hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race
[sfrench/cifs-2.6.git] / mm / hugetlb.c
1 /*
2  * Generic hugetlb support.
3  * (C) Nadia Yvette Chambers, April 2004
4  */
5 #include <linux/list.h>
6 #include <linux/init.h>
7 #include <linux/mm.h>
8 #include <linux/seq_file.h>
9 #include <linux/sysctl.h>
10 #include <linux/highmem.h>
11 #include <linux/mmu_notifier.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/compiler.h>
16 #include <linux/cpuset.h>
17 #include <linux/mutex.h>
18 #include <linux/memblock.h>
19 #include <linux/sysfs.h>
20 #include <linux/slab.h>
21 #include <linux/mmdebug.h>
22 #include <linux/sched/signal.h>
23 #include <linux/rmap.h>
24 #include <linux/string_helpers.h>
25 #include <linux/swap.h>
26 #include <linux/swapops.h>
27 #include <linux/jhash.h>
28
29 #include <asm/page.h>
30 #include <asm/pgtable.h>
31 #include <asm/tlb.h>
32
33 #include <linux/io.h>
34 #include <linux/hugetlb.h>
35 #include <linux/hugetlb_cgroup.h>
36 #include <linux/node.h>
37 #include <linux/userfaultfd_k.h>
38 #include <linux/page_owner.h>
39 #include "internal.h"
40
41 int hugetlb_max_hstate __read_mostly;
42 unsigned int default_hstate_idx;
43 struct hstate hstates[HUGE_MAX_HSTATE];
44 /*
45  * Minimum page order among possible hugepage sizes, set to a proper value
46  * at boot time.
47  */
48 static unsigned int minimum_order __read_mostly = UINT_MAX;
49
50 __initdata LIST_HEAD(huge_boot_pages);
51
52 /* for command line parsing */
53 static struct hstate * __initdata parsed_hstate;
54 static unsigned long __initdata default_hstate_max_huge_pages;
55 static unsigned long __initdata default_hstate_size;
56 static bool __initdata parsed_valid_hugepagesz = true;
57
58 /*
59  * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
60  * free_huge_pages, and surplus_huge_pages.
61  */
62 DEFINE_SPINLOCK(hugetlb_lock);
63
64 /*
65  * Serializes faults on the same logical page.  This is used to
66  * prevent spurious OOMs when the hugepage pool is fully utilized.
67  */
68 static int num_fault_mutexes;
69 struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
70
71 /* Forward declaration */
72 static int hugetlb_acct_memory(struct hstate *h, long delta);
73
74 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
75 {
76         bool free = (spool->count == 0) && (spool->used_hpages == 0);
77
78         spin_unlock(&spool->lock);
79
80         /* If no pages are used, and no other handles to the subpool
81          * remain, give up any reservations mased on minimum size and
82          * free the subpool */
83         if (free) {
84                 if (spool->min_hpages != -1)
85                         hugetlb_acct_memory(spool->hstate,
86                                                 -spool->min_hpages);
87                 kfree(spool);
88         }
89 }
90
91 struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
92                                                 long min_hpages)
93 {
94         struct hugepage_subpool *spool;
95
96         spool = kzalloc(sizeof(*spool), GFP_KERNEL);
97         if (!spool)
98                 return NULL;
99
100         spin_lock_init(&spool->lock);
101         spool->count = 1;
102         spool->max_hpages = max_hpages;
103         spool->hstate = h;
104         spool->min_hpages = min_hpages;
105
106         if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
107                 kfree(spool);
108                 return NULL;
109         }
110         spool->rsv_hpages = min_hpages;
111
112         return spool;
113 }
114
115 void hugepage_put_subpool(struct hugepage_subpool *spool)
116 {
117         spin_lock(&spool->lock);
118         BUG_ON(!spool->count);
119         spool->count--;
120         unlock_or_release_subpool(spool);
121 }
122
123 /*
124  * Subpool accounting for allocating and reserving pages.
125  * Return -ENOMEM if there are not enough resources to satisfy the
126  * the request.  Otherwise, return the number of pages by which the
127  * global pools must be adjusted (upward).  The returned value may
128  * only be different than the passed value (delta) in the case where
129  * a subpool minimum size must be manitained.
130  */
131 static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
132                                       long delta)
133 {
134         long ret = delta;
135
136         if (!spool)
137                 return ret;
138
139         spin_lock(&spool->lock);
140
141         if (spool->max_hpages != -1) {          /* maximum size accounting */
142                 if ((spool->used_hpages + delta) <= spool->max_hpages)
143                         spool->used_hpages += delta;
144                 else {
145                         ret = -ENOMEM;
146                         goto unlock_ret;
147                 }
148         }
149
150         /* minimum size accounting */
151         if (spool->min_hpages != -1 && spool->rsv_hpages) {
152                 if (delta > spool->rsv_hpages) {
153                         /*
154                          * Asking for more reserves than those already taken on
155                          * behalf of subpool.  Return difference.
156                          */
157                         ret = delta - spool->rsv_hpages;
158                         spool->rsv_hpages = 0;
159                 } else {
160                         ret = 0;        /* reserves already accounted for */
161                         spool->rsv_hpages -= delta;
162                 }
163         }
164
165 unlock_ret:
166         spin_unlock(&spool->lock);
167         return ret;
168 }
169
170 /*
171  * Subpool accounting for freeing and unreserving pages.
172  * Return the number of global page reservations that must be dropped.
173  * The return value may only be different than the passed value (delta)
174  * in the case where a subpool minimum size must be maintained.
175  */
176 static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
177                                        long delta)
178 {
179         long ret = delta;
180
181         if (!spool)
182                 return delta;
183
184         spin_lock(&spool->lock);
185
186         if (spool->max_hpages != -1)            /* maximum size accounting */
187                 spool->used_hpages -= delta;
188
189          /* minimum size accounting */
190         if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
191                 if (spool->rsv_hpages + delta <= spool->min_hpages)
192                         ret = 0;
193                 else
194                         ret = spool->rsv_hpages + delta - spool->min_hpages;
195
196                 spool->rsv_hpages += delta;
197                 if (spool->rsv_hpages > spool->min_hpages)
198                         spool->rsv_hpages = spool->min_hpages;
199         }
200
201         /*
202          * If hugetlbfs_put_super couldn't free spool due to an outstanding
203          * quota reference, free it now.
204          */
205         unlock_or_release_subpool(spool);
206
207         return ret;
208 }
209
210 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
211 {
212         return HUGETLBFS_SB(inode->i_sb)->spool;
213 }
214
215 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
216 {
217         return subpool_inode(file_inode(vma->vm_file));
218 }
219
220 /*
221  * Region tracking -- allows tracking of reservations and instantiated pages
222  *                    across the pages in a mapping.
223  *
224  * The region data structures are embedded into a resv_map and protected
225  * by a resv_map's lock.  The set of regions within the resv_map represent
226  * reservations for huge pages, or huge pages that have already been
227  * instantiated within the map.  The from and to elements are huge page
228  * indicies into the associated mapping.  from indicates the starting index
229  * of the region.  to represents the first index past the end of  the region.
230  *
231  * For example, a file region structure with from == 0 and to == 4 represents
232  * four huge pages in a mapping.  It is important to note that the to element
233  * represents the first element past the end of the region. This is used in
234  * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
235  *
236  * Interval notation of the form [from, to) will be used to indicate that
237  * the endpoint from is inclusive and to is exclusive.
238  */
239 struct file_region {
240         struct list_head link;
241         long from;
242         long to;
243 };
244
245 /*
246  * Add the huge page range represented by [f, t) to the reserve
247  * map.  In the normal case, existing regions will be expanded
248  * to accommodate the specified range.  Sufficient regions should
249  * exist for expansion due to the previous call to region_chg
250  * with the same range.  However, it is possible that region_del
251  * could have been called after region_chg and modifed the map
252  * in such a way that no region exists to be expanded.  In this
253  * case, pull a region descriptor from the cache associated with
254  * the map and use that for the new range.
255  *
256  * Return the number of new huge pages added to the map.  This
257  * number is greater than or equal to zero.
258  */
259 static long region_add(struct resv_map *resv, long f, long t)
260 {
261         struct list_head *head = &resv->regions;
262         struct file_region *rg, *nrg, *trg;
263         long add = 0;
264
265         spin_lock(&resv->lock);
266         /* Locate the region we are either in or before. */
267         list_for_each_entry(rg, head, link)
268                 if (f <= rg->to)
269                         break;
270
271         /*
272          * If no region exists which can be expanded to include the
273          * specified range, the list must have been modified by an
274          * interleving call to region_del().  Pull a region descriptor
275          * from the cache and use it for this range.
276          */
277         if (&rg->link == head || t < rg->from) {
278                 VM_BUG_ON(resv->region_cache_count <= 0);
279
280                 resv->region_cache_count--;
281                 nrg = list_first_entry(&resv->region_cache, struct file_region,
282                                         link);
283                 list_del(&nrg->link);
284
285                 nrg->from = f;
286                 nrg->to = t;
287                 list_add(&nrg->link, rg->link.prev);
288
289                 add += t - f;
290                 goto out_locked;
291         }
292
293         /* Round our left edge to the current segment if it encloses us. */
294         if (f > rg->from)
295                 f = rg->from;
296
297         /* Check for and consume any regions we now overlap with. */
298         nrg = rg;
299         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
300                 if (&rg->link == head)
301                         break;
302                 if (rg->from > t)
303                         break;
304
305                 /* If this area reaches higher then extend our area to
306                  * include it completely.  If this is not the first area
307                  * which we intend to reuse, free it. */
308                 if (rg->to > t)
309                         t = rg->to;
310                 if (rg != nrg) {
311                         /* Decrement return value by the deleted range.
312                          * Another range will span this area so that by
313                          * end of routine add will be >= zero
314                          */
315                         add -= (rg->to - rg->from);
316                         list_del(&rg->link);
317                         kfree(rg);
318                 }
319         }
320
321         add += (nrg->from - f);         /* Added to beginning of region */
322         nrg->from = f;
323         add += t - nrg->to;             /* Added to end of region */
324         nrg->to = t;
325
326 out_locked:
327         resv->adds_in_progress--;
328         spin_unlock(&resv->lock);
329         VM_BUG_ON(add < 0);
330         return add;
331 }
332
333 /*
334  * Examine the existing reserve map and determine how many
335  * huge pages in the specified range [f, t) are NOT currently
336  * represented.  This routine is called before a subsequent
337  * call to region_add that will actually modify the reserve
338  * map to add the specified range [f, t).  region_chg does
339  * not change the number of huge pages represented by the
340  * map.  However, if the existing regions in the map can not
341  * be expanded to represent the new range, a new file_region
342  * structure is added to the map as a placeholder.  This is
343  * so that the subsequent region_add call will have all the
344  * regions it needs and will not fail.
345  *
346  * Upon entry, region_chg will also examine the cache of region descriptors
347  * associated with the map.  If there are not enough descriptors cached, one
348  * will be allocated for the in progress add operation.
349  *
350  * Returns the number of huge pages that need to be added to the existing
351  * reservation map for the range [f, t).  This number is greater or equal to
352  * zero.  -ENOMEM is returned if a new file_region structure or cache entry
353  * is needed and can not be allocated.
354  */
355 static long region_chg(struct resv_map *resv, long f, long t)
356 {
357         struct list_head *head = &resv->regions;
358         struct file_region *rg, *nrg = NULL;
359         long chg = 0;
360
361 retry:
362         spin_lock(&resv->lock);
363 retry_locked:
364         resv->adds_in_progress++;
365
366         /*
367          * Check for sufficient descriptors in the cache to accommodate
368          * the number of in progress add operations.
369          */
370         if (resv->adds_in_progress > resv->region_cache_count) {
371                 struct file_region *trg;
372
373                 VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
374                 /* Must drop lock to allocate a new descriptor. */
375                 resv->adds_in_progress--;
376                 spin_unlock(&resv->lock);
377
378                 trg = kmalloc(sizeof(*trg), GFP_KERNEL);
379                 if (!trg) {
380                         kfree(nrg);
381                         return -ENOMEM;
382                 }
383
384                 spin_lock(&resv->lock);
385                 list_add(&trg->link, &resv->region_cache);
386                 resv->region_cache_count++;
387                 goto retry_locked;
388         }
389
390         /* Locate the region we are before or in. */
391         list_for_each_entry(rg, head, link)
392                 if (f <= rg->to)
393                         break;
394
395         /* If we are below the current region then a new region is required.
396          * Subtle, allocate a new region at the position but make it zero
397          * size such that we can guarantee to record the reservation. */
398         if (&rg->link == head || t < rg->from) {
399                 if (!nrg) {
400                         resv->adds_in_progress--;
401                         spin_unlock(&resv->lock);
402                         nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
403                         if (!nrg)
404                                 return -ENOMEM;
405
406                         nrg->from = f;
407                         nrg->to   = f;
408                         INIT_LIST_HEAD(&nrg->link);
409                         goto retry;
410                 }
411
412                 list_add(&nrg->link, rg->link.prev);
413                 chg = t - f;
414                 goto out_nrg;
415         }
416
417         /* Round our left edge to the current segment if it encloses us. */
418         if (f > rg->from)
419                 f = rg->from;
420         chg = t - f;
421
422         /* Check for and consume any regions we now overlap with. */
423         list_for_each_entry(rg, rg->link.prev, link) {
424                 if (&rg->link == head)
425                         break;
426                 if (rg->from > t)
427                         goto out;
428
429                 /* We overlap with this area, if it extends further than
430                  * us then we must extend ourselves.  Account for its
431                  * existing reservation. */
432                 if (rg->to > t) {
433                         chg += rg->to - t;
434                         t = rg->to;
435                 }
436                 chg -= rg->to - rg->from;
437         }
438
439 out:
440         spin_unlock(&resv->lock);
441         /*  We already know we raced and no longer need the new region */
442         kfree(nrg);
443         return chg;
444 out_nrg:
445         spin_unlock(&resv->lock);
446         return chg;
447 }
448
449 /*
450  * Abort the in progress add operation.  The adds_in_progress field
451  * of the resv_map keeps track of the operations in progress between
452  * calls to region_chg and region_add.  Operations are sometimes
453  * aborted after the call to region_chg.  In such cases, region_abort
454  * is called to decrement the adds_in_progress counter.
455  *
456  * NOTE: The range arguments [f, t) are not needed or used in this
457  * routine.  They are kept to make reading the calling code easier as
458  * arguments will match the associated region_chg call.
459  */
460 static void region_abort(struct resv_map *resv, long f, long t)
461 {
462         spin_lock(&resv->lock);
463         VM_BUG_ON(!resv->region_cache_count);
464         resv->adds_in_progress--;
465         spin_unlock(&resv->lock);
466 }
467
468 /*
469  * Delete the specified range [f, t) from the reserve map.  If the
470  * t parameter is LONG_MAX, this indicates that ALL regions after f
471  * should be deleted.  Locate the regions which intersect [f, t)
472  * and either trim, delete or split the existing regions.
473  *
474  * Returns the number of huge pages deleted from the reserve map.
475  * In the normal case, the return value is zero or more.  In the
476  * case where a region must be split, a new region descriptor must
477  * be allocated.  If the allocation fails, -ENOMEM will be returned.
478  * NOTE: If the parameter t == LONG_MAX, then we will never split
479  * a region and possibly return -ENOMEM.  Callers specifying
480  * t == LONG_MAX do not need to check for -ENOMEM error.
481  */
482 static long region_del(struct resv_map *resv, long f, long t)
483 {
484         struct list_head *head = &resv->regions;
485         struct file_region *rg, *trg;
486         struct file_region *nrg = NULL;
487         long del = 0;
488
489 retry:
490         spin_lock(&resv->lock);
491         list_for_each_entry_safe(rg, trg, head, link) {
492                 /*
493                  * Skip regions before the range to be deleted.  file_region
494                  * ranges are normally of the form [from, to).  However, there
495                  * may be a "placeholder" entry in the map which is of the form
496                  * (from, to) with from == to.  Check for placeholder entries
497                  * at the beginning of the range to be deleted.
498                  */
499                 if (rg->to <= f && (rg->to != rg->from || rg->to != f))
500                         continue;
501
502                 if (rg->from >= t)
503                         break;
504
505                 if (f > rg->from && t < rg->to) { /* Must split region */
506                         /*
507                          * Check for an entry in the cache before dropping
508                          * lock and attempting allocation.
509                          */
510                         if (!nrg &&
511                             resv->region_cache_count > resv->adds_in_progress) {
512                                 nrg = list_first_entry(&resv->region_cache,
513                                                         struct file_region,
514                                                         link);
515                                 list_del(&nrg->link);
516                                 resv->region_cache_count--;
517                         }
518
519                         if (!nrg) {
520                                 spin_unlock(&resv->lock);
521                                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
522                                 if (!nrg)
523                                         return -ENOMEM;
524                                 goto retry;
525                         }
526
527                         del += t - f;
528
529                         /* New entry for end of split region */
530                         nrg->from = t;
531                         nrg->to = rg->to;
532                         INIT_LIST_HEAD(&nrg->link);
533
534                         /* Original entry is trimmed */
535                         rg->to = f;
536
537                         list_add(&nrg->link, &rg->link);
538                         nrg = NULL;
539                         break;
540                 }
541
542                 if (f <= rg->from && t >= rg->to) { /* Remove entire region */
543                         del += rg->to - rg->from;
544                         list_del(&rg->link);
545                         kfree(rg);
546                         continue;
547                 }
548
549                 if (f <= rg->from) {    /* Trim beginning of region */
550                         del += t - rg->from;
551                         rg->from = t;
552                 } else {                /* Trim end of region */
553                         del += rg->to - f;
554                         rg->to = f;
555                 }
556         }
557
558         spin_unlock(&resv->lock);
559         kfree(nrg);
560         return del;
561 }
562
563 /*
564  * A rare out of memory error was encountered which prevented removal of
565  * the reserve map region for a page.  The huge page itself was free'ed
566  * and removed from the page cache.  This routine will adjust the subpool
567  * usage count, and the global reserve count if needed.  By incrementing
568  * these counts, the reserve map entry which could not be deleted will
569  * appear as a "reserved" entry instead of simply dangling with incorrect
570  * counts.
571  */
572 void hugetlb_fix_reserve_counts(struct inode *inode)
573 {
574         struct hugepage_subpool *spool = subpool_inode(inode);
575         long rsv_adjust;
576
577         rsv_adjust = hugepage_subpool_get_pages(spool, 1);
578         if (rsv_adjust) {
579                 struct hstate *h = hstate_inode(inode);
580
581                 hugetlb_acct_memory(h, 1);
582         }
583 }
584
585 /*
586  * Count and return the number of huge pages in the reserve map
587  * that intersect with the range [f, t).
588  */
589 static long region_count(struct resv_map *resv, long f, long t)
590 {
591         struct list_head *head = &resv->regions;
592         struct file_region *rg;
593         long chg = 0;
594
595         spin_lock(&resv->lock);
596         /* Locate each segment we overlap with, and count that overlap. */
597         list_for_each_entry(rg, head, link) {
598                 long seg_from;
599                 long seg_to;
600
601                 if (rg->to <= f)
602                         continue;
603                 if (rg->from >= t)
604                         break;
605
606                 seg_from = max(rg->from, f);
607                 seg_to = min(rg->to, t);
608
609                 chg += seg_to - seg_from;
610         }
611         spin_unlock(&resv->lock);
612
613         return chg;
614 }
615
616 /*
617  * Convert the address within this vma to the page offset within
618  * the mapping, in pagecache page units; huge pages here.
619  */
620 static pgoff_t vma_hugecache_offset(struct hstate *h,
621                         struct vm_area_struct *vma, unsigned long address)
622 {
623         return ((address - vma->vm_start) >> huge_page_shift(h)) +
624                         (vma->vm_pgoff >> huge_page_order(h));
625 }
626
627 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
628                                      unsigned long address)
629 {
630         return vma_hugecache_offset(hstate_vma(vma), vma, address);
631 }
632 EXPORT_SYMBOL_GPL(linear_hugepage_index);
633
634 /*
635  * Return the size of the pages allocated when backing a VMA. In the majority
636  * cases this will be same size as used by the page table entries.
637  */
638 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
639 {
640         if (vma->vm_ops && vma->vm_ops->pagesize)
641                 return vma->vm_ops->pagesize(vma);
642         return PAGE_SIZE;
643 }
644 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
645
646 /*
647  * Return the page size being used by the MMU to back a VMA. In the majority
648  * of cases, the page size used by the kernel matches the MMU size. On
649  * architectures where it differs, an architecture-specific 'strong'
650  * version of this symbol is required.
651  */
652 __weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
653 {
654         return vma_kernel_pagesize(vma);
655 }
656
657 /*
658  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
659  * bits of the reservation map pointer, which are always clear due to
660  * alignment.
661  */
662 #define HPAGE_RESV_OWNER    (1UL << 0)
663 #define HPAGE_RESV_UNMAPPED (1UL << 1)
664 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
665
666 /*
667  * These helpers are used to track how many pages are reserved for
668  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
669  * is guaranteed to have their future faults succeed.
670  *
671  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
672  * the reserve counters are updated with the hugetlb_lock held. It is safe
673  * to reset the VMA at fork() time as it is not in use yet and there is no
674  * chance of the global counters getting corrupted as a result of the values.
675  *
676  * The private mapping reservation is represented in a subtly different
677  * manner to a shared mapping.  A shared mapping has a region map associated
678  * with the underlying file, this region map represents the backing file
679  * pages which have ever had a reservation assigned which this persists even
680  * after the page is instantiated.  A private mapping has a region map
681  * associated with the original mmap which is attached to all VMAs which
682  * reference it, this region map represents those offsets which have consumed
683  * reservation ie. where pages have been instantiated.
684  */
685 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
686 {
687         return (unsigned long)vma->vm_private_data;
688 }
689
690 static void set_vma_private_data(struct vm_area_struct *vma,
691                                                         unsigned long value)
692 {
693         vma->vm_private_data = (void *)value;
694 }
695
696 struct resv_map *resv_map_alloc(void)
697 {
698         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
699         struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
700
701         if (!resv_map || !rg) {
702                 kfree(resv_map);
703                 kfree(rg);
704                 return NULL;
705         }
706
707         kref_init(&resv_map->refs);
708         spin_lock_init(&resv_map->lock);
709         INIT_LIST_HEAD(&resv_map->regions);
710
711         resv_map->adds_in_progress = 0;
712
713         INIT_LIST_HEAD(&resv_map->region_cache);
714         list_add(&rg->link, &resv_map->region_cache);
715         resv_map->region_cache_count = 1;
716
717         return resv_map;
718 }
719
720 void resv_map_release(struct kref *ref)
721 {
722         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
723         struct list_head *head = &resv_map->region_cache;
724         struct file_region *rg, *trg;
725
726         /* Clear out any active regions before we release the map. */
727         region_del(resv_map, 0, LONG_MAX);
728
729         /* ... and any entries left in the cache */
730         list_for_each_entry_safe(rg, trg, head, link) {
731                 list_del(&rg->link);
732                 kfree(rg);
733         }
734
735         VM_BUG_ON(resv_map->adds_in_progress);
736
737         kfree(resv_map);
738 }
739
740 static inline struct resv_map *inode_resv_map(struct inode *inode)
741 {
742         return inode->i_mapping->private_data;
743 }
744
745 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
746 {
747         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
748         if (vma->vm_flags & VM_MAYSHARE) {
749                 struct address_space *mapping = vma->vm_file->f_mapping;
750                 struct inode *inode = mapping->host;
751
752                 return inode_resv_map(inode);
753
754         } else {
755                 return (struct resv_map *)(get_vma_private_data(vma) &
756                                                         ~HPAGE_RESV_MASK);
757         }
758 }
759
760 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
761 {
762         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
763         VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
764
765         set_vma_private_data(vma, (get_vma_private_data(vma) &
766                                 HPAGE_RESV_MASK) | (unsigned long)map);
767 }
768
769 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
770 {
771         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
772         VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
773
774         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
775 }
776
777 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
778 {
779         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
780
781         return (get_vma_private_data(vma) & flag) != 0;
782 }
783
784 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
785 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
786 {
787         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
788         if (!(vma->vm_flags & VM_MAYSHARE))
789                 vma->vm_private_data = (void *)0;
790 }
791
792 /* Returns true if the VMA has associated reserve pages */
793 static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
794 {
795         if (vma->vm_flags & VM_NORESERVE) {
796                 /*
797                  * This address is already reserved by other process(chg == 0),
798                  * so, we should decrement reserved count. Without decrementing,
799                  * reserve count remains after releasing inode, because this
800                  * allocated page will go into page cache and is regarded as
801                  * coming from reserved pool in releasing step.  Currently, we
802                  * don't have any other solution to deal with this situation
803                  * properly, so add work-around here.
804                  */
805                 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
806                         return true;
807                 else
808                         return false;
809         }
810
811         /* Shared mappings always use reserves */
812         if (vma->vm_flags & VM_MAYSHARE) {
813                 /*
814                  * We know VM_NORESERVE is not set.  Therefore, there SHOULD
815                  * be a region map for all pages.  The only situation where
816                  * there is no region map is if a hole was punched via
817                  * fallocate.  In this case, there really are no reverves to
818                  * use.  This situation is indicated if chg != 0.
819                  */
820                 if (chg)
821                         return false;
822                 else
823                         return true;
824         }
825
826         /*
827          * Only the process that called mmap() has reserves for
828          * private mappings.
829          */
830         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
831                 /*
832                  * Like the shared case above, a hole punch or truncate
833                  * could have been performed on the private mapping.
834                  * Examine the value of chg to determine if reserves
835                  * actually exist or were previously consumed.
836                  * Very Subtle - The value of chg comes from a previous
837                  * call to vma_needs_reserves().  The reserve map for
838                  * private mappings has different (opposite) semantics
839                  * than that of shared mappings.  vma_needs_reserves()
840                  * has already taken this difference in semantics into
841                  * account.  Therefore, the meaning of chg is the same
842                  * as in the shared case above.  Code could easily be
843                  * combined, but keeping it separate draws attention to
844                  * subtle differences.
845                  */
846                 if (chg)
847                         return false;
848                 else
849                         return true;
850         }
851
852         return false;
853 }
854
855 static void enqueue_huge_page(struct hstate *h, struct page *page)
856 {
857         int nid = page_to_nid(page);
858         list_move(&page->lru, &h->hugepage_freelists[nid]);
859         h->free_huge_pages++;
860         h->free_huge_pages_node[nid]++;
861 }
862
863 static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
864 {
865         struct page *page;
866
867         list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
868                 if (!PageHWPoison(page))
869                         break;
870         /*
871          * if 'non-isolated free hugepage' not found on the list,
872          * the allocation fails.
873          */
874         if (&h->hugepage_freelists[nid] == &page->lru)
875                 return NULL;
876         list_move(&page->lru, &h->hugepage_activelist);
877         set_page_refcounted(page);
878         h->free_huge_pages--;
879         h->free_huge_pages_node[nid]--;
880         return page;
881 }
882
883 static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
884                 nodemask_t *nmask)
885 {
886         unsigned int cpuset_mems_cookie;
887         struct zonelist *zonelist;
888         struct zone *zone;
889         struct zoneref *z;
890         int node = -1;
891
892         zonelist = node_zonelist(nid, gfp_mask);
893
894 retry_cpuset:
895         cpuset_mems_cookie = read_mems_allowed_begin();
896         for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
897                 struct page *page;
898
899                 if (!cpuset_zone_allowed(zone, gfp_mask))
900                         continue;
901                 /*
902                  * no need to ask again on the same node. Pool is node rather than
903                  * zone aware
904                  */
905                 if (zone_to_nid(zone) == node)
906                         continue;
907                 node = zone_to_nid(zone);
908
909                 page = dequeue_huge_page_node_exact(h, node);
910                 if (page)
911                         return page;
912         }
913         if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
914                 goto retry_cpuset;
915
916         return NULL;
917 }
918
919 /* Movability of hugepages depends on migration support. */
920 static inline gfp_t htlb_alloc_mask(struct hstate *h)
921 {
922         if (hugepage_migration_supported(h))
923                 return GFP_HIGHUSER_MOVABLE;
924         else
925                 return GFP_HIGHUSER;
926 }
927
928 static struct page *dequeue_huge_page_vma(struct hstate *h,
929                                 struct vm_area_struct *vma,
930                                 unsigned long address, int avoid_reserve,
931                                 long chg)
932 {
933         struct page *page;
934         struct mempolicy *mpol;
935         gfp_t gfp_mask;
936         nodemask_t *nodemask;
937         int nid;
938
939         /*
940          * A child process with MAP_PRIVATE mappings created by their parent
941          * have no page reserves. This check ensures that reservations are
942          * not "stolen". The child may still get SIGKILLed
943          */
944         if (!vma_has_reserves(vma, chg) &&
945                         h->free_huge_pages - h->resv_huge_pages == 0)
946                 goto err;
947
948         /* If reserves cannot be used, ensure enough pages are in the pool */
949         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
950                 goto err;
951
952         gfp_mask = htlb_alloc_mask(h);
953         nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
954         page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
955         if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
956                 SetPagePrivate(page);
957                 h->resv_huge_pages--;
958         }
959
960         mpol_cond_put(mpol);
961         return page;
962
963 err:
964         return NULL;
965 }
966
967 /*
968  * common helper functions for hstate_next_node_to_{alloc|free}.
969  * We may have allocated or freed a huge page based on a different
970  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
971  * be outside of *nodes_allowed.  Ensure that we use an allowed
972  * node for alloc or free.
973  */
974 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
975 {
976         nid = next_node_in(nid, *nodes_allowed);
977         VM_BUG_ON(nid >= MAX_NUMNODES);
978
979         return nid;
980 }
981
982 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
983 {
984         if (!node_isset(nid, *nodes_allowed))
985                 nid = next_node_allowed(nid, nodes_allowed);
986         return nid;
987 }
988
989 /*
990  * returns the previously saved node ["this node"] from which to
991  * allocate a persistent huge page for the pool and advance the
992  * next node from which to allocate, handling wrap at end of node
993  * mask.
994  */
995 static int hstate_next_node_to_alloc(struct hstate *h,
996                                         nodemask_t *nodes_allowed)
997 {
998         int nid;
999
1000         VM_BUG_ON(!nodes_allowed);
1001
1002         nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
1003         h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
1004
1005         return nid;
1006 }
1007
1008 /*
1009  * helper for free_pool_huge_page() - return the previously saved
1010  * node ["this node"] from which to free a huge page.  Advance the
1011  * next node id whether or not we find a free huge page to free so
1012  * that the next attempt to free addresses the next node.
1013  */
1014 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
1015 {
1016         int nid;
1017
1018         VM_BUG_ON(!nodes_allowed);
1019
1020         nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
1021         h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
1022
1023         return nid;
1024 }
1025
1026 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask)           \
1027         for (nr_nodes = nodes_weight(*mask);                            \
1028                 nr_nodes > 0 &&                                         \
1029                 ((node = hstate_next_node_to_alloc(hs, mask)) || 1);    \
1030                 nr_nodes--)
1031
1032 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask)            \
1033         for (nr_nodes = nodes_weight(*mask);                            \
1034                 nr_nodes > 0 &&                                         \
1035                 ((node = hstate_next_node_to_free(hs, mask)) || 1);     \
1036                 nr_nodes--)
1037
1038 #ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
1039 static void destroy_compound_gigantic_page(struct page *page,
1040                                         unsigned int order)
1041 {
1042         int i;
1043         int nr_pages = 1 << order;
1044         struct page *p = page + 1;
1045
1046         atomic_set(compound_mapcount_ptr(page), 0);
1047         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1048                 clear_compound_head(p);
1049                 set_page_refcounted(p);
1050         }
1051
1052         set_compound_order(page, 0);
1053         __ClearPageHead(page);
1054 }
1055
1056 static void free_gigantic_page(struct page *page, unsigned int order)
1057 {
1058         free_contig_range(page_to_pfn(page), 1 << order);
1059 }
1060
1061 static int __alloc_gigantic_page(unsigned long start_pfn,
1062                                 unsigned long nr_pages, gfp_t gfp_mask)
1063 {
1064         unsigned long end_pfn = start_pfn + nr_pages;
1065         return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
1066                                   gfp_mask);
1067 }
1068
1069 static bool pfn_range_valid_gigantic(struct zone *z,
1070                         unsigned long start_pfn, unsigned long nr_pages)
1071 {
1072         unsigned long i, end_pfn = start_pfn + nr_pages;
1073         struct page *page;
1074
1075         for (i = start_pfn; i < end_pfn; i++) {
1076                 if (!pfn_valid(i))
1077                         return false;
1078
1079                 page = pfn_to_page(i);
1080
1081                 if (page_zone(page) != z)
1082                         return false;
1083
1084                 if (PageReserved(page))
1085                         return false;
1086
1087                 if (page_count(page) > 0)
1088                         return false;
1089
1090                 if (PageHuge(page))
1091                         return false;
1092         }
1093
1094         return true;
1095 }
1096
1097 static bool zone_spans_last_pfn(const struct zone *zone,
1098                         unsigned long start_pfn, unsigned long nr_pages)
1099 {
1100         unsigned long last_pfn = start_pfn + nr_pages - 1;
1101         return zone_spans_pfn(zone, last_pfn);
1102 }
1103
1104 static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
1105                 int nid, nodemask_t *nodemask)
1106 {
1107         unsigned int order = huge_page_order(h);
1108         unsigned long nr_pages = 1 << order;
1109         unsigned long ret, pfn, flags;
1110         struct zonelist *zonelist;
1111         struct zone *zone;
1112         struct zoneref *z;
1113
1114         zonelist = node_zonelist(nid, gfp_mask);
1115         for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nodemask) {
1116                 spin_lock_irqsave(&zone->lock, flags);
1117
1118                 pfn = ALIGN(zone->zone_start_pfn, nr_pages);
1119                 while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
1120                         if (pfn_range_valid_gigantic(zone, pfn, nr_pages)) {
1121                                 /*
1122                                  * We release the zone lock here because
1123                                  * alloc_contig_range() will also lock the zone
1124                                  * at some point. If there's an allocation
1125                                  * spinning on this lock, it may win the race
1126                                  * and cause alloc_contig_range() to fail...
1127                                  */
1128                                 spin_unlock_irqrestore(&zone->lock, flags);
1129                                 ret = __alloc_gigantic_page(pfn, nr_pages, gfp_mask);
1130                                 if (!ret)
1131                                         return pfn_to_page(pfn);
1132                                 spin_lock_irqsave(&zone->lock, flags);
1133                         }
1134                         pfn += nr_pages;
1135                 }
1136
1137                 spin_unlock_irqrestore(&zone->lock, flags);
1138         }
1139
1140         return NULL;
1141 }
1142
1143 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1144 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1145
1146 #else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
1147 static inline bool gigantic_page_supported(void) { return false; }
1148 static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
1149                 int nid, nodemask_t *nodemask) { return NULL; }
1150 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1151 static inline void destroy_compound_gigantic_page(struct page *page,
1152                                                 unsigned int order) { }
1153 #endif
1154
1155 static void update_and_free_page(struct hstate *h, struct page *page)
1156 {
1157         int i;
1158
1159         if (hstate_is_gigantic(h) && !gigantic_page_supported())
1160                 return;
1161
1162         h->nr_huge_pages--;
1163         h->nr_huge_pages_node[page_to_nid(page)]--;
1164         for (i = 0; i < pages_per_huge_page(h); i++) {
1165                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1166                                 1 << PG_referenced | 1 << PG_dirty |
1167                                 1 << PG_active | 1 << PG_private |
1168                                 1 << PG_writeback);
1169         }
1170         VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1171         set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1172         set_page_refcounted(page);
1173         if (hstate_is_gigantic(h)) {
1174                 destroy_compound_gigantic_page(page, huge_page_order(h));
1175                 free_gigantic_page(page, huge_page_order(h));
1176         } else {
1177                 __free_pages(page, huge_page_order(h));
1178         }
1179 }
1180
1181 struct hstate *size_to_hstate(unsigned long size)
1182 {
1183         struct hstate *h;
1184
1185         for_each_hstate(h) {
1186                 if (huge_page_size(h) == size)
1187                         return h;
1188         }
1189         return NULL;
1190 }
1191
1192 /*
1193  * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1194  * to hstate->hugepage_activelist.)
1195  *
1196  * This function can be called for tail pages, but never returns true for them.
1197  */
1198 bool page_huge_active(struct page *page)
1199 {
1200         VM_BUG_ON_PAGE(!PageHuge(page), page);
1201         return PageHead(page) && PagePrivate(&page[1]);
1202 }
1203
1204 /* never called for tail page */
1205 static void set_page_huge_active(struct page *page)
1206 {
1207         VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1208         SetPagePrivate(&page[1]);
1209 }
1210
1211 static void clear_page_huge_active(struct page *page)
1212 {
1213         VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1214         ClearPagePrivate(&page[1]);
1215 }
1216
1217 /*
1218  * Internal hugetlb specific page flag. Do not use outside of the hugetlb
1219  * code
1220  */
1221 static inline bool PageHugeTemporary(struct page *page)
1222 {
1223         if (!PageHuge(page))
1224                 return false;
1225
1226         return (unsigned long)page[2].mapping == -1U;
1227 }
1228
1229 static inline void SetPageHugeTemporary(struct page *page)
1230 {
1231         page[2].mapping = (void *)-1U;
1232 }
1233
1234 static inline void ClearPageHugeTemporary(struct page *page)
1235 {
1236         page[2].mapping = NULL;
1237 }
1238
1239 void free_huge_page(struct page *page)
1240 {
1241         /*
1242          * Can't pass hstate in here because it is called from the
1243          * compound page destructor.
1244          */
1245         struct hstate *h = page_hstate(page);
1246         int nid = page_to_nid(page);
1247         struct hugepage_subpool *spool =
1248                 (struct hugepage_subpool *)page_private(page);
1249         bool restore_reserve;
1250
1251         VM_BUG_ON_PAGE(page_count(page), page);
1252         VM_BUG_ON_PAGE(page_mapcount(page), page);
1253
1254         set_page_private(page, 0);
1255         page->mapping = NULL;
1256         restore_reserve = PagePrivate(page);
1257         ClearPagePrivate(page);
1258
1259         /*
1260          * A return code of zero implies that the subpool will be under its
1261          * minimum size if the reservation is not restored after page is free.
1262          * Therefore, force restore_reserve operation.
1263          */
1264         if (hugepage_subpool_put_pages(spool, 1) == 0)
1265                 restore_reserve = true;
1266
1267         spin_lock(&hugetlb_lock);
1268         clear_page_huge_active(page);
1269         hugetlb_cgroup_uncharge_page(hstate_index(h),
1270                                      pages_per_huge_page(h), page);
1271         if (restore_reserve)
1272                 h->resv_huge_pages++;
1273
1274         if (PageHugeTemporary(page)) {
1275                 list_del(&page->lru);
1276                 ClearPageHugeTemporary(page);
1277                 update_and_free_page(h, page);
1278         } else if (h->surplus_huge_pages_node[nid]) {
1279                 /* remove the page from active list */
1280                 list_del(&page->lru);
1281                 update_and_free_page(h, page);
1282                 h->surplus_huge_pages--;
1283                 h->surplus_huge_pages_node[nid]--;
1284         } else {
1285                 arch_clear_hugepage_flags(page);
1286                 enqueue_huge_page(h, page);
1287         }
1288         spin_unlock(&hugetlb_lock);
1289 }
1290
1291 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1292 {
1293         INIT_LIST_HEAD(&page->lru);
1294         set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1295         spin_lock(&hugetlb_lock);
1296         set_hugetlb_cgroup(page, NULL);
1297         h->nr_huge_pages++;
1298         h->nr_huge_pages_node[nid]++;
1299         spin_unlock(&hugetlb_lock);
1300 }
1301
1302 static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1303 {
1304         int i;
1305         int nr_pages = 1 << order;
1306         struct page *p = page + 1;
1307
1308         /* we rely on prep_new_huge_page to set the destructor */
1309         set_compound_order(page, order);
1310         __ClearPageReserved(page);
1311         __SetPageHead(page);
1312         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1313                 /*
1314                  * For gigantic hugepages allocated through bootmem at
1315                  * boot, it's safer to be consistent with the not-gigantic
1316                  * hugepages and clear the PG_reserved bit from all tail pages
1317                  * too.  Otherwse drivers using get_user_pages() to access tail
1318                  * pages may get the reference counting wrong if they see
1319                  * PG_reserved set on a tail page (despite the head page not
1320                  * having PG_reserved set).  Enforcing this consistency between
1321                  * head and tail pages allows drivers to optimize away a check
1322                  * on the head page when they need know if put_page() is needed
1323                  * after get_user_pages().
1324                  */
1325                 __ClearPageReserved(p);
1326                 set_page_count(p, 0);
1327                 set_compound_head(p, page);
1328         }
1329         atomic_set(compound_mapcount_ptr(page), -1);
1330 }
1331
1332 /*
1333  * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1334  * transparent huge pages.  See the PageTransHuge() documentation for more
1335  * details.
1336  */
1337 int PageHuge(struct page *page)
1338 {
1339         if (!PageCompound(page))
1340                 return 0;
1341
1342         page = compound_head(page);
1343         return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1344 }
1345 EXPORT_SYMBOL_GPL(PageHuge);
1346
1347 /*
1348  * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1349  * normal or transparent huge pages.
1350  */
1351 int PageHeadHuge(struct page *page_head)
1352 {
1353         if (!PageHead(page_head))
1354                 return 0;
1355
1356         return get_compound_page_dtor(page_head) == free_huge_page;
1357 }
1358
1359 pgoff_t __basepage_index(struct page *page)
1360 {
1361         struct page *page_head = compound_head(page);
1362         pgoff_t index = page_index(page_head);
1363         unsigned long compound_idx;
1364
1365         if (!PageHuge(page_head))
1366                 return page_index(page);
1367
1368         if (compound_order(page_head) >= MAX_ORDER)
1369                 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1370         else
1371                 compound_idx = page - page_head;
1372
1373         return (index << compound_order(page_head)) + compound_idx;
1374 }
1375
1376 static struct page *alloc_buddy_huge_page(struct hstate *h,
1377                 gfp_t gfp_mask, int nid, nodemask_t *nmask)
1378 {
1379         int order = huge_page_order(h);
1380         struct page *page;
1381
1382         gfp_mask |= __GFP_COMP|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
1383         if (nid == NUMA_NO_NODE)
1384                 nid = numa_mem_id();
1385         page = __alloc_pages_nodemask(gfp_mask, order, nid, nmask);
1386         if (page)
1387                 __count_vm_event(HTLB_BUDDY_PGALLOC);
1388         else
1389                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1390
1391         return page;
1392 }
1393
1394 /*
1395  * Common helper to allocate a fresh hugetlb page. All specific allocators
1396  * should use this function to get new hugetlb pages
1397  */
1398 static struct page *alloc_fresh_huge_page(struct hstate *h,
1399                 gfp_t gfp_mask, int nid, nodemask_t *nmask)
1400 {
1401         struct page *page;
1402
1403         if (hstate_is_gigantic(h))
1404                 page = alloc_gigantic_page(h, gfp_mask, nid, nmask);
1405         else
1406                 page = alloc_buddy_huge_page(h, gfp_mask,
1407                                 nid, nmask);
1408         if (!page)
1409                 return NULL;
1410
1411         if (hstate_is_gigantic(h))
1412                 prep_compound_gigantic_page(page, huge_page_order(h));
1413         prep_new_huge_page(h, page, page_to_nid(page));
1414
1415         return page;
1416 }
1417
1418 /*
1419  * Allocates a fresh page to the hugetlb allocator pool in the node interleaved
1420  * manner.
1421  */
1422 static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1423 {
1424         struct page *page;
1425         int nr_nodes, node;
1426         gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
1427
1428         for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1429                 page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed);
1430                 if (page)
1431                         break;
1432         }
1433
1434         if (!page)
1435                 return 0;
1436
1437         put_page(page); /* free it into the hugepage allocator */
1438
1439         return 1;
1440 }
1441
1442 /*
1443  * Free huge page from pool from next node to free.
1444  * Attempt to keep persistent huge pages more or less
1445  * balanced over allowed nodes.
1446  * Called with hugetlb_lock locked.
1447  */
1448 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1449                                                          bool acct_surplus)
1450 {
1451         int nr_nodes, node;
1452         int ret = 0;
1453
1454         for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1455                 /*
1456                  * If we're returning unused surplus pages, only examine
1457                  * nodes with surplus pages.
1458                  */
1459                 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1460                     !list_empty(&h->hugepage_freelists[node])) {
1461                         struct page *page =
1462                                 list_entry(h->hugepage_freelists[node].next,
1463                                           struct page, lru);
1464                         list_del(&page->lru);
1465                         h->free_huge_pages--;
1466                         h->free_huge_pages_node[node]--;
1467                         if (acct_surplus) {
1468                                 h->surplus_huge_pages--;
1469                                 h->surplus_huge_pages_node[node]--;
1470                         }
1471                         update_and_free_page(h, page);
1472                         ret = 1;
1473                         break;
1474                 }
1475         }
1476
1477         return ret;
1478 }
1479
1480 /*
1481  * Dissolve a given free hugepage into free buddy pages. This function does
1482  * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
1483  * dissolution fails because a give page is not a free hugepage, or because
1484  * free hugepages are fully reserved.
1485  */
1486 int dissolve_free_huge_page(struct page *page)
1487 {
1488         int rc = -EBUSY;
1489
1490         spin_lock(&hugetlb_lock);
1491         if (PageHuge(page) && !page_count(page)) {
1492                 struct page *head = compound_head(page);
1493                 struct hstate *h = page_hstate(head);
1494                 int nid = page_to_nid(head);
1495                 if (h->free_huge_pages - h->resv_huge_pages == 0)
1496                         goto out;
1497                 /*
1498                  * Move PageHWPoison flag from head page to the raw error page,
1499                  * which makes any subpages rather than the error page reusable.
1500                  */
1501                 if (PageHWPoison(head) && page != head) {
1502                         SetPageHWPoison(page);
1503                         ClearPageHWPoison(head);
1504                 }
1505                 list_del(&head->lru);
1506                 h->free_huge_pages--;
1507                 h->free_huge_pages_node[nid]--;
1508                 h->max_huge_pages--;
1509                 update_and_free_page(h, head);
1510                 rc = 0;
1511         }
1512 out:
1513         spin_unlock(&hugetlb_lock);
1514         return rc;
1515 }
1516
1517 /*
1518  * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1519  * make specified memory blocks removable from the system.
1520  * Note that this will dissolve a free gigantic hugepage completely, if any
1521  * part of it lies within the given range.
1522  * Also note that if dissolve_free_huge_page() returns with an error, all
1523  * free hugepages that were dissolved before that error are lost.
1524  */
1525 int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1526 {
1527         unsigned long pfn;
1528         struct page *page;
1529         int rc = 0;
1530
1531         if (!hugepages_supported())
1532                 return rc;
1533
1534         for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
1535                 page = pfn_to_page(pfn);
1536                 if (PageHuge(page) && !page_count(page)) {
1537                         rc = dissolve_free_huge_page(page);
1538                         if (rc)
1539                                 break;
1540                 }
1541         }
1542
1543         return rc;
1544 }
1545
1546 /*
1547  * Allocates a fresh surplus page from the page allocator.
1548  */
1549 static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
1550                 int nid, nodemask_t *nmask)
1551 {
1552         struct page *page = NULL;
1553
1554         if (hstate_is_gigantic(h))
1555                 return NULL;
1556
1557         spin_lock(&hugetlb_lock);
1558         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
1559                 goto out_unlock;
1560         spin_unlock(&hugetlb_lock);
1561
1562         page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask);
1563         if (!page)
1564                 return NULL;
1565
1566         spin_lock(&hugetlb_lock);
1567         /*
1568          * We could have raced with the pool size change.
1569          * Double check that and simply deallocate the new page
1570          * if we would end up overcommiting the surpluses. Abuse
1571          * temporary page to workaround the nasty free_huge_page
1572          * codeflow
1573          */
1574         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1575                 SetPageHugeTemporary(page);
1576                 put_page(page);
1577                 page = NULL;
1578         } else {
1579                 h->surplus_huge_pages++;
1580                 h->surplus_huge_pages_node[page_to_nid(page)]++;
1581         }
1582
1583 out_unlock:
1584         spin_unlock(&hugetlb_lock);
1585
1586         return page;
1587 }
1588
1589 static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
1590                 int nid, nodemask_t *nmask)
1591 {
1592         struct page *page;
1593
1594         if (hstate_is_gigantic(h))
1595                 return NULL;
1596
1597         page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask);
1598         if (!page)
1599                 return NULL;
1600
1601         /*
1602          * We do not account these pages as surplus because they are only
1603          * temporary and will be released properly on the last reference
1604          */
1605         SetPageHugeTemporary(page);
1606
1607         return page;
1608 }
1609
1610 /*
1611  * Use the VMA's mpolicy to allocate a huge page from the buddy.
1612  */
1613 static
1614 struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
1615                 struct vm_area_struct *vma, unsigned long addr)
1616 {
1617         struct page *page;
1618         struct mempolicy *mpol;
1619         gfp_t gfp_mask = htlb_alloc_mask(h);
1620         int nid;
1621         nodemask_t *nodemask;
1622
1623         nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
1624         page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
1625         mpol_cond_put(mpol);
1626
1627         return page;
1628 }
1629
1630 /* page migration callback function */
1631 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1632 {
1633         gfp_t gfp_mask = htlb_alloc_mask(h);
1634         struct page *page = NULL;
1635
1636         if (nid != NUMA_NO_NODE)
1637                 gfp_mask |= __GFP_THISNODE;
1638
1639         spin_lock(&hugetlb_lock);
1640         if (h->free_huge_pages - h->resv_huge_pages > 0)
1641                 page = dequeue_huge_page_nodemask(h, gfp_mask, nid, NULL);
1642         spin_unlock(&hugetlb_lock);
1643
1644         if (!page)
1645                 page = alloc_migrate_huge_page(h, gfp_mask, nid, NULL);
1646
1647         return page;
1648 }
1649
1650 /* page migration callback function */
1651 struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
1652                 nodemask_t *nmask)
1653 {
1654         gfp_t gfp_mask = htlb_alloc_mask(h);
1655
1656         spin_lock(&hugetlb_lock);
1657         if (h->free_huge_pages - h->resv_huge_pages > 0) {
1658                 struct page *page;
1659
1660                 page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
1661                 if (page) {
1662                         spin_unlock(&hugetlb_lock);
1663                         return page;
1664                 }
1665         }
1666         spin_unlock(&hugetlb_lock);
1667
1668         return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
1669 }
1670
1671 /* mempolicy aware migration callback */
1672 struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
1673                 unsigned long address)
1674 {
1675         struct mempolicy *mpol;
1676         nodemask_t *nodemask;
1677         struct page *page;
1678         gfp_t gfp_mask;
1679         int node;
1680
1681         gfp_mask = htlb_alloc_mask(h);
1682         node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
1683         page = alloc_huge_page_nodemask(h, node, nodemask);
1684         mpol_cond_put(mpol);
1685
1686         return page;
1687 }
1688
1689 /*
1690  * Increase the hugetlb pool such that it can accommodate a reservation
1691  * of size 'delta'.
1692  */
1693 static int gather_surplus_pages(struct hstate *h, int delta)
1694 {
1695         struct list_head surplus_list;
1696         struct page *page, *tmp;
1697         int ret, i;
1698         int needed, allocated;
1699         bool alloc_ok = true;
1700
1701         needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1702         if (needed <= 0) {
1703                 h->resv_huge_pages += delta;
1704                 return 0;
1705         }
1706
1707         allocated = 0;
1708         INIT_LIST_HEAD(&surplus_list);
1709
1710         ret = -ENOMEM;
1711 retry:
1712         spin_unlock(&hugetlb_lock);
1713         for (i = 0; i < needed; i++) {
1714                 page = alloc_surplus_huge_page(h, htlb_alloc_mask(h),
1715                                 NUMA_NO_NODE, NULL);
1716                 if (!page) {
1717                         alloc_ok = false;
1718                         break;
1719                 }
1720                 list_add(&page->lru, &surplus_list);
1721                 cond_resched();
1722         }
1723         allocated += i;
1724
1725         /*
1726          * After retaking hugetlb_lock, we need to recalculate 'needed'
1727          * because either resv_huge_pages or free_huge_pages may have changed.
1728          */
1729         spin_lock(&hugetlb_lock);
1730         needed = (h->resv_huge_pages + delta) -
1731                         (h->free_huge_pages + allocated);
1732         if (needed > 0) {
1733                 if (alloc_ok)
1734                         goto retry;
1735                 /*
1736                  * We were not able to allocate enough pages to
1737                  * satisfy the entire reservation so we free what
1738                  * we've allocated so far.
1739                  */
1740                 goto free;
1741         }
1742         /*
1743          * The surplus_list now contains _at_least_ the number of extra pages
1744          * needed to accommodate the reservation.  Add the appropriate number
1745          * of pages to the hugetlb pool and free the extras back to the buddy
1746          * allocator.  Commit the entire reservation here to prevent another
1747          * process from stealing the pages as they are added to the pool but
1748          * before they are reserved.
1749          */
1750         needed += allocated;
1751         h->resv_huge_pages += delta;
1752         ret = 0;
1753
1754         /* Free the needed pages to the hugetlb pool */
1755         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1756                 if ((--needed) < 0)
1757                         break;
1758                 /*
1759                  * This page is now managed by the hugetlb allocator and has
1760                  * no users -- drop the buddy allocator's reference.
1761                  */
1762                 put_page_testzero(page);
1763                 VM_BUG_ON_PAGE(page_count(page), page);
1764                 enqueue_huge_page(h, page);
1765         }
1766 free:
1767         spin_unlock(&hugetlb_lock);
1768
1769         /* Free unnecessary surplus pages to the buddy allocator */
1770         list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1771                 put_page(page);
1772         spin_lock(&hugetlb_lock);
1773
1774         return ret;
1775 }
1776
1777 /*
1778  * This routine has two main purposes:
1779  * 1) Decrement the reservation count (resv_huge_pages) by the value passed
1780  *    in unused_resv_pages.  This corresponds to the prior adjustments made
1781  *    to the associated reservation map.
1782  * 2) Free any unused surplus pages that may have been allocated to satisfy
1783  *    the reservation.  As many as unused_resv_pages may be freed.
1784  *
1785  * Called with hugetlb_lock held.  However, the lock could be dropped (and
1786  * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
1787  * we must make sure nobody else can claim pages we are in the process of
1788  * freeing.  Do this by ensuring resv_huge_page always is greater than the
1789  * number of huge pages we plan to free when dropping the lock.
1790  */
1791 static void return_unused_surplus_pages(struct hstate *h,
1792                                         unsigned long unused_resv_pages)
1793 {
1794         unsigned long nr_pages;
1795
1796         /* Cannot return gigantic pages currently */
1797         if (hstate_is_gigantic(h))
1798                 goto out;
1799
1800         /*
1801          * Part (or even all) of the reservation could have been backed
1802          * by pre-allocated pages. Only free surplus pages.
1803          */
1804         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1805
1806         /*
1807          * We want to release as many surplus pages as possible, spread
1808          * evenly across all nodes with memory. Iterate across these nodes
1809          * until we can no longer free unreserved surplus pages. This occurs
1810          * when the nodes with surplus pages have no free pages.
1811          * free_pool_huge_page() will balance the the freed pages across the
1812          * on-line nodes with memory and will handle the hstate accounting.
1813          *
1814          * Note that we decrement resv_huge_pages as we free the pages.  If
1815          * we drop the lock, resv_huge_pages will still be sufficiently large
1816          * to cover subsequent pages we may free.
1817          */
1818         while (nr_pages--) {
1819                 h->resv_huge_pages--;
1820                 unused_resv_pages--;
1821                 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1822                         goto out;
1823                 cond_resched_lock(&hugetlb_lock);
1824         }
1825
1826 out:
1827         /* Fully uncommit the reservation */
1828         h->resv_huge_pages -= unused_resv_pages;
1829 }
1830
1831
1832 /*
1833  * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1834  * are used by the huge page allocation routines to manage reservations.
1835  *
1836  * vma_needs_reservation is called to determine if the huge page at addr
1837  * within the vma has an associated reservation.  If a reservation is
1838  * needed, the value 1 is returned.  The caller is then responsible for
1839  * managing the global reservation and subpool usage counts.  After
1840  * the huge page has been allocated, vma_commit_reservation is called
1841  * to add the page to the reservation map.  If the page allocation fails,
1842  * the reservation must be ended instead of committed.  vma_end_reservation
1843  * is called in such cases.
1844  *
1845  * In the normal case, vma_commit_reservation returns the same value
1846  * as the preceding vma_needs_reservation call.  The only time this
1847  * is not the case is if a reserve map was changed between calls.  It
1848  * is the responsibility of the caller to notice the difference and
1849  * take appropriate action.
1850  *
1851  * vma_add_reservation is used in error paths where a reservation must
1852  * be restored when a newly allocated huge page must be freed.  It is
1853  * to be called after calling vma_needs_reservation to determine if a
1854  * reservation exists.
1855  */
1856 enum vma_resv_mode {
1857         VMA_NEEDS_RESV,
1858         VMA_COMMIT_RESV,
1859         VMA_END_RESV,
1860         VMA_ADD_RESV,
1861 };
1862 static long __vma_reservation_common(struct hstate *h,
1863                                 struct vm_area_struct *vma, unsigned long addr,
1864                                 enum vma_resv_mode mode)
1865 {
1866         struct resv_map *resv;
1867         pgoff_t idx;
1868         long ret;
1869
1870         resv = vma_resv_map(vma);
1871         if (!resv)
1872                 return 1;
1873
1874         idx = vma_hugecache_offset(h, vma, addr);
1875         switch (mode) {
1876         case VMA_NEEDS_RESV:
1877                 ret = region_chg(resv, idx, idx + 1);
1878                 break;
1879         case VMA_COMMIT_RESV:
1880                 ret = region_add(resv, idx, idx + 1);
1881                 break;
1882         case VMA_END_RESV:
1883                 region_abort(resv, idx, idx + 1);
1884                 ret = 0;
1885                 break;
1886         case VMA_ADD_RESV:
1887                 if (vma->vm_flags & VM_MAYSHARE)
1888                         ret = region_add(resv, idx, idx + 1);
1889                 else {
1890                         region_abort(resv, idx, idx + 1);
1891                         ret = region_del(resv, idx, idx + 1);
1892                 }
1893                 break;
1894         default:
1895                 BUG();
1896         }
1897
1898         if (vma->vm_flags & VM_MAYSHARE)
1899                 return ret;
1900         else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
1901                 /*
1902                  * In most cases, reserves always exist for private mappings.
1903                  * However, a file associated with mapping could have been
1904                  * hole punched or truncated after reserves were consumed.
1905                  * As subsequent fault on such a range will not use reserves.
1906                  * Subtle - The reserve map for private mappings has the
1907                  * opposite meaning than that of shared mappings.  If NO
1908                  * entry is in the reserve map, it means a reservation exists.
1909                  * If an entry exists in the reserve map, it means the
1910                  * reservation has already been consumed.  As a result, the
1911                  * return value of this routine is the opposite of the
1912                  * value returned from reserve map manipulation routines above.
1913                  */
1914                 if (ret)
1915                         return 0;
1916                 else
1917                         return 1;
1918         }
1919         else
1920                 return ret < 0 ? ret : 0;
1921 }
1922
1923 static long vma_needs_reservation(struct hstate *h,
1924                         struct vm_area_struct *vma, unsigned long addr)
1925 {
1926         return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1927 }
1928
1929 static long vma_commit_reservation(struct hstate *h,
1930                         struct vm_area_struct *vma, unsigned long addr)
1931 {
1932         return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1933 }
1934
1935 static void vma_end_reservation(struct hstate *h,
1936                         struct vm_area_struct *vma, unsigned long addr)
1937 {
1938         (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1939 }
1940
1941 static long vma_add_reservation(struct hstate *h,
1942                         struct vm_area_struct *vma, unsigned long addr)
1943 {
1944         return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
1945 }
1946
1947 /*
1948  * This routine is called to restore a reservation on error paths.  In the
1949  * specific error paths, a huge page was allocated (via alloc_huge_page)
1950  * and is about to be freed.  If a reservation for the page existed,
1951  * alloc_huge_page would have consumed the reservation and set PagePrivate
1952  * in the newly allocated page.  When the page is freed via free_huge_page,
1953  * the global reservation count will be incremented if PagePrivate is set.
1954  * However, free_huge_page can not adjust the reserve map.  Adjust the
1955  * reserve map here to be consistent with global reserve count adjustments
1956  * to be made by free_huge_page.
1957  */
1958 static void restore_reserve_on_error(struct hstate *h,
1959                         struct vm_area_struct *vma, unsigned long address,
1960                         struct page *page)
1961 {
1962         if (unlikely(PagePrivate(page))) {
1963                 long rc = vma_needs_reservation(h, vma, address);
1964
1965                 if (unlikely(rc < 0)) {
1966                         /*
1967                          * Rare out of memory condition in reserve map
1968                          * manipulation.  Clear PagePrivate so that
1969                          * global reserve count will not be incremented
1970                          * by free_huge_page.  This will make it appear
1971                          * as though the reservation for this page was
1972                          * consumed.  This may prevent the task from
1973                          * faulting in the page at a later time.  This
1974                          * is better than inconsistent global huge page
1975                          * accounting of reserve counts.
1976                          */
1977                         ClearPagePrivate(page);
1978                 } else if (rc) {
1979                         rc = vma_add_reservation(h, vma, address);
1980                         if (unlikely(rc < 0))
1981                                 /*
1982                                  * See above comment about rare out of
1983                                  * memory condition.
1984                                  */
1985                                 ClearPagePrivate(page);
1986                 } else
1987                         vma_end_reservation(h, vma, address);
1988         }
1989 }
1990
1991 struct page *alloc_huge_page(struct vm_area_struct *vma,
1992                                     unsigned long addr, int avoid_reserve)
1993 {
1994         struct hugepage_subpool *spool = subpool_vma(vma);
1995         struct hstate *h = hstate_vma(vma);
1996         struct page *page;
1997         long map_chg, map_commit;
1998         long gbl_chg;
1999         int ret, idx;
2000         struct hugetlb_cgroup *h_cg;
2001
2002         idx = hstate_index(h);
2003         /*
2004          * Examine the region/reserve map to determine if the process
2005          * has a reservation for the page to be allocated.  A return
2006          * code of zero indicates a reservation exists (no change).
2007          */
2008         map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
2009         if (map_chg < 0)
2010                 return ERR_PTR(-ENOMEM);
2011
2012         /*
2013          * Processes that did not create the mapping will have no
2014          * reserves as indicated by the region/reserve map. Check
2015          * that the allocation will not exceed the subpool limit.
2016          * Allocations for MAP_NORESERVE mappings also need to be
2017          * checked against any subpool limit.
2018          */
2019         if (map_chg || avoid_reserve) {
2020                 gbl_chg = hugepage_subpool_get_pages(spool, 1);
2021                 if (gbl_chg < 0) {
2022                         vma_end_reservation(h, vma, addr);
2023                         return ERR_PTR(-ENOSPC);
2024                 }
2025
2026                 /*
2027                  * Even though there was no reservation in the region/reserve
2028                  * map, there could be reservations associated with the
2029                  * subpool that can be used.  This would be indicated if the
2030                  * return value of hugepage_subpool_get_pages() is zero.
2031                  * However, if avoid_reserve is specified we still avoid even
2032                  * the subpool reservations.
2033                  */
2034                 if (avoid_reserve)
2035                         gbl_chg = 1;
2036         }
2037
2038         ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2039         if (ret)
2040                 goto out_subpool_put;
2041
2042         spin_lock(&hugetlb_lock);
2043         /*
2044          * glb_chg is passed to indicate whether or not a page must be taken
2045          * from the global free pool (global change).  gbl_chg == 0 indicates
2046          * a reservation exists for the allocation.
2047          */
2048         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
2049         if (!page) {
2050                 spin_unlock(&hugetlb_lock);
2051                 page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
2052                 if (!page)
2053                         goto out_uncharge_cgroup;
2054                 if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
2055                         SetPagePrivate(page);
2056                         h->resv_huge_pages--;
2057                 }
2058                 spin_lock(&hugetlb_lock);
2059                 list_move(&page->lru, &h->hugepage_activelist);
2060                 /* Fall through */
2061         }
2062         hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
2063         spin_unlock(&hugetlb_lock);
2064
2065         set_page_private(page, (unsigned long)spool);
2066
2067         map_commit = vma_commit_reservation(h, vma, addr);
2068         if (unlikely(map_chg > map_commit)) {
2069                 /*
2070                  * The page was added to the reservation map between
2071                  * vma_needs_reservation and vma_commit_reservation.
2072                  * This indicates a race with hugetlb_reserve_pages.
2073                  * Adjust for the subpool count incremented above AND
2074                  * in hugetlb_reserve_pages for the same page.  Also,
2075                  * the reservation count added in hugetlb_reserve_pages
2076                  * no longer applies.
2077                  */
2078                 long rsv_adjust;
2079
2080                 rsv_adjust = hugepage_subpool_put_pages(spool, 1);
2081                 hugetlb_acct_memory(h, -rsv_adjust);
2082         }
2083         return page;
2084
2085 out_uncharge_cgroup:
2086         hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
2087 out_subpool_put:
2088         if (map_chg || avoid_reserve)
2089                 hugepage_subpool_put_pages(spool, 1);
2090         vma_end_reservation(h, vma, addr);
2091         return ERR_PTR(-ENOSPC);
2092 }
2093
2094 int alloc_bootmem_huge_page(struct hstate *h)
2095         __attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
2096 int __alloc_bootmem_huge_page(struct hstate *h)
2097 {
2098         struct huge_bootmem_page *m;
2099         int nr_nodes, node;
2100
2101         for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2102                 void *addr;
2103
2104                 addr = memblock_alloc_try_nid_raw(
2105                                 huge_page_size(h), huge_page_size(h),
2106                                 0, MEMBLOCK_ALLOC_ACCESSIBLE, node);
2107                 if (addr) {
2108                         /*
2109                          * Use the beginning of the huge page to store the
2110                          * huge_bootmem_page struct (until gather_bootmem
2111                          * puts them into the mem_map).
2112                          */
2113                         m = addr;
2114                         goto found;
2115                 }
2116         }
2117         return 0;
2118
2119 found:
2120         BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2121         /* Put them into a private list first because mem_map is not up yet */
2122         INIT_LIST_HEAD(&m->list);
2123         list_add(&m->list, &huge_boot_pages);
2124         m->hstate = h;
2125         return 1;
2126 }
2127
2128 static void __init prep_compound_huge_page(struct page *page,
2129                 unsigned int order)
2130 {
2131         if (unlikely(order > (MAX_ORDER - 1)))
2132                 prep_compound_gigantic_page(page, order);
2133         else
2134                 prep_compound_page(page, order);
2135 }
2136
2137 /* Put bootmem huge pages into the standard lists after mem_map is up */
2138 static void __init gather_bootmem_prealloc(void)
2139 {
2140         struct huge_bootmem_page *m;
2141
2142         list_for_each_entry(m, &huge_boot_pages, list) {
2143                 struct page *page = virt_to_page(m);
2144                 struct hstate *h = m->hstate;
2145
2146                 WARN_ON(page_count(page) != 1);
2147                 prep_compound_huge_page(page, h->order);
2148                 WARN_ON(PageReserved(page));
2149                 prep_new_huge_page(h, page, page_to_nid(page));
2150                 put_page(page); /* free it into the hugepage allocator */
2151
2152                 /*
2153                  * If we had gigantic hugepages allocated at boot time, we need
2154                  * to restore the 'stolen' pages to totalram_pages in order to
2155                  * fix confusing memory reports from free(1) and another
2156                  * side-effects, like CommitLimit going negative.
2157                  */
2158                 if (hstate_is_gigantic(h))
2159                         adjust_managed_page_count(page, 1 << h->order);
2160                 cond_resched();
2161         }
2162 }
2163
2164 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2165 {
2166         unsigned long i;
2167
2168         for (i = 0; i < h->max_huge_pages; ++i) {
2169                 if (hstate_is_gigantic(h)) {
2170                         if (!alloc_bootmem_huge_page(h))
2171                                 break;
2172                 } else if (!alloc_pool_huge_page(h,
2173                                          &node_states[N_MEMORY]))
2174                         break;
2175                 cond_resched();
2176         }
2177         if (i < h->max_huge_pages) {
2178                 char buf[32];
2179
2180                 string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2181                 pr_warn("HugeTLB: allocating %lu of page size %s failed.  Only allocated %lu hugepages.\n",
2182                         h->max_huge_pages, buf, i);
2183                 h->max_huge_pages = i;
2184         }
2185 }
2186
2187 static void __init hugetlb_init_hstates(void)
2188 {
2189         struct hstate *h;
2190
2191         for_each_hstate(h) {
2192                 if (minimum_order > huge_page_order(h))
2193                         minimum_order = huge_page_order(h);
2194
2195                 /* oversize hugepages were init'ed in early boot */
2196                 if (!hstate_is_gigantic(h))
2197                         hugetlb_hstate_alloc_pages(h);
2198         }
2199         VM_BUG_ON(minimum_order == UINT_MAX);
2200 }
2201
2202 static void __init report_hugepages(void)
2203 {
2204         struct hstate *h;
2205
2206         for_each_hstate(h) {
2207                 char buf[32];
2208
2209                 string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2210                 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2211                         buf, h->free_huge_pages);
2212         }
2213 }
2214
2215 #ifdef CONFIG_HIGHMEM
2216 static void try_to_free_low(struct hstate *h, unsigned long count,
2217                                                 nodemask_t *nodes_allowed)
2218 {
2219         int i;
2220
2221         if (hstate_is_gigantic(h))
2222                 return;
2223
2224         for_each_node_mask(i, *nodes_allowed) {
2225                 struct page *page, *next;
2226                 struct list_head *freel = &h->hugepage_freelists[i];
2227                 list_for_each_entry_safe(page, next, freel, lru) {
2228                         if (count >= h->nr_huge_pages)
2229                                 return;
2230                         if (PageHighMem(page))
2231                                 continue;
2232                         list_del(&page->lru);
2233                         update_and_free_page(h, page);
2234                         h->free_huge_pages--;
2235                         h->free_huge_pages_node[page_to_nid(page)]--;
2236                 }
2237         }
2238 }
2239 #else
2240 static inline void try_to_free_low(struct hstate *h, unsigned long count,
2241                                                 nodemask_t *nodes_allowed)
2242 {
2243 }
2244 #endif
2245
2246 /*
2247  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
2248  * balanced by operating on them in a round-robin fashion.
2249  * Returns 1 if an adjustment was made.
2250  */
2251 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2252                                 int delta)
2253 {
2254         int nr_nodes, node;
2255
2256         VM_BUG_ON(delta != -1 && delta != 1);
2257
2258         if (delta < 0) {
2259                 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2260                         if (h->surplus_huge_pages_node[node])
2261                                 goto found;
2262                 }
2263         } else {
2264                 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2265                         if (h->surplus_huge_pages_node[node] <
2266                                         h->nr_huge_pages_node[node])
2267                                 goto found;
2268                 }
2269         }
2270         return 0;
2271
2272 found:
2273         h->surplus_huge_pages += delta;
2274         h->surplus_huge_pages_node[node] += delta;
2275         return 1;
2276 }
2277
2278 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2279 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2280                                                 nodemask_t *nodes_allowed)
2281 {
2282         unsigned long min_count, ret;
2283
2284         if (hstate_is_gigantic(h) && !gigantic_page_supported())
2285                 return h->max_huge_pages;
2286
2287         /*
2288          * Increase the pool size
2289          * First take pages out of surplus state.  Then make up the
2290          * remaining difference by allocating fresh huge pages.
2291          *
2292          * We might race with alloc_surplus_huge_page() here and be unable
2293          * to convert a surplus huge page to a normal huge page. That is
2294          * not critical, though, it just means the overall size of the
2295          * pool might be one hugepage larger than it needs to be, but
2296          * within all the constraints specified by the sysctls.
2297          */
2298         spin_lock(&hugetlb_lock);
2299         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2300                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
2301                         break;
2302         }
2303
2304         while (count > persistent_huge_pages(h)) {
2305                 /*
2306                  * If this allocation races such that we no longer need the
2307                  * page, free_huge_page will handle it by freeing the page
2308                  * and reducing the surplus.
2309                  */
2310                 spin_unlock(&hugetlb_lock);
2311
2312                 /* yield cpu to avoid soft lockup */
2313                 cond_resched();
2314
2315                 ret = alloc_pool_huge_page(h, nodes_allowed);
2316                 spin_lock(&hugetlb_lock);
2317                 if (!ret)
2318                         goto out;
2319
2320                 /* Bail for signals. Probably ctrl-c from user */
2321                 if (signal_pending(current))
2322                         goto out;
2323         }
2324
2325         /*
2326          * Decrease the pool size
2327          * First return free pages to the buddy allocator (being careful
2328          * to keep enough around to satisfy reservations).  Then place
2329          * pages into surplus state as needed so the pool will shrink
2330          * to the desired size as pages become free.
2331          *
2332          * By placing pages into the surplus state independent of the
2333          * overcommit value, we are allowing the surplus pool size to
2334          * exceed overcommit. There are few sane options here. Since
2335          * alloc_surplus_huge_page() is checking the global counter,
2336          * though, we'll note that we're not allowed to exceed surplus
2337          * and won't grow the pool anywhere else. Not until one of the
2338          * sysctls are changed, or the surplus pages go out of use.
2339          */
2340         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2341         min_count = max(count, min_count);
2342         try_to_free_low(h, min_count, nodes_allowed);
2343         while (min_count < persistent_huge_pages(h)) {
2344                 if (!free_pool_huge_page(h, nodes_allowed, 0))
2345                         break;
2346                 cond_resched_lock(&hugetlb_lock);
2347         }
2348         while (count < persistent_huge_pages(h)) {
2349                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
2350                         break;
2351         }
2352 out:
2353         ret = persistent_huge_pages(h);
2354         spin_unlock(&hugetlb_lock);
2355         return ret;
2356 }
2357
2358 #define HSTATE_ATTR_RO(_name) \
2359         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2360
2361 #define HSTATE_ATTR(_name) \
2362         static struct kobj_attribute _name##_attr = \
2363                 __ATTR(_name, 0644, _name##_show, _name##_store)
2364
2365 static struct kobject *hugepages_kobj;
2366 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2367
2368 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2369
2370 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2371 {
2372         int i;
2373
2374         for (i = 0; i < HUGE_MAX_HSTATE; i++)
2375                 if (hstate_kobjs[i] == kobj) {
2376                         if (nidp)
2377                                 *nidp = NUMA_NO_NODE;
2378                         return &hstates[i];
2379                 }
2380
2381         return kobj_to_node_hstate(kobj, nidp);
2382 }
2383
2384 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2385                                         struct kobj_attribute *attr, char *buf)
2386 {
2387         struct hstate *h;
2388         unsigned long nr_huge_pages;
2389         int nid;
2390
2391         h = kobj_to_hstate(kobj, &nid);
2392         if (nid == NUMA_NO_NODE)
2393                 nr_huge_pages = h->nr_huge_pages;
2394         else
2395                 nr_huge_pages = h->nr_huge_pages_node[nid];
2396
2397         return sprintf(buf, "%lu\n", nr_huge_pages);
2398 }
2399
2400 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2401                                            struct hstate *h, int nid,
2402                                            unsigned long count, size_t len)
2403 {
2404         int err;
2405         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2406
2407         if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2408                 err = -EINVAL;
2409                 goto out;
2410         }
2411
2412         if (nid == NUMA_NO_NODE) {
2413                 /*
2414                  * global hstate attribute
2415                  */
2416                 if (!(obey_mempolicy &&
2417                                 init_nodemask_of_mempolicy(nodes_allowed))) {
2418                         NODEMASK_FREE(nodes_allowed);
2419                         nodes_allowed = &node_states[N_MEMORY];
2420                 }
2421         } else if (nodes_allowed) {
2422                 /*
2423                  * per node hstate attribute: adjust count to global,
2424                  * but restrict alloc/free to the specified node.
2425                  */
2426                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2427                 init_nodemask_of_node(nodes_allowed, nid);
2428         } else
2429                 nodes_allowed = &node_states[N_MEMORY];
2430
2431         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2432
2433         if (nodes_allowed != &node_states[N_MEMORY])
2434                 NODEMASK_FREE(nodes_allowed);
2435
2436         return len;
2437 out:
2438         NODEMASK_FREE(nodes_allowed);
2439         return err;
2440 }
2441
2442 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2443                                          struct kobject *kobj, const char *buf,
2444                                          size_t len)
2445 {
2446         struct hstate *h;
2447         unsigned long count;
2448         int nid;
2449         int err;
2450
2451         err = kstrtoul(buf, 10, &count);
2452         if (err)
2453                 return err;
2454
2455         h = kobj_to_hstate(kobj, &nid);
2456         return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2457 }
2458
2459 static ssize_t nr_hugepages_show(struct kobject *kobj,
2460                                        struct kobj_attribute *attr, char *buf)
2461 {
2462         return nr_hugepages_show_common(kobj, attr, buf);
2463 }
2464
2465 static ssize_t nr_hugepages_store(struct kobject *kobj,
2466                struct kobj_attribute *attr, const char *buf, size_t len)
2467 {
2468         return nr_hugepages_store_common(false, kobj, buf, len);
2469 }
2470 HSTATE_ATTR(nr_hugepages);
2471
2472 #ifdef CONFIG_NUMA
2473
2474 /*
2475  * hstate attribute for optionally mempolicy-based constraint on persistent
2476  * huge page alloc/free.
2477  */
2478 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2479                                        struct kobj_attribute *attr, char *buf)
2480 {
2481         return nr_hugepages_show_common(kobj, attr, buf);
2482 }
2483
2484 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2485                struct kobj_attribute *attr, const char *buf, size_t len)
2486 {
2487         return nr_hugepages_store_common(true, kobj, buf, len);
2488 }
2489 HSTATE_ATTR(nr_hugepages_mempolicy);
2490 #endif
2491
2492
2493 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2494                                         struct kobj_attribute *attr, char *buf)
2495 {
2496         struct hstate *h = kobj_to_hstate(kobj, NULL);
2497         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2498 }
2499
2500 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2501                 struct kobj_attribute *attr, const char *buf, size_t count)
2502 {
2503         int err;
2504         unsigned long input;
2505         struct hstate *h = kobj_to_hstate(kobj, NULL);
2506
2507         if (hstate_is_gigantic(h))
2508                 return -EINVAL;
2509
2510         err = kstrtoul(buf, 10, &input);
2511         if (err)
2512                 return err;
2513
2514         spin_lock(&hugetlb_lock);
2515         h->nr_overcommit_huge_pages = input;
2516         spin_unlock(&hugetlb_lock);
2517
2518         return count;
2519 }
2520 HSTATE_ATTR(nr_overcommit_hugepages);
2521
2522 static ssize_t free_hugepages_show(struct kobject *kobj,
2523                                         struct kobj_attribute *attr, char *buf)
2524 {
2525         struct hstate *h;
2526         unsigned long free_huge_pages;
2527         int nid;
2528
2529         h = kobj_to_hstate(kobj, &nid);
2530         if (nid == NUMA_NO_NODE)
2531                 free_huge_pages = h->free_huge_pages;
2532         else
2533                 free_huge_pages = h->free_huge_pages_node[nid];
2534
2535         return sprintf(buf, "%lu\n", free_huge_pages);
2536 }
2537 HSTATE_ATTR_RO(free_hugepages);
2538
2539 static ssize_t resv_hugepages_show(struct kobject *kobj,
2540                                         struct kobj_attribute *attr, char *buf)
2541 {
2542         struct hstate *h = kobj_to_hstate(kobj, NULL);
2543         return sprintf(buf, "%lu\n", h->resv_huge_pages);
2544 }
2545 HSTATE_ATTR_RO(resv_hugepages);
2546
2547 static ssize_t surplus_hugepages_show(struct kobject *kobj,
2548                                         struct kobj_attribute *attr, char *buf)
2549 {
2550         struct hstate *h;
2551         unsigned long surplus_huge_pages;
2552         int nid;
2553
2554         h = kobj_to_hstate(kobj, &nid);
2555         if (nid == NUMA_NO_NODE)
2556                 surplus_huge_pages = h->surplus_huge_pages;
2557         else
2558                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
2559
2560         return sprintf(buf, "%lu\n", surplus_huge_pages);
2561 }
2562 HSTATE_ATTR_RO(surplus_hugepages);
2563
2564 static struct attribute *hstate_attrs[] = {
2565         &nr_hugepages_attr.attr,
2566         &nr_overcommit_hugepages_attr.attr,
2567         &free_hugepages_attr.attr,
2568         &resv_hugepages_attr.attr,
2569         &surplus_hugepages_attr.attr,
2570 #ifdef CONFIG_NUMA
2571         &nr_hugepages_mempolicy_attr.attr,
2572 #endif
2573         NULL,
2574 };
2575
2576 static const struct attribute_group hstate_attr_group = {
2577         .attrs = hstate_attrs,
2578 };
2579
2580 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2581                                     struct kobject **hstate_kobjs,
2582                                     const struct attribute_group *hstate_attr_group)
2583 {
2584         int retval;
2585         int hi = hstate_index(h);
2586
2587         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2588         if (!hstate_kobjs[hi])
2589                 return -ENOMEM;
2590
2591         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2592         if (retval)
2593                 kobject_put(hstate_kobjs[hi]);
2594
2595         return retval;
2596 }
2597
2598 static void __init hugetlb_sysfs_init(void)
2599 {
2600         struct hstate *h;
2601         int err;
2602
2603         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2604         if (!hugepages_kobj)
2605                 return;
2606
2607         for_each_hstate(h) {
2608                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2609                                          hstate_kobjs, &hstate_attr_group);
2610                 if (err)
2611                         pr_err("Hugetlb: Unable to add hstate %s", h->name);
2612         }
2613 }
2614
2615 #ifdef CONFIG_NUMA
2616
2617 /*
2618  * node_hstate/s - associate per node hstate attributes, via their kobjects,
2619  * with node devices in node_devices[] using a parallel array.  The array
2620  * index of a node device or _hstate == node id.
2621  * This is here to avoid any static dependency of the node device driver, in
2622  * the base kernel, on the hugetlb module.
2623  */
2624 struct node_hstate {
2625         struct kobject          *hugepages_kobj;
2626         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
2627 };
2628 static struct node_hstate node_hstates[MAX_NUMNODES];
2629
2630 /*
2631  * A subset of global hstate attributes for node devices
2632  */
2633 static struct attribute *per_node_hstate_attrs[] = {
2634         &nr_hugepages_attr.attr,
2635         &free_hugepages_attr.attr,
2636         &surplus_hugepages_attr.attr,
2637         NULL,
2638 };
2639
2640 static const struct attribute_group per_node_hstate_attr_group = {
2641         .attrs = per_node_hstate_attrs,
2642 };
2643
2644 /*
2645  * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2646  * Returns node id via non-NULL nidp.
2647  */
2648 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2649 {
2650         int nid;
2651
2652         for (nid = 0; nid < nr_node_ids; nid++) {
2653                 struct node_hstate *nhs = &node_hstates[nid];
2654                 int i;
2655                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2656                         if (nhs->hstate_kobjs[i] == kobj) {
2657                                 if (nidp)
2658                                         *nidp = nid;
2659                                 return &hstates[i];
2660                         }
2661         }
2662
2663         BUG();
2664         return NULL;
2665 }
2666
2667 /*
2668  * Unregister hstate attributes from a single node device.
2669  * No-op if no hstate attributes attached.
2670  */
2671 static void hugetlb_unregister_node(struct node *node)
2672 {
2673         struct hstate *h;
2674         struct node_hstate *nhs = &node_hstates[node->dev.id];
2675
2676         if (!nhs->hugepages_kobj)
2677                 return;         /* no hstate attributes */
2678
2679         for_each_hstate(h) {
2680                 int idx = hstate_index(h);
2681                 if (nhs->hstate_kobjs[idx]) {
2682                         kobject_put(nhs->hstate_kobjs[idx]);
2683                         nhs->hstate_kobjs[idx] = NULL;
2684                 }
2685         }
2686
2687         kobject_put(nhs->hugepages_kobj);
2688         nhs->hugepages_kobj = NULL;
2689 }
2690
2691
2692 /*
2693  * Register hstate attributes for a single node device.
2694  * No-op if attributes already registered.
2695  */
2696 static void hugetlb_register_node(struct node *node)
2697 {
2698         struct hstate *h;
2699         struct node_hstate *nhs = &node_hstates[node->dev.id];
2700         int err;
2701
2702         if (nhs->hugepages_kobj)
2703                 return;         /* already allocated */
2704
2705         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2706                                                         &node->dev.kobj);
2707         if (!nhs->hugepages_kobj)
2708                 return;
2709
2710         for_each_hstate(h) {
2711                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2712                                                 nhs->hstate_kobjs,
2713                                                 &per_node_hstate_attr_group);
2714                 if (err) {
2715                         pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2716                                 h->name, node->dev.id);
2717                         hugetlb_unregister_node(node);
2718                         break;
2719                 }
2720         }
2721 }
2722
2723 /*
2724  * hugetlb init time:  register hstate attributes for all registered node
2725  * devices of nodes that have memory.  All on-line nodes should have
2726  * registered their associated device by this time.
2727  */
2728 static void __init hugetlb_register_all_nodes(void)
2729 {
2730         int nid;
2731
2732         for_each_node_state(nid, N_MEMORY) {
2733                 struct node *node = node_devices[nid];
2734                 if (node->dev.id == nid)
2735                         hugetlb_register_node(node);
2736         }
2737
2738         /*
2739          * Let the node device driver know we're here so it can
2740          * [un]register hstate attributes on node hotplug.
2741          */
2742         register_hugetlbfs_with_node(hugetlb_register_node,
2743                                      hugetlb_unregister_node);
2744 }
2745 #else   /* !CONFIG_NUMA */
2746
2747 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2748 {
2749         BUG();
2750         if (nidp)
2751                 *nidp = -1;
2752         return NULL;
2753 }
2754
2755 static void hugetlb_register_all_nodes(void) { }
2756
2757 #endif
2758
2759 static int __init hugetlb_init(void)
2760 {
2761         int i;
2762
2763         if (!hugepages_supported())
2764                 return 0;
2765
2766         if (!size_to_hstate(default_hstate_size)) {
2767                 if (default_hstate_size != 0) {
2768                         pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
2769                                default_hstate_size, HPAGE_SIZE);
2770                 }
2771
2772                 default_hstate_size = HPAGE_SIZE;
2773                 if (!size_to_hstate(default_hstate_size))
2774                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2775         }
2776         default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2777         if (default_hstate_max_huge_pages) {
2778                 if (!default_hstate.max_huge_pages)
2779                         default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2780         }
2781
2782         hugetlb_init_hstates();
2783         gather_bootmem_prealloc();
2784         report_hugepages();
2785
2786         hugetlb_sysfs_init();
2787         hugetlb_register_all_nodes();
2788         hugetlb_cgroup_file_init();
2789
2790 #ifdef CONFIG_SMP
2791         num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2792 #else
2793         num_fault_mutexes = 1;
2794 #endif
2795         hugetlb_fault_mutex_table =
2796                 kmalloc_array(num_fault_mutexes, sizeof(struct mutex),
2797                               GFP_KERNEL);
2798         BUG_ON(!hugetlb_fault_mutex_table);
2799
2800         for (i = 0; i < num_fault_mutexes; i++)
2801                 mutex_init(&hugetlb_fault_mutex_table[i]);
2802         return 0;
2803 }
2804 subsys_initcall(hugetlb_init);
2805
2806 /* Should be called on processing a hugepagesz=... option */
2807 void __init hugetlb_bad_size(void)
2808 {
2809         parsed_valid_hugepagesz = false;
2810 }
2811
2812 void __init hugetlb_add_hstate(unsigned int order)
2813 {
2814         struct hstate *h;
2815         unsigned long i;
2816
2817         if (size_to_hstate(PAGE_SIZE << order)) {
2818                 pr_warn("hugepagesz= specified twice, ignoring\n");
2819                 return;
2820         }
2821         BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2822         BUG_ON(order == 0);
2823         h = &hstates[hugetlb_max_hstate++];
2824         h->order = order;
2825         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2826         h->nr_huge_pages = 0;
2827         h->free_huge_pages = 0;
2828         for (i = 0; i < MAX_NUMNODES; ++i)
2829                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2830         INIT_LIST_HEAD(&h->hugepage_activelist);
2831         h->next_nid_to_alloc = first_memory_node;
2832         h->next_nid_to_free = first_memory_node;
2833         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2834                                         huge_page_size(h)/1024);
2835
2836         parsed_hstate = h;
2837 }
2838
2839 static int __init hugetlb_nrpages_setup(char *s)
2840 {
2841         unsigned long *mhp;
2842         static unsigned long *last_mhp;
2843
2844         if (!parsed_valid_hugepagesz) {
2845                 pr_warn("hugepages = %s preceded by "
2846                         "an unsupported hugepagesz, ignoring\n", s);
2847                 parsed_valid_hugepagesz = true;
2848                 return 1;
2849         }
2850         /*
2851          * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2852          * so this hugepages= parameter goes to the "default hstate".
2853          */
2854         else if (!hugetlb_max_hstate)
2855                 mhp = &default_hstate_max_huge_pages;
2856         else
2857                 mhp = &parsed_hstate->max_huge_pages;
2858
2859         if (mhp == last_mhp) {
2860                 pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2861                 return 1;
2862         }
2863
2864         if (sscanf(s, "%lu", mhp) <= 0)
2865                 *mhp = 0;
2866
2867         /*
2868          * Global state is always initialized later in hugetlb_init.
2869          * But we need to allocate >= MAX_ORDER hstates here early to still
2870          * use the bootmem allocator.
2871          */
2872         if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2873                 hugetlb_hstate_alloc_pages(parsed_hstate);
2874
2875         last_mhp = mhp;
2876
2877         return 1;
2878 }
2879 __setup("hugepages=", hugetlb_nrpages_setup);
2880
2881 static int __init hugetlb_default_setup(char *s)
2882 {
2883         default_hstate_size = memparse(s, &s);
2884         return 1;
2885 }
2886 __setup("default_hugepagesz=", hugetlb_default_setup);
2887
2888 static unsigned int cpuset_mems_nr(unsigned int *array)
2889 {
2890         int node;
2891         unsigned int nr = 0;
2892
2893         for_each_node_mask(node, cpuset_current_mems_allowed)
2894                 nr += array[node];
2895
2896         return nr;
2897 }
2898
2899 #ifdef CONFIG_SYSCTL
2900 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2901                          struct ctl_table *table, int write,
2902                          void __user *buffer, size_t *length, loff_t *ppos)
2903 {
2904         struct hstate *h = &default_hstate;
2905         unsigned long tmp = h->max_huge_pages;
2906         int ret;
2907
2908         if (!hugepages_supported())
2909                 return -EOPNOTSUPP;
2910
2911         table->data = &tmp;
2912         table->maxlen = sizeof(unsigned long);
2913         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2914         if (ret)
2915                 goto out;
2916
2917         if (write)
2918                 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2919                                                   NUMA_NO_NODE, tmp, *length);
2920 out:
2921         return ret;
2922 }
2923
2924 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2925                           void __user *buffer, size_t *length, loff_t *ppos)
2926 {
2927
2928         return hugetlb_sysctl_handler_common(false, table, write,
2929                                                         buffer, length, ppos);
2930 }
2931
2932 #ifdef CONFIG_NUMA
2933 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2934                           void __user *buffer, size_t *length, loff_t *ppos)
2935 {
2936         return hugetlb_sysctl_handler_common(true, table, write,
2937                                                         buffer, length, ppos);
2938 }
2939 #endif /* CONFIG_NUMA */
2940
2941 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2942                         void __user *buffer,
2943                         size_t *length, loff_t *ppos)
2944 {
2945         struct hstate *h = &default_hstate;
2946         unsigned long tmp;
2947         int ret;
2948
2949         if (!hugepages_supported())
2950                 return -EOPNOTSUPP;
2951
2952         tmp = h->nr_overcommit_huge_pages;
2953
2954         if (write && hstate_is_gigantic(h))
2955                 return -EINVAL;
2956
2957         table->data = &tmp;
2958         table->maxlen = sizeof(unsigned long);
2959         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2960         if (ret)
2961                 goto out;
2962
2963         if (write) {
2964                 spin_lock(&hugetlb_lock);
2965                 h->nr_overcommit_huge_pages = tmp;
2966                 spin_unlock(&hugetlb_lock);
2967         }
2968 out:
2969         return ret;
2970 }
2971
2972 #endif /* CONFIG_SYSCTL */
2973
2974 void hugetlb_report_meminfo(struct seq_file *m)
2975 {
2976         struct hstate *h;
2977         unsigned long total = 0;
2978
2979         if (!hugepages_supported())
2980                 return;
2981
2982         for_each_hstate(h) {
2983                 unsigned long count = h->nr_huge_pages;
2984
2985                 total += (PAGE_SIZE << huge_page_order(h)) * count;
2986
2987                 if (h == &default_hstate)
2988                         seq_printf(m,
2989                                    "HugePages_Total:   %5lu\n"
2990                                    "HugePages_Free:    %5lu\n"
2991                                    "HugePages_Rsvd:    %5lu\n"
2992                                    "HugePages_Surp:    %5lu\n"
2993                                    "Hugepagesize:   %8lu kB\n",
2994                                    count,
2995                                    h->free_huge_pages,
2996                                    h->resv_huge_pages,
2997                                    h->surplus_huge_pages,
2998                                    (PAGE_SIZE << huge_page_order(h)) / 1024);
2999         }
3000
3001         seq_printf(m, "Hugetlb:        %8lu kB\n", total / 1024);
3002 }
3003
3004 int hugetlb_report_node_meminfo(int nid, char *buf)
3005 {
3006         struct hstate *h = &default_hstate;
3007         if (!hugepages_supported())
3008                 return 0;
3009         return sprintf(buf,
3010                 "Node %d HugePages_Total: %5u\n"
3011                 "Node %d HugePages_Free:  %5u\n"
3012                 "Node %d HugePages_Surp:  %5u\n",
3013                 nid, h->nr_huge_pages_node[nid],
3014                 nid, h->free_huge_pages_node[nid],
3015                 nid, h->surplus_huge_pages_node[nid]);
3016 }
3017
3018 void hugetlb_show_meminfo(void)
3019 {
3020         struct hstate *h;
3021         int nid;
3022
3023         if (!hugepages_supported())
3024                 return;
3025
3026         for_each_node_state(nid, N_MEMORY)
3027                 for_each_hstate(h)
3028                         pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
3029                                 nid,
3030                                 h->nr_huge_pages_node[nid],
3031                                 h->free_huge_pages_node[nid],
3032                                 h->surplus_huge_pages_node[nid],
3033                                 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
3034 }
3035
3036 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
3037 {
3038         seq_printf(m, "HugetlbPages:\t%8lu kB\n",
3039                    atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
3040 }
3041
3042 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
3043 unsigned long hugetlb_total_pages(void)
3044 {
3045         struct hstate *h;
3046         unsigned long nr_total_pages = 0;
3047
3048         for_each_hstate(h)
3049                 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
3050         return nr_total_pages;
3051 }
3052
3053 static int hugetlb_acct_memory(struct hstate *h, long delta)
3054 {
3055         int ret = -ENOMEM;
3056
3057         spin_lock(&hugetlb_lock);
3058         /*
3059          * When cpuset is configured, it breaks the strict hugetlb page
3060          * reservation as the accounting is done on a global variable. Such
3061          * reservation is completely rubbish in the presence of cpuset because
3062          * the reservation is not checked against page availability for the
3063          * current cpuset. Application can still potentially OOM'ed by kernel
3064          * with lack of free htlb page in cpuset that the task is in.
3065          * Attempt to enforce strict accounting with cpuset is almost
3066          * impossible (or too ugly) because cpuset is too fluid that
3067          * task or memory node can be dynamically moved between cpusets.
3068          *
3069          * The change of semantics for shared hugetlb mapping with cpuset is
3070          * undesirable. However, in order to preserve some of the semantics,
3071          * we fall back to check against current free page availability as
3072          * a best attempt and hopefully to minimize the impact of changing
3073          * semantics that cpuset has.
3074          */
3075         if (delta > 0) {
3076                 if (gather_surplus_pages(h, delta) < 0)
3077                         goto out;
3078
3079                 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
3080                         return_unused_surplus_pages(h, delta);
3081                         goto out;
3082                 }
3083         }
3084
3085         ret = 0;
3086         if (delta < 0)
3087                 return_unused_surplus_pages(h, (unsigned long) -delta);
3088
3089 out:
3090         spin_unlock(&hugetlb_lock);
3091         return ret;
3092 }
3093
3094 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
3095 {
3096         struct resv_map *resv = vma_resv_map(vma);
3097
3098         /*
3099          * This new VMA should share its siblings reservation map if present.
3100          * The VMA will only ever have a valid reservation map pointer where
3101          * it is being copied for another still existing VMA.  As that VMA
3102          * has a reference to the reservation map it cannot disappear until
3103          * after this open call completes.  It is therefore safe to take a
3104          * new reference here without additional locking.
3105          */
3106         if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3107                 kref_get(&resv->refs);
3108 }
3109
3110 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
3111 {
3112         struct hstate *h = hstate_vma(vma);
3113         struct resv_map *resv = vma_resv_map(vma);
3114         struct hugepage_subpool *spool = subpool_vma(vma);
3115         unsigned long reserve, start, end;
3116         long gbl_reserve;
3117
3118         if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3119                 return;
3120
3121         start = vma_hugecache_offset(h, vma, vma->vm_start);
3122         end = vma_hugecache_offset(h, vma, vma->vm_end);
3123
3124         reserve = (end - start) - region_count(resv, start, end);
3125
3126         kref_put(&resv->refs, resv_map_release);
3127
3128         if (reserve) {
3129                 /*
3130                  * Decrement reserve counts.  The global reserve count may be
3131                  * adjusted if the subpool has a minimum size.
3132                  */
3133                 gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
3134                 hugetlb_acct_memory(h, -gbl_reserve);
3135         }
3136 }
3137
3138 static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
3139 {
3140         if (addr & ~(huge_page_mask(hstate_vma(vma))))
3141                 return -EINVAL;
3142         return 0;
3143 }
3144
3145 static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma)
3146 {
3147         struct hstate *hstate = hstate_vma(vma);
3148
3149         return 1UL << huge_page_shift(hstate);
3150 }
3151
3152 /*
3153  * We cannot handle pagefaults against hugetlb pages at all.  They cause
3154  * handle_mm_fault() to try to instantiate regular-sized pages in the
3155  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
3156  * this far.
3157  */
3158 static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf)
3159 {
3160         BUG();
3161         return 0;
3162 }
3163
3164 /*
3165  * When a new function is introduced to vm_operations_struct and added
3166  * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops.
3167  * This is because under System V memory model, mappings created via
3168  * shmget/shmat with "huge page" specified are backed by hugetlbfs files,
3169  * their original vm_ops are overwritten with shm_vm_ops.
3170  */
3171 const struct vm_operations_struct hugetlb_vm_ops = {
3172         .fault = hugetlb_vm_op_fault,
3173         .open = hugetlb_vm_op_open,
3174         .close = hugetlb_vm_op_close,
3175         .split = hugetlb_vm_op_split,
3176         .pagesize = hugetlb_vm_op_pagesize,
3177 };
3178
3179 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3180                                 int writable)
3181 {
3182         pte_t entry;
3183
3184         if (writable) {
3185                 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3186                                          vma->vm_page_prot)));
3187         } else {
3188                 entry = huge_pte_wrprotect(mk_huge_pte(page,
3189                                            vma->vm_page_prot));
3190         }
3191         entry = pte_mkyoung(entry);
3192         entry = pte_mkhuge(entry);
3193         entry = arch_make_huge_pte(entry, vma, page, writable);
3194
3195         return entry;
3196 }
3197
3198 static void set_huge_ptep_writable(struct vm_area_struct *vma,
3199                                    unsigned long address, pte_t *ptep)
3200 {
3201         pte_t entry;
3202
3203         entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3204         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3205                 update_mmu_cache(vma, address, ptep);
3206 }
3207
3208 bool is_hugetlb_entry_migration(pte_t pte)
3209 {
3210         swp_entry_t swp;
3211
3212         if (huge_pte_none(pte) || pte_present(pte))
3213                 return false;
3214         swp = pte_to_swp_entry(pte);
3215         if (non_swap_entry(swp) && is_migration_entry(swp))
3216                 return true;
3217         else
3218                 return false;
3219 }
3220
3221 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3222 {
3223         swp_entry_t swp;
3224
3225         if (huge_pte_none(pte) || pte_present(pte))
3226                 return 0;
3227         swp = pte_to_swp_entry(pte);
3228         if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3229                 return 1;
3230         else
3231                 return 0;
3232 }
3233
3234 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3235                             struct vm_area_struct *vma)
3236 {
3237         pte_t *src_pte, *dst_pte, entry, dst_entry;
3238         struct page *ptepage;
3239         unsigned long addr;
3240         int cow;
3241         struct address_space *mapping = vma->vm_file->f_mapping;
3242         struct hstate *h = hstate_vma(vma);
3243         unsigned long sz = huge_page_size(h);
3244         struct mmu_notifier_range range;
3245         int ret = 0;
3246
3247         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3248
3249         if (cow) {
3250                 mmu_notifier_range_init(&range, src, vma->vm_start,
3251                                         vma->vm_end);
3252                 mmu_notifier_invalidate_range_start(&range);
3253         } else {
3254                 /*
3255                  * For shared mappings i_mmap_rwsem must be held to call
3256                  * huge_pte_alloc, otherwise the returned ptep could go
3257                  * away if part of a shared pmd and another thread calls
3258                  * huge_pmd_unshare.
3259                  */
3260                 i_mmap_lock_read(mapping);
3261         }
3262
3263         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3264                 spinlock_t *src_ptl, *dst_ptl;
3265
3266                 src_pte = huge_pte_offset(src, addr, sz);
3267                 if (!src_pte)
3268                         continue;
3269
3270                 dst_pte = huge_pte_alloc(dst, addr, sz);
3271                 if (!dst_pte) {
3272                         ret = -ENOMEM;
3273                         break;
3274                 }
3275
3276                 /*
3277                  * If the pagetables are shared don't copy or take references.
3278                  * dst_pte == src_pte is the common case of src/dest sharing.
3279                  *
3280                  * However, src could have 'unshared' and dst shares with
3281                  * another vma.  If dst_pte !none, this implies sharing.
3282                  * Check here before taking page table lock, and once again
3283                  * after taking the lock below.
3284                  */
3285                 dst_entry = huge_ptep_get(dst_pte);
3286                 if ((dst_pte == src_pte) || !huge_pte_none(dst_entry))
3287                         continue;
3288
3289                 dst_ptl = huge_pte_lock(h, dst, dst_pte);
3290                 src_ptl = huge_pte_lockptr(h, src, src_pte);
3291                 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3292                 entry = huge_ptep_get(src_pte);
3293                 dst_entry = huge_ptep_get(dst_pte);
3294                 if (huge_pte_none(entry) || !huge_pte_none(dst_entry)) {
3295                         /*
3296                          * Skip if src entry none.  Also, skip in the
3297                          * unlikely case dst entry !none as this implies
3298                          * sharing with another vma.
3299                          */
3300                         ;
3301                 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
3302                                     is_hugetlb_entry_hwpoisoned(entry))) {
3303                         swp_entry_t swp_entry = pte_to_swp_entry(entry);
3304
3305                         if (is_write_migration_entry(swp_entry) && cow) {
3306                                 /*
3307                                  * COW mappings require pages in both
3308                                  * parent and child to be set to read.
3309                                  */
3310                                 make_migration_entry_read(&swp_entry);
3311                                 entry = swp_entry_to_pte(swp_entry);
3312                                 set_huge_swap_pte_at(src, addr, src_pte,
3313                                                      entry, sz);
3314                         }
3315                         set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
3316                 } else {
3317                         if (cow) {
3318                                 /*
3319                                  * No need to notify as we are downgrading page
3320                                  * table protection not changing it to point
3321                                  * to a new page.
3322                                  *
3323                                  * See Documentation/vm/mmu_notifier.rst
3324                                  */
3325                                 huge_ptep_set_wrprotect(src, addr, src_pte);
3326                         }
3327                         entry = huge_ptep_get(src_pte);
3328                         ptepage = pte_page(entry);
3329                         get_page(ptepage);
3330                         page_dup_rmap(ptepage, true);
3331                         set_huge_pte_at(dst, addr, dst_pte, entry);
3332                         hugetlb_count_add(pages_per_huge_page(h), dst);
3333                 }
3334                 spin_unlock(src_ptl);
3335                 spin_unlock(dst_ptl);
3336         }
3337
3338         if (cow)
3339                 mmu_notifier_invalidate_range_end(&range);
3340         else
3341                 i_mmap_unlock_read(mapping);
3342
3343         return ret;
3344 }
3345
3346 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3347                             unsigned long start, unsigned long end,
3348                             struct page *ref_page)
3349 {
3350         struct mm_struct *mm = vma->vm_mm;
3351         unsigned long address;
3352         pte_t *ptep;
3353         pte_t pte;
3354         spinlock_t *ptl;
3355         struct page *page;
3356         struct hstate *h = hstate_vma(vma);
3357         unsigned long sz = huge_page_size(h);
3358         struct mmu_notifier_range range;
3359
3360         WARN_ON(!is_vm_hugetlb_page(vma));
3361         BUG_ON(start & ~huge_page_mask(h));
3362         BUG_ON(end & ~huge_page_mask(h));
3363
3364         /*
3365          * This is a hugetlb vma, all the pte entries should point
3366          * to huge page.
3367          */
3368      &nb