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Linux/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/bootmem.h>
 19 #include <linux/sysfs.h>
 20 #include <linux/slab.h>
 21 #include <linux/rmap.h>
 22 #include <linux/swap.h>
 23 #include <linux/swapops.h>
 24 #include <linux/page-isolation.h>
 25 #include <linux/jhash.h>
 26 
 27 #include <asm/page.h>
 28 #include <asm/pgtable.h>
 29 #include <asm/tlb.h>
 30 
 31 #include <linux/io.h>
 32 #include <linux/hugetlb.h>
 33 #include <linux/hugetlb_cgroup.h>
 34 #include <linux/node.h>
 35 #include "internal.h"
 36 
 37 int hugepages_treat_as_movable;
 38 
 39 int hugetlb_max_hstate __read_mostly;
 40 unsigned int default_hstate_idx;
 41 struct hstate hstates[HUGE_MAX_HSTATE];
 42 /*
 43  * Minimum page order among possible hugepage sizes, set to a proper value
 44  * at boot time.
 45  */
 46 static unsigned int minimum_order __read_mostly = UINT_MAX;
 47 
 48 __initdata LIST_HEAD(huge_boot_pages);
 49 
 50 /* for command line parsing */
 51 static struct hstate * __initdata parsed_hstate;
 52 static unsigned long __initdata default_hstate_max_huge_pages;
 53 static unsigned long __initdata default_hstate_size;
 54 static bool __initdata parsed_valid_hugepagesz = true;
 55 
 56 /*
 57  * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
 58  * free_huge_pages, and surplus_huge_pages.
 59  */
 60 DEFINE_SPINLOCK(hugetlb_lock);
 61 
 62 /*
 63  * Serializes faults on the same logical page.  This is used to
 64  * prevent spurious OOMs when the hugepage pool is fully utilized.
 65  */
 66 static int num_fault_mutexes;
 67 struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
 68 
 69 /* Forward declaration */
 70 static int hugetlb_acct_memory(struct hstate *h, long delta);
 71 
 72 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
 73 {
 74         bool free = (spool->count == 0) && (spool->used_hpages == 0);
 75 
 76         spin_unlock(&spool->lock);
 77 
 78         /* If no pages are used, and no other handles to the subpool
 79          * remain, give up any reservations mased on minimum size and
 80          * free the subpool */
 81         if (free) {
 82                 if (spool->min_hpages != -1)
 83                         hugetlb_acct_memory(spool->hstate,
 84                                                 -spool->min_hpages);
 85                 kfree(spool);
 86         }
 87 }
 88 
 89 struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
 90                                                 long min_hpages)
 91 {
 92         struct hugepage_subpool *spool;
 93 
 94         spool = kzalloc(sizeof(*spool), GFP_KERNEL);
 95         if (!spool)
 96                 return NULL;
 97 
 98         spin_lock_init(&spool->lock);
 99         spool->count = 1;
100         spool->max_hpages = max_hpages;
101         spool->hstate = h;
102         spool->min_hpages = min_hpages;
103 
104         if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
105                 kfree(spool);
106                 return NULL;
107         }
108         spool->rsv_hpages = min_hpages;
109 
110         return spool;
111 }
112 
113 void hugepage_put_subpool(struct hugepage_subpool *spool)
114 {
115         spin_lock(&spool->lock);
116         BUG_ON(!spool->count);
117         spool->count--;
118         unlock_or_release_subpool(spool);
119 }
120 
121 /*
122  * Subpool accounting for allocating and reserving pages.
123  * Return -ENOMEM if there are not enough resources to satisfy the
124  * the request.  Otherwise, return the number of pages by which the
125  * global pools must be adjusted (upward).  The returned value may
126  * only be different than the passed value (delta) in the case where
127  * a subpool minimum size must be manitained.
128  */
129 static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
130                                       long delta)
131 {
132         long ret = delta;
133 
134         if (!spool)
135                 return ret;
136 
137         spin_lock(&spool->lock);
138 
139         if (spool->max_hpages != -1) {          /* maximum size accounting */
140                 if ((spool->used_hpages + delta) <= spool->max_hpages)
141                         spool->used_hpages += delta;
142                 else {
143                         ret = -ENOMEM;
144                         goto unlock_ret;
145                 }
146         }
147 
148         /* minimum size accounting */
149         if (spool->min_hpages != -1 && spool->rsv_hpages) {
150                 if (delta > spool->rsv_hpages) {
151                         /*
152                          * Asking for more reserves than those already taken on
153                          * behalf of subpool.  Return difference.
154                          */
155                         ret = delta - spool->rsv_hpages;
156                         spool->rsv_hpages = 0;
157                 } else {
158                         ret = 0;        /* reserves already accounted for */
159                         spool->rsv_hpages -= delta;
160                 }
161         }
162 
163 unlock_ret:
164         spin_unlock(&spool->lock);
165         return ret;
166 }
167 
168 /*
169  * Subpool accounting for freeing and unreserving pages.
170  * Return the number of global page reservations that must be dropped.
171  * The return value may only be different than the passed value (delta)
172  * in the case where a subpool minimum size must be maintained.
173  */
174 static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
175                                        long delta)
176 {
177         long ret = delta;
178 
179         if (!spool)
180                 return delta;
181 
182         spin_lock(&spool->lock);
183 
184         if (spool->max_hpages != -1)            /* maximum size accounting */
185                 spool->used_hpages -= delta;
186 
187          /* minimum size accounting */
188         if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
189                 if (spool->rsv_hpages + delta <= spool->min_hpages)
190                         ret = 0;
191                 else
192                         ret = spool->rsv_hpages + delta - spool->min_hpages;
193 
194                 spool->rsv_hpages += delta;
195                 if (spool->rsv_hpages > spool->min_hpages)
196                         spool->rsv_hpages = spool->min_hpages;
197         }
198 
199         /*
200          * If hugetlbfs_put_super couldn't free spool due to an outstanding
201          * quota reference, free it now.
202          */
203         unlock_or_release_subpool(spool);
204 
205         return ret;
206 }
207 
208 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
209 {
210         return HUGETLBFS_SB(inode->i_sb)->spool;
211 }
212 
213 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
214 {
215         return subpool_inode(file_inode(vma->vm_file));
216 }
217 
218 /*
219  * Region tracking -- allows tracking of reservations and instantiated pages
220  *                    across the pages in a mapping.
221  *
222  * The region data structures are embedded into a resv_map and protected
223  * by a resv_map's lock.  The set of regions within the resv_map represent
224  * reservations for huge pages, or huge pages that have already been
225  * instantiated within the map.  The from and to elements are huge page
226  * indicies into the associated mapping.  from indicates the starting index
227  * of the region.  to represents the first index past the end of  the region.
228  *
229  * For example, a file region structure with from == 0 and to == 4 represents
230  * four huge pages in a mapping.  It is important to note that the to element
231  * represents the first element past the end of the region. This is used in
232  * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
233  *
234  * Interval notation of the form [from, to) will be used to indicate that
235  * the endpoint from is inclusive and to is exclusive.
236  */
237 struct file_region {
238         struct list_head link;
239         long from;
240         long to;
241 };
242 
243 /*
244  * Add the huge page range represented by [f, t) to the reserve
245  * map.  In the normal case, existing regions will be expanded
246  * to accommodate the specified range.  Sufficient regions should
247  * exist for expansion due to the previous call to region_chg
248  * with the same range.  However, it is possible that region_del
249  * could have been called after region_chg and modifed the map
250  * in such a way that no region exists to be expanded.  In this
251  * case, pull a region descriptor from the cache associated with
252  * the map and use that for the new range.
253  *
254  * Return the number of new huge pages added to the map.  This
255  * number is greater than or equal to zero.
256  */
257 static long region_add(struct resv_map *resv, long f, long t)
258 {
259         struct list_head *head = &resv->regions;
260         struct file_region *rg, *nrg, *trg;
261         long add = 0;
262 
263         spin_lock(&resv->lock);
264         /* Locate the region we are either in or before. */
265         list_for_each_entry(rg, head, link)
266                 if (f <= rg->to)
267                         break;
268 
269         /*
270          * If no region exists which can be expanded to include the
271          * specified range, the list must have been modified by an
272          * interleving call to region_del().  Pull a region descriptor
273          * from the cache and use it for this range.
274          */
275         if (&rg->link == head || t < rg->from) {
276                 VM_BUG_ON(resv->region_cache_count <= 0);
277 
278                 resv->region_cache_count--;
279                 nrg = list_first_entry(&resv->region_cache, struct file_region,
280                                         link);
281                 list_del(&nrg->link);
282 
283                 nrg->from = f;
284                 nrg->to = t;
285                 list_add(&nrg->link, rg->link.prev);
286 
287                 add += t - f;
288                 goto out_locked;
289         }
290 
291         /* Round our left edge to the current segment if it encloses us. */
292         if (f > rg->from)
293                 f = rg->from;
294 
295         /* Check for and consume any regions we now overlap with. */
296         nrg = rg;
297         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
298                 if (&rg->link == head)
299                         break;
300                 if (rg->from > t)
301                         break;
302 
303                 /* If this area reaches higher then extend our area to
304                  * include it completely.  If this is not the first area
305                  * which we intend to reuse, free it. */
306                 if (rg->to > t)
307                         t = rg->to;
308                 if (rg != nrg) {
309                         /* Decrement return value by the deleted range.
310                          * Another range will span this area so that by
311                          * end of routine add will be >= zero
312                          */
313                         add -= (rg->to - rg->from);
314                         list_del(&rg->link);
315                         kfree(rg);
316                 }
317         }
318 
319         add += (nrg->from - f);         /* Added to beginning of region */
320         nrg->from = f;
321         add += t - nrg->to;             /* Added to end of region */
322         nrg->to = t;
323 
324 out_locked:
325         resv->adds_in_progress--;
326         spin_unlock(&resv->lock);
327         VM_BUG_ON(add < 0);
328         return add;
329 }
330 
331 /*
332  * Examine the existing reserve map and determine how many
333  * huge pages in the specified range [f, t) are NOT currently
334  * represented.  This routine is called before a subsequent
335  * call to region_add that will actually modify the reserve
336  * map to add the specified range [f, t).  region_chg does
337  * not change the number of huge pages represented by the
338  * map.  However, if the existing regions in the map can not
339  * be expanded to represent the new range, a new file_region
340  * structure is added to the map as a placeholder.  This is
341  * so that the subsequent region_add call will have all the
342  * regions it needs and will not fail.
343  *
344  * Upon entry, region_chg will also examine the cache of region descriptors
345  * associated with the map.  If there are not enough descriptors cached, one
346  * will be allocated for the in progress add operation.
347  *
348  * Returns the number of huge pages that need to be added to the existing
349  * reservation map for the range [f, t).  This number is greater or equal to
350  * zero.  -ENOMEM is returned if a new file_region structure or cache entry
351  * is needed and can not be allocated.
352  */
353 static long region_chg(struct resv_map *resv, long f, long t)
354 {
355         struct list_head *head = &resv->regions;
356         struct file_region *rg, *nrg = NULL;
357         long chg = 0;
358 
359 retry:
360         spin_lock(&resv->lock);
361 retry_locked:
362         resv->adds_in_progress++;
363 
364         /*
365          * Check for sufficient descriptors in the cache to accommodate
366          * the number of in progress add operations.
367          */
368         if (resv->adds_in_progress > resv->region_cache_count) {
369                 struct file_region *trg;
370 
371                 VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
372                 /* Must drop lock to allocate a new descriptor. */
373                 resv->adds_in_progress--;
374                 spin_unlock(&resv->lock);
375 
376                 trg = kmalloc(sizeof(*trg), GFP_KERNEL);
377                 if (!trg) {
378                         kfree(nrg);
379                         return -ENOMEM;
380                 }
381 
382                 spin_lock(&resv->lock);
383                 list_add(&trg->link, &resv->region_cache);
384                 resv->region_cache_count++;
385                 goto retry_locked;
386         }
387 
388         /* Locate the region we are before or in. */
389         list_for_each_entry(rg, head, link)
390                 if (f <= rg->to)
391                         break;
392 
393         /* If we are below the current region then a new region is required.
394          * Subtle, allocate a new region at the position but make it zero
395          * size such that we can guarantee to record the reservation. */
396         if (&rg->link == head || t < rg->from) {
397                 if (!nrg) {
398                         resv->adds_in_progress--;
399                         spin_unlock(&resv->lock);
400                         nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
401                         if (!nrg)
402                                 return -ENOMEM;
403 
404                         nrg->from = f;
405                         nrg->to   = f;
406                         INIT_LIST_HEAD(&nrg->link);
407                         goto retry;
408                 }
409 
410                 list_add(&nrg->link, rg->link.prev);
411                 chg = t - f;
412                 goto out_nrg;
413         }
414 
415         /* Round our left edge to the current segment if it encloses us. */
416         if (f > rg->from)
417                 f = rg->from;
418         chg = t - f;
419 
420         /* Check for and consume any regions we now overlap with. */
421         list_for_each_entry(rg, rg->link.prev, link) {
422                 if (&rg->link == head)
423                         break;
424                 if (rg->from > t)
425                         goto out;
426 
427                 /* We overlap with this area, if it extends further than
428                  * us then we must extend ourselves.  Account for its
429                  * existing reservation. */
430                 if (rg->to > t) {
431                         chg += rg->to - t;
432                         t = rg->to;
433                 }
434                 chg -= rg->to - rg->from;
435         }
436 
437 out:
438         spin_unlock(&resv->lock);
439         /*  We already know we raced and no longer need the new region */
440         kfree(nrg);
441         return chg;
442 out_nrg:
443         spin_unlock(&resv->lock);
444         return chg;
445 }
446 
447 /*
448  * Abort the in progress add operation.  The adds_in_progress field
449  * of the resv_map keeps track of the operations in progress between
450  * calls to region_chg and region_add.  Operations are sometimes
451  * aborted after the call to region_chg.  In such cases, region_abort
452  * is called to decrement the adds_in_progress counter.
453  *
454  * NOTE: The range arguments [f, t) are not needed or used in this
455  * routine.  They are kept to make reading the calling code easier as
456  * arguments will match the associated region_chg call.
457  */
458 static void region_abort(struct resv_map *resv, long f, long t)
459 {
460         spin_lock(&resv->lock);
461         VM_BUG_ON(!resv->region_cache_count);
462         resv->adds_in_progress--;
463         spin_unlock(&resv->lock);
464 }
465 
466 /*
467  * Delete the specified range [f, t) from the reserve map.  If the
468  * t parameter is LONG_MAX, this indicates that ALL regions after f
469  * should be deleted.  Locate the regions which intersect [f, t)
470  * and either trim, delete or split the existing regions.
471  *
472  * Returns the number of huge pages deleted from the reserve map.
473  * In the normal case, the return value is zero or more.  In the
474  * case where a region must be split, a new region descriptor must
475  * be allocated.  If the allocation fails, -ENOMEM will be returned.
476  * NOTE: If the parameter t == LONG_MAX, then we will never split
477  * a region and possibly return -ENOMEM.  Callers specifying
478  * t == LONG_MAX do not need to check for -ENOMEM error.
479  */
480 static long region_del(struct resv_map *resv, long f, long t)
481 {
482         struct list_head *head = &resv->regions;
483         struct file_region *rg, *trg;
484         struct file_region *nrg = NULL;
485         long del = 0;
486 
487 retry:
488         spin_lock(&resv->lock);
489         list_for_each_entry_safe(rg, trg, head, link) {
490                 /*
491                  * Skip regions before the range to be deleted.  file_region
492                  * ranges are normally of the form [from, to).  However, there
493                  * may be a "placeholder" entry in the map which is of the form
494                  * (from, to) with from == to.  Check for placeholder entries
495                  * at the beginning of the range to be deleted.
496                  */
497                 if (rg->to <= f && (rg->to != rg->from || rg->to != f))
498                         continue;
499 
500                 if (rg->from >= t)
501                         break;
502 
503                 if (f > rg->from && t < rg->to) { /* Must split region */
504                         /*
505                          * Check for an entry in the cache before dropping
506                          * lock and attempting allocation.
507                          */
508                         if (!nrg &&
509                             resv->region_cache_count > resv->adds_in_progress) {
510                                 nrg = list_first_entry(&resv->region_cache,
511                                                         struct file_region,
512                                                         link);
513                                 list_del(&nrg->link);
514                                 resv->region_cache_count--;
515                         }
516 
517                         if (!nrg) {
518                                 spin_unlock(&resv->lock);
519                                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
520                                 if (!nrg)
521                                         return -ENOMEM;
522                                 goto retry;
523                         }
524 
525                         del += t - f;
526 
527                         /* New entry for end of split region */
528                         nrg->from = t;
529                         nrg->to = rg->to;
530                         INIT_LIST_HEAD(&nrg->link);
531 
532                         /* Original entry is trimmed */
533                         rg->to = f;
534 
535                         list_add(&nrg->link, &rg->link);
536                         nrg = NULL;
537                         break;
538                 }
539 
540                 if (f <= rg->from && t >= rg->to) { /* Remove entire region */
541                         del += rg->to - rg->from;
542                         list_del(&rg->link);
543                         kfree(rg);
544                         continue;
545                 }
546 
547                 if (f <= rg->from) {    /* Trim beginning of region */
548                         del += t - rg->from;
549                         rg->from = t;
550                 } else {                /* Trim end of region */
551                         del += rg->to - f;
552                         rg->to = f;
553                 }
554         }
555 
556         spin_unlock(&resv->lock);
557         kfree(nrg);
558         return del;
559 }
560 
561 /*
562  * A rare out of memory error was encountered which prevented removal of
563  * the reserve map region for a page.  The huge page itself was free'ed
564  * and removed from the page cache.  This routine will adjust the subpool
565  * usage count, and the global reserve count if needed.  By incrementing
566  * these counts, the reserve map entry which could not be deleted will
567  * appear as a "reserved" entry instead of simply dangling with incorrect
568  * counts.
569  */
570 void hugetlb_fix_reserve_counts(struct inode *inode)
571 {
572         struct hugepage_subpool *spool = subpool_inode(inode);
573         long rsv_adjust;
574 
575         rsv_adjust = hugepage_subpool_get_pages(spool, 1);
576         if (rsv_adjust) {
577                 struct hstate *h = hstate_inode(inode);
578 
579                 hugetlb_acct_memory(h, 1);
580         }
581 }
582 
583 /*
584  * Count and return the number of huge pages in the reserve map
585  * that intersect with the range [f, t).
586  */
587 static long region_count(struct resv_map *resv, long f, long t)
588 {
589         struct list_head *head = &resv->regions;
590         struct file_region *rg;
591         long chg = 0;
592 
593         spin_lock(&resv->lock);
594         /* Locate each segment we overlap with, and count that overlap. */
595         list_for_each_entry(rg, head, link) {
596                 long seg_from;
597                 long seg_to;
598 
599                 if (rg->to <= f)
600                         continue;
601                 if (rg->from >= t)
602                         break;
603 
604                 seg_from = max(rg->from, f);
605                 seg_to = min(rg->to, t);
606 
607                 chg += seg_to - seg_from;
608         }
609         spin_unlock(&resv->lock);
610 
611         return chg;
612 }
613 
614 /*
615  * Convert the address within this vma to the page offset within
616  * the mapping, in pagecache page units; huge pages here.
617  */
618 static pgoff_t vma_hugecache_offset(struct hstate *h,
619                         struct vm_area_struct *vma, unsigned long address)
620 {
621         return ((address - vma->vm_start) >> huge_page_shift(h)) +
622                         (vma->vm_pgoff >> huge_page_order(h));
623 }
624 
625 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
626                                      unsigned long address)
627 {
628         return vma_hugecache_offset(hstate_vma(vma), vma, address);
629 }
630 EXPORT_SYMBOL_GPL(linear_hugepage_index);
631 
632 /*
633  * Return the size of the pages allocated when backing a VMA. In the majority
634  * cases this will be same size as used by the page table entries.
635  */
636 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
637 {
638         struct hstate *hstate;
639 
640         if (!is_vm_hugetlb_page(vma))
641                 return PAGE_SIZE;
642 
643         hstate = hstate_vma(vma);
644 
645         return 1UL << huge_page_shift(hstate);
646 }
647 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
648 
649 /*
650  * Return the page size being used by the MMU to back a VMA. In the majority
651  * of cases, the page size used by the kernel matches the MMU size. On
652  * architectures where it differs, an architecture-specific version of this
653  * function is required.
654  */
655 #ifndef vma_mmu_pagesize
656 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
657 {
658         return vma_kernel_pagesize(vma);
659 }
660 #endif
661 
662 /*
663  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
664  * bits of the reservation map pointer, which are always clear due to
665  * alignment.
666  */
667 #define HPAGE_RESV_OWNER    (1UL << 0)
668 #define HPAGE_RESV_UNMAPPED (1UL << 1)
669 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
670 
671 /*
672  * These helpers are used to track how many pages are reserved for
673  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
674  * is guaranteed to have their future faults succeed.
675  *
676  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
677  * the reserve counters are updated with the hugetlb_lock held. It is safe
678  * to reset the VMA at fork() time as it is not in use yet and there is no
679  * chance of the global counters getting corrupted as a result of the values.
680  *
681  * The private mapping reservation is represented in a subtly different
682  * manner to a shared mapping.  A shared mapping has a region map associated
683  * with the underlying file, this region map represents the backing file
684  * pages which have ever had a reservation assigned which this persists even
685  * after the page is instantiated.  A private mapping has a region map
686  * associated with the original mmap which is attached to all VMAs which
687  * reference it, this region map represents those offsets which have consumed
688  * reservation ie. where pages have been instantiated.
689  */
690 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
691 {
692         return (unsigned long)vma->vm_private_data;
693 }
694 
695 static void set_vma_private_data(struct vm_area_struct *vma,
696                                                         unsigned long value)
697 {
698         vma->vm_private_data = (void *)value;
699 }
700 
701 struct resv_map *resv_map_alloc(void)
702 {
703         struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
704         struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
705 
706         if (!resv_map || !rg) {
707                 kfree(resv_map);
708                 kfree(rg);
709                 return NULL;
710         }
711 
712         kref_init(&resv_map->refs);
713         spin_lock_init(&resv_map->lock);
714         INIT_LIST_HEAD(&resv_map->regions);
715 
716         resv_map->adds_in_progress = 0;
717 
718         INIT_LIST_HEAD(&resv_map->region_cache);
719         list_add(&rg->link, &resv_map->region_cache);
720         resv_map->region_cache_count = 1;
721 
722         return resv_map;
723 }
724 
725 void resv_map_release(struct kref *ref)
726 {
727         struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
728         struct list_head *head = &resv_map->region_cache;
729         struct file_region *rg, *trg;
730 
731         /* Clear out any active regions before we release the map. */
732         region_del(resv_map, 0, LONG_MAX);
733 
734         /* ... and any entries left in the cache */
735         list_for_each_entry_safe(rg, trg, head, link) {
736                 list_del(&rg->link);
737                 kfree(rg);
738         }
739 
740         VM_BUG_ON(resv_map->adds_in_progress);
741 
742         kfree(resv_map);
743 }
744 
745 static inline struct resv_map *inode_resv_map(struct inode *inode)
746 {
747         return inode->i_mapping->private_data;
748 }
749 
750 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
751 {
752         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
753         if (vma->vm_flags & VM_MAYSHARE) {
754                 struct address_space *mapping = vma->vm_file->f_mapping;
755                 struct inode *inode = mapping->host;
756 
757                 return inode_resv_map(inode);
758 
759         } else {
760                 return (struct resv_map *)(get_vma_private_data(vma) &
761                                                         ~HPAGE_RESV_MASK);
762         }
763 }
764 
765 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
766 {
767         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
768         VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
769 
770         set_vma_private_data(vma, (get_vma_private_data(vma) &
771                                 HPAGE_RESV_MASK) | (unsigned long)map);
772 }
773 
774 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
775 {
776         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
777         VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
778 
779         set_vma_private_data(vma, get_vma_private_data(vma) | flags);
780 }
781 
782 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
783 {
784         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
785 
786         return (get_vma_private_data(vma) & flag) != 0;
787 }
788 
789 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
790 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
791 {
792         VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
793         if (!(vma->vm_flags & VM_MAYSHARE))
794                 vma->vm_private_data = (void *)0;
795 }
796 
797 /* Returns true if the VMA has associated reserve pages */
798 static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
799 {
800         if (vma->vm_flags & VM_NORESERVE) {
801                 /*
802                  * This address is already reserved by other process(chg == 0),
803                  * so, we should decrement reserved count. Without decrementing,
804                  * reserve count remains after releasing inode, because this
805                  * allocated page will go into page cache and is regarded as
806                  * coming from reserved pool in releasing step.  Currently, we
807                  * don't have any other solution to deal with this situation
808                  * properly, so add work-around here.
809                  */
810                 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
811                         return true;
812                 else
813                         return false;
814         }
815 
816         /* Shared mappings always use reserves */
817         if (vma->vm_flags & VM_MAYSHARE) {
818                 /*
819                  * We know VM_NORESERVE is not set.  Therefore, there SHOULD
820                  * be a region map for all pages.  The only situation where
821                  * there is no region map is if a hole was punched via
822                  * fallocate.  In this case, there really are no reverves to
823                  * use.  This situation is indicated if chg != 0.
824                  */
825                 if (chg)
826                         return false;
827                 else
828                         return true;
829         }
830 
831         /*
832          * Only the process that called mmap() has reserves for
833          * private mappings.
834          */
835         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
836                 /*
837                  * Like the shared case above, a hole punch or truncate
838                  * could have been performed on the private mapping.
839                  * Examine the value of chg to determine if reserves
840                  * actually exist or were previously consumed.
841                  * Very Subtle - The value of chg comes from a previous
842                  * call to vma_needs_reserves().  The reserve map for
843                  * private mappings has different (opposite) semantics
844                  * than that of shared mappings.  vma_needs_reserves()
845                  * has already taken this difference in semantics into
846                  * account.  Therefore, the meaning of chg is the same
847                  * as in the shared case above.  Code could easily be
848                  * combined, but keeping it separate draws attention to
849                  * subtle differences.
850                  */
851                 if (chg)
852                         return false;
853                 else
854                         return true;
855         }
856 
857         return false;
858 }
859 
860 static void enqueue_huge_page(struct hstate *h, struct page *page)
861 {
862         int nid = page_to_nid(page);
863         list_move(&page->lru, &h->hugepage_freelists[nid]);
864         h->free_huge_pages++;
865         h->free_huge_pages_node[nid]++;
866 }
867 
868 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
869 {
870         struct page *page;
871 
872         list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
873                 if (!is_migrate_isolate_page(page))
874                         break;
875         /*
876          * if 'non-isolated free hugepage' not found on the list,
877          * the allocation fails.
878          */
879         if (&h->hugepage_freelists[nid] == &page->lru)
880                 return NULL;
881         list_move(&page->lru, &h->hugepage_activelist);
882         set_page_refcounted(page);
883         h->free_huge_pages--;
884         h->free_huge_pages_node[nid]--;
885         return page;
886 }
887 
888 /* Movability of hugepages depends on migration support. */
889 static inline gfp_t htlb_alloc_mask(struct hstate *h)
890 {
891         if (hugepages_treat_as_movable || hugepage_migration_supported(h))
892                 return GFP_HIGHUSER_MOVABLE;
893         else
894                 return GFP_HIGHUSER;
895 }
896 
897 static struct page *dequeue_huge_page_vma(struct hstate *h,
898                                 struct vm_area_struct *vma,
899                                 unsigned long address, int avoid_reserve,
900                                 long chg)
901 {
902         struct page *page = NULL;
903         struct mempolicy *mpol;
904         nodemask_t *nodemask;
905         struct zonelist *zonelist;
906         struct zone *zone;
907         struct zoneref *z;
908         unsigned int cpuset_mems_cookie;
909 
910         /*
911          * A child process with MAP_PRIVATE mappings created by their parent
912          * have no page reserves. This check ensures that reservations are
913          * not "stolen". The child may still get SIGKILLed
914          */
915         if (!vma_has_reserves(vma, chg) &&
916                         h->free_huge_pages - h->resv_huge_pages == 0)
917                 goto err;
918 
919         /* If reserves cannot be used, ensure enough pages are in the pool */
920         if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
921                 goto err;
922 
923 retry_cpuset:
924         cpuset_mems_cookie = read_mems_allowed_begin();
925         zonelist = huge_zonelist(vma, address,
926                                         htlb_alloc_mask(h), &mpol, &nodemask);
927 
928         for_each_zone_zonelist_nodemask(zone, z, zonelist,
929                                                 MAX_NR_ZONES - 1, nodemask) {
930                 if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
931                         page = dequeue_huge_page_node(h, zone_to_nid(zone));
932                         if (page) {
933                                 if (avoid_reserve)
934                                         break;
935                                 if (!vma_has_reserves(vma, chg))
936                                         break;
937 
938                                 SetPagePrivate(page);
939                                 h->resv_huge_pages--;
940                                 break;
941                         }
942                 }
943         }
944 
945         mpol_cond_put(mpol);
946         if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
947                 goto retry_cpuset;
948         return page;
949 
950 err:
951         return NULL;
952 }
953 
954 /*
955  * common helper functions for hstate_next_node_to_{alloc|free}.
956  * We may have allocated or freed a huge page based on a different
957  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
958  * be outside of *nodes_allowed.  Ensure that we use an allowed
959  * node for alloc or free.
960  */
961 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
962 {
963         nid = next_node_in(nid, *nodes_allowed);
964         VM_BUG_ON(nid >= MAX_NUMNODES);
965 
966         return nid;
967 }
968 
969 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
970 {
971         if (!node_isset(nid, *nodes_allowed))
972                 nid = next_node_allowed(nid, nodes_allowed);
973         return nid;
974 }
975 
976 /*
977  * returns the previously saved node ["this node"] from which to
978  * allocate a persistent huge page for the pool and advance the
979  * next node from which to allocate, handling wrap at end of node
980  * mask.
981  */
982 static int hstate_next_node_to_alloc(struct hstate *h,
983                                         nodemask_t *nodes_allowed)
984 {
985         int nid;
986 
987         VM_BUG_ON(!nodes_allowed);
988 
989         nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
990         h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
991 
992         return nid;
993 }
994 
995 /*
996  * helper for free_pool_huge_page() - return the previously saved
997  * node ["this node"] from which to free a huge page.  Advance the
998  * next node id whether or not we find a free huge page to free so
999  * that the next attempt to free addresses the next node.
1000  */
1001 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
1002 {
1003         int nid;
1004 
1005         VM_BUG_ON(!nodes_allowed);
1006 
1007         nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
1008         h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
1009 
1010         return nid;
1011 }
1012 
1013 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask)           \
1014         for (nr_nodes = nodes_weight(*mask);                            \
1015                 nr_nodes > 0 &&                                         \
1016                 ((node = hstate_next_node_to_alloc(hs, mask)) || 1);    \
1017                 nr_nodes--)
1018 
1019 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask)            \
1020         for (nr_nodes = nodes_weight(*mask);                            \
1021                 nr_nodes > 0 &&                                         \
1022                 ((node = hstate_next_node_to_free(hs, mask)) || 1);     \
1023                 nr_nodes--)
1024 
1025 #if defined(CONFIG_ARCH_HAS_GIGANTIC_PAGE) && \
1026         ((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || \
1027         defined(CONFIG_CMA))
1028 static void destroy_compound_gigantic_page(struct page *page,
1029                                         unsigned int order)
1030 {
1031         int i;
1032         int nr_pages = 1 << order;
1033         struct page *p = page + 1;
1034 
1035         atomic_set(compound_mapcount_ptr(page), 0);
1036         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1037                 clear_compound_head(p);
1038                 set_page_refcounted(p);
1039         }
1040 
1041         set_compound_order(page, 0);
1042         __ClearPageHead(page);
1043 }
1044 
1045 static void free_gigantic_page(struct page *page, unsigned int order)
1046 {
1047         free_contig_range(page_to_pfn(page), 1 << order);
1048 }
1049 
1050 static int __alloc_gigantic_page(unsigned long start_pfn,
1051                                 unsigned long nr_pages)
1052 {
1053         unsigned long end_pfn = start_pfn + nr_pages;
1054         return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1055 }
1056 
1057 static bool pfn_range_valid_gigantic(struct zone *z,
1058                         unsigned long start_pfn, unsigned long nr_pages)
1059 {
1060         unsigned long i, end_pfn = start_pfn + nr_pages;
1061         struct page *page;
1062 
1063         for (i = start_pfn; i < end_pfn; i++) {
1064                 if (!pfn_valid(i))
1065                         return false;
1066 
1067                 page = pfn_to_page(i);
1068 
1069                 if (page_zone(page) != z)
1070                         return false;
1071 
1072                 if (PageReserved(page))
1073                         return false;
1074 
1075                 if (page_count(page) > 0)
1076                         return false;
1077 
1078                 if (PageHuge(page))
1079                         return false;
1080         }
1081 
1082         return true;
1083 }
1084 
1085 static bool zone_spans_last_pfn(const struct zone *zone,
1086                         unsigned long start_pfn, unsigned long nr_pages)
1087 {
1088         unsigned long last_pfn = start_pfn + nr_pages - 1;
1089         return zone_spans_pfn(zone, last_pfn);
1090 }
1091 
1092 static struct page *alloc_gigantic_page(int nid, unsigned int order)
1093 {
1094         unsigned long nr_pages = 1 << order;
1095         unsigned long ret, pfn, flags;
1096         struct zone *z;
1097 
1098         z = NODE_DATA(nid)->node_zones;
1099         for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
1100                 spin_lock_irqsave(&z->lock, flags);
1101 
1102                 pfn = ALIGN(z->zone_start_pfn, nr_pages);
1103                 while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1104                         if (pfn_range_valid_gigantic(z, pfn, nr_pages)) {
1105                                 /*
1106                                  * We release the zone lock here because
1107                                  * alloc_contig_range() will also lock the zone
1108                                  * at some point. If there's an allocation
1109                                  * spinning on this lock, it may win the race
1110                                  * and cause alloc_contig_range() to fail...
1111                                  */
1112                                 spin_unlock_irqrestore(&z->lock, flags);
1113                                 ret = __alloc_gigantic_page(pfn, nr_pages);
1114                                 if (!ret)
1115                                         return pfn_to_page(pfn);
1116                                 spin_lock_irqsave(&z->lock, flags);
1117                         }
1118                         pfn += nr_pages;
1119                 }
1120 
1121                 spin_unlock_irqrestore(&z->lock, flags);
1122         }
1123 
1124         return NULL;
1125 }
1126 
1127 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1128 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1129 
1130 static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
1131 {
1132         struct page *page;
1133 
1134         page = alloc_gigantic_page(nid, huge_page_order(h));
1135         if (page) {
1136                 prep_compound_gigantic_page(page, huge_page_order(h));
1137                 prep_new_huge_page(h, page, nid);
1138         }
1139 
1140         return page;
1141 }
1142 
1143 static int alloc_fresh_gigantic_page(struct hstate *h,
1144                                 nodemask_t *nodes_allowed)
1145 {
1146         struct page *page = NULL;
1147         int nr_nodes, node;
1148 
1149         for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1150                 page = alloc_fresh_gigantic_page_node(h, node);
1151                 if (page)
1152                         return 1;
1153         }
1154 
1155         return 0;
1156 }
1157 
1158 static inline bool gigantic_page_supported(void) { return true; }
1159 #else
1160 static inline bool gigantic_page_supported(void) { return false; }
1161 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1162 static inline void destroy_compound_gigantic_page(struct page *page,
1163                                                 unsigned int order) { }
1164 static inline int alloc_fresh_gigantic_page(struct hstate *h,
1165                                         nodemask_t *nodes_allowed) { return 0; }
1166 #endif
1167 
1168 static void update_and_free_page(struct hstate *h, struct page *page)
1169 {
1170         int i;
1171 
1172         if (hstate_is_gigantic(h) && !gigantic_page_supported())
1173                 return;
1174 
1175         h->nr_huge_pages--;
1176         h->nr_huge_pages_node[page_to_nid(page)]--;
1177         for (i = 0; i < pages_per_huge_page(h); i++) {
1178                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1179                                 1 << PG_referenced | 1 << PG_dirty |
1180                                 1 << PG_active | 1 << PG_private |
1181                                 1 << PG_writeback);
1182         }
1183         VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1184         set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1185         set_page_refcounted(page);
1186         if (hstate_is_gigantic(h)) {
1187                 destroy_compound_gigantic_page(page, huge_page_order(h));
1188                 free_gigantic_page(page, huge_page_order(h));
1189         } else {
1190                 __free_pages(page, huge_page_order(h));
1191         }
1192 }
1193 
1194 struct hstate *size_to_hstate(unsigned long size)
1195 {
1196         struct hstate *h;
1197 
1198         for_each_hstate(h) {
1199                 if (huge_page_size(h) == size)
1200                         return h;
1201         }
1202         return NULL;
1203 }
1204 
1205 /*
1206  * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1207  * to hstate->hugepage_activelist.)
1208  *
1209  * This function can be called for tail pages, but never returns true for them.
1210  */
1211 bool page_huge_active(struct page *page)
1212 {
1213         VM_BUG_ON_PAGE(!PageHuge(page), page);
1214         return PageHead(page) && PagePrivate(&page[1]);
1215 }
1216 
1217 /* never called for tail page */
1218 static void set_page_huge_active(struct page *page)
1219 {
1220         VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1221         SetPagePrivate(&page[1]);
1222 }
1223 
1224 static void clear_page_huge_active(struct page *page)
1225 {
1226         VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1227         ClearPagePrivate(&page[1]);
1228 }
1229 
1230 void free_huge_page(struct page *page)
1231 {
1232         /*
1233          * Can't pass hstate in here because it is called from the
1234          * compound page destructor.
1235          */
1236         struct hstate *h = page_hstate(page);
1237         int nid = page_to_nid(page);
1238         struct hugepage_subpool *spool =
1239                 (struct hugepage_subpool *)page_private(page);
1240         bool restore_reserve;
1241 
1242         set_page_private(page, 0);
1243         page->mapping = NULL;
1244         VM_BUG_ON_PAGE(page_count(page), page);
1245         VM_BUG_ON_PAGE(page_mapcount(page), page);
1246         restore_reserve = PagePrivate(page);
1247         ClearPagePrivate(page);
1248 
1249         /*
1250          * A return code of zero implies that the subpool will be under its
1251          * minimum size if the reservation is not restored after page is free.
1252          * Therefore, force restore_reserve operation.
1253          */
1254         if (hugepage_subpool_put_pages(spool, 1) == 0)
1255                 restore_reserve = true;
1256 
1257         spin_lock(&hugetlb_lock);
1258         clear_page_huge_active(page);
1259         hugetlb_cgroup_uncharge_page(hstate_index(h),
1260                                      pages_per_huge_page(h), page);
1261         if (restore_reserve)
1262                 h->resv_huge_pages++;
1263 
1264         if (h->surplus_huge_pages_node[nid]) {
1265                 /* remove the page from active list */
1266                 list_del(&page->lru);
1267                 update_and_free_page(h, page);
1268                 h->surplus_huge_pages--;
1269                 h->surplus_huge_pages_node[nid]--;
1270         } else {
1271                 arch_clear_hugepage_flags(page);
1272                 enqueue_huge_page(h, page);
1273         }
1274         spin_unlock(&hugetlb_lock);
1275 }
1276 
1277 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1278 {
1279         INIT_LIST_HEAD(&page->lru);
1280         set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1281         spin_lock(&hugetlb_lock);
1282         set_hugetlb_cgroup(page, NULL);
1283         h->nr_huge_pages++;
1284         h->nr_huge_pages_node[nid]++;
1285         spin_unlock(&hugetlb_lock);
1286         put_page(page); /* free it into the hugepage allocator */
1287 }
1288 
1289 static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1290 {
1291         int i;
1292         int nr_pages = 1 << order;
1293         struct page *p = page + 1;
1294 
1295         /* we rely on prep_new_huge_page to set the destructor */
1296         set_compound_order(page, order);
1297         __ClearPageReserved(page);
1298         __SetPageHead(page);
1299         for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1300                 /*
1301                  * For gigantic hugepages allocated through bootmem at
1302                  * boot, it's safer to be consistent with the not-gigantic
1303                  * hugepages and clear the PG_reserved bit from all tail pages
1304                  * too.  Otherwse drivers using get_user_pages() to access tail
1305                  * pages may get the reference counting wrong if they see
1306                  * PG_reserved set on a tail page (despite the head page not
1307                  * having PG_reserved set).  Enforcing this consistency between
1308                  * head and tail pages allows drivers to optimize away a check
1309                  * on the head page when they need know if put_page() is needed
1310                  * after get_user_pages().
1311                  */
1312                 __ClearPageReserved(p);
1313                 set_page_count(p, 0);
1314                 set_compound_head(p, page);
1315         }
1316         atomic_set(compound_mapcount_ptr(page), -1);
1317 }
1318 
1319 /*
1320  * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1321  * transparent huge pages.  See the PageTransHuge() documentation for more
1322  * details.
1323  */
1324 int PageHuge(struct page *page)
1325 {
1326         if (!PageCompound(page))
1327                 return 0;
1328 
1329         page = compound_head(page);
1330         return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1331 }
1332 EXPORT_SYMBOL_GPL(PageHuge);
1333 
1334 /*
1335  * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1336  * normal or transparent huge pages.
1337  */
1338 int PageHeadHuge(struct page *page_head)
1339 {
1340         if (!PageHead(page_head))
1341                 return 0;
1342 
1343         return get_compound_page_dtor(page_head) == free_huge_page;
1344 }
1345 
1346 pgoff_t __basepage_index(struct page *page)
1347 {
1348         struct page *page_head = compound_head(page);
1349         pgoff_t index = page_index(page_head);
1350         unsigned long compound_idx;
1351 
1352         if (!PageHuge(page_head))
1353                 return page_index(page);
1354 
1355         if (compound_order(page_head) >= MAX_ORDER)
1356                 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1357         else
1358                 compound_idx = page - page_head;
1359 
1360         return (index << compound_order(page_head)) + compound_idx;
1361 }
1362 
1363 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
1364 {
1365         struct page *page;
1366 
1367         page = __alloc_pages_node(nid,
1368                 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1369                                                 __GFP_REPEAT|__GFP_NOWARN,
1370                 huge_page_order(h));
1371         if (page) {
1372                 prep_new_huge_page(h, page, nid);
1373         }
1374 
1375         return page;
1376 }
1377 
1378 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1379 {
1380         struct page *page;
1381         int nr_nodes, node;
1382         int ret = 0;
1383 
1384         for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1385                 page = alloc_fresh_huge_page_node(h, node);
1386                 if (page) {
1387                         ret = 1;
1388                         break;
1389                 }
1390         }
1391 
1392         if (ret)
1393                 count_vm_event(HTLB_BUDDY_PGALLOC);
1394         else
1395                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1396 
1397         return ret;
1398 }
1399 
1400 /*
1401  * Free huge page from pool from next node to free.
1402  * Attempt to keep persistent huge pages more or less
1403  * balanced over allowed nodes.
1404  * Called with hugetlb_lock locked.
1405  */
1406 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1407                                                          bool acct_surplus)
1408 {
1409         int nr_nodes, node;
1410         int ret = 0;
1411 
1412         for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1413                 /*
1414                  * If we're returning unused surplus pages, only examine
1415                  * nodes with surplus pages.
1416                  */
1417                 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1418                     !list_empty(&h->hugepage_freelists[node])) {
1419                         struct page *page =
1420                                 list_entry(h->hugepage_freelists[node].next,
1421                                           struct page, lru);
1422                         list_del(&page->lru);
1423                         h->free_huge_pages--;
1424                         h->free_huge_pages_node[node]--;
1425                         if (acct_surplus) {
1426                                 h->surplus_huge_pages--;
1427                                 h->surplus_huge_pages_node[node]--;
1428                         }
1429                         update_and_free_page(h, page);
1430                         ret = 1;
1431                         break;
1432                 }
1433         }
1434 
1435         return ret;
1436 }
1437 
1438 /*
1439  * Dissolve a given free hugepage into free buddy pages. This function does
1440  * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
1441  * number of free hugepages would be reduced below the number of reserved
1442  * hugepages.
1443  */
1444 static int dissolve_free_huge_page(struct page *page)
1445 {
1446         int rc = 0;
1447 
1448         spin_lock(&hugetlb_lock);
1449         if (PageHuge(page) && !page_count(page)) {
1450                 struct page *head = compound_head(page);
1451                 struct hstate *h = page_hstate(head);
1452                 int nid = page_to_nid(head);
1453                 if (h->free_huge_pages - h->resv_huge_pages == 0) {
1454                         rc = -EBUSY;
1455                         goto out;
1456                 }
1457                 list_del(&head->lru);
1458                 h->free_huge_pages--;
1459                 h->free_huge_pages_node[nid]--;
1460                 h->max_huge_pages--;
1461                 update_and_free_page(h, head);
1462         }
1463 out:
1464         spin_unlock(&hugetlb_lock);
1465         return rc;
1466 }
1467 
1468 /*
1469  * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1470  * make specified memory blocks removable from the system.
1471  * Note that this will dissolve a free gigantic hugepage completely, if any
1472  * part of it lies within the given range.
1473  * Also note that if dissolve_free_huge_page() returns with an error, all
1474  * free hugepages that were dissolved before that error are lost.
1475  */
1476 int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1477 {
1478         unsigned long pfn;
1479         struct page *page;
1480         int rc = 0;
1481 
1482         if (!hugepages_supported())
1483                 return rc;
1484 
1485         for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
1486                 page = pfn_to_page(pfn);
1487                 if (PageHuge(page) && !page_count(page)) {
1488                         rc = dissolve_free_huge_page(page);
1489                         if (rc)
1490                                 break;
1491                 }
1492         }
1493 
1494         return rc;
1495 }
1496 
1497 /*
1498  * There are 3 ways this can get called:
1499  * 1. With vma+addr: we use the VMA's memory policy
1500  * 2. With !vma, but nid=NUMA_NO_NODE:  We try to allocate a huge
1501  *    page from any node, and let the buddy allocator itself figure
1502  *    it out.
1503  * 3. With !vma, but nid!=NUMA_NO_NODE.  We allocate a huge page
1504  *    strictly from 'nid'
1505  */
1506 static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
1507                 struct vm_area_struct *vma, unsigned long addr, int nid)
1508 {
1509         int order = huge_page_order(h);
1510         gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
1511         unsigned int cpuset_mems_cookie;
1512 
1513         /*
1514          * We need a VMA to get a memory policy.  If we do not
1515          * have one, we use the 'nid' argument.
1516          *
1517          * The mempolicy stuff below has some non-inlined bits
1518          * and calls ->vm_ops.  That makes it hard to optimize at
1519          * compile-time, even when NUMA is off and it does
1520          * nothing.  This helps the compiler optimize it out.
1521          */
1522         if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1523                 /*
1524                  * If a specific node is requested, make sure to
1525                  * get memory from there, but only when a node
1526                  * is explicitly specified.
1527                  */
1528                 if (nid != NUMA_NO_NODE)
1529                         gfp |= __GFP_THISNODE;
1530                 /*
1531                  * Make sure to call something that can handle
1532                  * nid=NUMA_NO_NODE
1533                  */
1534                 return alloc_pages_node(nid, gfp, order);
1535         }
1536 
1537         /*
1538          * OK, so we have a VMA.  Fetch the mempolicy and try to
1539          * allocate a huge page with it.  We will only reach this
1540          * when CONFIG_NUMA=y.
1541          */
1542         do {
1543                 struct page *page;
1544                 struct mempolicy *mpol;
1545                 struct zonelist *zl;
1546                 nodemask_t *nodemask;
1547 
1548                 cpuset_mems_cookie = read_mems_allowed_begin();
1549                 zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
1550                 mpol_cond_put(mpol);
1551                 page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
1552                 if (page)
1553                         return page;
1554         } while (read_mems_allowed_retry(cpuset_mems_cookie));
1555 
1556         return NULL;
1557 }
1558 
1559 /*
1560  * There are two ways to allocate a huge page:
1561  * 1. When you have a VMA and an address (like a fault)
1562  * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
1563  *
1564  * 'vma' and 'addr' are only for (1).  'nid' is always NUMA_NO_NODE in
1565  * this case which signifies that the allocation should be done with
1566  * respect for the VMA's memory policy.
1567  *
1568  * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
1569  * implies that memory policies will not be taken in to account.
1570  */
1571 static struct page *__alloc_buddy_huge_page(struct hstate *h,
1572                 struct vm_area_struct *vma, unsigned long addr, int nid)
1573 {
1574         struct page *page;
1575         unsigned int r_nid;
1576 
1577         if (hstate_is_gigantic(h))
1578                 return NULL;
1579 
1580         /*
1581          * Make sure that anyone specifying 'nid' is not also specifying a VMA.
1582          * This makes sure the caller is picking _one_ of the modes with which
1583          * we can call this function, not both.
1584          */
1585         if (vma || (addr != -1)) {
1586                 VM_WARN_ON_ONCE(addr == -1);
1587                 VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1588         }
1589         /*
1590          * Assume we will successfully allocate the surplus page to
1591          * prevent racing processes from causing the surplus to exceed
1592          * overcommit
1593          *
1594          * This however introduces a different race, where a process B
1595          * tries to grow the static hugepage pool while alloc_pages() is
1596          * called by process A. B will only examine the per-node
1597          * counters in determining if surplus huge pages can be
1598          * converted to normal huge pages in adjust_pool_surplus(). A
1599          * won't be able to increment the per-node counter, until the
1600          * lock is dropped by B, but B doesn't drop hugetlb_lock until
1601          * no more huge pages can be converted from surplus to normal
1602          * state (and doesn't try to convert again). Thus, we have a
1603          * case where a surplus huge page exists, the pool is grown, and
1604          * the surplus huge page still exists after, even though it
1605          * should just have been converted to a normal huge page. This
1606          * does not leak memory, though, as the hugepage will be freed
1607          * once it is out of use. It also does not allow the counters to
1608          * go out of whack in adjust_pool_surplus() as we don't modify
1609          * the node values until we've gotten the hugepage and only the
1610          * per-node value is checked there.
1611          */
1612         spin_lock(&hugetlb_lock);
1613         if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1614                 spin_unlock(&hugetlb_lock);
1615                 return NULL;
1616         } else {
1617                 h->nr_huge_pages++;
1618                 h->surplus_huge_pages++;
1619         }
1620         spin_unlock(&hugetlb_lock);
1621 
1622         page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1623 
1624         spin_lock(&hugetlb_lock);
1625         if (page) {
1626                 INIT_LIST_HEAD(&page->lru);
1627                 r_nid = page_to_nid(page);
1628                 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1629                 set_hugetlb_cgroup(page, NULL);
1630                 /*
1631                  * We incremented the global counters already
1632                  */
1633                 h->nr_huge_pages_node[r_nid]++;
1634                 h->surplus_huge_pages_node[r_nid]++;
1635                 __count_vm_event(HTLB_BUDDY_PGALLOC);
1636         } else {
1637                 h->nr_huge_pages--;
1638                 h->surplus_huge_pages--;
1639                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1640         }
1641         spin_unlock(&hugetlb_lock);
1642 
1643         return page;
1644 }
1645 
1646 /*
1647  * Allocate a huge page from 'nid'.  Note, 'nid' may be
1648  * NUMA_NO_NODE, which means that it may be allocated
1649  * anywhere.
1650  */
1651 static
1652 struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
1653 {
1654         unsigned long addr = -1;
1655 
1656         return __alloc_buddy_huge_page(h, NULL, addr, nid);
1657 }
1658 
1659 /*
1660  * Use the VMA's mpolicy to allocate a huge page from the buddy.
1661  */
1662 static
1663 struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
1664                 struct vm_area_struct *vma, unsigned long addr)
1665 {
1666         return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
1667 }
1668 
1669 /*
1670  * This allocation function is useful in the context where vma is irrelevant.
1671  * E.g. soft-offlining uses this function because it only cares physical
1672  * address of error page.
1673  */
1674 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1675 {
1676         struct page *page = NULL;
1677 
1678         spin_lock(&hugetlb_lock);
1679         if (h->free_huge_pages - h->resv_huge_pages > 0)
1680                 page = dequeue_huge_page_node(h, nid);
1681         spin_unlock(&hugetlb_lock);
1682 
1683         if (!page)
1684                 page = __alloc_buddy_huge_page_no_mpol(h, nid);
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_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1715                 if (!page) {
1716                         alloc_ok = false;
1717                         break;
1718                 }
1719                 list_add(&page->lru, &surplus_list);
1720         }
1721         allocated += i;
1722 
1723         /*
1724          * After retaking hugetlb_lock, we need to recalculate 'needed'
1725          * because either resv_huge_pages or free_huge_pages may have changed.
1726          */
1727         spin_lock(&hugetlb_lock);
1728         needed = (h->resv_huge_pages + delta) -
1729                         (h->free_huge_pages + allocated);
1730         if (needed > 0) {
1731                 if (alloc_ok)
1732                         goto retry;
1733                 /*
1734                  * We were not able to allocate enough pages to
1735                  * satisfy the entire reservation so we free what
1736                  * we've allocated so far.
1737                  */
1738                 goto free;
1739         }
1740         /*
1741          * The surplus_list now contains _at_least_ the number of extra pages
1742          * needed to accommodate the reservation.  Add the appropriate number
1743          * of pages to the hugetlb pool and free the extras back to the buddy
1744          * allocator.  Commit the entire reservation here to prevent another
1745          * process from stealing the pages as they are added to the pool but
1746          * before they are reserved.
1747          */
1748         needed += allocated;
1749         h->resv_huge_pages += delta;
1750         ret = 0;
1751 
1752         /* Free the needed pages to the hugetlb pool */
1753         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1754                 if ((--needed) < 0)
1755                         break;
1756                 /*
1757                  * This page is now managed by the hugetlb allocator and has
1758                  * no users -- drop the buddy allocator's reference.
1759                  */
1760                 put_page_testzero(page);
1761                 VM_BUG_ON_PAGE(page_count(page), page);
1762                 enqueue_huge_page(h, page);
1763         }
1764 free:
1765         spin_unlock(&hugetlb_lock);
1766 
1767         /* Free unnecessary surplus pages to the buddy allocator */
1768         list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1769                 put_page(page);
1770         spin_lock(&hugetlb_lock);
1771 
1772         return ret;
1773 }
1774 
1775 /*
1776  * This routine has two main purposes:
1777  * 1) Decrement the reservation count (resv_huge_pages) by the value passed
1778  *    in unused_resv_pages.  This corresponds to the prior adjustments made
1779  *    to the associated reservation map.
1780  * 2) Free any unused surplus pages that may have been allocated to satisfy
1781  *    the reservation.  As many as unused_resv_pages may be freed.
1782  *
1783  * Called with hugetlb_lock held.  However, the lock could be dropped (and
1784  * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
1785  * we must make sure nobody else can claim pages we are in the process of
1786  * freeing.  Do this by ensuring resv_huge_page always is greater than the
1787  * number of huge pages we plan to free when dropping the lock.
1788  */
1789 static void return_unused_surplus_pages(struct hstate *h,
1790                                         unsigned long unused_resv_pages)
1791 {
1792         unsigned long nr_pages;
1793 
1794         /* Cannot return gigantic pages currently */
1795         if (hstate_is_gigantic(h))
1796                 goto out;
1797 
1798         /*
1799          * Part (or even all) of the reservation could have been backed
1800          * by pre-allocated pages. Only free surplus pages.
1801          */
1802         nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1803 
1804         /*
1805          * We want to release as many surplus pages as possible, spread
1806          * evenly across all nodes with memory. Iterate across these nodes
1807          * until we can no longer free unreserved surplus pages. This occurs
1808          * when the nodes with surplus pages have no free pages.
1809          * free_pool_huge_page() will balance the the freed pages across the
1810          * on-line nodes with memory and will handle the hstate accounting.
1811          *
1812          * Note that we decrement resv_huge_pages as we free the pages.  If
1813          * we drop the lock, resv_huge_pages will still be sufficiently large
1814          * to cover subsequent pages we may free.
1815          */
1816         while (nr_pages--) {
1817                 h->resv_huge_pages--;
1818                 unused_resv_pages--;
1819                 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1820                         goto out;
1821                 cond_resched_lock(&hugetlb_lock);
1822         }
1823 
1824 out:
1825         /* Fully uncommit the reservation */
1826         h->resv_huge_pages -= unused_resv_pages;
1827 }
1828 
1829 
1830 /*
1831  * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1832  * are used by the huge page allocation routines to manage reservations.
1833  *
1834  * vma_needs_reservation is called to determine if the huge page at addr
1835  * within the vma has an associated reservation.  If a reservation is
1836  * needed, the value 1 is returned.  The caller is then responsible for
1837  * managing the global reservation and subpool usage counts.  After
1838  * the huge page has been allocated, vma_commit_reservation is called
1839  * to add the page to the reservation map.  If the page allocation fails,
1840  * the reservation must be ended instead of committed.  vma_end_reservation
1841  * is called in such cases.
1842  *
1843  * In the normal case, vma_commit_reservation returns the same value
1844  * as the preceding vma_needs_reservation call.  The only time this
1845  * is not the case is if a reserve map was changed between calls.  It
1846  * is the responsibility of the caller to notice the difference and
1847  * take appropriate action.
1848  *
1849  * vma_add_reservation is used in error paths where a reservation must
1850  * be restored when a newly allocated huge page must be freed.  It is
1851  * to be called after calling vma_needs_reservation to determine if a
1852  * reservation exists.
1853  */
1854 enum vma_resv_mode {
1855         VMA_NEEDS_RESV,
1856         VMA_COMMIT_RESV,
1857         VMA_END_RESV,
1858         VMA_ADD_RESV,
1859 };
1860 static long __vma_reservation_common(struct hstate *h,
1861                                 struct vm_area_struct *vma, unsigned long addr,
1862                                 enum vma_resv_mode mode)
1863 {
1864         struct resv_map *resv;
1865         pgoff_t idx;
1866         long ret;
1867 
1868         resv = vma_resv_map(vma);
1869         if (!resv)
1870                 return 1;
1871 
1872         idx = vma_hugecache_offset(h, vma, addr);
1873         switch (mode) {
1874         case VMA_NEEDS_RESV:
1875                 ret = region_chg(resv, idx, idx + 1);
1876                 break;
1877         case VMA_COMMIT_RESV:
1878                 ret = region_add(resv, idx, idx + 1);
1879                 break;
1880         case VMA_END_RESV:
1881                 region_abort(resv, idx, idx + 1);
1882                 ret = 0;
1883                 break;
1884         case VMA_ADD_RESV:
1885                 if (vma->vm_flags & VM_MAYSHARE)
1886                         ret = region_add(resv, idx, idx + 1);
1887                 else {
1888                         region_abort(resv, idx, idx + 1);
1889                         ret = region_del(resv, idx, idx + 1);
1890                 }
1891                 break;
1892         default:
1893                 BUG();
1894         }
1895 
1896         if (vma->vm_flags & VM_MAYSHARE)
1897                 return ret;
1898         else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
1899                 /*
1900                  * In most cases, reserves always exist for private mappings.
1901                  * However, a file associated with mapping could have been
1902                  * hole punched or truncated after reserves were consumed.
1903                  * As subsequent fault on such a range will not use reserves.
1904                  * Subtle - The reserve map for private mappings has the
1905                  * opposite meaning than that of shared mappings.  If NO
1906                  * entry is in the reserve map, it means a reservation exists.
1907                  * If an entry exists in the reserve map, it means the
1908                  * reservation has already been consumed.  As a result, the
1909                  * return value of this routine is the opposite of the
1910                  * value returned from reserve map manipulation routines above.
1911                  */
1912                 if (ret)
1913                         return 0;
1914                 else
1915                         return 1;
1916         }
1917         else
1918                 return ret < 0 ? ret : 0;
1919 }
1920 
1921 static long vma_needs_reservation(struct hstate *h,
1922                         struct vm_area_struct *vma, unsigned long addr)
1923 {
1924         return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1925 }
1926 
1927 static long vma_commit_reservation(struct hstate *h,
1928                         struct vm_area_struct *vma, unsigned long addr)
1929 {
1930         return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1931 }
1932 
1933 static void vma_end_reservation(struct hstate *h,
1934                         struct vm_area_struct *vma, unsigned long addr)
1935 {
1936         (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1937 }
1938 
1939 static long vma_add_reservation(struct hstate *h,
1940                         struct vm_area_struct *vma, unsigned long addr)
1941 {
1942         return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
1943 }
1944 
1945 /*
1946  * This routine is called to restore a reservation on error paths.  In the
1947  * specific error paths, a huge page was allocated (via alloc_huge_page)
1948  * and is about to be freed.  If a reservation for the page existed,
1949  * alloc_huge_page would have consumed the reservation and set PagePrivate
1950  * in the newly allocated page.  When the page is freed via free_huge_page,
1951  * the global reservation count will be incremented if PagePrivate is set.
1952  * However, free_huge_page can not adjust the reserve map.  Adjust the
1953  * reserve map here to be consistent with global reserve count adjustments
1954  * to be made by free_huge_page.
1955  */
1956 static void restore_reserve_on_error(struct hstate *h,
1957                         struct vm_area_struct *vma, unsigned long address,
1958                         struct page *page)
1959 {
1960         if (unlikely(PagePrivate(page))) {
1961                 long rc = vma_needs_reservation(h, vma, address);
1962 
1963                 if (unlikely(rc < 0)) {
1964                         /*
1965                          * Rare out of memory condition in reserve map
1966                          * manipulation.  Clear PagePrivate so that
1967                          * global reserve count will not be incremented
1968                          * by free_huge_page.  This will make it appear
1969                          * as though the reservation for this page was
1970                          * consumed.  This may prevent the task from
1971                          * faulting in the page at a later time.  This
1972                          * is better than inconsistent global huge page
1973                          * accounting of reserve counts.
1974                          */
1975                         ClearPagePrivate(page);
1976                 } else if (rc) {
1977                         rc = vma_add_reservation(h, vma, address);
1978                         if (unlikely(rc < 0))
1979                                 /*
1980                                  * See above comment about rare out of
1981                                  * memory condition.
1982                                  */
1983                                 ClearPagePrivate(page);
1984                 } else
1985                         vma_end_reservation(h, vma, address);
1986         }
1987 }
1988 
1989 struct page *alloc_huge_page(struct vm_area_struct *vma,
1990                                     unsigned long addr, int avoid_reserve)
1991 {
1992         struct hugepage_subpool *spool = subpool_vma(vma);
1993         struct hstate *h = hstate_vma(vma);
1994         struct page *page;
1995         long map_chg, map_commit;
1996         long gbl_chg;
1997         int ret, idx;
1998         struct hugetlb_cgroup *h_cg;
1999 
2000         idx = hstate_index(h);
2001         /*
2002          * Examine the region/reserve map to determine if the process
2003          * has a reservation for the page to be allocated.  A return
2004          * code of zero indicates a reservation exists (no change).
2005          */
2006         map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
2007         if (map_chg < 0)
2008                 return ERR_PTR(-ENOMEM);
2009 
2010         /*
2011          * Processes that did not create the mapping will have no
2012          * reserves as indicated by the region/reserve map. Check
2013          * that the allocation will not exceed the subpool limit.
2014          * Allocations for MAP_NORESERVE mappings also need to be
2015          * checked against any subpool limit.
2016          */
2017         if (map_chg || avoid_reserve) {
2018                 gbl_chg = hugepage_subpool_get_pages(spool, 1);
2019                 if (gbl_chg < 0) {
2020                         vma_end_reservation(h, vma, addr);
2021                         return ERR_PTR(-ENOSPC);
2022                 }
2023 
2024                 /*
2025                  * Even though there was no reservation in the region/reserve
2026                  * map, there could be reservations associated with the
2027                  * subpool that can be used.  This would be indicated if the
2028                  * return value of hugepage_subpool_get_pages() is zero.
2029                  * However, if avoid_reserve is specified we still avoid even
2030                  * the subpool reservations.
2031                  */
2032                 if (avoid_reserve)
2033                         gbl_chg = 1;
2034         }
2035 
2036         ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2037         if (ret)
2038                 goto out_subpool_put;
2039 
2040         spin_lock(&hugetlb_lock);
2041         /*
2042          * glb_chg is passed to indicate whether or not a page must be taken
2043          * from the global free pool (global change).  gbl_chg == 0 indicates
2044          * a reservation exists for the allocation.
2045          */
2046         page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
2047         if (!page) {
2048                 spin_unlock(&hugetlb_lock);
2049                 page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
2050                 if (!page)
2051                         goto out_uncharge_cgroup;
2052                 if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
2053                         SetPagePrivate(page);
2054                         h->resv_huge_pages--;
2055                 }
2056                 spin_lock(&hugetlb_lock);
2057                 list_move(&page->lru, &h->hugepage_activelist);
2058                 /* Fall through */
2059         }
2060         hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
2061         spin_unlock(&hugetlb_lock);
2062 
2063         set_page_private(page, (unsigned long)spool);
2064 
2065         map_commit = vma_commit_reservation(h, vma, addr);
2066         if (unlikely(map_chg > map_commit)) {
2067                 /*
2068                  * The page was added to the reservation map between
2069                  * vma_needs_reservation and vma_commit_reservation.
2070                  * This indicates a race with hugetlb_reserve_pages.
2071                  * Adjust for the subpool count incremented above AND
2072                  * in hugetlb_reserve_pages for the same page.  Also,
2073                  * the reservation count added in hugetlb_reserve_pages
2074                  * no longer applies.
2075                  */
2076                 long rsv_adjust;
2077 
2078                 rsv_adjust = hugepage_subpool_put_pages(spool, 1);
2079                 hugetlb_acct_memory(h, -rsv_adjust);
2080         }
2081         return page;
2082 
2083 out_uncharge_cgroup:
2084         hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
2085 out_subpool_put:
2086         if (map_chg || avoid_reserve)
2087                 hugepage_subpool_put_pages(spool, 1);
2088         vma_end_reservation(h, vma, addr);
2089         return ERR_PTR(-ENOSPC);
2090 }
2091 
2092 /*
2093  * alloc_huge_page()'s wrapper which simply returns the page if allocation
2094  * succeeds, otherwise NULL. This function is called from new_vma_page(),
2095  * where no ERR_VALUE is expected to be returned.
2096  */
2097 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
2098                                 unsigned long addr, int avoid_reserve)
2099 {
2100         struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
2101         if (IS_ERR(page))
2102                 page = NULL;
2103         return page;
2104 }
2105 
2106 int __weak alloc_bootmem_huge_page(struct hstate *h)
2107 {
2108         struct huge_bootmem_page *m;
2109         int nr_nodes, node;
2110 
2111         for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2112                 void *addr;
2113 
2114                 addr = memblock_virt_alloc_try_nid_nopanic(
2115                                 huge_page_size(h), huge_page_size(h),
2116                                 0, BOOTMEM_ALLOC_ACCESSIBLE, node);
2117                 if (addr) {
2118                         /*
2119                          * Use the beginning of the huge page to store the
2120                          * huge_bootmem_page struct (until gather_bootmem
2121                          * puts them into the mem_map).
2122                          */
2123                         m = addr;
2124                         goto found;
2125                 }
2126         }
2127         return 0;
2128 
2129 found:
2130         BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2131         /* Put them into a private list first because mem_map is not up yet */
2132         list_add(&m->list, &huge_boot_pages);
2133         m->hstate = h;
2134         return 1;
2135 }
2136 
2137 static void __init prep_compound_huge_page(struct page *page,
2138                 unsigned int order)
2139 {
2140         if (unlikely(order > (MAX_ORDER - 1)))
2141                 prep_compound_gigantic_page(page, order);
2142         else
2143                 prep_compound_page(page, order);
2144 }
2145 
2146 /* Put bootmem huge pages into the standard lists after mem_map is up */
2147 static void __init gather_bootmem_prealloc(void)
2148 {
2149         struct huge_bootmem_page *m;
2150 
2151         list_for_each_entry(m, &huge_boot_pages, list) {
2152                 struct hstate *h = m->hstate;
2153                 struct page *page;
2154 
2155 #ifdef CONFIG_HIGHMEM
2156                 page = pfn_to_page(m->phys >> PAGE_SHIFT);
2157                 memblock_free_late(__pa(m),
2158                                    sizeof(struct huge_bootmem_page));
2159 #else
2160                 page = virt_to_page(m);
2161 #endif
2162                 WARN_ON(page_count(page) != 1);
2163                 prep_compound_huge_page(page, h->order);
2164                 WARN_ON(PageReserved(page));
2165                 prep_new_huge_page(h, page, page_to_nid(page));
2166                 /*
2167                  * If we had gigantic hugepages allocated at boot time, we need
2168                  * to restore the 'stolen' pages to totalram_pages in order to
2169                  * fix confusing memory reports from free(1) and another
2170                  * side-effects, like CommitLimit going negative.
2171                  */
2172                 if (hstate_is_gigantic(h))
2173                         adjust_managed_page_count(page, 1 << h->order);
2174         }
2175 }
2176 
2177 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2178 {
2179         unsigned long i;
2180 
2181         for (i = 0; i < h->max_huge_pages; ++i) {
2182                 if (hstate_is_gigantic(h)) {
2183                         if (!alloc_bootmem_huge_page(h))
2184                                 break;
2185                 } else if (!alloc_fresh_huge_page(h,
2186                                          &node_states[N_MEMORY]))
2187                         break;
2188         }
2189         h->max_huge_pages = i;
2190 }
2191 
2192 static void __init hugetlb_init_hstates(void)
2193 {
2194         struct hstate *h;
2195 
2196         for_each_hstate(h) {
2197                 if (minimum_order > huge_page_order(h))
2198                         minimum_order = huge_page_order(h);
2199 
2200                 /* oversize hugepages were init'ed in early boot */
2201                 if (!hstate_is_gigantic(h))
2202                         hugetlb_hstate_alloc_pages(h);
2203         }
2204         VM_BUG_ON(minimum_order == UINT_MAX);
2205 }
2206 
2207 static char * __init memfmt(char *buf, unsigned long n)
2208 {
2209         if (n >= (1UL << 30))
2210                 sprintf(buf, "%lu GB", n >> 30);
2211         else if (n >= (1UL << 20))
2212                 sprintf(buf, "%lu MB", n >> 20);
2213         else
2214                 sprintf(buf, "%lu KB", n >> 10);
2215         return buf;
2216 }
2217 
2218 static void __init report_hugepages(void)
2219 {
2220         struct hstate *h;
2221 
2222         for_each_hstate(h) {
2223                 char buf[32];
2224                 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2225                         memfmt(buf, huge_page_size(h)),
2226                         h->free_huge_pages);
2227         }
2228 }
2229 
2230 #ifdef CONFIG_HIGHMEM
2231 static void try_to_free_low(struct hstate *h, unsigned long count,
2232                                                 nodemask_t *nodes_allowed)
2233 {
2234         int i;
2235 
2236         if (hstate_is_gigantic(h))
2237                 return;
2238 
2239         for_each_node_mask(i, *nodes_allowed) {
2240                 struct page *page, *next;
2241                 struct list_head *freel = &h->hugepage_freelists[i];
2242                 list_for_each_entry_safe(page, next, freel, lru) {
2243                         if (count >= h->nr_huge_pages)
2244                                 return;
2245                         if (PageHighMem(page))
2246                                 continue;
2247                         list_del(&page->lru);
2248                         update_and_free_page(h, page);
2249                         h->free_huge_pages--;
2250                         h->free_huge_pages_node[page_to_nid(page)]--;
2251                 }
2252         }
2253 }
2254 #else
2255 static inline void try_to_free_low(struct hstate *h, unsigned long count,
2256                                                 nodemask_t *nodes_allowed)
2257 {
2258 }
2259 #endif
2260 
2261 /*
2262  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
2263  * balanced by operating on them in a round-robin fashion.
2264  * Returns 1 if an adjustment was made.
2265  */
2266 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2267                                 int delta)
2268 {
2269         int nr_nodes, node;
2270 
2271         VM_BUG_ON(delta != -1 && delta != 1);
2272 
2273         if (delta < 0) {
2274                 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2275                         if (h->surplus_huge_pages_node[node])
2276                                 goto found;
2277                 }
2278         } else {
2279                 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2280                         if (h->surplus_huge_pages_node[node] <
2281                                         h->nr_huge_pages_node[node])
2282                                 goto found;
2283                 }
2284         }
2285         return 0;
2286 
2287 found:
2288         h->surplus_huge_pages += delta;
2289         h->surplus_huge_pages_node[node] += delta;
2290         return 1;
2291 }
2292 
2293 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2294 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2295                                                 nodemask_t *nodes_allowed)
2296 {
2297         unsigned long min_count, ret;
2298 
2299         if (hstate_is_gigantic(h) && !gigantic_page_supported())
2300                 return h->max_huge_pages;
2301 
2302         /*
2303          * Increase the pool size
2304          * First take pages out of surplus state.  Then make up the
2305          * remaining difference by allocating fresh huge pages.
2306          *
2307          * We might race with __alloc_buddy_huge_page() here and be unable
2308          * to convert a surplus huge page to a normal huge page. That is
2309          * not critical, though, it just means the overall size of the
2310          * pool might be one hugepage larger than it needs to be, but
2311          * within all the constraints specified by the sysctls.
2312          */
2313         spin_lock(&hugetlb_lock);
2314         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2315                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
2316                         break;
2317         }
2318 
2319         while (count > persistent_huge_pages(h)) {
2320                 /*
2321                  * If this allocation races such that we no longer need the
2322                  * page, free_huge_page will handle it by freeing the page
2323                  * and reducing the surplus.
2324                  */
2325                 spin_unlock(&hugetlb_lock);
2326 
2327                 /* yield cpu to avoid soft lockup */
2328                 cond_resched();
2329 
2330                 if (hstate_is_gigantic(h))
2331                         ret = alloc_fresh_gigantic_page(h, nodes_allowed);
2332                 else
2333                         ret = alloc_fresh_huge_page(h, nodes_allowed);
2334                 spin_lock(&hugetlb_lock);
2335                 if (!ret)
2336                         goto out;
2337 
2338                 /* Bail for signals. Probably ctrl-c from user */
2339                 if (signal_pending(current))
2340                         goto out;
2341         }
2342 
2343         /*
2344          * Decrease the pool size
2345          * First return free pages to the buddy allocator (being careful
2346          * to keep enough around to satisfy reservations).  Then place
2347          * pages into surplus state as needed so the pool will shrink
2348          * to the desired size as pages become free.
2349          *
2350          * By placing pages into the surplus state independent of the
2351          * overcommit value, we are allowing the surplus pool size to
2352          * exceed overcommit. There are few sane options here. Since
2353          * __alloc_buddy_huge_page() is checking the global counter,
2354          * though, we'll note that we're not allowed to exceed surplus
2355          * and won't grow the pool anywhere else. Not until one of the
2356          * sysctls are changed, or the surplus pages go out of use.
2357          */
2358         min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2359         min_count = max(count, min_count);
2360         try_to_free_low(h, min_count, nodes_allowed);
2361         while (min_count < persistent_huge_pages(h)) {
2362                 if (!free_pool_huge_page(h, nodes_allowed, 0))
2363                         break;
2364                 cond_resched_lock(&hugetlb_lock);
2365         }
2366         while (count < persistent_huge_pages(h)) {
2367                 if (!adjust_pool_surplus(h, nodes_allowed, 1))
2368                         break;
2369         }
2370 out:
2371         ret = persistent_huge_pages(h);
2372         spin_unlock(&hugetlb_lock);
2373         return ret;
2374 }
2375 
2376 #define HSTATE_ATTR_RO(_name) \
2377         static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2378 
2379 #define HSTATE_ATTR(_name) \
2380         static struct kobj_attribute _name##_attr = \
2381                 __ATTR(_name, 0644, _name##_show, _name##_store)
2382 
2383 static struct kobject *hugepages_kobj;
2384 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2385 
2386 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2387 
2388 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2389 {
2390         int i;
2391 
2392         for (i = 0; i < HUGE_MAX_HSTATE; i++)
2393                 if (hstate_kobjs[i] == kobj) {
2394                         if (nidp)
2395                                 *nidp = NUMA_NO_NODE;
2396                         return &hstates[i];
2397                 }
2398 
2399         return kobj_to_node_hstate(kobj, nidp);
2400 }
2401 
2402 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2403                                         struct kobj_attribute *attr, char *buf)
2404 {
2405         struct hstate *h;
2406         unsigned long nr_huge_pages;
2407         int nid;
2408 
2409         h = kobj_to_hstate(kobj, &nid);
2410         if (nid == NUMA_NO_NODE)
2411                 nr_huge_pages = h->nr_huge_pages;
2412         else
2413                 nr_huge_pages = h->nr_huge_pages_node[nid];
2414 
2415         return sprintf(buf, "%lu\n", nr_huge_pages);
2416 }
2417 
2418 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2419                                            struct hstate *h, int nid,
2420                                            unsigned long count, size_t len)
2421 {
2422         int err;
2423         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2424 
2425         if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2426                 err = -EINVAL;
2427                 goto out;
2428         }
2429 
2430         if (nid == NUMA_NO_NODE) {
2431                 /*
2432                  * global hstate attribute
2433                  */
2434                 if (!(obey_mempolicy &&
2435                                 init_nodemask_of_mempolicy(nodes_allowed))) {
2436                         NODEMASK_FREE(nodes_allowed);
2437                         nodes_allowed = &node_states[N_MEMORY];
2438                 }
2439         } else if (nodes_allowed) {
2440                 /*
2441                  * per node hstate attribute: adjust count to global,
2442                  * but restrict alloc/free to the specified node.
2443                  */
2444                 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2445                 init_nodemask_of_node(nodes_allowed, nid);
2446         } else
2447                 nodes_allowed = &node_states[N_MEMORY];
2448 
2449         h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2450 
2451         if (nodes_allowed != &node_states[N_MEMORY])
2452                 NODEMASK_FREE(nodes_allowed);
2453 
2454         return len;
2455 out:
2456         NODEMASK_FREE(nodes_allowed);
2457         return err;
2458 }
2459 
2460 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2461                                          struct kobject *kobj, const char *buf,
2462                                          size_t len)
2463 {
2464         struct hstate *h;
2465         unsigned long count;
2466         int nid;
2467         int err;
2468 
2469         err = kstrtoul(buf, 10, &count);
2470         if (err)
2471                 return err;
2472 
2473         h = kobj_to_hstate(kobj, &nid);
2474         return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2475 }
2476 
2477 static ssize_t nr_hugepages_show(struct kobject *kobj,
2478                                        struct kobj_attribute *attr, char *buf)
2479 {
2480         return nr_hugepages_show_common(kobj, attr, buf);
2481 }
2482 
2483 static ssize_t nr_hugepages_store(struct kobject *kobj,
2484                struct kobj_attribute *attr, const char *buf, size_t len)
2485 {
2486         return nr_hugepages_store_common(false, kobj, buf, len);
2487 }
2488 HSTATE_ATTR(nr_hugepages);
2489 
2490 #ifdef CONFIG_NUMA
2491 
2492 /*
2493  * hstate attribute for optionally mempolicy-based constraint on persistent
2494  * huge page alloc/free.
2495  */
2496 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2497                                        struct kobj_attribute *attr, char *buf)
2498 {
2499         return nr_hugepages_show_common(kobj, attr, buf);
2500 }
2501 
2502 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2503                struct kobj_attribute *attr, const char *buf, size_t len)
2504 {
2505         return nr_hugepages_store_common(true, kobj, buf, len);
2506 }
2507 HSTATE_ATTR(nr_hugepages_mempolicy);
2508 #endif
2509 
2510 
2511 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2512                                         struct kobj_attribute *attr, char *buf)
2513 {
2514         struct hstate *h = kobj_to_hstate(kobj, NULL);
2515         return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2516 }
2517 
2518 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2519                 struct kobj_attribute *attr, const char *buf, size_t count)
2520 {
2521         int err;
2522         unsigned long input;
2523         struct hstate *h = kobj_to_hstate(kobj, NULL);
2524 
2525         if (hstate_is_gigantic(h))
2526                 return -EINVAL;
2527 
2528         err = kstrtoul(buf, 10, &input);
2529         if (err)
2530                 return err;
2531 
2532         spin_lock(&hugetlb_lock);
2533         h->nr_overcommit_huge_pages = input;
2534         spin_unlock(&hugetlb_lock);
2535 
2536         return count;
2537 }
2538 HSTATE_ATTR(nr_overcommit_hugepages);
2539 
2540 static ssize_t free_hugepages_show(struct kobject *kobj,
2541                                         struct kobj_attribute *attr, char *buf)
2542 {
2543         struct hstate *h;
2544         unsigned long free_huge_pages;
2545         int nid;
2546 
2547         h = kobj_to_hstate(kobj, &nid);
2548         if (nid == NUMA_NO_NODE)
2549                 free_huge_pages = h->free_huge_pages;
2550         else
2551                 free_huge_pages = h->free_huge_pages_node[nid];
2552 
2553         return sprintf(buf, "%lu\n", free_huge_pages);
2554 }
2555 HSTATE_ATTR_RO(free_hugepages);
2556 
2557 static ssize_t resv_hugepages_show(struct kobject *kobj,
2558                                         struct kobj_attribute *attr, char *buf)
2559 {
2560         struct hstate *h = kobj_to_hstate(kobj, NULL);
2561         return sprintf(buf, "%lu\n", h->resv_huge_pages);
2562 }
2563 HSTATE_ATTR_RO(resv_hugepages);
2564 
2565 static ssize_t surplus_hugepages_show(struct kobject *kobj,
2566                                         struct kobj_attribute *attr, char *buf)
2567 {
2568         struct hstate *h;
2569         unsigned long surplus_huge_pages;
2570         int nid;
2571 
2572         h = kobj_to_hstate(kobj, &nid);
2573         if (nid == NUMA_NO_NODE)
2574                 surplus_huge_pages = h->surplus_huge_pages;
2575         else
2576                 surplus_huge_pages = h->surplus_huge_pages_node[nid];
2577 
2578         return sprintf(buf, "%lu\n", surplus_huge_pages);
2579 }
2580 HSTATE_ATTR_RO(surplus_hugepages);
2581 
2582 static struct attribute *hstate_attrs[] = {
2583         &nr_hugepages_attr.attr,
2584         &nr_overcommit_hugepages_attr.attr,
2585         &free_hugepages_attr.attr,
2586         &resv_hugepages_attr.attr,
2587         &surplus_hugepages_attr.attr,
2588 #ifdef CONFIG_NUMA
2589         &nr_hugepages_mempolicy_attr.attr,
2590 #endif
2591         NULL,
2592 };
2593 
2594 static struct attribute_group hstate_attr_group = {
2595         .attrs = hstate_attrs,
2596 };
2597 
2598 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2599                                     struct kobject **hstate_kobjs,
2600                                     struct attribute_group *hstate_attr_group)
2601 {
2602         int retval;
2603         int hi = hstate_index(h);
2604 
2605         hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2606         if (!hstate_kobjs[hi])
2607                 return -ENOMEM;
2608 
2609         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2610         if (retval)
2611                 kobject_put(hstate_kobjs[hi]);
2612 
2613         return retval;
2614 }
2615 
2616 static void __init hugetlb_sysfs_init(void)
2617 {
2618         struct hstate *h;
2619         int err;
2620 
2621         hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2622         if (!hugepages_kobj)
2623                 return;
2624 
2625         for_each_hstate(h) {
2626                 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2627                                          hstate_kobjs, &hstate_attr_group);
2628                 if (err)
2629                         pr_err("Hugetlb: Unable to add hstate %s", h->name);
2630         }
2631 }
2632 
2633 #ifdef CONFIG_NUMA
2634 
2635 /*
2636  * node_hstate/s - associate per node hstate attributes, via their kobjects,
2637  * with node devices in node_devices[] using a parallel array.  The array
2638  * index of a node device or _hstate == node id.
2639  * This is here to avoid any static dependency of the node device driver, in
2640  * the base kernel, on the hugetlb module.
2641  */
2642 struct node_hstate {
2643         struct kobject          *hugepages_kobj;
2644         struct kobject          *hstate_kobjs[HUGE_MAX_HSTATE];
2645 };
2646 static struct node_hstate node_hstates[MAX_NUMNODES];
2647 
2648 /*
2649  * A subset of global hstate attributes for node devices
2650  */
2651 static struct attribute *per_node_hstate_attrs[] = {
2652         &nr_hugepages_attr.attr,
2653         &free_hugepages_attr.attr,
2654         &surplus_hugepages_attr.attr,
2655         NULL,
2656 };
2657 
2658 static struct attribute_group per_node_hstate_attr_group = {
2659         .attrs = per_node_hstate_attrs,
2660 };
2661 
2662 /*
2663  * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2664  * Returns node id via non-NULL nidp.
2665  */
2666 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2667 {
2668         int nid;
2669 
2670         for (nid = 0; nid < nr_node_ids; nid++) {
2671                 struct node_hstate *nhs = &node_hstates[nid];
2672                 int i;
2673                 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2674                         if (nhs->hstate_kobjs[i] == kobj) {
2675                                 if (nidp)
2676                                         *nidp = nid;
2677                                 return &hstates[i];
2678                         }
2679         }
2680 
2681         BUG();
2682         return NULL;
2683 }
2684 
2685 /*
2686  * Unregister hstate attributes from a single node device.
2687  * No-op if no hstate attributes attached.
2688  */
2689 static void hugetlb_unregister_node(struct node *node)
2690 {
2691         struct hstate *h;
2692         struct node_hstate *nhs = &node_hstates[node->dev.id];
2693 
2694         if (!nhs->hugepages_kobj)
2695                 return;         /* no hstate attributes */
2696 
2697         for_each_hstate(h) {
2698                 int idx = hstate_index(h);
2699                 if (nhs->hstate_kobjs[idx]) {
2700                         kobject_put(nhs->hstate_kobjs[idx]);
2701                         nhs->hstate_kobjs[idx] = NULL;
2702                 }
2703         }
2704 
2705         kobject_put(nhs->hugepages_kobj);
2706         nhs->hugepages_kobj = NULL;
2707 }
2708 
2709 
2710 /*
2711  * Register hstate attributes for a single node device.
2712  * No-op if attributes already registered.
2713  */
2714 static void hugetlb_register_node(struct node *node)
2715 {
2716         struct hstate *h;
2717         struct node_hstate *nhs = &node_hstates[node->dev.id];
2718         int err;
2719 
2720         if (nhs->hugepages_kobj)
2721                 return;         /* already allocated */
2722 
2723         nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2724                                                         &node->dev.kobj);
2725         if (!nhs->hugepages_kobj)
2726                 return;
2727 
2728         for_each_hstate(h) {
2729                 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2730                                                 nhs->hstate_kobjs,
2731                                                 &per_node_hstate_attr_group);
2732                 if (err) {
2733                         pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2734                                 h->name, node->dev.id);
2735                         hugetlb_unregister_node(node);
2736                         break;
2737                 }
2738         }
2739 }
2740 
2741 /*
2742  * hugetlb init time:  register hstate attributes for all registered node
2743  * devices of nodes that have memory.  All on-line nodes should have
2744  * registered their associated device by this time.
2745  */
2746 static void __init hugetlb_register_all_nodes(void)
2747 {
2748         int nid;
2749 
2750         for_each_node_state(nid, N_MEMORY) {
2751                 struct node *node = node_devices[nid];
2752                 if (node->dev.id == nid)
2753                         hugetlb_register_node(node);
2754         }
2755 
2756         /*
2757          * Let the node device driver know we're here so it can
2758          * [un]register hstate attributes on node hotplug.
2759          */
2760         register_hugetlbfs_with_node(hugetlb_register_node,
2761                                      hugetlb_unregister_node);
2762 }
2763 #else   /* !CONFIG_NUMA */
2764 
2765 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2766 {
2767         BUG();
2768         if (nidp)
2769                 *nidp = -1;
2770         return NULL;
2771 }
2772 
2773 static void hugetlb_register_all_nodes(void) { }
2774 
2775 #endif
2776 
2777 static int __init hugetlb_init(void)
2778 {
2779         int i;
2780 
2781         if (!hugepages_supported())
2782                 return 0;
2783 
2784         if (!size_to_hstate(default_hstate_size)) {
2785                 default_hstate_size = HPAGE_SIZE;
2786                 if (!size_to_hstate(default_hstate_size))
2787                         hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2788         }
2789         default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2790         if (default_hstate_max_huge_pages) {
2791                 if (!default_hstate.max_huge_pages)
2792                         default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2793         }
2794 
2795         hugetlb_init_hstates();
2796         gather_bootmem_prealloc();
2797         report_hugepages();
2798 
2799         hugetlb_sysfs_init();
2800         hugetlb_register_all_nodes();
2801         hugetlb_cgroup_file_init();
2802 
2803 #ifdef CONFIG_SMP
2804         num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2805 #else
2806         num_fault_mutexes = 1;
2807 #endif
2808         hugetlb_fault_mutex_table =
2809                 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2810         BUG_ON(!hugetlb_fault_mutex_table);
2811 
2812         for (i = 0; i < num_fault_mutexes; i++)
2813                 mutex_init(&hugetlb_fault_mutex_table[i]);
2814         return 0;
2815 }
2816 subsys_initcall(hugetlb_init);
2817 
2818 /* Should be called on processing a hugepagesz=... option */
2819 void __init hugetlb_bad_size(void)
2820 {
2821         parsed_valid_hugepagesz = false;
2822 }
2823 
2824 void __init hugetlb_add_hstate(unsigned int order)
2825 {
2826         struct hstate *h;
2827         unsigned long i;
2828 
2829         if (size_to_hstate(PAGE_SIZE << order)) {
2830                 pr_warn("hugepagesz= specified twice, ignoring\n");
2831                 return;
2832         }
2833         BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2834         BUG_ON(order == 0);
2835         h = &hstates[hugetlb_max_hstate++];
2836         h->order = order;
2837         h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2838         h->nr_huge_pages = 0;
2839         h->free_huge_pages = 0;
2840         for (i = 0; i < MAX_NUMNODES; ++i)
2841                 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2842         INIT_LIST_HEAD(&h->hugepage_activelist);
2843         h->next_nid_to_alloc = first_memory_node;
2844         h->next_nid_to_free = first_memory_node;
2845         snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2846                                         huge_page_size(h)/1024);
2847 
2848         parsed_hstate = h;
2849 }
2850 
2851 static int __init hugetlb_nrpages_setup(char *s)
2852 {
2853         unsigned long *mhp;
2854         static unsigned long *last_mhp;
2855 
2856         if (!parsed_valid_hugepagesz) {
2857                 pr_warn("hugepages = %s preceded by "
2858                         "an unsupported hugepagesz, ignoring\n", s);
2859                 parsed_valid_hugepagesz = true;
2860                 return 1;
2861         }
2862         /*
2863          * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2864          * so this hugepages= parameter goes to the "default hstate".
2865          */
2866         else if (!hugetlb_max_hstate)
2867                 mhp = &default_hstate_max_huge_pages;
2868         else
2869                 mhp = &parsed_hstate->max_huge_pages;
2870 
2871         if (mhp == last_mhp) {
2872                 pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2873                 return 1;
2874         }
2875 
2876         if (sscanf(s, "%lu", mhp) <= 0)
2877                 *mhp = 0;
2878 
2879         /*
2880          * Global state is always initialized later in hugetlb_init.
2881          * But we need to allocate >= MAX_ORDER hstates here early to still
2882          * use the bootmem allocator.
2883          */
2884         if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2885                 hugetlb_hstate_alloc_pages(parsed_hstate);
2886 
2887         last_mhp = mhp;
2888 
2889         return 1;
2890 }
2891 __setup("hugepages=", hugetlb_nrpages_setup);
2892 
2893 static int __init hugetlb_default_setup(char *s)
2894 {
2895         default_hstate_size = memparse(s, &s);
2896         return 1;
2897 }
2898 __setup("default_hugepagesz=", hugetlb_default_setup);
2899 
2900 static unsigned int cpuset_mems_nr(unsigned int *array)
2901 {
2902         int node;
2903         unsigned int nr = 0;
2904 
2905         for_each_node_mask(node, cpuset_current_mems_allowed)
2906                 nr += array[node];
2907 
2908         return nr;
2909 }
2910 
2911 #ifdef CONFIG_SYSCTL
2912 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2913                          struct ctl_table *table, int write,
2914                          void __user *buffer, size_t *length, loff_t *ppos)
2915 {
2916         struct hstate *h = &default_hstate;
2917         unsigned long tmp = h->max_huge_pages;
2918         int ret;
2919 
2920         if (!hugepages_supported())
2921                 return -EOPNOTSUPP;
2922 
2923         table->data = &tmp;
2924         table->maxlen = sizeof(unsigned long);
2925         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2926         if (ret)
2927                 goto out;
2928 
2929         if (write)
2930                 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2931                                                   NUMA_NO_NODE, tmp, *length);
2932 out:
2933         return ret;
2934 }
2935 
2936 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2937                           void __user *buffer, size_t *length, loff_t *ppos)
2938 {
2939 
2940         return hugetlb_sysctl_handler_common(false, table, write,
2941                                                         buffer, length, ppos);
2942 }
2943 
2944 #ifdef CONFIG_NUMA
2945 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2946                           void __user *buffer, size_t *length, loff_t *ppos)
2947 {
2948         return hugetlb_sysctl_handler_common(true, table, write,
2949                                                         buffer, length, ppos);
2950 }
2951 #endif /* CONFIG_NUMA */
2952 
2953 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2954                         void __user *buffer,
2955                         size_t *length, loff_t *ppos)
2956 {
2957         struct hstate *h = &default_hstate;
2958         unsigned long tmp;
2959         int ret;
2960 
2961         if (!hugepages_supported())
2962                 return -EOPNOTSUPP;
2963 
2964         tmp = h->nr_overcommit_huge_pages;
2965 
2966         if (write && hstate_is_gigantic(h))
2967                 return -EINVAL;
2968 
2969         table->data = &tmp;
2970         table->maxlen = sizeof(unsigned long);
2971         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2972         if (ret)
2973                 goto out;
2974 
2975         if (write) {
2976                 spin_lock(&hugetlb_lock);
2977                 h->nr_overcommit_huge_pages = tmp;
2978                 spin_unlock(&hugetlb_lock);
2979         }
2980 out:
2981         return ret;
2982 }
2983 
2984 #endif /* CONFIG_SYSCTL */
2985 
2986 void hugetlb_report_meminfo(struct seq_file *m)
2987 {
2988         struct hstate *h = &default_hstate;
2989         if (!hugepages_supported())
2990                 return;
2991         seq_printf(m,
2992                         "HugePages_Total:   %5lu\n"
2993                         "HugePages_Free:    %5lu\n"
2994                         "HugePages_Rsvd:    %5lu\n"
2995                         "HugePages_Surp:    %5lu\n"
2996                         "Hugepagesize:   %8lu kB\n",
2997                         h->nr_huge_pages,
2998                         h->free_huge_pages,
2999                         h->resv_huge_pages,
3000                         h->surplus_huge_pages,
3001                         1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
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 /*
3139  * We cannot handle pagefaults against hugetlb pages at all.  They cause
3140  * handle_mm_fault() to try to instantiate regular-sized pages in the
3141  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
3142  * this far.
3143  */
3144 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
3145 {
3146         BUG();
3147         return 0;
3148 }
3149 
3150 const struct vm_operations_struct hugetlb_vm_ops = {
3151         .fault = hugetlb_vm_op_fault,
3152         .open = hugetlb_vm_op_open,
3153         .close = hugetlb_vm_op_close,
3154 };
3155 
3156 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3157                                 int writable)
3158 {
3159         pte_t entry;
3160 
3161         if (writable) {
3162                 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3163                                          vma->vm_page_prot)));
3164         } else {
3165                 entry = huge_pte_wrprotect(mk_huge_pte(page,
3166                                            vma->vm_page_prot));
3167         }
3168         entry = pte_mkyoung(entry);
3169         entry = pte_mkhuge(entry);
3170         entry = arch_make_huge_pte(entry, vma, page, writable);
3171 
3172         return entry;
3173 }
3174 
3175 static void set_huge_ptep_writable(struct vm_area_struct *vma,
3176                                    unsigned long address, pte_t *ptep)
3177 {
3178         pte_t entry;
3179 
3180         entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3181         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3182                 update_mmu_cache(vma, address, ptep);
3183 }
3184 
3185 static int is_hugetlb_entry_migration(pte_t pte)
3186 {
3187         swp_entry_t swp;
3188 
3189         if (huge_pte_none(pte) || pte_present(pte))
3190                 return 0;
3191         swp = pte_to_swp_entry(pte);
3192         if (non_swap_entry(swp) && is_migration_entry(swp))
3193                 return 1;
3194         else
3195                 return 0;
3196 }
3197 
3198 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3199 {
3200         swp_entry_t swp;
3201 
3202         if (huge_pte_none(pte) || pte_present(pte))
3203                 return 0;
3204         swp = pte_to_swp_entry(pte);
3205         if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3206                 return 1;
3207         else
3208                 return 0;
3209 }
3210 
3211 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3212                             struct vm_area_struct *vma)
3213 {
3214         pte_t *src_pte, *dst_pte, entry;
3215         struct page *ptepage;
3216         unsigned long addr;
3217         int cow;
3218         struct hstate *h = hstate_vma(vma);
3219         unsigned long sz = huge_page_size(h);
3220         unsigned long mmun_start;       /* For mmu_notifiers */
3221         unsigned long mmun_end;         /* For mmu_notifiers */
3222         int ret = 0;
3223 
3224         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3225 
3226         mmun_start = vma->vm_start;
3227         mmun_end = vma->vm_end;
3228         if (cow)
3229                 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
3230 
3231         for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3232                 spinlock_t *src_ptl, *dst_ptl;
3233                 src_pte = huge_pte_offset(src, addr);
3234                 if (!src_pte)
3235                         continue;
3236                 dst_pte = huge_pte_alloc(dst, addr, sz);
3237                 if (!dst_pte) {
3238                         ret = -ENOMEM;
3239                         break;
3240                 }
3241 
3242                 /* If the pagetables are shared don't copy or take references */
3243                 if (dst_pte == src_pte)
3244                         continue;
3245 
3246                 dst_ptl = huge_pte_lock(h, dst, dst_pte);
3247                 src_ptl = huge_pte_lockptr(h, src, src_pte);
3248                 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3249                 entry = huge_ptep_get(src_pte);
3250                 if (huge_pte_none(entry)) { /* skip none entry */
3251                         ;
3252                 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
3253                                     is_hugetlb_entry_hwpoisoned(entry))) {
3254                         swp_entry_t swp_entry = pte_to_swp_entry(entry);
3255 
3256                         if (is_write_migration_entry(swp_entry) && cow) {
3257                                 /*
3258                                  * COW mappings require pages in both
3259                                  * parent and child to be set to read.
3260                                  */
3261                                 make_migration_entry_read(&swp_entry);
3262                                 entry = swp_entry_to_pte(swp_entry);
3263                                 set_huge_pte_at(src, addr, src_pte, entry);
3264                         }
3265                         set_huge_pte_at(dst, addr, dst_pte, entry);
3266                 } else {
3267                         if (cow) {
3268                                 huge_ptep_set_wrprotect(src, addr, src_pte);
3269                                 mmu_notifier_invalidate_range(src, mmun_start,
3270                                                                    mmun_end);
3271                         }
3272                         entry = huge_ptep_get(src_pte);
3273                         ptepage = pte_page(entry);
3274                         get_page(ptepage);
3275                         page_dup_rmap(ptepage, true);
3276                         set_huge_pte_at(dst, addr, dst_pte, entry);
3277                         hugetlb_count_add(pages_per_huge_page(h), dst);
3278                 }
3279                 spin_unlock(src_ptl);
3280                 spin_unlock(dst_ptl);
3281         }
3282 
3283         if (cow)
3284                 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
3285 
3286         return ret;
3287 }
3288 
3289 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3290                             unsigned long start, unsigned long end,
3291                             struct page *ref_page)
3292 {
3293         struct mm_struct *mm = vma->vm_mm;
3294         unsigned long address;
3295         pte_t *ptep;
3296         pte_t pte;
3297         spinlock_t *ptl;
3298         struct page *page;
3299         struct hstate *h = hstate_vma(vma);
3300         unsigned long sz = huge_page_size(h);
3301         const unsigned long mmun_start = start; /* For mmu_notifiers */
3302         const unsigned long mmun_end   = end;   /* For mmu_notifiers */
3303 
3304         WARN_ON(!is_vm_hugetlb_page(vma));
3305         BUG_ON(start & ~huge_page_mask(h));
3306         BUG_ON(end & ~huge_page_mask(h));
3307 
3308         /*
3309          * This is a hugetlb vma, all the pte entries should point
3310          * to huge page.
3311          */
3312         tlb_remove_check_page_size_change(tlb, sz);
3313         tlb_start_vma(tlb, vma);
3314         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3315         address = start;
3316         for (; address < end; address += sz) {
3317                 ptep = huge_pte_offset(mm, address);
3318                 if (!ptep)
3319                         continue;
3320 
3321                 ptl = huge_pte_lock(h, mm, ptep);
3322                 if (huge_pmd_unshare(mm, &address, ptep)) {
3323                         spin_unlock(ptl);
3324                         continue;
3325                 }
3326 
3327                 pte = huge_ptep_get(ptep);
3328                 if (huge_pte_none(pte)) {
3329                         spin_unlock(ptl);
3330                         continue;
3331                 }
3332 
3333                 /*
3334                  * Migrating hugepage or HWPoisoned hugepage is already
3335                  * unmapped and its refcount is dropped, so just clear pte here.
3336                  */
3337                 if (unlikely(!pte_present(pte))) {
3338                         huge_pte_clear(mm, address, ptep);
3339                         spin_unlock(ptl);
3340                         continue;
3341                 }
3342 
3343                 page = pte_page(pte);
3344                 /*
3345                  * If a reference page is supplied, it is because a specific
3346                  * page is being unmapped, not a range. Ensure the page we
3347                  * are about to unmap is the actual page of interest.
3348                  */
3349                 if (ref_page) {
3350                         if (page != ref_page) {
3351                                 spin_unlock(ptl);
3352                                 continue;
3353                         }
3354                         /*
3355                          * Mark the VMA as having unmapped its page so that
3356                          * future faults in this VMA will fail rather than
3357                          * looking like data was lost
3358                          */
3359                         set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
3360                 }
3361 
3362                 pte = huge_ptep_get_and_clear(mm, address, ptep);
3363                 tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
3364                 if (huge_pte_dirty(pte))
3365                         set_page_dirty(page);
3366 
3367                 hugetlb_count_sub(pages_per_huge_page(h), mm);
3368                 page_remove_rmap(page, true);
3369 
3370                 spin_unlock(ptl);
3371                 tlb_remove_page_size(tlb, page, huge_page_size(h));
3372                 /*
3373                  * Bail out after unmapping reference page if supplied
3374                  */
3375                 if (ref_page)
3376                         break;
3377         }
3378         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3379         tlb_end_vma(tlb, vma);
3380 }
3381 
3382 void __unmap_hugepage_range_final(struct mmu_gather *tlb,
3383                           struct vm_area_struct *vma, unsigned long start,
3384                           unsigned long end, struct page *ref_page)
3385 {
3386         __unmap_hugepage_range(tlb, vma, start, end, ref_page);
3387 
3388         /*
3389          * Clear this flag so that x86's huge_pmd_share page_table_shareable
3390          * test will fail on a vma being torn down, and not grab a page table
3391          * on its way out.  We're lucky that the flag has such an appropriate
3392          * name, and can in fact be safely cleared here. We could clear it
3393          * before the __unmap_hugepage_range above, but all that's necessary
3394          * is to clear it before releasing the i_mmap_rwsem. This works
3395          * because in the context this is called, the VMA is about to be
3396          * destroyed and the i_mmap_rwsem is held.
3397          */
3398         vma->vm_flags &= ~VM_MAYSHARE;
3399 }
3400 
3401 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3402                           unsigned long end, struct page *ref_page)
3403 {
3404         struct mm_struct *mm;
3405         struct mmu_gather tlb;
3406 
3407         mm = vma->vm_mm;
3408 
3409         tlb_gather_mmu(&tlb, mm, start, end);
3410         __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3411         tlb_finish_mmu(&tlb, start, end);
3412 }
3413 
3414 /*
3415  * This is called when the original mapper is failing to COW a MAP_PRIVATE
3416  * mappping it owns the reserve page for. The intention is to unmap the page
3417  * from other VMAs and let the children be SIGKILLed if they are faulting the
3418  * same region.
3419  */
3420 static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
3421                               struct page *page, unsigned long address)
3422 {
3423         struct hstate *h = hstate_vma(vma);
3424         struct vm_area_struct *iter_vma;
3425         struct address_space *mapping;
3426         pgoff_t pgoff;
3427 
3428         /*
3429          * vm_pgoff is in PAGE_SIZE units, hence the different calculation
3430          * from page cache lookup which is in HPAGE_SIZE units.
3431          */
3432         address = address & huge_page_mask(h);
3433         pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
3434                         vma->vm_pgoff;
3435         mapping = vma->vm_file->f_mapping;
3436 
3437         /*
3438          * Take the mapping lock for the duration of the table walk. As
3439          * this mapping should be shared between all the VMAs,
3440          * __unmap_hugepage_range() is called as the lock is already held
3441          */
3442         i_mmap_lock_write(mapping);
3443         vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3444                 /* Do not unmap the current VMA */
3445                 if (iter_vma == vma)
3446                         continue;
3447 
3448                 /*
3449                  * Shared VMAs have their own reserves and do not affect
3450                  * MAP_PRIVATE accounting but it is possible that a shared
3451                  * VMA is using the same page so check and skip such VMAs.
3452                  */
3453                 if (iter_vma->vm_flags & VM_MAYSHARE)
3454                         continue;
3455 
3456                 /*
3457                  * Unmap the page from other VMAs without their own reserves.
3458                  * They get marked to be SIGKILLed if they fault in these
3459                  * areas. This is because a future no-page fault on this VMA
3460                  * could insert a zeroed page instead of the data existing
3461                  * from the time of fork. This would look like data corruption
3462                  */
3463                 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3464                         unmap_hugepage_range(iter_vma, address,
3465                                              address + huge_page_size(h), page);
3466         }
3467         i_mmap_unlock_write(mapping);
3468 }
3469 
3470 /*
3471  * Hugetlb_cow() should be called with page lock of the original hugepage held.
3472  * Called with hugetlb_instantiation_mutex held and pte_page locked so we
3473  * cannot race with other handlers or page migration.
3474  * Keep the pte_same checks anyway to make transition from the mutex easier.
3475  */
3476 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3477                        unsigned long address, pte_t *ptep,
3478                        struct page *pagecache_page, spinlock_t *ptl)
3479 {
3480         pte_t pte;
3481         struct hstate *h = hstate_vma(vma);
3482         struct page *old_page, *new_page;
3483         int ret = 0, outside_reserve = 0;
3484         unsigned long mmun_start;       /* For mmu_notifiers */
3485         unsigned long mmun_end;         /* For mmu_notifiers */
3486 
3487         pte = huge_ptep_get(ptep);
3488         old_page = pte_page(pte);
3489 
3490 retry_avoidcopy:
3491         /* If no-one else is actually using this page, avoid the copy
3492          * and just make the page writable */
3493         if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3494                 page_move_anon_rmap(old_page, vma);
3495                 set_huge_ptep_writable(vma, address, ptep);
3496                 return 0;
3497         }
3498 
3499         /*
3500          * If the process that created a MAP_PRIVATE mapping is about to
3501          * perform a COW due to a shared page count, attempt to satisfy
3502          * the allocation without using the existing reserves. The pagecache
3503          * page is used to determine if the reserve at this address was
3504          * consumed or not. If reserves were used, a partial faulted mapping
3505          * at the time of fork() could consume its reserves on COW instead
3506          * of the full address range.
3507          */
3508         if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3509                         old_page != pagecache_page)
3510                 outside_reserve = 1;
3511 
3512         get_page(old_page);
3513 
3514         /*
3515          * Drop page table lock as buddy allocator may be called. It will
3516          * be acquired again before returning to the caller, as expected.
3517          */
3518         spin_unlock(ptl);
3519         new_page = alloc_huge_page(vma, address, outside_reserve);
3520 
3521         if (IS_ERR(new_page)) {
3522                 /*
3523                  * If a process owning a MAP_PRIVATE mapping fails to COW,
3524                  * it is due to references held by a child and an insufficient
3525                  * huge page pool. To guarantee the original mappers
3526                  * reliability, unmap the page from child processes. The child
3527                  * may get SIGKILLed if it later faults.
3528                  */
3529                 if (outside_reserve) {
3530                         put_page(old_page);
3531                         BUG_ON(huge_pte_none(pte));
3532                         unmap_ref_private(mm, vma, old_page, address);
3533                         BUG_ON(huge_pte_none(pte));
3534                         spin_lock(ptl);
3535                         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3536                         if (likely(ptep &&
3537                                    pte_same(huge_ptep_get(ptep), pte)))
3538                                 goto retry_avoidcopy;
3539                         /*
3540                          * race occurs while re-acquiring page table
3541                          * lock, and our job is done.
3542                          */
3543                         return 0;
3544                 }
3545 
3546                 ret = (PTR_ERR(new_page) == -ENOMEM) ?
3547                         VM_FAULT_OOM : VM_FAULT_SIGBUS;
3548                 goto out_release_old;
3549         }
3550 
3551         /*
3552          * When the original hugepage is shared one, it does not have
3553          * anon_vma prepared.
3554          */
3555         if (unlikely(anon_vma_prepare(vma))) {
3556                 ret = VM_FAULT_OOM;
3557                 goto out_release_all;
3558         }
3559 
3560         copy_user_huge_page(new_page, old_page, address, vma,
3561                             pages_per_huge_page(h));
3562         __SetPageUptodate(new_page);
3563         set_page_huge_active(new_page);
3564 
3565         mmun_start = address & huge_page_mask(h);
3566         mmun_end = mmun_start + huge_page_size(h);
3567         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3568 
3569         /*
3570          * Retake the page table lock to check for racing updates
3571          * before the page tables are altered
3572          */
3573         spin_lock(ptl);
3574         ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3575         if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3576                 ClearPagePrivate(new_page);
3577 
3578                 /* Break COW */
3579                 huge_ptep_clear_flush(vma, address, ptep);
3580                 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3581                 set_huge_pte_at(mm, address, ptep,
3582                                 make_huge_pte(vma, new_page, 1));
3583                 page_remove_rmap(old_page, true);
3584                 hugepage_add_new_anon_rmap(new_page, vma, address);
3585                 /* Make the old page be freed below */
3586                 new_page = old_page;
3587         }
3588         spin_unlock(ptl);
3589         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3590 out_release_all:
3591         restore_reserve_on_error(h, vma, address, new_page);
3592         put_page(new_page);
3593 out_release_old:
3594         put_page(old_page);
3595 
3596         spin_lock(ptl); /* Caller expects lock to be held */
3597         return ret;
3598 }
3599 
3600 /* Return the pagecache page at a given address within a VMA */
3601 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
3602                         struct vm_area_struct *vma, unsigned long address)
3603 {
3604         struct address_space *mapping;
3605         pgoff_t idx;
3606 
3607         mapping = vma->vm_file->f_mapping;
3608         idx = vma_hugecache_offset(h, vma, address);
3609 
3610         return find_lock_page(mapping, idx);
3611 }
3612 
3613 /*
3614  * Return whether there is a pagecache page to back given address within VMA.
3615  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
3616  */
3617 static bool hugetlbfs_pagecache_present(struct hstate *h,
3618                         struct vm_area_struct *vma, unsigned long address)
3619 {
3620         struct address_space *mapping;
3621         pgoff_t idx;
3622         struct page *page;
3623 
3624         mapping = vma->vm_file->f_mapping;
3625         idx = vma_hugecache_offset(h, vma, address);
3626 
3627         page = find_get_page(mapping, idx);
3628         if (page)
3629                 put_page(page);
3630         return page != NULL;
3631 }
3632 
3633 int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
3634                            pgoff_t idx)
3635 {
3636         struct inode *inode = mapping->host;
3637         struct hstate *h = hstate_inode(inode);
3638         int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3639 
3640         if (err)
3641                 return err;
3642         ClearPagePrivate(page);
3643 
3644         spin_lock(&inode->i_lock);
3645         inode->i_blocks += blocks_per_huge_page(h);
3646         spin_unlock(&inode->i_lock);
3647         return 0;
3648 }
3649 
3650 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3651                            struct address_space *mapping, pgoff_t idx,
3652                            unsigned long address, pte_t *ptep, unsigned int flags)
3653 {
3654         struct hstate *h = hstate_vma(vma);
3655         int ret = VM_FAULT_SIGBUS;
3656         int anon_rmap = 0;
3657         unsigned long size;
3658         struct page *page;
3659         pte_t new_pte;
3660         spinlock_t *ptl;
3661 
3662         /*
3663          * Currently, we are forced to kill the process in the event the
3664          * original mapper has unmapped pages from the child due to a failed
3665          * COW. Warn that such a situation has occurred as it may not be obvious
3666          */
3667         if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3668                 pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3669                            current->pid);
3670                 return ret;
3671         }
3672 
3673         /*
3674          * Use page lock to guard against racing truncation
3675          * before we get page_table_lock.
3676          */
3677 retry:
3678         page = find_lock_page(mapping, idx);
3679         if (!page) {
3680                 size = i_size_read(mapping->host) >> huge_page_shift(h);
3681                 if (idx >= size)
3682                         goto out;
3683                 page = alloc_huge_page(vma, address, 0);
3684                 if (IS_ERR(page)) {
3685                         ret = PTR_ERR(page);
3686                         if (ret == -ENOMEM)
3687                                 ret = VM_FAULT_OOM;
3688                         else
3689                                 ret = VM_FAULT_SIGBUS;
3690                         goto out;
3691                 }
3692                 clear_huge_page(page, address, pages_per_huge_page(h));
3693                 __SetPageUptodate(page);
3694                 set_page_huge_active(page);
3695 
3696                 if (vma->vm_flags & VM_MAYSHARE) {
3697                         int err = huge_add_to_page_cache(page, mapping, idx);
3698                         if (err) {
3699                                 put_page(page);
3700                                 if (err == -EEXIST)
3701                                         goto retry;
3702                                 goto out;
3703                         }
3704                 } else {
3705                         lock_page(page);
3706                         if (unlikely(anon_vma_prepare(vma))) {
3707                                 ret = VM_FAULT_OOM;
3708                                 goto backout_unlocked;
3709                         }
3710                         anon_rmap = 1;
3711                 }
3712         } else {
3713                 /*
3714                  * If memory error occurs between mmap() and fault, some process
3715                  * don't have hwpoisoned swap entry for errored virtual address.
3716                  * So we need to block hugepage fault by PG_hwpoison bit check.
3717                  */
3718                 if (unlikely(PageHWPoison(page))) {
3719                         ret = VM_FAULT_HWPOISON |
3720                                 VM_FAULT_SET_HINDEX(hstate_index(h));
3721                         goto backout_unlocked;
3722                 }
3723         }
3724 
3725         /*
3726          * If we are going to COW a private mapping later, we examine the
3727          * pending reservations for this page now. This will ensure that
3728          * any allocations necessary to record that reservation occur outside
3729          * the spinlock.
3730          */
3731         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3732                 if (vma_needs_reservation(h, vma, address) < 0) {
3733                         ret = VM_FAULT_OOM;
3734                         goto backout_unlocked;
3735                 }
3736                 /* Just decrements count, does not deallocate */
3737                 vma_end_reservation(h, vma, address);
3738         }
3739 
3740         ptl = huge_pte_lock(h, mm, ptep);
3741         size = i_size_read(mapping->host) >> huge_page_shift(h);
3742         if (idx >= size)
3743                 goto backout;
3744 
3745         ret = 0;
3746         if (!huge_pte_none(huge_ptep_get(ptep)))
3747                 goto backout;
3748 
3749         if (anon_rmap) {
3750                 ClearPagePrivate(page);
3751                 hugepage_add_new_anon_rmap(page, vma, address);
3752         } else
3753                 page_dup_rmap(page, true);
3754         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3755                                 && (vma->vm_flags & VM_SHARED)));
3756         set_huge_pte_at(mm, address, ptep, new_pte);
3757 
3758         hugetlb_count_add(pages_per_huge_page(h), mm);
3759         if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3760                 /* Optimization, do the COW without a second fault */
3761                 ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
3762         }
3763 
3764         spin_unlock(ptl);
3765         unlock_page(page);
3766 out:
3767         return ret;
3768 
3769 backout:
3770         spin_unlock(ptl);
3771 backout_unlocked:
3772         unlock_page(page);
3773         restore_reserve_on_error(h, vma, address, page);
3774         put_page(page);
3775         goto out;
3776 }
3777 
3778 #ifdef CONFIG_SMP
3779 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3780                             struct vm_area_struct *vma,
3781                             struct address_space *mapping,
3782                             pgoff_t idx, unsigned long address)
3783 {
3784         unsigned long key[2];
3785         u32 hash;
3786 
3787         if (vma->vm_flags & VM_SHARED) {
3788                 key[0] = (unsigned long) mapping;
3789                 key[1] = idx;
3790         } else {
3791                 key[0] = (unsigned long) mm;
3792                 key[1] = address >> huge_page_shift(h);
3793         }
3794 
3795         hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3796 
3797         return hash & (num_fault_mutexes - 1);
3798 }
3799 #else
3800 /*
3801  * For uniprocesor systems we always use a single mutex, so just
3802  * return 0 and avoid the hashing overhead.
3803  */
3804 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3805                             struct vm_area_struct *vma,
3806                             struct address_space *mapping,
3807                             pgoff_t idx, unsigned long address)
3808 {
3809         return 0;
3810 }
3811 #endif
3812 
3813 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3814                         unsigned long address, unsigned int flags)
3815 {
3816         pte_t *ptep, entry;
3817         spinlock_t *ptl;
3818         int ret;
3819         u32 hash;
3820         pgoff_t idx;
3821         struct page *page = NULL;
3822         struct page *pagecache_page = NULL;
3823         struct hstate *h = hstate_vma(vma);
3824         struct address_space *mapping;
3825         int need_wait_lock = 0;
3826 
3827         address &= huge_page_mask(h);
3828 
3829         ptep = huge_pte_offset(mm, address);
3830         if (ptep) {
3831                 entry = huge_ptep_get(ptep);
3832                 if (unlikely(is_hugetlb_entry_migration(entry))) {
3833                         migration_entry_wait_huge(vma, mm, ptep);
3834                         return 0;
3835                 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3836                         return VM_FAULT_HWPOISON_LARGE |
3837                                 VM_FAULT_SET_HINDEX(hstate_index(h));
3838         } else {
3839                 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3840                 if (!ptep)
3841                         return VM_FAULT_OOM;
3842         }
3843 
3844         mapping = vma->vm_file->f_mapping;
3845         idx = vma_hugecache_offset(h, vma, address);
3846 
3847         /*
3848          * Serialize hugepage allocation and instantiation, so that we don't
3849          * get spurious allocation failures if two CPUs race to instantiate
3850          * the same page in the page cache.
3851          */
3852         hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
3853         mutex_lock(&hugetlb_fault_mutex_table[hash]);
3854 
3855         entry = huge_ptep_get(ptep);
3856         if (huge_pte_none(entry)) {
3857                 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3858                 goto out_mutex;
3859         }
3860 
3861         ret = 0;
3862 
3863         /*
3864          * entry could be a migration/hwpoison entry at this point, so this
3865          * check prevents the kernel from going below assuming that we have
3866          * a active hugepage in pagecache. This goto expects the 2nd page fault,
3867          * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3868          * handle it.
3869          */
3870         if (!pte_present(entry))
3871                 goto out_mutex;
3872 
3873         /*
3874          * If we are going to COW the mapping later, we examine the pending
3875          * reservations for this page now. This will ensure that any
3876          * allocations necessary to record that reservation occur outside the
3877          * spinlock. For private mappings, we also lookup the pagecache
3878          * page now as it is used to determine if a reservation has been
3879          * consumed.
3880          */
3881         if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3882                 if (vma_needs_reservation(h, vma, address) < 0) {
3883                         ret = VM_FAULT_OOM;
3884                         goto out_mutex;
3885                 }
3886                 /* Just decrements count, does not deallocate */
3887                 vma_end_reservation(h, vma, address);
3888 
3889                 if (!(vma->vm_flags & VM_MAYSHARE))
3890                         pagecache_page = hugetlbfs_pagecache_page(h,
3891                                                                 vma, address);
3892         }
3893 
3894         ptl = huge_pte_lock(h, mm, ptep);
3895 
3896         /* Check for a racing update before calling hugetlb_cow */
3897         if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3898                 goto out_ptl;
3899 
3900         /*
3901          * hugetlb_cow() requires page locks of pte_page(entry) and
3902          * pagecache_page, so here we need take the former one
3903          * when page != pagecache_page or !pagecache_page.
3904          */
3905         page = pte_page(entry);
3906         if (page != pagecache_page)
3907                 if (!trylock_page(page)) {
3908                         need_wait_lock = 1;
3909                         goto out_ptl;
3910                 }
3911 
3912         get_page(page);
3913 
3914         if (flags & FAULT_FLAG_WRITE) {
3915                 if (!huge_pte_write(entry)) {
3916                         ret = hugetlb_cow(mm, vma, address, ptep,
3917                                           pagecache_page, ptl);
3918                         goto out_put_page;
3919                 }
3920                 entry = huge_pte_mkdirty(entry);
3921         }
3922         entry = pte_mkyoung(entry);
3923         if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3924                                                 flags & FAULT_FLAG_WRITE))
3925                 update_mmu_cache(vma, address, ptep);
3926 out_put_page:
3927         if (page != pagecache_page)
3928                 unlock_page(page);
3929         put_page(page);
3930 out_ptl:
3931         spin_unlock(ptl);
3932 
3933         if (pagecache_page) {
3934                 unlock_page(pagecache_page);
3935                 put_page(pagecache_page);
3936         }
3937 out_mutex:
3938         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3939         /*
3940          * Generally it's safe to hold refcount during waiting page lock. But
3941          * here we just wait to defer the next page fault to avoid busy loop and
3942          * the page is not used after unlocked before returning from the current
3943          * page fault. So we are safe from accessing freed page, even if we wait
3944          * here without taking refcount.
3945          */
3946         if (need_wait_lock)
3947                 wait_on_page_locked(page);
3948         return ret;
3949 }
3950 
3951 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
3952                          struct page **pages, struct vm_area_struct **vmas,
3953                          unsigned long *position, unsigned long *nr_pages,
3954                          long i, unsigned int flags)
3955 {
3956         unsigned long pfn_offset;
3957         unsigned long vaddr = *position;
3958         unsigned long remainder = *nr_pages;
3959         struct hstate *h = hstate_vma(vma);
3960 
3961         while (vaddr < vma->vm_end && remainder) {
3962                 pte_t *pte;
3963                 spinlock_t *ptl = NULL;
3964                 int absent;
3965                 struct page *page;
3966 
3967                 /*
3968                  * If we have a pending SIGKILL, don't keep faulting pages and
3969                  * potentially allocating memory.
3970                  */
3971                 if (unlikely(fatal_signal_pending(current))) {
3972                         remainder = 0;
3973                         break;
3974                 }
3975 
3976                 /*
3977                  * Some archs (sparc64, sh*) have multiple pte_ts to
3978                  * each hugepage.  We have to make sure we get the
3979                  * first, for the page indexing below to work.
3980                  *
3981                  * Note that page table lock is not held when pte is null.
3982                  */
3983                 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
3984                 if (pte)
3985                         ptl = huge_pte_lock(h, mm, pte);
3986                 absent = !pte || huge_pte_none(huge_ptep_get(pte));
3987 
3988                 /*
3989                  * When coredumping, it suits get_dump_page if we just return
3990                  * an error where there's an empty slot with no huge pagecache
3991                  * to back it.  This way, we avoid allocating a hugepage, and
3992                  * the sparse dumpfile avoids allocating disk blocks, but its
3993                  * huge holes still show up with zeroes where they need to be.
3994                  */
3995                 if (absent && (flags & FOLL_DUMP) &&
3996                     !hugetlbfs_pagecache_present(h, vma, vaddr)) {
3997                         if (pte)
3998                                 spin_unlock(ptl);
3999                         remainder = 0;
4000                         break;
4001                 }
4002 
4003                 /*
4004                  * We need call hugetlb_fault for both hugepages under migration
4005                  * (in which case hugetlb_fault waits for the migration,) and
4006                  * hwpoisoned hugepages (in which case we need to prevent the
4007                  * caller from accessing to them.) In order to do this, we use
4008                  * here is_swap_pte instead of is_hugetlb_entry_migration and
4009                  * is_hugetlb_entry_hwpoisoned. This is because it simply covers
4010                  * both cases, and because we can't follow correct pages
4011                  * directly from any kind of swap entries.
4012                  */
4013                 if (absent || is_swap_pte(huge_ptep_get(pte)) ||
4014                     ((flags & FOLL_WRITE) &&
4015                       !huge_pte_write(huge_ptep_get(pte)))) {
4016                         int ret;
4017 
4018                         if (pte)
4019                                 spin_unlock(ptl);
4020                         ret = hugetlb_fault(mm, vma, vaddr,
4021                                 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
4022                         if (!(ret & VM_FAULT_ERROR))
4023                                 continue;
4024 
4025                         remainder = 0;
4026                         break;
4027                 }
4028 
4029                 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
4030                 page = pte_page(huge_ptep_get(pte));
4031 same_page:
4032                 if (pages) {
4033                         pages[i] = mem_map_offset(page, pfn_offset);
4034                         get_page(pages[i]);
4035                 }
4036 
4037                 if (vmas)
4038                         vmas[i] = vma;
4039 
4040                 vaddr += PAGE_SIZE;
4041                 ++pfn_offset;
4042                 --remainder;
4043                 ++i;
4044                 if (vaddr < vma->vm_end && remainder &&
4045                                 pfn_offset < pages_per_huge_page(h)) {
4046                         /*
4047                          * We use pfn_offset to avoid touching the pageframes
4048                          * of this compound page.
4049                          */
4050                         goto same_page;
4051                 }
4052                 spin_unlock(ptl);
4053         }
4054         *nr_pages = remainder;
4055         *position = vaddr;
4056 
4057         return i ? i : -EFAULT;
4058 }
4059 
4060 #ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
4061 /*
4062  * ARCHes with special requirements for evicting HUGETLB backing TLB entries can
4063  * implement this.
4064  */
4065 #define flush_hugetlb_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end)
4066 #endif
4067 
4068 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
4069                 unsigned long address, unsigned long end, pgprot_t newprot)
4070 {
4071         struct mm_struct *mm = vma->vm_mm;
4072         unsigned long start = address;
4073         pte_t *ptep;
4074         pte_t pte;
4075         struct hstate *h = hstate_vma(vma);
4076         unsigned long pages = 0;
4077 
4078         BUG_ON(address >= end);
4079         flush_cache_range(vma, address, end);
4080 
4081         mmu_notifier_invalidate_range_start(mm, start, end);
4082         i_mmap_lock_write(vma->vm_file->f_mapping);
4083         for (; address < end; address += huge_page_size(h)) {
4084                 spinlock_t *ptl;
4085                 ptep = huge_pte_offset(mm, address);
4086                 if (!ptep)
4087                         continue;
4088                 ptl = huge_pte_lock(h, mm, ptep);
4089                 if (huge_pmd_unshare(mm, &address, ptep)) {
4090                         pages++;
4091                         spin_unlock(ptl);
4092                         continue;
4093                 }
4094                 pte = huge_ptep_get(ptep);
4095                 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
4096                         spin_unlock(ptl);
4097                         continue;
4098                 }
4099                 if (unlikely(is_hugetlb_entry_migration(pte))) {
4100                         swp_entry_t entry = pte_to_swp_entry(pte);
4101 
4102                         if (is_write_migration_entry(entry)) {
4103                                 pte_t newpte;
4104 
4105                                 make_migration_entry_read(&entry);
4106                                 newpte = swp_entry_to_pte(entry);
4107                                 set_huge_pte_at(mm, address, ptep, newpte);
4108                                 pages++;
4109                         }
4110                         spin_unlock(ptl);
4111                         continue;
4112                 }
4113                 if (!huge_pte_none(pte)) {
4114                         pte = huge_ptep_get_and_clear(mm, address, ptep);
4115                         pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4116                         pte = arch_make_huge_pte(pte, vma, NULL, 0);
4117                         set_huge_pte_at(mm, address, ptep, pte);
4118                         pages++;
4119                 }
4120                 spin_unlock(ptl);
4121         }
4122         /*
4123          * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4124          * may have cleared our pud entry and done put_page on the page table:
4125          * once we release i_mmap_rwsem, another task can do the final put_page
4126          * and that page table be reused and filled with junk.
4127          */
4128         flush_hugetlb_tlb_range(vma, start, end);
4129         mmu_notifier_invalidate_range(mm, start, end);
4130         i_mmap_unlock_write(vma->vm_file->f_mapping);
4131         mmu_notifier_invalidate_range_end(mm, start, end);
4132 
4133         return pages << h->order;
4134 }
4135 
4136 int hugetlb_reserve_pages(struct inode *inode,
4137                                         long from, long to,
4138                                         struct vm_area_struct *vma,
4139                                         vm_flags_t vm_flags)
4140 {
4141         long ret, chg;
4142         struct hstate *h = hstate_inode(inode);
4143         struct hugepage_subpool *spool = subpool_inode(inode);
4144         struct resv_map *resv_map;
4145         long gbl_reserve;
4146 
4147         /*
4148          * Only apply hugepage reservation if asked. At fault time, an
4149          * attempt will be made for VM_NORESERVE to allocate a page
4150          * without using reserves
4151          */
4152         if (vm_flags & VM_NORESERVE)
4153                 return 0;
4154 
4155         /*
4156          * Shared mappings base their reservation on the number of pages that
4157          * are already allocated on behalf of the file. Private mappings need
4158          * to reserve the full area even if read-only as mprotect() may be
4159          * called to make the mapping read-write. Assume !vma is a shm mapping
4160          */
4161         if (!vma || vma->vm_flags & VM_MAYSHARE) {
4162                 resv_map = inode_resv_map(inode);
4163 
4164                 chg = region_chg(resv_map, from, to);
4165 
4166         } else {
4167                 resv_map = resv_map_alloc();
4168                 if (!resv_map)
4169                         return -ENOMEM;
4170 
4171                 chg = to - from;
4172 
4173                 set_vma_resv_map(vma, resv_map);
4174                 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
4175         }
4176 
4177         if (chg < 0) {
4178                 ret = chg;
4179                 goto out_err;
4180         }
4181 
4182         /*
4183          * There must be enough pages in the subpool for the mapping. If
4184          * the subpool has a minimum size, there may be some global
4185          * reservations already in place (gbl_reserve).
4186          */
4187         gbl_reserve = hugepage_subpool_get_pages(spool, chg);
4188         if (gbl_reserve < 0) {
4189                 ret = -ENOSPC;
4190                 goto out_err;
4191         }
4192 
4193         /*
4194          * Check enough hugepages are available for the reservation.
4195          * Hand the pages back to the subpool if there are not
4196          */
4197         ret = hugetlb_acct_memory(h, gbl_reserve);
4198         if (ret < 0) {
4199                 /* put back original number of pages, chg */
4200                 (void)hugepage_subpool_put_pages(spool, chg);
4201                 goto out_err;
4202         }
4203 
4204         /*
4205          * Account for the reservations made. Shared mappings record regions
4206          * that have reservations as they are shared by multiple VMAs.
4207          * When the last VMA disappears, the region map says how much
4208          * the reservation was and the page cache tells how much of
4209          * the reservation was consumed. Private mappings are per-VMA and
4210          * only the consumed reservations are tracked. When the VMA
4211          * disappears, the original reservation is the VMA size and the
4212          * consumed reservations are stored in the map. Hence, nothing
4213          * else has to be done for private mappings here
4214          */
4215         if (!vma || vma->vm_flags & VM_MAYSHARE) {
4216                 long add = region_add(resv_map, from, to);
4217 
4218                 if (unlikely(chg > add)) {
4219                         /*
4220                          * pages in this range were added to the reserve
4221                          * map between region_chg and region_add.  This
4222                          * indicates a race with alloc_huge_page.  Adjust
4223                          * the subpool and reserve counts modified above
4224                          * based on the difference.
4225                          */
4226                         long rsv_adjust;
4227 
4228                         rsv_adjust = hugepage_subpool_put_pages(spool,
4229                                                                 chg - add);
4230                         hugetlb_acct_memory(h, -rsv_adjust);
4231                 }
4232         }
4233         return 0;
4234 out_err:
4235         if (!vma || vma->vm_flags & VM_MAYSHARE)
4236                 region_abort(resv_map, from, to);
4237         if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
4238                 kref_put(&resv_map->refs, resv_map_release);
4239         return ret;
4240 }
4241 
4242 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
4243                                                                 long freed)
4244 {
4245         struct hstate *h = hstate_inode(inode);
4246         struct resv_map *resv_map = inode_resv_map(inode);
4247         long chg = 0;
4248         struct hugepage_subpool *spool = subpool_inode(inode);
4249         long gbl_reserve;
4250 
4251         if (resv_map) {
4252                 chg = region_del(resv_map, start, end);
4253                 /*
4254                  * region_del() can fail in the rare case where a region
4255                  * must be split and another region descriptor can not be
4256                  * allocated.  If end == LONG_MAX, it will not fail.
4257                  */
4258                 if (chg < 0)
4259                         return chg;
4260         }
4261 
4262         spin_lock(&inode->i_lock);
4263         inode->i_blocks -= (blocks_per_huge_page(h) * freed);
4264         spin_unlock(&inode->i_lock);
4265 
4266         /*
4267          * If the subpool has a minimum size, the number of global
4268          * reservations to be released may be adjusted.
4269          */
4270         gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
4271         hugetlb_acct_memory(h, -gbl_reserve);
4272 
4273         return 0;
4274 }
4275 
4276 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
4277 static unsigned long page_table_shareable(struct vm_area_struct *svma,
4278                                 struct vm_area_struct *vma,
4279                                 unsigned long addr, pgoff_t idx)
4280 {
4281         unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
4282                                 svma->vm_start;
4283         unsigned long sbase = saddr & PUD_MASK;
4284         unsigned long s_end = sbase + PUD_SIZE;
4285 
4286         /* Allow segments to share if only one is marked locked */
4287         unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
4288         unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4289 
4290         /*
4291          * match the virtual addresses, permission and the alignment of the
4292          * page table page.
4293          */
4294         if (pmd_index(addr) != pmd_index(saddr) ||
4295             vm_flags != svm_flags ||
4296             sbase < svma->vm_start || svma->vm_end < s_end)
4297                 return 0;
4298 
4299         return saddr;
4300 }
4301 
4302 static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4303 {
4304         unsigned long base = addr & PUD_MASK;
4305         unsigned long end = base + PUD_SIZE;
4306 
4307         /*
4308          * check on proper vm_flags and page table alignment
4309          */
4310         if (vma->vm_flags & VM_MAYSHARE &&
4311             vma->vm_start <= base && end <= vma->vm_end)
4312                 return true;
4313         return false;
4314 }
4315 
4316 /*
4317  * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
4318  * and returns the corresponding pte. While this is not necessary for the
4319  * !shared pmd case because we can allocate the pmd later as well, it makes the
4320  * code much cleaner. pmd allocation is essential for the shared case because
4321  * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4322  * racing tasks could either miss the sharing (see huge_pte_offset) or select a
4323  * bad pmd for sharing.
4324  */
4325 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4326 {
4327         struct vm_area_struct *vma = find_vma(mm, addr);
4328         struct address_space *mapping = vma->vm_file->f_mapping;
4329         pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
4330                         vma->vm_pgoff;
4331         struct vm_area_struct *svma;
4332         unsigned long saddr;
4333         pte_t *spte = NULL;
4334         pte_t *pte;
4335         spinlock_t *ptl;
4336 
4337         if (!vma_shareable(vma, addr))
4338                 return (pte_t *)pmd_alloc(mm, pud, addr);
4339 
4340         i_mmap_lock_write(mapping);
4341         vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
4342                 if (svma == vma)
4343                         continue;
4344 
4345                 saddr = page_table_shareable(svma, vma, addr, idx);
4346                 if (saddr) {
4347                         spte = huge_pte_offset(svma->vm_mm, saddr);
4348                         if (spte) {
4349                                 get_page(virt_to_page(spte));
4350                                 break;
4351                         }
4352                 }
4353         }
4354 
4355         if (!spte)
4356                 goto out;
4357 
4358         ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
4359         if (pud_none(*pud)) {
4360                 pud_populate(mm, pud,
4361                                 (pmd_t *)((unsigned long)spte & PAGE_MASK));
4362                 mm_inc_nr_pmds(mm);
4363         } else {
4364                 put_page(virt_to_page(spte));
4365         }
4366         spin_unlock(ptl);
4367 out:
4368         pte = (pte_t *)pmd_alloc(mm, pud, addr);
4369         i_mmap_unlock_write(mapping);
4370         return pte;
4371 }
4372 
4373 /*
4374  * unmap huge page backed by shared pte.
4375  *
4376  * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
4377  * indicated by page_count > 1, unmap is achieved by clearing pud and
4378  * decrementing the ref count. If count == 1, the pte page is not shared.
4379  *
4380  * called with page table lock held.
4381  *
4382  * returns: 1 successfully unmapped a shared pte page
4383  *          0 the underlying pte page is not shared, or it is the last user
4384  */
4385 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4386 {
4387         pgd_t *pgd = pgd_offset(mm, *addr);
4388         pud_t *pud = pud_offset(pgd, *addr);
4389 
4390         BUG_ON(page_count(virt_to_page(ptep)) == 0);
4391         if (page_count(virt_to_page(ptep)) == 1)
4392                 return 0;
4393 
4394         pud_clear(pud);
4395         put_page(virt_to_page(ptep));
4396         mm_dec_nr_pmds(mm);
4397         *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
4398         return 1;
4399 }
4400 #define want_pmd_share()        (1)
4401 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4402 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4403 {
4404         return NULL;
4405 }
4406 
4407 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4408 {
4409         return 0;
4410 }
4411 #define want_pmd_share()        (0)
4412 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4413 
4414 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
4415 pte_t *huge_pte_alloc(struct mm_struct *mm,
4416                         unsigned long addr, unsigned long sz)
4417 {
4418         pgd_t *pgd;
4419         pud_t *pud;
4420         pte_t *pte = NULL;
4421 
4422         pgd = pgd_offset(mm, addr);
4423         pud = pud_alloc(mm, pgd, addr);
4424         if (pud) {
4425                 if (sz == PUD_SIZE) {
4426                         pte = (pte_t *)pud;
4427                 } else {
4428                         BUG_ON(sz != PMD_SIZE);
4429                         if (want_pmd_share() && pud_none(*pud))
4430                                 pte = huge_pmd_share(mm, addr, pud);
4431                         else
4432                                 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4433                 }
4434         }
4435         BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
4436 
4437         return pte;
4438 }
4439 
4440 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
4441 {
4442         pgd_t *pgd;
4443         pud_t *pud;
4444         pmd_t *pmd = NULL;
4445 
4446         pgd = pgd_offset(mm, addr);
4447         if (pgd_present(*pgd)) {
4448                 pud = pud_offset(pgd, addr);
4449                 if (pud_present(*pud)) {
4450                         if (pud_huge(*pud))
4451                                 return (pte_t *)pud;
4452                         pmd = pmd_offset(pud, addr);
4453                 }
4454         }
4455         return (pte_t *) pmd;
4456 }
4457 
4458 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
4459 
4460 /*
4461  * These functions are overwritable if your architecture needs its own
4462  * behavior.
4463  */
4464 struct page * __weak
4465 follow_huge_addr(struct mm_struct *mm, unsigned long address,
4466                               int write)
4467 {
4468         return ERR_PTR(-EINVAL);
4469 }
4470 
4471 struct page * __weak
4472 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4473                 pmd_t *pmd, int flags)
4474 {
4475         struct page *page = NULL;
4476         spinlock_t *ptl;
4477 retry:
4478         ptl = pmd_lockptr(mm, pmd);
4479         spin_lock(ptl);
4480         /*
4481          * make sure that the address range covered by this pmd is not
4482          * unmapped from other threads.
4483          */
4484         if (!pmd_huge(*pmd))
4485                 goto out;
4486         if (pmd_present(*pmd)) {
4487                 page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4488                 if (flags & FOLL_GET)
4489                         get_page(page);
4490         } else {
4491                 if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
4492                         spin_unlock(ptl);
4493                         __migration_entry_wait(mm, (pte_t *)pmd, ptl);
4494                         goto retry;
4495                 }
4496                 /*
4497                  * hwpoisoned entry is treated as no_page_table in
4498                  * follow_page_mask().
4499                  */
4500         }
4501 out:
4502         spin_unlock(ptl);
4503         return page;
4504 }
4505 
4506 struct page * __weak
4507 follow_huge_pud(struct mm_struct *mm, unsigned long address,
4508                 pud_t *pud, int flags)
4509 {
4510         if (flags & FOLL_GET)
4511                 return NULL;
4512 
4513         return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4514 }
4515 
4516 #ifdef CONFIG_MEMORY_FAILURE
4517 
4518 /*
4519  * This function is called from memory failure code.
4520  */
4521 int dequeue_hwpoisoned_huge_page(struct page *hpage)
4522 {
4523         struct hstate *h = page_hstate(hpage);
4524         int nid = page_to_nid(hpage);
4525         int ret = -EBUSY;
4526 
4527         spin_lock(&hugetlb_lock);
4528         /*
4529          * Just checking !page_huge_active is not enough, because that could be
4530          * an isolated/hwpoisoned hugepage (which have >0 refcount).
4531          */
4532         if (!page_huge_active(hpage) && !page_count(hpage)) {
4533                 /*
4534                  * Hwpoisoned hugepage isn't linked to activelist or freelist,
4535                  * but dangling hpage->lru can trigger list-debug warnings
4536                  * (this happens when we call unpoison_memory() on it),
4537                  * so let it point to itself with list_del_init().
4538                  */
4539                 list_del_init(&hpage->lru);
4540                 set_page_refcounted(hpage);
4541                 h->free_huge_pages--;
4542                 h->free_huge_pages_node[nid]--;
4543                 ret = 0;
4544         }
4545         spin_unlock(&hugetlb_lock);
4546         return ret;
4547 }
4548 #endif
4549 
4550 bool isolate_huge_page(struct page *page, struct list_head *list)
4551 {
4552         bool ret = true;
4553 
4554         VM_BUG_ON_PAGE(!PageHead(page), page);
4555         spin_lock(&hugetlb_lock);
4556         if (!page_huge_active(page) || !get_page_unless_zero(page)) {
4557                 ret = false;
4558                 goto unlock;
4559         }
4560         clear_page_huge_active(page);
4561         list_move_tail(&page->lru, list);
4562 unlock:
4563         spin_unlock(&hugetlb_lock);
4564         return ret;
4565 }
4566 
4567 void putback_active_hugepage(struct page *page)
4568 {
4569         VM_BUG_ON_PAGE(!PageHead(page), page);
4570         spin_lock(&hugetlb_lock);
4571         set_page_huge_active(page);
4572         list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
4573         spin_unlock(&hugetlb_lock);
4574         put_page(page);
4575 }
4576 

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