
2170         ret = 0;
2171         if (delta < 0)
2172                 return_unused_surplus_pages(h, (unsigned long) -delta);
2173
2174 out:
2175         spin_unlock(&hugetlb_lock);
2176         return ret;
2177 }
2178
2179 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2180 {
2181         struct resv_map *reservations = vma_resv_map(vma);
2182
2183         /*
2184          * This new VMA should share its siblings reservation map if present.
2185          * The VMA will only ever have a valid reservation map pointer where
2186          * it is being copied for another still existing VMA.  As that VMA
2187          * has a reference to the reservation map it cannot disappear until
2188          * after this open call completes.  It is therefore safe to take a
2189          * new reference here without additional locking.
2190          */
2191         if (reservations)
2192                 kref_get(&reservations->refs);
2193 }
2194
2195 static void resv_map_put(struct vm_area_struct *vma)
2196 {
2197         struct resv_map *reservations = vma_resv_map(vma);
2198
2199         if (!reservations)
2200                 return;
2201         kref_put(&reservations->refs, resv_map_release);
2202 }
2203
2204 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2205 {
2206         struct hstate *h = hstate_vma(vma);
2207         struct resv_map *reservations = vma_resv_map(vma);
2208         struct hugepage_subpool *spool = subpool_vma(vma);
2209         unsigned long reserve;
2210         unsigned long start;
2211         unsigned long end;
2212
2213         if (reservations) {
2214                 start = vma_hugecache_offset(h, vma, vma->vm_start);
2215                 end = vma_hugecache_offset(h, vma, vma->vm_end);
2216
2217                 reserve = (end - start) -
2218                         region_count(&reservations->regions, start, end);
2219
2220                 resv_map_put(vma);
2221
2222                 if (reserve) {
2223                         hugetlb_acct_memory(h, -reserve);
2224                         hugepage_subpool_put_pages(spool, reserve);
2225                 }
2226         }
2227 }
2228
2229 /*
2230  * We cannot handle pagefaults against hugetlb pages at all.  They cause
2231  * handle_mm_fault() to try to instantiate regular-sized pages in the
2232  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2233  * this far.
2234  */
2235 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2236 {
2237         BUG();
2238         return 0;
2239 }
2240
2241 const struct vm_operations_struct hugetlb_vm_ops = {
2242         .fault = hugetlb_vm_op_fault,
2243         .open = hugetlb_vm_op_open,
2244         .close = hugetlb_vm_op_close,
2245 };
2246
2247 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2248                                 int writable)
2249 {
2250         pte_t entry;
2251
2252         if (writable) {
2253                 entry =
2254                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2255         } else {
2256                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2257         }
2258         entry = pte_mkyoung(entry);
2259         entry = pte_mkhuge(entry);
2260         entry = arch_make_huge_pte(entry, vma, page, writable);
2261
2262         return entry;
2263 }
2264
2265 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2266                                    unsigned long address, pte_t *ptep)
2267 {
2268         pte_t entry;
2269
2270         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2271         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
2272                 update_mmu_cache(vma, address, ptep);
2273 }
2274
2275
2276 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2277                             struct vm_area_struct *vma)
2278 {
2279         pte_t *src_pte, *dst_pte, entry;
2280         struct page *ptepage;
2281         unsigned long addr;
2282         int cow;
2283         struct hstate *h = hstate_vma(vma);
2284         unsigned long sz = huge_page_size(h);
2285
2286         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2287
2288         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2289                 src_pte = huge_pte_offset(src, addr);
2290                 if (!src_pte)
2291                         continue;
2292                 dst_pte = huge_pte_alloc(dst, addr, sz);
2293                 if (!dst_pte)
2294                         goto nomem;
2295
2296                 /* If the pagetables are shared don't copy or take references */
2297                 if (dst_pte == src_pte)
2298                         continue;
2299
2300                 spin_lock(&dst->page_table_lock);
2301                 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2302                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
2303                         if (cow)
2304                                 huge_ptep_set_wrprotect(src, addr, src_pte);
2305                         entry = huge_ptep_get(src_pte);
2306                         ptepage = pte_page(entry);
2307                         get_page(ptepage);
2308                         page_dup_rmap(ptepage);
2309                         set_huge_pte_at(dst, addr, dst_pte, entry);
2310                 }
2311                 spin_unlock(&src->page_table_lock);
2312                 spin_unlock(&dst->page_table_lock);
2313         }
2314         return 0;
2315
2316 nomem:
2317         return -ENOMEM;
2318 }
2319
2320 static int is_hugetlb_entry_migration(pte_t pte)
2321 {
2322         swp_entry_t swp;
2323
2324         if (huge_pte_none(pte) || pte_present(pte))
2325                 return 0;
2326         swp = pte_to_swp_entry(pte);
2327         if (non_swap_entry(swp) && is_migration_entry(swp))
2328                 return 1;
2329         else
2330                 return 0;
2331 }
2332
2333 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
2334 {
2335         swp_entry_t swp;
2336
2337         if (huge_pte_none(pte) || pte_present(pte))
2338                 return 0;
2339         swp = pte_to_swp_entry(pte);
2340         if (non_swap_entry(swp) && is_hwpoison_entry(swp))
2341                 return 1;
2342         else
2343                 return 0;
2344 }
2345
2346 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
2347                             unsigned long start, unsigned long end,
2348                             struct page *ref_page)
2349 {
2350         int force_flush = 0;
2351         struct mm_struct *mm = vma->vm_mm;
2352         unsigned long address;
2353         pte_t *ptep;
2354         pte_t pte;
2355         struct page *page;
2356         struct hstate *h = hstate_vma(vma);
2357         unsigned long sz = huge_page_size(h);
2358
2359         WARN_ON(!is_vm_hugetlb_page(vma));
2360         BUG_ON(start & ~huge_page_mask(h));
2361         BUG_ON(end & ~huge_page_mask(h));
2362
2363         tlb_start_vma(tlb, vma);
2364         mmu_notifier_invalidate_range_start(mm, start, end);
2365 again:
2366         spin_lock(&mm->page_table_lock);
2367         for (address = start; address < end; address += sz) {
2368                 ptep = huge_pte_offset(mm, address);
2369                 if (!ptep)
2370                         continue;
2371
2372                 if (huge_pmd_unshare(mm, &address, ptep))
2373                         continue;
2374
2375                 pte = huge_ptep_get(ptep);
2376                 if (huge_pte_none(pte))
2377                         continue;
2378
2379                 /*
2380                  * HWPoisoned hugepage is already unmapped and dropped reference
2381                  */
2382                 if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
2383                         continue;
2384
2385                 page = pte_page(pte);
2386                 /*
2387                  * If a reference page is supplied, it is because a specific
2388                  * page is being unmapped, not a range. Ensure the page we
2389                  * are about to unmap is the actual page of interest.
2390                  */
2391                 if (ref_page) {
2392                         if (page != ref_page)
2393                                 continue;
2394
2395                         /*
2396                          * Mark the VMA as having unmapped its page so that
2397                          * future faults in this VMA will fail rather than
2398                          * looking like data was lost
2399                          */
2400                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2401                 }
2402
2403                 pte = huge_ptep_get_and_clear(mm, address, ptep);
2404                 tlb_remove_tlb_entry(tlb, ptep, address);
2405                 if (pte_dirty(pte))
2406                         set_page_dirty(page);
2407
2408                 page_remove_rmap(page);
2409                 force_flush = !__tlb_remove_page(tlb, page);
2410                 if (force_flush)
2411                         break;
2412                 /* Bail out after unmapping reference page if supplied */
2413                 if (ref_page)
2414                         break;
2415         }
2416         spin_unlock(&mm->page_table_lock);
2417         /*
2418          * mmu_gather ran out of room to batch pages, we break out of
2419          * the PTE lock to avoid doing the potential expensive TLB invalidate
2420          * and page-free while holding it.
2421          */
2422         if (force_flush) {
2423                 force_flush = 0;
2424                 tlb_flush_mmu(tlb);
2425                 if (address < end && !ref_page)
2426                         goto again;
2427         }
2428         mmu_notifier_invalidate_range_end(mm, start, end);
2429         tlb_end_vma(tlb, vma);
2430 }
2431
2432 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2433                           unsigned long end, struct page *ref_page)
2434 {
2435         struct mm_struct *mm;
2436         struct mmu_gather tlb;
2437
2438         mm = vma->vm_mm;
2439
2440         tlb_gather_mmu(&tlb, mm, 0);
2441         __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
2442         tlb_finish_mmu(&tlb, start, end);
2443 }
2444
2445 /*
2446  * This is called when the original mapper is failing to COW a MAP_PRIVATE
2447  * mappping it owns the reserve page for. The intention is to unmap the page
2448  * from other VMAs and let the children be SIGKILLed if they are faulting the
2449  * same region.
2450  */
2451 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2452                                 struct page *page, unsigned long address)
2453 {
2454         struct hstate *h = hstate_vma(vma);
2455         struct vm_area_struct *iter_vma;
2456         struct address_space *mapping;
2457         struct prio_tree_iter iter;
2458         pgoff_t pgoff;
2459
2460         /*
2461          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2462          * from page cache lookup which is in HPAGE_SIZE units.
2463          */
2464         address = address & huge_page_mask(h);
2465         pgoff = vma_hugecache_offset(h, vma, address);
2466         mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
2467
2468         /*
2469          * Take the mapping lock for the duration of the table walk. As
2470          * this mapping should be shared between all the VMAs,
2471          * __unmap_hugepage_range() is called as the lock is already held
2472          */
2473         mutex_lock(&mapping->i_mmap_mutex);
2474         vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2475                 /* Do not unmap the current VMA */
2476                 if (iter_vma == vma)
2477                         continue;
2478
2479                 /*
2480                  * Unmap the page from other VMAs without their own reserves.
2481                  * They get marked to be SIGKILLed if they fault in these
2482                  * areas. This is because a future no-page fault on this VMA
2483                  * could insert a zeroed page instead of the data existing
2484                  * from the time of fork. This would look like data corruption
2485                  */
2486                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2487                         unmap_hugepage_range(iter_vma, address,
2488                                              address + huge_page_size(h), page);
2489         }
2490         mutex_unlock(&mapping->i_mmap_mutex);
2491
2492         return 1;
2493 }
2494
2495 /*
2496  * Hugetlb_cow() should be called with page lock of the original hugepage held.
2497  * Called with hugetlb_instantiation_mutex held and pte_page locked so we
2498  * cannot race with other handlers or page migration.
2499  * Keep the pte_same checks anyway to make transition from the mutex easier.
2500  */
2501 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2502                         unsigned long address, pte_t *ptep, pte_t pte,
2503                         struct page *pagecache_page)
2504 {
2505         struct hstate *h = hstate_vma(vma);
2506         struct page *old_page, *new_page;
2507         int avoidcopy;
2508         int outside_reserve = 0;
2509
2510         old_page = pte_page(pte);
2511
2512 retry_avoidcopy:
2513         /* If no-one else is actually using this page, avoid the copy
2514          * and just make the page writable */
2515         avoidcopy = (page_mapcount(old_page) == 1);
2516         if (avoidcopy) {
2517                 if (PageAnon(old_page))
2518                         page_move_anon_rmap(old_page, vma, address);
2519                 set_huge_ptep_writable(vma, address, ptep);
2520                 return 0;
2521         }
2522
2523         /*
2524          * If the process that created a MAP_PRIVATE mapping is about to
2525          * perform a COW due to a shared page count, attempt to satisfy
2526          * the allocation without using the existing reserves. The pagecache
2527          * page is used to determine if the reserve at this address was
2528          * consumed or not. If reserves were used, a partial faulted mapping
2529          * at the time of fork() could consume its reserves on COW instead
2530          * of the full address range.
2531          */
2532         if (!(vma->vm_flags & VM_MAYSHARE) &&
2533                         is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2534                         old_page != pagecache_page)
2535                 outside_reserve = 1;
2536
2537         page_cache_get(old_page);
2538
2539         /* Drop page_table_lock as buddy allocator may be called */
2540         spin_unlock(&mm->page_table_lock);
2541         new_page = alloc_huge_page(vma, address, outside_reserve);
2542
2543         if (IS_ERR(new_page)) {
2544                 long err = PTR_ERR(new_page);
2545                 page_cache_release(old_page);
2546
2547                 /*
2548                  * If a process owning a MAP_PRIVATE mapping fails to COW,
2549                  * it is due to references held by a child and an insufficient
2550                  * huge page pool. To guarantee the original mappers
2551                  * reliability, unmap the page from child processes. The child
2552                  * may get SIGKILLed if it later faults.
2553                  */
2554                 if (outside_reserve) {
2555                         BUG_ON(huge_pte_none(pte));
2556                         if (unmap_ref_private(mm, vma, old_page, address)) {
2557                                 BUG_ON(huge_pte_none(pte));
2558                                 spin_lock(&mm->page_table_lock);
2559                                 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2560                                 if (likely(pte_same(huge_ptep_get(ptep), pte)))
2561                                         goto retry_avoidcopy;
2562                                 /*
2563                                  * race occurs while re-acquiring page_table_lock, and
2564                                  * our job is done.
2565                                  */
2566                                 return 0;
2567                         }
2568                         WARN_ON_ONCE(1);
2569                 }
2570
2571                 /* Caller expects lock to be held */
2572                 spin_lock(&mm->page_table_lock);
2573                 if (err == -ENOMEM)
2574                         return VM_FAULT_OOM;
2575                 else
2576                         return VM_FAULT_SIGBUS;
2577         }
2578
2579         /*
2580          * When the original hugepage is shared one, it does not have
2581          * anon_vma prepared.
2582          */
2583         if (unlikely(anon_vma_prepare(vma))) {
2584                 page_cache_release(new_page);
2585                 page_cache_release(old_page);
2586                 /* Caller expects lock to be held */
2587                 spin_lock(&mm->page_table_lock);
2588                 return VM_FAULT_OOM;
2589         }
2590
2591         copy_user_huge_page(new_page, old_page, address, vma,
2592                             pages_per_huge_page(h));
2593         __SetPageUptodate(new_page);
2594
2595         /*
2596          * Retake the page_table_lock to check for racing updates
2597          * before the page tables are altered
2598          */
2599         spin_lock(&mm->page_table_lock);
2600         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2601         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2602                 /* Break COW */
2603                 mmu_notifier_invalidate_range_start(mm,
2604                         address & huge_page_mask(h),
2605                         (address & huge_page_mask(h)) + huge_page_size(h));
2606                 huge_ptep_clear_flush(vma, address, ptep);
2607                 set_huge_pte_at(mm, address, ptep,
2608                                 make_huge_pte(vma, new_page, 1));
2609                 page_remove_rmap(old_page);
2610                 hugepage_add_new_anon_rmap(new_page, vma, address);
2611                 /* Make the old page be freed below */
2612                 new_page = old_page;
2613                 mmu_notifier_invalidate_range_end(mm,
2614                         address & huge_page_mask(h),
2615                         (address & huge_page_mask(h)) + huge_page_size(h));
2616         }
2617         page_cache_release(new_page);
2618         page_cache_release(old_page);
2619         return 0;
2620 }
2621
2622 /* Return the pagecache page at a given address within a VMA */
2623 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2624                         struct vm_area_struct *vma, unsigned long address)
2625 {
2626         struct address_space *mapping;
2627         pgoff_t idx;
2628
2629         mapping = vma->vm_file->f_mapping;
2630         idx = vma_hugecache_offset(h, vma, address);
2631
2632         return find_lock_page(mapping, idx);
2633 }
2634
2635 /*
2636  * Return whether there is a pagecache page to back given address within VMA.
2637  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2638  */
2639 static bool hugetlbfs_pagecache_present(struct hstate *h,
2640                         struct vm_area_struct *vma, unsigned long address)
2641 {
2642         struct address_space *mapping;
2643         pgoff_t idx;
2644         struct page *page;
2645
2646         mapping = vma->vm_file->f_mapping;
2647         idx = vma_hugecache_offset(h, vma, address);
2648
2649         page = find_get_page(mapping, idx);
2650         if (page)
2651                 put_page(page);
2652         return page != NULL;
2653 }
2654
2655 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2656                         unsigned long address, pte_t *ptep, unsigned int flags)
2657 {
2658         struct hstate *h = hstate_vma(vma);
2659         int ret = VM_FAULT_SIGBUS;
2660         int anon_rmap = 0;
2661         pgoff_t idx;
2662         unsigned long size;
2663         struct page *page;
2664         struct address_space *mapping;
2665         pte_t new_pte;
2666
2667         /*
2668          * Currently, we are forced to kill the process in the event the
2669          * original mapper has unmapped pages from the child due to a failed
2670          * COW. Warn that such a situation has occurred as it may not be obvious
2671          */
2672         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2673                 printk(KERN_WARNING
2674                         "PID %d killed due to inadequate hugepage pool\n",
2675                         current->pid);
2676                 return ret;
2677         }
2678
2679         mapping = vma->vm_file->f_mapping;
2680         idx = vma_hugecache_offset(h, vma, address);
2681
2682         /*
2683          * Use page lock to guard against racing truncation
2684          * before we get page_table_lock.
2685          */
2686 retry:
2687         page = find_lock_page(mapping, idx);
2688         if (!page) {
2689                 size = i_size_read(mapping->host) >> huge_page_shift(h);
2690                 if (idx >= size)
2691                         goto out;
2692                 page = alloc_huge_page(vma, address, 0);
2693                 if (IS_ERR(page)) {
2694                         ret = PTR_ERR(page);
2695                         if (ret == -ENOMEM)
2696                                 ret = VM_FAULT_OOM;
2697                         else
2698                                 ret = VM_FAULT_SIGBUS;
2699                         goto out;
2700                 }
2701                 clear_huge_page(page, address, pages_per_huge_page(h));
2702                 __SetPageUptodate(page);
2703
2704                 if (vma->vm_flags & VM_MAYSHARE) {
2705                         int err;
2706                         struct inode *inode = mapping->host;
2707
2708                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2709                         if (err) {
2710                                 put_page(page);
2711                                 if (err == -EEXIST)
2712                                         goto retry;
2713                                 goto out;
2714                         }
2715
2716                         spin_lock(&inode->i_lock);
2717                         inode->i_blocks += blocks_per_huge_page(h);
2718                         spin_unlock(&inode->i_lock);
2719                 } else {
2720                         lock_page(page);
2721                         if (unlikely(anon_vma_prepare(vma))) {
2722                                 ret = VM_FAULT_OOM;
2723                                 goto backout_unlocked;
2724                         }
2725                         anon_rmap = 1;
2726                 }
2727         } else {
2728                 /*
2729                  * If memory error occurs between mmap() and fault, some process
2730                  * don't have hwpoisoned swap entry for errored virtual address.
2731                  * So we need to block hugepage fault by PG_hwpoison bit check.
2732                  */
2733                 if (unlikely(PageHWPoison(page))) {
2734                         ret = VM_FAULT_HWPOISON |
2735                                 VM_FAULT_SET_HINDEX(hstate_index(h));
2736                         goto backout_unlocked;
2737                 }
2738         }
2739
2740         /*
2741          * If we are going to COW a private mapping later, we examine the
2742          * pending reservations for this page now. This will ensure that
2743          * any allocations necessary to record that reservation occur outside
2744          * the spinlock.
2745          */
2746         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2747                 if (vma_needs_reservation(h, vma, address) < 0) {
2748                         ret = VM_FAULT_OOM;
2749                         goto backout_unlocked;
2750                 }
2751
2752         spin_lock(&mm->page_table_lock);
2753         size = i_size_read(mapping->host) >> huge_page_shift(h);
2754         if (idx >= size)
2755                 goto backout;
2756
2757         ret = 0;
2758         if (!huge_pte_none(huge_ptep_get(ptep)))
2759                 goto backout;
2760
2761         if (anon_rmap)
2762                 hugepage_add_new_anon_rmap(page, vma, address);
2763         else
2764                 page_dup_rmap(page);
2765         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2766                                 && (vma->vm_flags & VM_SHARED)));
2767         set_huge_pte_at(mm, address, ptep, new_pte);
2768
2769         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2770                 /* Optimization, do the COW without a second fault */
2771                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2772         }
2773
2774         spin_unlock(&mm->page_table_lock);
2775         unlock_page(page);
2776 out:
2777         return ret;
2778
2779 backout:
2780         spin_unlock(&mm->page_table_lock);
2781 backout_unlocked:
2782         unlock_page(page);
2783         put_page(page);
2784         goto out;
2785 }
2786
2787 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2788                         unsigned long address, unsigned int flags)
2789 {
2790         pte_t *ptep;
2791         pte_t entry;
2792         int ret;
2793         struct page *page = NULL;
2794         struct page *pagecache_page = NULL;
2795         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2796         struct hstate *h = hstate_vma(vma);
2797
2798         address &= huge_page_mask(h);
2799
2800         ptep = huge_pte_offset(mm, address);
2801         if (ptep) {
2802                 entry = huge_ptep_get(ptep);
2803                 if (unlikely(is_hugetlb_entry_migration(entry))) {
2804                         migration_entry_wait(mm, (pmd_t *)ptep, address);
2805                         return 0;
2806                 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
2807                         return VM_FAULT_HWPOISON_LARGE |
2808                                 VM_FAULT_SET_HINDEX(hstate_index(h));
2809         }
2810
2811         ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2812         if (!ptep)
2813                 return VM_FAULT_OOM;
2814
2815         /*
2816          * Serialize hugepage allocation and instantiation, so that we don't
2817          * get spurious allocation failures if two CPUs race to instantiate
2818          * the same page in the page cache.
2819          */
2820         mutex_lock(&hugetlb_instantiation_mutex);
2821         entry = huge_ptep_get(ptep);
2822         if (huge_pte_none(entry)) {
2823                 ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2824                 goto out_mutex;
2825         }
2826
2827         ret = 0;
2828
2829         /*
2830          * If we are going to COW the mapping later, we examine the pending
2831          * reservations for this page now. This will ensure that any
2832          * allocations necessary to record that reservation occur outside the
2833          * spinlock. For private mappings, we also lookup the pagecache
2834          * page now as it is used to determine if a reservation has been
2835          * consumed.
2836          */
2837         if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2838                 if (vma_needs_reservation(h, vma, address) < 0) {
2839                         ret = VM_FAULT_OOM;
2840                         goto out_mutex;
2841                 }
2842
2843                 if (!(vma->vm_flags & VM_MAYSHARE))
2844                         pagecache_page = hugetlbfs_pagecache_page(h,
2845                                                                 vma, address);
2846         }
2847
2848         /*
2849          * hugetlb_cow() requires page locks of pte_page(entry) and
2850          * pagecache_page, so here we need take the former one
2851          * when page != pagecache_page or !pagecache_page.
2852          * Note that locking order is always pagecache_page -> page,
2853          * so no worry about deadlock.
2854          */
2855         page = pte_page(entry);
2856         get_page(page);
2857         if (page != pagecache_page)
2858                 lock_page(page);
2859
2860         spin_lock(&mm->page_table_lock);
2861         /* Check for a racing update before calling hugetlb_cow */
2862         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2863                 goto out_page_table_lock;
2864
2865
2866         if (flags & FAULT_FLAG_WRITE) {
2867                 if (!pte_write(entry)) {
2868                         ret = hugetlb_cow(mm, vma, address, ptep, entry,
2869                                                         pagecache_page);
2870                         goto out_page_table_lock;
2871                 }
2872                 entry = pte_mkdirty(entry);
2873         }
2874         entry = pte_mkyoung(entry);
2875         if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2876                                                 flags & FAULT_FLAG_WRITE))
2877                 update_mmu_cache(vma, address, ptep);
2878
2879 out_page_table_lock:
2880         spin_unlock(&mm->page_table_lock);
2881
2882         if (pagecache_page) {
2883                 unlock_page(pagecache_page);
2884                 put_page(pagecache_page);
2885         }
2886         if (page != pagecache_page)
2887                 unlock_page(page);
2888         put_page(page);
2889
2890 out_mutex:
2891         mutex_unlock(&hugetlb_instantiation_mutex);
2892
2893         return ret;
2894 }
2895
2896 /* Can be overriden by architectures */
2897 __attribute__((weak)) struct page *
2898 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2899                pud_t *pud, int write)
2900 {
2901         BUG();
2902         return NULL;
2903 }
2904
2905 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2906                         struct page **pages, struct vm_area_struct **vmas,
2907                         unsigned long *position, int *length, int i,
2908                         unsigned int flags)
2909 {
2910         unsigned long pfn_offset;
2911         unsigned long vaddr = *position;
2912         int remainder = *length;
2913         struct hstate *h = hstate_vma(vma);
2914
2915         spin_lock(&mm->page_table_lock);
2916         while (vaddr < vma->vm_end && remainder) {
2917                 pte_t *pte;
2918                 int absent;
2919                 struct page *page;
2920
2921                 /*
2922                  * Some archs (sparc64, sh*) have multiple pte_ts to
2923                  * each hugepage.  We have to make sure we get the
2924                  * first, for the page indexing below to work.
2925                  */
2926                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2927                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
2928
2929                 /*
2930                  * When coredumping, it suits get_dump_page if we just return
2931                  * an error where there's an empty slot with no huge pagecache
2932                  * to back it.  This way, we avoid allocating a hugepage, and
2933                  * the sparse dumpfile avoids allocating disk blocks, but its
2934                  * huge holes still show up with zeroes where they need to be.
2935                  */
2936                 if (absent && (flags & FOLL_DUMP) &&
2937                     !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2938                         remainder = 0;
2939                         break;
2940                 }
2941
2942                 if (absent ||
2943                     ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2944                         int ret;
2945
2946                         spin_unlock(&mm->page_table_lock);
2947                         ret = hugetlb_fault(mm, vma, vaddr,
2948                                 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2949                         spin_lock(&mm->page_table_lock);
2950                         if (!(ret & VM_FAULT_ERROR))
2951                                 continue;
2952
2953                         remainder = 0;
2954                         break;
2955                 }
2956
2957                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2958                 page = pte_page(huge_ptep_get(pte));
2959 same_page:
2960                 if (pages) {
2961                         pages[i] = mem_map_offset(page, pfn_offset);
2962                         get_page(pages[i]);
2963                 }
2964
2965                 if (vmas)
2966                         vmas[i] = vma;
2967
2968                 vaddr += PAGE_SIZE;
2969                 ++pfn_offset;
2970                 --remainder;
2971                 ++i;
2972                 if (vaddr < vma->vm_end && remainder &&
2973                                 pfn_offset < pages_per_huge_page(h)) {
2974                         /*
2975                          * We use pfn_offset to avoid touching the pageframes
2976                          * of this compound page.
2977                          */
2978                         goto same_page;
2979                 }
2980         }
2981         spin_unlock(&mm->page_table_lock);
2982         *length = remainder;
2983         *position = vaddr;
2984
2985         return i ? i : -EFAULT;
2986 }
2987
2988 void hugetlb_change_protection(struct vm_area_struct *vma,
2989                 unsigned long address, unsigned long end, pgprot_t newprot)
2990 {
2991         struct mm_struct *mm = vma->vm_mm;
2992         unsigned long start = address;
2993         pte_t *ptep;
2994         pte_t pte;
2995         struct hstate *h = hstate_vma(vma);
2996
2997         BUG_ON(address >= end);
2998         flush_cache_range(vma, address, end);
2999
3000         mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
3001         spin_lock(&mm->page_table_lock);
3002         for (; address < end; address += huge_page_size(h)) {
3003                 ptep = huge_pte_offset(mm, address);
3004                 if (!ptep)
3005                         continue;
3006                 if (huge_pmd_unshare(mm, &address, ptep))
3007                         continue;
3008                 if (!huge_pte_none(huge_ptep_get(ptep))) {
3009                         pte = huge_ptep_get_and_clear(mm, address, ptep);
3010                         pte = pte_mkhuge(pte_modify(pte, newprot));
3011                         set_huge_pte_at(mm, address, ptep, pte);
3012                 }
3013         }
3014         spin_unlock(&mm->page_table_lock);
3015         mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
3016
3017         flush_tlb_range(vma, start, end);
3018 }
3019
3020 int hugetlb_reserve_pages(struct inode *inode,
3021                                         long from, long to,
3022                                         struct vm_area_struct *vma,
3023                                         vm_flags_t vm_flags)
3024 {
3025         long ret, chg;
3026         struct hstate *h = hstate_inode(inode);
3027         struct hugepage_subpool *spool = subpool_inode(inode);
3028
3029         /*
3030          * Only apply hugepage reservation if asked. At fault time, an
3031          * attempt will be made for VM_NORESERVE to allocate a page
3032          * without using reserves
3033          */
3034         if (vm_flags & VM_NORESERVE)
3035                 return 0;
3036
3037         /*
3038          * Shared mappings base their reservation on the number of pages that
3039          * are already allocated on behalf of the file. Private mappings need
3040          * to reserve the full area even if read-only as mprotect() may be
3041          * called to make the mapping read-write. Assume !vma is a shm mapping
3042          */
3043         if (!vma || vma->vm_flags & VM_MAYSHARE)
3044                 chg = region_chg(&inode->i_mapping->private_list, from, to);
3045         else {
3046                 struct resv_map *resv_map = resv_map_alloc();
3047                 if (!resv_map)
3048                         return -ENOMEM;
3049
3050                 chg = to - from;
3051
3052                 set_vma_resv_map(vma, resv_map);
3053                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
3054         }
3055
3056         if (chg < 0) {
3057                 ret = chg;
3058                 goto out_err;
3059         }
3060
3061         /* There must be enough pages in the subpool for the mapping */
3062         if (hugepage_subpool_get_pages(spool, chg)) {
3063                 ret = -ENOSPC;
3064                 goto out_err;
3065         }
3066
3067         /*
3068          * Check enough hugepages are available for the reservation.
3069          * Hand the pages back to the subpool if there are not
3070          */
3071         ret = hugetlb_acct_memory(h, chg);
3072         if (ret < 0) {
3073                 hugepage_subpool_put_pages(spool, chg);
3074                 goto out_err;
3075         }
3076
3077         /*
3078          * Account for the reservations made. Shared mappings record regions
3079          * that have reservations as they are shared by multiple VMAs.
3080          * When the last VMA disappears, the region map says how much
3081          * the reservation was and the page cache tells how much of
3082          * the reservation was consumed. Private mappings are per-VMA and
3083          * only the consumed reservations are tracked. When the VMA
3084          * disappears, the original reservation is the VMA size and the
3085          * consumed reservations are stored in the map. Hence, nothing
3086          * else has to be done for private mappings here
3087          */
3088         if (!vma || vma->vm_flags & VM_MAYSHARE)
3089                 region_add(&inode->i_mapping->private_list, from, to);
3090         return 0;
3091 out_err:
3092         if (vma)
3093                 resv_map_put(vma);
3094         return ret;
3095 }
3096
3097 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
3098 {
3099         struct hstate *h = hstate_inode(inode);
3100         long chg = region_truncate(&inode->i_mapping->private_list, offset);
3101         struct hugepage_subpool *spool = subpool_inode(inode);
3102
3103         spin_lock(&inode->i_lock);
3104         inode->i_blocks -= (blocks_per_huge_page(h) * freed);
3105         spin_unlock(&inode->i_lock);
3106
3107         hugepage_subpool_put_pages(spool, (chg - freed));
3108         hugetlb_acct_memory(h, -(chg - freed));
3109 }
3110
3111 #ifdef CONFIG_MEMORY_FAILURE
3112
3113 /* Should be called in hugetlb_lock */
3114 static int is_hugepage_on_freelist(struct page *hpage)
3115 {
3116         struct page *page;
3117         struct page *tmp;
3118         struct hstate *h = page_hstate(hpage);
3119         int nid = page_to_nid(hpage);
3120
3121         list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
3122                 if (page == hpage)
3123                         return 1;
3124         return 0;
3125 }
3126
3127 /*
3128  * This function is called from memory failure code.
3129  * Assume the caller holds page lock of the head page.
3130  */
3131 int dequeue_hwpoisoned_huge_page(struct page *hpage)
3132 {
3133         struct hstate *h = page_hstate(hpage);
3134         int nid = page_to_nid(hpage);
3135         int ret = -EBUSY;
3136
3137         spin_lock(&hugetlb_lock);
3138         if (is_hugepage_on_freelist(hpage)) {
3139                 list_del(&hpage->lru);
3140                 set_page_refcounted(hpage);
3141                 h->free_huge_pages--;
3142                 h->free_huge_pages_node[nid]--;
3143                 ret = 0;
3144         }
3145         spin_unlock(&hugetlb_lock);
3146         return ret;
3147 }
3148 #endif