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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/module.h>
8 #include <linux/mm.h>
9 #include <linux/seq_file.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/nodemask.h>
14 #include <linux/pagemap.h>
15 #include <linux/mempolicy.h>
16 #include <linux/compiler.h>
17 #include <linux/cpuset.h>
18 #include <linux/mutex.h>
19 #include <linux/bootmem.h>
20 #include <linux/sysfs.h>
21 #include <linux/slab.h>
22 #include <linux/rmap.h>
23 #include <linux/swap.h>
24 #include <linux/swapops.h>
25 #include <linux/page-isolation.h>
26 #include <linux/jhash.h>
27
28 #include <asm/page.h>
29 #include <asm/pgtable.h>
30 #include <asm/tlb.h>
31
32 #include <linux/io.h>
33 #include <linux/hugetlb.h>
34 #include <linux/hugetlb_cgroup.h>
35 #include <linux/node.h>
36 #include "internal.h"
37
38 int hugepages_treat_as_movable;
39
40 int hugetlb_max_hstate __read_mostly;
41 unsigned int default_hstate_idx;
42 struct hstate hstates[HUGE_MAX_HSTATE];
43 /*
44 * Minimum page order among possible hugepage sizes, set to a proper value
45 * at boot time.
46 */
47 static unsigned int minimum_order __read_mostly = UINT_MAX;
48
49 __initdata LIST_HEAD(huge_boot_pages);
50
51 /* for command line parsing */
52 static struct hstate * __initdata parsed_hstate;
53 static unsigned long __initdata default_hstate_max_huge_pages;
54 static unsigned long __initdata default_hstate_size;
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 if (spool->min_hpages != -1) { /* minimum size accounting */
149 if (delta > spool->rsv_hpages) {
150 /*
151 * Asking for more reserves than those already taken on
152 * behalf of subpool. Return difference.
153 */
154 ret = delta - spool->rsv_hpages;
155 spool->rsv_hpages = 0;
156 } else {
157 ret = 0; /* reserves already accounted for */
158 spool->rsv_hpages -= delta;
159 }
160 }
161
162 unlock_ret:
163 spin_unlock(&spool->lock);
164 return ret;
165 }
166
167 /*
168 * Subpool accounting for freeing and unreserving pages.
169 * Return the number of global page reservations that must be dropped.
170 * The return value may only be different than the passed value (delta)
171 * in the case where a subpool minimum size must be maintained.
172 */
173 static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
174 long delta)
175 {
176 long ret = delta;
177
178 if (!spool)
179 return delta;
180
181 spin_lock(&spool->lock);
182
183 if (spool->max_hpages != -1) /* maximum size accounting */
184 spool->used_hpages -= delta;
185
186 if (spool->min_hpages != -1) { /* minimum size accounting */
187 if (spool->rsv_hpages + delta <= spool->min_hpages)
188 ret = 0;
189 else
190 ret = spool->rsv_hpages + delta - spool->min_hpages;
191
192 spool->rsv_hpages += delta;
193 if (spool->rsv_hpages > spool->min_hpages)
194 spool->rsv_hpages = spool->min_hpages;
195 }
196
197 /*
198 * If hugetlbfs_put_super couldn't free spool due to an outstanding
199 * quota reference, free it now.
200 */
201 unlock_or_release_subpool(spool);
202
203 return ret;
204 }
205
206 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
207 {
208 return HUGETLBFS_SB(inode->i_sb)->spool;
209 }
210
211 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
212 {
213 return subpool_inode(file_inode(vma->vm_file));
214 }
215
216 /*
217 * Region tracking -- allows tracking of reservations and instantiated pages
218 * across the pages in a mapping.
219 *
220 * The region data structures are embedded into a resv_map and protected
221 * by a resv_map's lock. The set of regions within the resv_map represent
222 * reservations for huge pages, or huge pages that have already been
223 * instantiated within the map. The from and to elements are huge page
224 * indicies into the associated mapping. from indicates the starting index
225 * of the region. to represents the first index past the end of the region.
226 *
227 * For example, a file region structure with from == 0 and to == 4 represents
228 * four huge pages in a mapping. It is important to note that the to element
229 * represents the first element past the end of the region. This is used in
230 * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
231 *
232 * Interval notation of the form [from, to) will be used to indicate that
233 * the endpoint from is inclusive and to is exclusive.
234 */
235 struct file_region {
236 struct list_head link;
237 long from;
238 long to;
239 };
240
241 /*
242 * Add the huge page range represented by [f, t) to the reserve
243 * map. In the normal case, existing regions will be expanded
244 * to accommodate the specified range. Sufficient regions should
245 * exist for expansion due to the previous call to region_chg
246 * with the same range. However, it is possible that region_del
247 * could have been called after region_chg and modifed the map
248 * in such a way that no region exists to be expanded. In this
249 * case, pull a region descriptor from the cache associated with
250 * the map and use that for the new range.
251 *
252 * Return the number of new huge pages added to the map. This
253 * number is greater than or equal to zero.
254 */
255 static long region_add(struct resv_map *resv, long f, long t)
256 {
257 struct list_head *head = &resv->regions;
258 struct file_region *rg, *nrg, *trg;
259 long add = 0;
260
261 spin_lock(&resv->lock);
262 /* Locate the region we are either in or before. */
263 list_for_each_entry(rg, head, link)
264 if (f <= rg->to)
265 break;
266
267 /*
268 * If no region exists which can be expanded to include the
269 * specified range, the list must have been modified by an
270 * interleving call to region_del(). Pull a region descriptor
271 * from the cache and use it for this range.
272 */
273 if (&rg->link == head || t < rg->from) {
274 VM_BUG_ON(resv->region_cache_count <= 0);
275
276 resv->region_cache_count--;
277 nrg = list_first_entry(&resv->region_cache, struct file_region,
278 link);
279 list_del(&nrg->link);
280
281 nrg->from = f;
282 nrg->to = t;
283 list_add(&nrg->link, rg->link.prev);
284
285 add += t - f;
286 goto out_locked;
287 }
288
289 /* Round our left edge to the current segment if it encloses us. */
290 if (f > rg->from)
291 f = rg->from;
292
293 /* Check for and consume any regions we now overlap with. */
294 nrg = rg;
295 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
296 if (&rg->link == head)
297 break;
298 if (rg->from > t)
299 break;
300
301 /* If this area reaches higher then extend our area to
302 * include it completely. If this is not the first area
303 * which we intend to reuse, free it. */
304 if (rg->to > t)
305 t = rg->to;
306 if (rg != nrg) {
307 /* Decrement return value by the deleted range.
308 * Another range will span this area so that by
309 * end of routine add will be >= zero
310 */
311 add -= (rg->to - rg->from);
312 list_del(&rg->link);
313 kfree(rg);
314 }
315 }
316
317 add += (nrg->from - f); /* Added to beginning of region */
318 nrg->from = f;
319 add += t - nrg->to; /* Added to end of region */
320 nrg->to = t;
321
322 out_locked:
323 resv->adds_in_progress--;
324 spin_unlock(&resv->lock);
325 VM_BUG_ON(add < 0);
326 return add;
327 }
328
329 /*
330 * Examine the existing reserve map and determine how many
331 * huge pages in the specified range [f, t) are NOT currently
332 * represented. This routine is called before a subsequent
333 * call to region_add that will actually modify the reserve
334 * map to add the specified range [f, t). region_chg does
335 * not change the number of huge pages represented by the
336 * map. However, if the existing regions in the map can not
337 * be expanded to represent the new range, a new file_region
338 * structure is added to the map as a placeholder. This is
339 * so that the subsequent region_add call will have all the
340 * regions it needs and will not fail.
341 *
342 * Upon entry, region_chg will also examine the cache of region descriptors
343 * associated with the map. If there are not enough descriptors cached, one
344 * will be allocated for the in progress add operation.
345 *
346 * Returns the number of huge pages that need to be added to the existing
347 * reservation map for the range [f, t). This number is greater or equal to
348 * zero. -ENOMEM is returned if a new file_region structure or cache entry
349 * is needed and can not be allocated.
350 */
351 static long region_chg(struct resv_map *resv, long f, long t)
352 {
353 struct list_head *head = &resv->regions;
354 struct file_region *rg, *nrg = NULL;
355 long chg = 0;
356
357 retry:
358 spin_lock(&resv->lock);
359 retry_locked:
360 resv->adds_in_progress++;
361
362 /*
363 * Check for sufficient descriptors in the cache to accommodate
364 * the number of in progress add operations.
365 */
366 if (resv->adds_in_progress > resv->region_cache_count) {
367 struct file_region *trg;
368
369 VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
370 /* Must drop lock to allocate a new descriptor. */
371 resv->adds_in_progress--;
372 spin_unlock(&resv->lock);
373
374 trg = kmalloc(sizeof(*trg), GFP_KERNEL);
375 if (!trg) {
376 kfree(nrg);
377 return -ENOMEM;
378 }
379
380 spin_lock(&resv->lock);
381 list_add(&trg->link, &resv->region_cache);
382 resv->region_cache_count++;
383 goto retry_locked;
384 }
385
386 /* Locate the region we are before or in. */
387 list_for_each_entry(rg, head, link)
388 if (f <= rg->to)
389 break;
390
391 /* If we are below the current region then a new region is required.
392 * Subtle, allocate a new region at the position but make it zero
393 * size such that we can guarantee to record the reservation. */
394 if (&rg->link == head || t < rg->from) {
395 if (!nrg) {
396 resv->adds_in_progress--;
397 spin_unlock(&resv->lock);
398 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
399 if (!nrg)
400 return -ENOMEM;
401
402 nrg->from = f;
403 nrg->to = f;
404 INIT_LIST_HEAD(&nrg->link);
405 goto retry;
406 }
407
408 list_add(&nrg->link, rg->link.prev);
409 chg = t - f;
410 goto out_nrg;
411 }
412
413 /* Round our left edge to the current segment if it encloses us. */
414 if (f > rg->from)
415 f = rg->from;
416 chg = t - f;
417
418 /* Check for and consume any regions we now overlap with. */
419 list_for_each_entry(rg, rg->link.prev, link) {
420 if (&rg->link == head)
421 break;
422 if (rg->from > t)
423 goto out;
424
425 /* We overlap with this area, if it extends further than
426 * us then we must extend ourselves. Account for its
427 * existing reservation. */
428 if (rg->to > t) {
429 chg += rg->to - t;
430 t = rg->to;
431 }
432 chg -= rg->to - rg->from;
433 }
434
435 out:
436 spin_unlock(&resv->lock);
437 /* We already know we raced and no longer need the new region */
438 kfree(nrg);
439 return chg;
440 out_nrg:
441 spin_unlock(&resv->lock);
442 return chg;
443 }
444
445 /*
446 * Abort the in progress add operation. The adds_in_progress field
447 * of the resv_map keeps track of the operations in progress between
448 * calls to region_chg and region_add. Operations are sometimes
449 * aborted after the call to region_chg. In such cases, region_abort
450 * is called to decrement the adds_in_progress counter.
451 *
452 * NOTE: The range arguments [f, t) are not needed or used in this
453 * routine. They are kept to make reading the calling code easier as
454 * arguments will match the associated region_chg call.
455 */
456 static void region_abort(struct resv_map *resv, long f, long t)
457 {
458 spin_lock(&resv->lock);
459 VM_BUG_ON(!resv->region_cache_count);
460 resv->adds_in_progress--;
461 spin_unlock(&resv->lock);
462 }
463
464 /*
465 * Delete the specified range [f, t) from the reserve map. If the
466 * t parameter is LONG_MAX, this indicates that ALL regions after f
467 * should be deleted. Locate the regions which intersect [f, t)
468 * and either trim, delete or split the existing regions.
469 *
470 * Returns the number of huge pages deleted from the reserve map.
471 * In the normal case, the return value is zero or more. In the
472 * case where a region must be split, a new region descriptor must
473 * be allocated. If the allocation fails, -ENOMEM will be returned.
474 * NOTE: If the parameter t == LONG_MAX, then we will never split
475 * a region and possibly return -ENOMEM. Callers specifying
476 * t == LONG_MAX do not need to check for -ENOMEM error.
477 */
478 static long region_del(struct resv_map *resv, long f, long t)
479 {
480 struct list_head *head = &resv->regions;
481 struct file_region *rg, *trg;
482 struct file_region *nrg = NULL;
483 long del = 0;
484
485 retry:
486 spin_lock(&resv->lock);
487 list_for_each_entry_safe(rg, trg, head, link) {
488 /*
489 * Skip regions before the range to be deleted. file_region
490 * ranges are normally of the form [from, to). However, there
491 * may be a "placeholder" entry in the map which is of the form
492 * (from, to) with from == to. Check for placeholder entries
493 * at the beginning of the range to be deleted.
494 */
495 if (rg->to <= f && (rg->to != rg->from || rg->to != f))
496 continue;
497
498 if (rg->from >= t)
499 break;
500
501 if (f > rg->from && t < rg->to) { /* Must split region */
502 /*
503 * Check for an entry in the cache before dropping
504 * lock and attempting allocation.
505 */
506 if (!nrg &&
507 resv->region_cache_count > resv->adds_in_progress) {
508 nrg = list_first_entry(&resv->region_cache,
509 struct file_region,
510 link);
511 list_del(&nrg->link);
512 resv->region_cache_count--;
513 }
514
515 if (!nrg) {
516 spin_unlock(&resv->lock);
517 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
518 if (!nrg)
519 return -ENOMEM;
520 goto retry;
521 }
522
523 del += t - f;
524
525 /* New entry for end of split region */
526 nrg->from = t;
527 nrg->to = rg->to;
528 INIT_LIST_HEAD(&nrg->link);
529
530 /* Original entry is trimmed */
531 rg->to = f;
532
533 list_add(&nrg->link, &rg->link);
534 nrg = NULL;
535 break;
536 }
537
538 if (f <= rg->from && t >= rg->to) { /* Remove entire region */
539 del += rg->to - rg->from;
540 list_del(&rg->link);
541 kfree(rg);
542 continue;
543 }
544
545 if (f <= rg->from) { /* Trim beginning of region */
546 del += t - rg->from;
547 rg->from = t;
548 } else { /* Trim end of region */
549 del += rg->to - f;
550 rg->to = f;
551 }
552 }
553
554 spin_unlock(&resv->lock);
555 kfree(nrg);
556 return del;
557 }
558
559 /*
560 * A rare out of memory error was encountered which prevented removal of
561 * the reserve map region for a page. The huge page itself was free'ed
562 * and removed from the page cache. This routine will adjust the subpool
563 * usage count, and the global reserve count if needed. By incrementing
564 * these counts, the reserve map entry which could not be deleted will
565 * appear as a "reserved" entry instead of simply dangling with incorrect
566 * counts.
567 */
568 void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve)
569 {
570 struct hugepage_subpool *spool = subpool_inode(inode);
571 long rsv_adjust;
572
573 rsv_adjust = hugepage_subpool_get_pages(spool, 1);
574 if (restore_reserve && rsv_adjust) {
575 struct hstate *h = hstate_inode(inode);
576
577 hugetlb_acct_memory(h, 1);
578 }
579 }
580
581 /*
582 * Count and return the number of huge pages in the reserve map
583 * that intersect with the range [f, t).
584 */
585 static long region_count(struct resv_map *resv, long f, long t)
586 {
587 struct list_head *head = &resv->regions;
588 struct file_region *rg;
589 long chg = 0;
590
591 spin_lock(&resv->lock);
592 /* Locate each segment we overlap with, and count that overlap. */
593 list_for_each_entry(rg, head, link) {
594 long seg_from;
595 long seg_to;
596
597 if (rg->to <= f)
598 continue;
599 if (rg->from >= t)
600 break;
601
602 seg_from = max(rg->from, f);
603 seg_to = min(rg->to, t);
604
605 chg += seg_to - seg_from;
606 }
607 spin_unlock(&resv->lock);
608
609 return chg;
610 }
611
612 /*
613 * Convert the address within this vma to the page offset within
614 * the mapping, in pagecache page units; huge pages here.
615 */
616 static pgoff_t vma_hugecache_offset(struct hstate *h,
617 struct vm_area_struct *vma, unsigned long address)
618 {
619 return ((address - vma->vm_start) >> huge_page_shift(h)) +
620 (vma->vm_pgoff >> huge_page_order(h));
621 }
622
623 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
624 unsigned long address)
625 {
626 return vma_hugecache_offset(hstate_vma(vma), vma, address);
627 }
628
629 /*
630 * Return the size of the pages allocated when backing a VMA. In the majority
631 * cases this will be same size as used by the page table entries.
632 */
633 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
634 {
635 struct hstate *hstate;
636
637 if (!is_vm_hugetlb_page(vma))
638 return PAGE_SIZE;
639
640 hstate = hstate_vma(vma);
641
642 return 1UL << huge_page_shift(hstate);
643 }
644 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
645
646 /*
647 * Return the page size being used by the MMU to back a VMA. In the majority
648 * of cases, the page size used by the kernel matches the MMU size. On
649 * architectures where it differs, an architecture-specific version of this
650 * function is required.
651 */
652 #ifndef vma_mmu_pagesize
653 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
654 {
655 return vma_kernel_pagesize(vma);
656 }
657 #endif
658
659 /*
660 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
661 * bits of the reservation map pointer, which are always clear due to
662 * alignment.
663 */
664 #define HPAGE_RESV_OWNER (1UL << 0)
665 #define HPAGE_RESV_UNMAPPED (1UL << 1)
666 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
667
668 /*
669 * These helpers are used to track how many pages are reserved for
670 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
671 * is guaranteed to have their future faults succeed.
672 *
673 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
674 * the reserve counters are updated with the hugetlb_lock held. It is safe
675 * to reset the VMA at fork() time as it is not in use yet and there is no
676 * chance of the global counters getting corrupted as a result of the values.
677 *
678 * The private mapping reservation is represented in a subtly different
679 * manner to a shared mapping. A shared mapping has a region map associated
680 * with the underlying file, this region map represents the backing file
681 * pages which have ever had a reservation assigned which this persists even
682 * after the page is instantiated. A private mapping has a region map
683 * associated with the original mmap which is attached to all VMAs which
684 * reference it, this region map represents those offsets which have consumed
685 * reservation ie. where pages have been instantiated.
686 */
687 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
688 {
689 return (unsigned long)vma->vm_private_data;
690 }
691
692 static void set_vma_private_data(struct vm_area_struct *vma,
693 unsigned long value)
694 {
695 vma->vm_private_data = (void *)value;
696 }
697
698 struct resv_map *resv_map_alloc(void)
699 {
700 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
701 struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
702
703 if (!resv_map || !rg) {
704 kfree(resv_map);
705 kfree(rg);
706 return NULL;
707 }
708
709 kref_init(&resv_map->refs);
710 spin_lock_init(&resv_map->lock);
711 INIT_LIST_HEAD(&resv_map->regions);
712
713 resv_map->adds_in_progress = 0;
714
715 INIT_LIST_HEAD(&resv_map->region_cache);
716 list_add(&rg->link, &resv_map->region_cache);
717 resv_map->region_cache_count = 1;
718
719 return resv_map;
720 }
721
722 void resv_map_release(struct kref *ref)
723 {
724 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
725 struct list_head *head = &resv_map->region_cache;
726 struct file_region *rg, *trg;
727
728 /* Clear out any active regions before we release the map. */
729 region_del(resv_map, 0, LONG_MAX);
730
731 /* ... and any entries left in the cache */
732 list_for_each_entry_safe(rg, trg, head, link) {
733 list_del(&rg->link);
734 kfree(rg);
735 }
736
737 VM_BUG_ON(resv_map->adds_in_progress);
738
739 kfree(resv_map);
740 }
741
742 static inline struct resv_map *inode_resv_map(struct inode *inode)
743 {
744 return inode->i_mapping->private_data;
745 }
746
747 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
748 {
749 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
750 if (vma->vm_flags & VM_MAYSHARE) {
751 struct address_space *mapping = vma->vm_file->f_mapping;
752 struct inode *inode = mapping->host;
753
754 return inode_resv_map(inode);
755
756 } else {
757 return (struct resv_map *)(get_vma_private_data(vma) &
758 ~HPAGE_RESV_MASK);
759 }
760 }
761
762 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
763 {
764 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
765 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
766
767 set_vma_private_data(vma, (get_vma_private_data(vma) &
768 HPAGE_RESV_MASK) | (unsigned long)map);
769 }
770
771 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
772 {
773 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
774 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
775
776 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
777 }
778
779 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
780 {
781 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
782
783 return (get_vma_private_data(vma) & flag) != 0;
784 }
785
786 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
787 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
788 {
789 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
790 if (!(vma->vm_flags & VM_MAYSHARE))
791 vma->vm_private_data = (void *)0;
792 }
793
794 /* Returns true if the VMA has associated reserve pages */
795 static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
796 {
797 if (vma->vm_flags & VM_NORESERVE) {
798 /*
799 * This address is already reserved by other process(chg == 0),
800 * so, we should decrement reserved count. Without decrementing,
801 * reserve count remains after releasing inode, because this
802 * allocated page will go into page cache and is regarded as
803 * coming from reserved pool in releasing step. Currently, we
804 * don't have any other solution to deal with this situation
805 * properly, so add work-around here.
806 */
807 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
808 return true;
809 else
810 return false;
811 }
812
813 /* Shared mappings always use reserves */
814 if (vma->vm_flags & VM_MAYSHARE) {
815 /*
816 * We know VM_NORESERVE is not set. Therefore, there SHOULD
817 * be a region map for all pages. The only situation where
818 * there is no region map is if a hole was punched via
819 * fallocate. In this case, there really are no reverves to
820 * use. This situation is indicated if chg != 0.
821 */
822 if (chg)
823 return false;
824 else
825 return true;
826 }
827
828 /*
829 * Only the process that called mmap() has reserves for
830 * private mappings.
831 */
832 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
833 return true;
834
835 return false;
836 }
837
838 static void enqueue_huge_page(struct hstate *h, struct page *page)
839 {
840 int nid = page_to_nid(page);
841 list_move(&page->lru, &h->hugepage_freelists[nid]);
842 h->free_huge_pages++;
843 h->free_huge_pages_node[nid]++;
844 }
845
846 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
847 {
848 struct page *page;
849
850 list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
851 if (!is_migrate_isolate_page(page))
852 break;
853 /*
854 * if 'non-isolated free hugepage' not found on the list,
855 * the allocation fails.
856 */
857 if (&h->hugepage_freelists[nid] == &page->lru)
858 return NULL;
859 list_move(&page->lru, &h->hugepage_activelist);
860 set_page_refcounted(page);
861 h->free_huge_pages--;
862 h->free_huge_pages_node[nid]--;
863 return page;
864 }
865
866 /* Movability of hugepages depends on migration support. */
867 static inline gfp_t htlb_alloc_mask(struct hstate *h)
868 {
869 if (hugepages_treat_as_movable || hugepage_migration_supported(h))
870 return GFP_HIGHUSER_MOVABLE;
871 else
872 return GFP_HIGHUSER;
873 }
874
875 static struct page *dequeue_huge_page_vma(struct hstate *h,
876 struct vm_area_struct *vma,
877 unsigned long address, int avoid_reserve,
878 long chg)
879 {
880 struct page *page = NULL;
881 struct mempolicy *mpol;
882 nodemask_t *nodemask;
883 struct zonelist *zonelist;
884 struct zone *zone;
885 struct zoneref *z;
886 unsigned int cpuset_mems_cookie;
887
888 /*
889 * A child process with MAP_PRIVATE mappings created by their parent
890 * have no page reserves. This check ensures that reservations are
891 * not "stolen". The child may still get SIGKILLed
892 */
893 if (!vma_has_reserves(vma, chg) &&
894 h->free_huge_pages - h->resv_huge_pages == 0)
895 goto err;
896
897 /* If reserves cannot be used, ensure enough pages are in the pool */
898 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
899 goto err;
900
901 retry_cpuset:
902 cpuset_mems_cookie = read_mems_allowed_begin();
903 zonelist = huge_zonelist(vma, address,
904 htlb_alloc_mask(h), &mpol, &nodemask);
905
906 for_each_zone_zonelist_nodemask(zone, z, zonelist,
907 MAX_NR_ZONES - 1, nodemask) {
908 if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
909 page = dequeue_huge_page_node(h, zone_to_nid(zone));
910 if (page) {
911 if (avoid_reserve)
912 break;
913 if (!vma_has_reserves(vma, chg))
914 break;
915
916 SetPagePrivate(page);
917 h->resv_huge_pages--;
918 break;
919 }
920 }
921 }
922
923 mpol_cond_put(mpol);
924 if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
925 goto retry_cpuset;
926 return page;
927
928 err:
929 return NULL;
930 }
931
932 /*
933 * common helper functions for hstate_next_node_to_{alloc|free}.
934 * We may have allocated or freed a huge page based on a different
935 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
936 * be outside of *nodes_allowed. Ensure that we use an allowed
937 * node for alloc or free.
938 */
939 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
940 {
941 nid = next_node(nid, *nodes_allowed);
942 if (nid == MAX_NUMNODES)
943 nid = first_node(*nodes_allowed);
944 VM_BUG_ON(nid >= MAX_NUMNODES);
945
946 return nid;
947 }
948
949 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
950 {
951 if (!node_isset(nid, *nodes_allowed))
952 nid = next_node_allowed(nid, nodes_allowed);
953 return nid;
954 }
955
956 /*
957 * returns the previously saved node ["this node"] from which to
958 * allocate a persistent huge page for the pool and advance the
959 * next node from which to allocate, handling wrap at end of node
960 * mask.
961 */
962 static int hstate_next_node_to_alloc(struct hstate *h,
963 nodemask_t *nodes_allowed)
964 {
965 int nid;
966
967 VM_BUG_ON(!nodes_allowed);
968
969 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
970 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
971
972 return nid;
973 }
974
975 /*
976 * helper for free_pool_huge_page() - return the previously saved
977 * node ["this node"] from which to free a huge page. Advance the
978 * next node id whether or not we find a free huge page to free so
979 * that the next attempt to free addresses the next node.
980 */
981 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
982 {
983 int nid;
984
985 VM_BUG_ON(!nodes_allowed);
986
987 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
988 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
989
990 return nid;
991 }
992
993 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
994 for (nr_nodes = nodes_weight(*mask); \
995 nr_nodes > 0 && \
996 ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \
997 nr_nodes--)
998
999 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
1000 for (nr_nodes = nodes_weight(*mask); \
1001 nr_nodes > 0 && \
1002 ((node = hstate_next_node_to_free(hs, mask)) || 1); \
1003 nr_nodes--)
1004
1005 #if defined(CONFIG_CMA) && defined(CONFIG_X86_64)
1006 static void destroy_compound_gigantic_page(struct page *page,
1007 unsigned int order)
1008 {
1009 int i;
1010 int nr_pages = 1 << order;
1011 struct page *p = page + 1;
1012
1013 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1014 clear_compound_head(p);
1015 set_page_refcounted(p);
1016 }
1017
1018 set_compound_order(page, 0);
1019 __ClearPageHead(page);
1020 }
1021
1022 static void free_gigantic_page(struct page *page, unsigned int order)
1023 {
1024 free_contig_range(page_to_pfn(page), 1 << order);
1025 }
1026
1027 static int __alloc_gigantic_page(unsigned long start_pfn,
1028 unsigned long nr_pages)
1029 {
1030 unsigned long end_pfn = start_pfn + nr_pages;
1031 return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1032 }
1033
1034 static bool pfn_range_valid_gigantic(unsigned long start_pfn,
1035 unsigned long nr_pages)
1036 {
1037 unsigned long i, end_pfn = start_pfn + nr_pages;
1038 struct page *page;
1039
1040 for (i = start_pfn; i < end_pfn; i++) {
1041 if (!pfn_valid(i))
1042 return false;
1043
1044 page = pfn_to_page(i);
1045
1046 if (PageReserved(page))
1047 return false;
1048
1049 if (page_count(page) > 0)
1050 return false;
1051
1052 if (PageHuge(page))
1053 return false;
1054 }
1055
1056 return true;
1057 }
1058
1059 static bool zone_spans_last_pfn(const struct zone *zone,
1060 unsigned long start_pfn, unsigned long nr_pages)
1061 {
1062 unsigned long last_pfn = start_pfn + nr_pages - 1;
1063 return zone_spans_pfn(zone, last_pfn);
1064 }
1065
1066 static struct page *alloc_gigantic_page(int nid, unsigned int order)
1067 {
1068 unsigned long nr_pages = 1 << order;
1069 unsigned long ret, pfn, flags;
1070 struct zone *z;
1071
1072 z = NODE_DATA(nid)->node_zones;
1073 for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
1074 spin_lock_irqsave(&z->lock, flags);
1075
1076 pfn = ALIGN(z->zone_start_pfn, nr_pages);
1077 while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1078 if (pfn_range_valid_gigantic(pfn, nr_pages)) {
1079 /*
1080 * We release the zone lock here because
1081 * alloc_contig_range() will also lock the zone
1082 * at some point. If there's an allocation
1083 * spinning on this lock, it may win the race
1084 * and cause alloc_contig_range() to fail...
1085 */
1086 spin_unlock_irqrestore(&z->lock, flags);
1087 ret = __alloc_gigantic_page(pfn, nr_pages);
1088 if (!ret)
1089 return pfn_to_page(pfn);
1090 spin_lock_irqsave(&z->lock, flags);
1091 }
1092 pfn += nr_pages;
1093 }
1094
1095 spin_unlock_irqrestore(&z->lock, flags);
1096 }
1097
1098 return NULL;
1099 }
1100
1101 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1102 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1103
1104 static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
1105 {
1106 struct page *page;
1107
1108 page = alloc_gigantic_page(nid, huge_page_order(h));
1109 if (page) {
1110 prep_compound_gigantic_page(page, huge_page_order(h));
1111 prep_new_huge_page(h, page, nid);
1112 }
1113
1114 return page;
1115 }
1116
1117 static int alloc_fresh_gigantic_page(struct hstate *h,
1118 nodemask_t *nodes_allowed)
1119 {
1120 struct page *page = NULL;
1121 int nr_nodes, node;
1122
1123 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1124 page = alloc_fresh_gigantic_page_node(h, node);
1125 if (page)
1126 return 1;
1127 }
1128
1129 return 0;
1130 }
1131
1132 static inline bool gigantic_page_supported(void) { return true; }
1133 #else
1134 static inline bool gigantic_page_supported(void) { return false; }
1135 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1136 static inline void destroy_compound_gigantic_page(struct page *page,
1137 unsigned int order) { }
1138 static inline int alloc_fresh_gigantic_page(struct hstate *h,
1139 nodemask_t *nodes_allowed) { return 0; }
1140 #endif
1141
1142 static void update_and_free_page(struct hstate *h, struct page *page)
1143 {
1144 int i;
1145
1146 if (hstate_is_gigantic(h) && !gigantic_page_supported())
1147 return;
1148
1149 h->nr_huge_pages--;
1150 h->nr_huge_pages_node[page_to_nid(page)]--;
1151 for (i = 0; i < pages_per_huge_page(h); i++) {
1152 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1153 1 << PG_referenced | 1 << PG_dirty |
1154 1 << PG_active | 1 << PG_private |
1155 1 << PG_writeback);
1156 }
1157 VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1158 set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1159 set_page_refcounted(page);
1160 if (hstate_is_gigantic(h)) {
1161 destroy_compound_gigantic_page(page, huge_page_order(h));
1162 free_gigantic_page(page, huge_page_order(h));
1163 } else {
1164 __free_pages(page, huge_page_order(h));
1165 }
1166 }
1167
1168 struct hstate *size_to_hstate(unsigned long size)
1169 {
1170 struct hstate *h;
1171
1172 for_each_hstate(h) {
1173 if (huge_page_size(h) == size)
1174 return h;
1175 }
1176 return NULL;
1177 }
1178
1179 /*
1180 * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1181 * to hstate->hugepage_activelist.)
1182 *
1183 * This function can be called for tail pages, but never returns true for them.
1184 */
1185 bool page_huge_active(struct page *page)
1186 {
1187 VM_BUG_ON_PAGE(!PageHuge(page), page);
1188 return PageHead(page) && PagePrivate(&page[1]);
1189 }
1190
1191 /* never called for tail page */
1192 static void set_page_huge_active(struct page *page)
1193 {
1194 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1195 SetPagePrivate(&page[1]);
1196 }
1197
1198 static void clear_page_huge_active(struct page *page)
1199 {
1200 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1201 ClearPagePrivate(&page[1]);
1202 }
1203
1204 void free_huge_page(struct page *page)
1205 {
1206 /*
1207 * Can't pass hstate in here because it is called from the
1208 * compound page destructor.
1209 */
1210 struct hstate *h = page_hstate(page);
1211 int nid = page_to_nid(page);
1212 struct hugepage_subpool *spool =
1213 (struct hugepage_subpool *)page_private(page);
1214 bool restore_reserve;
1215
1216 set_page_private(page, 0);
1217 page->mapping = NULL;
1218 BUG_ON(page_count(page));
1219 BUG_ON(page_mapcount(page));
1220 restore_reserve = PagePrivate(page);
1221 ClearPagePrivate(page);
1222
1223 /*
1224 * A return code of zero implies that the subpool will be under its
1225 * minimum size if the reservation is not restored after page is free.
1226 * Therefore, force restore_reserve operation.
1227 */
1228 if (hugepage_subpool_put_pages(spool, 1) == 0)
1229 restore_reserve = true;
1230
1231 spin_lock(&hugetlb_lock);
1232 clear_page_huge_active(page);
1233 hugetlb_cgroup_uncharge_page(hstate_index(h),
1234 pages_per_huge_page(h), page);
1235 if (restore_reserve)
1236 h->resv_huge_pages++;
1237
1238 if (h->surplus_huge_pages_node[nid]) {
1239 /* remove the page from active list */
1240 list_del(&page->lru);
1241 update_and_free_page(h, page);
1242 h->surplus_huge_pages--;
1243 h->surplus_huge_pages_node[nid]--;
1244 } else {
1245 arch_clear_hugepage_flags(page);
1246 enqueue_huge_page(h, page);
1247 }
1248 spin_unlock(&hugetlb_lock);
1249 }
1250
1251 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1252 {
1253 INIT_LIST_HEAD(&page->lru);
1254 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1255 spin_lock(&hugetlb_lock);
1256 set_hugetlb_cgroup(page, NULL);
1257 h->nr_huge_pages++;
1258 h->nr_huge_pages_node[nid]++;
1259 spin_unlock(&hugetlb_lock);
1260 put_page(page); /* free it into the hugepage allocator */
1261 }
1262
1263 static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1264 {
1265 int i;
1266 int nr_pages = 1 << order;
1267 struct page *p = page + 1;
1268
1269 /* we rely on prep_new_huge_page to set the destructor */
1270 set_compound_order(page, order);
1271 __SetPageHead(page);
1272 __ClearPageReserved(page);
1273 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1274 /*
1275 * For gigantic hugepages allocated through bootmem at
1276 * boot, it's safer to be consistent with the not-gigantic
1277 * hugepages and clear the PG_reserved bit from all tail pages
1278 * too. Otherwse drivers using get_user_pages() to access tail
1279 * pages may get the reference counting wrong if they see
1280 * PG_reserved set on a tail page (despite the head page not
1281 * having PG_reserved set). Enforcing this consistency between
1282 * head and tail pages allows drivers to optimize away a check
1283 * on the head page when they need know if put_page() is needed
1284 * after get_user_pages().
1285 */
1286 __ClearPageReserved(p);
1287 set_page_count(p, 0);
1288 set_compound_head(p, page);
1289 }
1290 }
1291
1292 /*
1293 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1294 * transparent huge pages. See the PageTransHuge() documentation for more
1295 * details.
1296 */
1297 int PageHuge(struct page *page)
1298 {
1299 if (!PageCompound(page))
1300 return 0;
1301
1302 page = compound_head(page);
1303 return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1304 }
1305 EXPORT_SYMBOL_GPL(PageHuge);
1306
1307 /*
1308 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1309 * normal or transparent huge pages.
1310 */
1311 int PageHeadHuge(struct page *page_head)
1312 {
1313 if (!PageHead(page_head))
1314 return 0;
1315
1316 return get_compound_page_dtor(page_head) == free_huge_page;
1317 }
1318
1319 pgoff_t __basepage_index(struct page *page)
1320 {
1321 struct page *page_head = compound_head(page);
1322 pgoff_t index = page_index(page_head);
1323 unsigned long compound_idx;
1324
1325 if (!PageHuge(page_head))
1326 return page_index(page);
1327
1328 if (compound_order(page_head) >= MAX_ORDER)
1329 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1330 else
1331 compound_idx = page - page_head;
1332
1333 return (index << compound_order(page_head)) + compound_idx;
1334 }
1335
1336 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
1337 {
1338 struct page *page;
1339
1340 page = __alloc_pages_node(nid,
1341 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1342 __GFP_REPEAT|__GFP_NOWARN,
1343 huge_page_order(h));
1344 if (page) {
1345 prep_new_huge_page(h, page, nid);
1346 }
1347
1348 return page;
1349 }
1350
1351 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1352 {
1353 struct page *page;
1354 int nr_nodes, node;
1355 int ret = 0;
1356
1357 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1358 page = alloc_fresh_huge_page_node(h, node);
1359 if (page) {
1360 ret = 1;
1361 break;
1362 }
1363 }
1364
1365 if (ret)
1366 count_vm_event(HTLB_BUDDY_PGALLOC);
1367 else
1368 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1369
1370 return ret;
1371 }
1372
1373 /*
1374 * Free huge page from pool from next node to free.
1375 * Attempt to keep persistent huge pages more or less
1376 * balanced over allowed nodes.
1377 * Called with hugetlb_lock locked.
1378 */
1379 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1380 bool acct_surplus)
1381 {
1382 int nr_nodes, node;
1383 int ret = 0;
1384
1385 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1386 /*
1387 * If we're returning unused surplus pages, only examine
1388 * nodes with surplus pages.
1389 */
1390 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1391 !list_empty(&h->hugepage_freelists[node])) {
1392 struct page *page =
1393 list_entry(h->hugepage_freelists[node].next,
1394 struct page, lru);
1395 list_del(&page->lru);
1396 h->free_huge_pages--;
1397 h->free_huge_pages_node[node]--;
1398 if (acct_surplus) {
1399 h->surplus_huge_pages--;
1400 h->surplus_huge_pages_node[node]--;
1401 }
1402 update_and_free_page(h, page);
1403 ret = 1;
1404 break;
1405 }
1406 }
1407
1408 return ret;
1409 }
1410
1411 /*
1412 * Dissolve a given free hugepage into free buddy pages. This function does
1413 * nothing for in-use (including surplus) hugepages.
1414 */
1415 static void dissolve_free_huge_page(struct page *page)
1416 {
1417 spin_lock(&hugetlb_lock);
1418 if (PageHuge(page) && !page_count(page)) {
1419 struct hstate *h = page_hstate(page);
1420 int nid = page_to_nid(page);
1421 list_del(&page->lru);
1422 h->free_huge_pages--;
1423 h->free_huge_pages_node[nid]--;
1424 update_and_free_page(h, page);
1425 }
1426 spin_unlock(&hugetlb_lock);
1427 }
1428
1429 /*
1430 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1431 * make specified memory blocks removable from the system.
1432 * Note that start_pfn should aligned with (minimum) hugepage size.
1433 */
1434 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1435 {
1436 unsigned long pfn;
1437
1438 if (!hugepages_supported())
1439 return;
1440
1441 VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << minimum_order));
1442 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
1443 dissolve_free_huge_page(pfn_to_page(pfn));
1444 }
1445
1446 /*
1447 * There are 3 ways this can get called:
1448 * 1. With vma+addr: we use the VMA's memory policy
1449 * 2. With !vma, but nid=NUMA_NO_NODE: We try to allocate a huge
1450 * page from any node, and let the buddy allocator itself figure
1451 * it out.
1452 * 3. With !vma, but nid!=NUMA_NO_NODE. We allocate a huge page
1453 * strictly from 'nid'
1454 */
1455 static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
1456 struct vm_area_struct *vma, unsigned long addr, int nid)
1457 {
1458 int order = huge_page_order(h);
1459 gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
1460 unsigned int cpuset_mems_cookie;
1461
1462 /*
1463 * We need a VMA to get a memory policy. If we do not
1464 * have one, we use the 'nid' argument.
1465 *
1466 * The mempolicy stuff below has some non-inlined bits
1467 * and calls ->vm_ops. That makes it hard to optimize at
1468 * compile-time, even when NUMA is off and it does
1469 * nothing. This helps the compiler optimize it out.
1470 */
1471 if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1472 /*
1473 * If a specific node is requested, make sure to
1474 * get memory from there, but only when a node
1475 * is explicitly specified.
1476 */
1477 if (nid != NUMA_NO_NODE)
1478 gfp |= __GFP_THISNODE;
1479 /*
1480 * Make sure to call something that can handle
1481 * nid=NUMA_NO_NODE
1482 */
1483 return alloc_pages_node(nid, gfp, order);
1484 }
1485
1486 /*
1487 * OK, so we have a VMA. Fetch the mempolicy and try to
1488 * allocate a huge page with it. We will only reach this
1489 * when CONFIG_NUMA=y.
1490 */
1491 do {
1492 struct page *page;
1493 struct mempolicy *mpol;
1494 struct zonelist *zl;
1495 nodemask_t *nodemask;
1496
1497 cpuset_mems_cookie = read_mems_allowed_begin();
1498 zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
1499 mpol_cond_put(mpol);
1500 page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
1501 if (page)
1502 return page;
1503 } while (read_mems_allowed_retry(cpuset_mems_cookie));
1504
1505 return NULL;
1506 }
1507
1508 /*
1509 * There are two ways to allocate a huge page:
1510 * 1. When you have a VMA and an address (like a fault)
1511 * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
1512 *
1513 * 'vma' and 'addr' are only for (1). 'nid' is always NUMA_NO_NODE in
1514 * this case which signifies that the allocation should be done with
1515 * respect for the VMA's memory policy.
1516 *
1517 * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
1518 * implies that memory policies will not be taken in to account.
1519 */
1520 static struct page *__alloc_buddy_huge_page(struct hstate *h,
1521 struct vm_area_struct *vma, unsigned long addr, int nid)
1522 {
1523 struct page *page;
1524 unsigned int r_nid;
1525
1526 if (hstate_is_gigantic(h))
1527 return NULL;
1528
1529 /*
1530 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
1531 * This makes sure the caller is picking _one_ of the modes with which
1532 * we can call this function, not both.
1533 */
1534 if (vma || (addr != -1)) {
1535 VM_WARN_ON_ONCE(addr == -1);
1536 VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1537 }
1538 /*
1539 * Assume we will successfully allocate the surplus page to
1540 * prevent racing processes from causing the surplus to exceed
1541 * overcommit
1542 *
1543 * This however introduces a different race, where a process B
1544 * tries to grow the static hugepage pool while alloc_pages() is
1545 * called by process A. B will only examine the per-node
1546 * counters in determining if surplus huge pages can be
1547 * converted to normal huge pages in adjust_pool_surplus(). A
1548 * won't be able to increment the per-node counter, until the
1549 * lock is dropped by B, but B doesn't drop hugetlb_lock until
1550 * no more huge pages can be converted from surplus to normal
1551 * state (and doesn't try to convert again). Thus, we have a
1552 * case where a surplus huge page exists, the pool is grown, and
1553 * the surplus huge page still exists after, even though it
1554 * should just have been converted to a normal huge page. This
1555 * does not leak memory, though, as the hugepage will be freed
1556 * once it is out of use. It also does not allow the counters to
1557 * go out of whack in adjust_pool_surplus() as we don't modify
1558 * the node values until we've gotten the hugepage and only the
1559 * per-node value is checked there.
1560 */
1561 spin_lock(&hugetlb_lock);
1562 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1563 spin_unlock(&hugetlb_lock);
1564 return NULL;
1565 } else {
1566 h->nr_huge_pages++;
1567 h->surplus_huge_pages++;
1568 }
1569 spin_unlock(&hugetlb_lock);
1570
1571 page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1572
1573 spin_lock(&hugetlb_lock);
1574 if (page) {
1575 INIT_LIST_HEAD(&page->lru);
1576 r_nid = page_to_nid(page);
1577 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1578 set_hugetlb_cgroup(page, NULL);
1579 /*
1580 * We incremented the global counters already
1581 */
1582 h->nr_huge_pages_node[r_nid]++;
1583 h->surplus_huge_pages_node[r_nid]++;
1584 __count_vm_event(HTLB_BUDDY_PGALLOC);
1585 } else {
1586 h->nr_huge_pages--;
1587 h->surplus_huge_pages--;
1588 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1589 }
1590 spin_unlock(&hugetlb_lock);
1591
1592 return page;
1593 }
1594
1595 /*
1596 * Allocate a huge page from 'nid'. Note, 'nid' may be
1597 * NUMA_NO_NODE, which means that it may be allocated
1598 * anywhere.
1599 */
1600 static
1601 struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
1602 {
1603 unsigned long addr = -1;
1604
1605 return __alloc_buddy_huge_page(h, NULL, addr, nid);
1606 }
1607
1608 /*
1609 * Use the VMA's mpolicy to allocate a huge page from the buddy.
1610 */
1611 static
1612 struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
1613 struct vm_area_struct *vma, unsigned long addr)
1614 {
1615 return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
1616 }
1617
1618 /*
1619 * This allocation function is useful in the context where vma is irrelevant.
1620 * E.g. soft-offlining uses this function because it only cares physical
1621 * address of error page.
1622 */
1623 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1624 {
1625 struct page *page = NULL;
1626
1627 spin_lock(&hugetlb_lock);
1628 if (h->free_huge_pages - h->resv_huge_pages > 0)
1629 page = dequeue_huge_page_node(h, nid);
1630 spin_unlock(&hugetlb_lock);
1631
1632 if (!page)
1633 page = __alloc_buddy_huge_page_no_mpol(h, nid);
1634
1635 return page;
1636 }
1637
1638 /*
1639 * Increase the hugetlb pool such that it can accommodate a reservation
1640 * of size 'delta'.
1641 */
1642 static int gather_surplus_pages(struct hstate *h, int delta)
1643 {
1644 struct list_head surplus_list;
1645 struct page *page, *tmp;
1646 int ret, i;
1647 int needed, allocated;
1648 bool alloc_ok = true;
1649
1650 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1651 if (needed <= 0) {
1652 h->resv_huge_pages += delta;
1653 return 0;
1654 }
1655
1656 allocated = 0;
1657 INIT_LIST_HEAD(&surplus_list);
1658
1659 ret = -ENOMEM;
1660 retry:
1661 spin_unlock(&hugetlb_lock);
1662 for (i = 0; i < needed; i++) {
1663 page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1664 if (!page) {
1665 alloc_ok = false;
1666 break;
1667 }
1668 list_add(&page->lru, &surplus_list);
1669 }
1670 allocated += i;
1671
1672 /*
1673 * After retaking hugetlb_lock, we need to recalculate 'needed'
1674 * because either resv_huge_pages or free_huge_pages may have changed.
1675 */
1676 spin_lock(&hugetlb_lock);
1677 needed = (h->resv_huge_pages + delta) -
1678 (h->free_huge_pages + allocated);
1679 if (needed > 0) {
1680 if (alloc_ok)
1681 goto retry;
1682 /*
1683 * We were not able to allocate enough pages to
1684 * satisfy the entire reservation so we free what
1685 * we've allocated so far.
1686 */
1687 goto free;
1688 }
1689 /*
1690 * The surplus_list now contains _at_least_ the number of extra pages
1691 * needed to accommodate the reservation. Add the appropriate number
1692 * of pages to the hugetlb pool and free the extras back to the buddy
1693 * allocator. Commit the entire reservation here to prevent another
1694 * process from stealing the pages as they are added to the pool but
1695 * before they are reserved.
1696 */
1697 needed += allocated;
1698 h->resv_huge_pages += delta;
1699 ret = 0;
1700
1701 /* Free the needed pages to the hugetlb pool */
1702 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1703 if ((--needed) < 0)
1704 break;
1705 /*
1706 * This page is now managed by the hugetlb allocator and has
1707 * no users -- drop the buddy allocator's reference.
1708 */
1709 put_page_testzero(page);
1710 VM_BUG_ON_PAGE(page_count(page), page);
1711 enqueue_huge_page(h, page);
1712 }
1713 free:
1714 spin_unlock(&hugetlb_lock);
1715
1716 /* Free unnecessary surplus pages to the buddy allocator */
1717 list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1718 put_page(page);
1719 spin_lock(&hugetlb_lock);
1720
1721 return ret;
1722 }
1723
1724 /*
1725 * When releasing a hugetlb pool reservation, any surplus pages that were
1726 * allocated to satisfy the reservation must be explicitly freed if they were
1727 * never used.
1728 * Called with hugetlb_lock held.
1729 */
1730 static void return_unused_surplus_pages(struct hstate *h,
1731 unsigned long unused_resv_pages)
1732 {
1733 unsigned long nr_pages;
1734
1735 /* Uncommit the reservation */
1736 h->resv_huge_pages -= unused_resv_pages;
1737
1738 /* Cannot return gigantic pages currently */
1739 if (hstate_is_gigantic(h))
1740 return;
1741
1742 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1743
1744 /*
1745 * We want to release as many surplus pages as possible, spread
1746 * evenly across all nodes with memory. Iterate across these nodes
1747 * until we can no longer free unreserved surplus pages. This occurs
1748 * when the nodes with surplus pages have no free pages.
1749 * free_pool_huge_page() will balance the the freed pages across the
1750 * on-line nodes with memory and will handle the hstate accounting.
1751 */
1752 while (nr_pages--) {
1753 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1754 break;
1755 cond_resched_lock(&hugetlb_lock);
1756 }
1757 }
1758
1759
1760 /*
1761 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1762 * are used by the huge page allocation routines to manage reservations.
1763 *
1764 * vma_needs_reservation is called to determine if the huge page at addr
1765 * within the vma has an associated reservation. If a reservation is
1766 * needed, the value 1 is returned. The caller is then responsible for
1767 * managing the global reservation and subpool usage counts. After
1768 * the huge page has been allocated, vma_commit_reservation is called
1769 * to add the page to the reservation map. If the page allocation fails,
1770 * the reservation must be ended instead of committed. vma_end_reservation
1771 * is called in such cases.
1772 *
1773 * In the normal case, vma_commit_reservation returns the same value
1774 * as the preceding vma_needs_reservation call. The only time this
1775 * is not the case is if a reserve map was changed between calls. It
1776 * is the responsibility of the caller to notice the difference and
1777 * take appropriate action.
1778 */
1779 enum vma_resv_mode {
1780 VMA_NEEDS_RESV,
1781 VMA_COMMIT_RESV,
1782 VMA_END_RESV,
1783 };
1784 static long __vma_reservation_common(struct hstate *h,
1785 struct vm_area_struct *vma, unsigned long addr,
1786 enum vma_resv_mode mode)
1787 {
1788 struct resv_map *resv;
1789 pgoff_t idx;
1790 long ret;
1791
1792 resv = vma_resv_map(vma);
1793 if (!resv)
1794 return 1;
1795
1796 idx = vma_hugecache_offset(h, vma, addr);
1797 switch (mode) {
1798 case VMA_NEEDS_RESV:
1799 ret = region_chg(resv, idx, idx + 1);
1800 break;
1801 case VMA_COMMIT_RESV:
1802 ret = region_add(resv, idx, idx + 1);
1803 break;
1804 case VMA_END_RESV:
1805 region_abort(resv, idx, idx + 1);
1806 ret = 0;
1807 break;
1808 default:
1809 BUG();
1810 }
1811
1812 if (vma->vm_flags & VM_MAYSHARE)
1813 return ret;
1814 else
1815 return ret < 0 ? ret : 0;
1816 }
1817
1818 static long vma_needs_reservation(struct hstate *h,
1819 struct vm_area_struct *vma, unsigned long addr)
1820 {
1821 return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1822 }
1823
1824 static long vma_commit_reservation(struct hstate *h,
1825 struct vm_area_struct *vma, unsigned long addr)
1826 {
1827 return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1828 }
1829
1830 static void vma_end_reservation(struct hstate *h,
1831 struct vm_area_struct *vma, unsigned long addr)
1832 {
1833 (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1834 }
1835
1836 struct page *alloc_huge_page(struct vm_area_struct *vma,
1837 unsigned long addr, int avoid_reserve)
1838 {
1839 struct hugepage_subpool *spool = subpool_vma(vma);
1840 struct hstate *h = hstate_vma(vma);
1841 struct page *page;
1842 long map_chg, map_commit;
1843 long gbl_chg;
1844 int ret, idx;
1845 struct hugetlb_cgroup *h_cg;
1846
1847 idx = hstate_index(h);
1848 /*
1849 * Examine the region/reserve map to determine if the process
1850 * has a reservation for the page to be allocated. A return
1851 * code of zero indicates a reservation exists (no change).
1852 */
1853 map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
1854 if (map_chg < 0)
1855 return ERR_PTR(-ENOMEM);
1856
1857 /*
1858 * Processes that did not create the mapping will have no
1859 * reserves as indicated by the region/reserve map. Check
1860 * that the allocation will not exceed the subpool limit.
1861 * Allocations for MAP_NORESERVE mappings also need to be
1862 * checked against any subpool limit.
1863 */
1864 if (map_chg || avoid_reserve) {
1865 gbl_chg = hugepage_subpool_get_pages(spool, 1);
1866 if (gbl_chg < 0) {
1867 vma_end_reservation(h, vma, addr);
1868 return ERR_PTR(-ENOSPC);
1869 }
1870
1871 /*
1872 * Even though there was no reservation in the region/reserve
1873 * map, there could be reservations associated with the
1874 * subpool that can be used. This would be indicated if the
1875 * return value of hugepage_subpool_get_pages() is zero.
1876 * However, if avoid_reserve is specified we still avoid even
1877 * the subpool reservations.
1878 */
1879 if (avoid_reserve)
1880 gbl_chg = 1;
1881 }
1882
1883 ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1884 if (ret)
1885 goto out_subpool_put;
1886
1887 spin_lock(&hugetlb_lock);
1888 /*
1889 * glb_chg is passed to indicate whether or not a page must be taken
1890 * from the global free pool (global change). gbl_chg == 0 indicates
1891 * a reservation exists for the allocation.
1892 */
1893 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
1894 if (!page) {
1895 spin_unlock(&hugetlb_lock);
1896 page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
1897 if (!page)
1898 goto out_uncharge_cgroup;
1899 if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
1900 SetPagePrivate(page);
1901 h->resv_huge_pages--;
1902 }
1903 spin_lock(&hugetlb_lock);
1904 list_move(&page->lru, &h->hugepage_activelist);
1905 /* Fall through */
1906 }
1907 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
1908 spin_unlock(&hugetlb_lock);
1909
1910 set_page_private(page, (unsigned long)spool);
1911
1912 map_commit = vma_commit_reservation(h, vma, addr);
1913 if (unlikely(map_chg > map_commit)) {
1914 /*
1915 * The page was added to the reservation map between
1916 * vma_needs_reservation and vma_commit_reservation.
1917 * This indicates a race with hugetlb_reserve_pages.
1918 * Adjust for the subpool count incremented above AND
1919 * in hugetlb_reserve_pages for the same page. Also,
1920 * the reservation count added in hugetlb_reserve_pages
1921 * no longer applies.
1922 */
1923 long rsv_adjust;
1924
1925 rsv_adjust = hugepage_subpool_put_pages(spool, 1);
1926 hugetlb_acct_memory(h, -rsv_adjust);
1927 }
1928 return page;
1929
1930 out_uncharge_cgroup:
1931 hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
1932 out_subpool_put:
1933 if (map_chg || avoid_reserve)
1934 hugepage_subpool_put_pages(spool, 1);
1935 vma_end_reservation(h, vma, addr);
1936 return ERR_PTR(-ENOSPC);
1937 }
1938
1939 /*
1940 * alloc_huge_page()'s wrapper which simply returns the page if allocation
1941 * succeeds, otherwise NULL. This function is called from new_vma_page(),
1942 * where no ERR_VALUE is expected to be returned.
1943 */
1944 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
1945 unsigned long addr, int avoid_reserve)
1946 {
1947 struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
1948 if (IS_ERR(page))
1949 page = NULL;
1950 return page;
1951 }
1952
1953 int __weak alloc_bootmem_huge_page(struct hstate *h)
1954 {
1955 struct huge_bootmem_page *m;
1956 int nr_nodes, node;
1957
1958 for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
1959 void *addr;
1960
1961 addr = memblock_virt_alloc_try_nid_nopanic(
1962 huge_page_size(h), huge_page_size(h),
1963 0, BOOTMEM_ALLOC_ACCESSIBLE, node);
1964 if (addr) {
1965 /*
1966 * Use the beginning of the huge page to store the
1967 * huge_bootmem_page struct (until gather_bootmem
1968 * puts them into the mem_map).
1969 */
1970 m = addr;
1971 goto found;
1972 }
1973 }
1974 return 0;
1975
1976 found:
1977 BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
1978 /* Put them into a private list first because mem_map is not up yet */
1979 list_add(&m->list, &huge_boot_pages);
1980 m->hstate = h;
1981 return 1;
1982 }
1983
1984 static void __init prep_compound_huge_page(struct page *page,
1985 unsigned int order)
1986 {
1987 if (unlikely(order > (MAX_ORDER - 1)))
1988 prep_compound_gigantic_page(page, order);
1989 else
1990 prep_compound_page(page, order);
1991 }
1992
1993 /* Put bootmem huge pages into the standard lists after mem_map is up */
1994 static void __init gather_bootmem_prealloc(void)
1995 {
1996 struct huge_bootmem_page *m;
1997
1998 list_for_each_entry(m, &huge_boot_pages, list) {
1999 struct hstate *h = m->hstate;
2000 struct page *page;
2001
2002 #ifdef CONFIG_HIGHMEM
2003 page = pfn_to_page(m->phys >> PAGE_SHIFT);
2004 memblock_free_late(__pa(m),
2005 sizeof(struct huge_bootmem_page));
2006 #else
2007 page = virt_to_page(m);
2008 #endif
2009 WARN_ON(page_count(page) != 1);
2010 prep_compound_huge_page(page, h->order);
2011 WARN_ON(PageReserved(page));
2012 prep_new_huge_page(h, page, page_to_nid(page));
2013 /*
2014 * If we had gigantic hugepages allocated at boot time, we need
2015 * to restore the 'stolen' pages to totalram_pages in order to
2016 * fix confusing memory reports from free(1) and another
2017 * side-effects, like CommitLimit going negative.
2018 */
2019 if (hstate_is_gigantic(h))
2020 adjust_managed_page_count(page, 1 << h->order);
2021 }
2022 }
2023
2024 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2025 {
2026 unsigned long i;
2027
2028 for (i = 0; i < h->max_huge_pages; ++i) {
2029 if (hstate_is_gigantic(h)) {
2030 if (!alloc_bootmem_huge_page(h))
2031 break;
2032 } else if (!alloc_fresh_huge_page(h,
2033 &node_states[N_MEMORY]))
2034 break;
2035 }
2036 h->max_huge_pages = i;
2037 }
2038
2039 static void __init hugetlb_init_hstates(void)
2040 {
2041 struct hstate *h;
2042
2043 for_each_hstate(h) {
2044 if (minimum_order > huge_page_order(h))
2045 minimum_order = huge_page_order(h);
2046
2047 /* oversize hugepages were init'ed in early boot */
2048 if (!hstate_is_gigantic(h))
2049 hugetlb_hstate_alloc_pages(h);
2050 }
2051 VM_BUG_ON(minimum_order == UINT_MAX);
2052 }
2053
2054 static char * __init memfmt(char *buf, unsigned long n)
2055 {
2056 if (n >= (1UL << 30))
2057 sprintf(buf, "%lu GB", n >> 30);
2058 else if (n >= (1UL << 20))
2059 sprintf(buf, "%lu MB", n >> 20);
2060 else
2061 sprintf(buf, "%lu KB", n >> 10);
2062 return buf;
2063 }
2064
2065 static void __init report_hugepages(void)
2066 {
2067 struct hstate *h;
2068
2069 for_each_hstate(h) {
2070 char buf[32];
2071 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2072 memfmt(buf, huge_page_size(h)),
2073 h->free_huge_pages);
2074 }
2075 }
2076
2077 #ifdef CONFIG_HIGHMEM
2078 static void try_to_free_low(struct hstate *h, unsigned long count,
2079 nodemask_t *nodes_allowed)
2080 {
2081 int i;
2082
2083 if (hstate_is_gigantic(h))
2084 return;
2085
2086 for_each_node_mask(i, *nodes_allowed) {
2087 struct page *page, *next;
2088 struct list_head *freel = &h->hugepage_freelists[i];
2089 list_for_each_entry_safe(page, next, freel, lru) {
2090 if (count >= h->nr_huge_pages)
2091 return;
2092 if (PageHighMem(page))
2093 continue;
2094 list_del(&page->lru);
2095 update_and_free_page(h, page);
2096 h->free_huge_pages--;
2097 h->free_huge_pages_node[page_to_nid(page)]--;
2098 }
2099 }
2100 }
2101 #else
2102 static inline void try_to_free_low(struct hstate *h, unsigned long count,
2103 nodemask_t *nodes_allowed)
2104 {
2105 }
2106 #endif
2107
2108 /*
2109 * Increment or decrement surplus_huge_pages. Keep node-specific counters
2110 * balanced by operating on them in a round-robin fashion.
2111 * Returns 1 if an adjustment was made.
2112 */
2113 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2114 int delta)
2115 {
2116 int nr_nodes, node;
2117
2118 VM_BUG_ON(delta != -1 && delta != 1);
2119
2120 if (delta < 0) {
2121 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2122 if (h->surplus_huge_pages_node[node])
2123 goto found;
2124 }
2125 } else {
2126 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2127 if (h->surplus_huge_pages_node[node] <
2128 h->nr_huge_pages_node[node])
2129 goto found;
2130 }
2131 }
2132 return 0;
2133
2134 found:
2135 h->surplus_huge_pages += delta;
2136 h->surplus_huge_pages_node[node] += delta;
2137 return 1;
2138 }
2139
2140 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2141 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2142 nodemask_t *nodes_allowed)
2143 {
2144 unsigned long min_count, ret;
2145
2146 if (hstate_is_gigantic(h) && !gigantic_page_supported())
2147 return h->max_huge_pages;
2148
2149 /*
2150 * Increase the pool size
2151 * First take pages out of surplus state. Then make up the
2152 * remaining difference by allocating fresh huge pages.
2153 *
2154 * We might race with __alloc_buddy_huge_page() here and be unable
2155 * to convert a surplus huge page to a normal huge page. That is
2156 * not critical, though, it just means the overall size of the
2157 * pool might be one hugepage larger than it needs to be, but
2158 * within all the constraints specified by the sysctls.
2159 */
2160 spin_lock(&hugetlb_lock);
2161 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2162 if (!adjust_pool_surplus(h, nodes_allowed, -1))
2163 break;
2164 }
2165
2166 while (count > persistent_huge_pages(h)) {
2167 /*
2168 * If this allocation races such that we no longer need the
2169 * page, free_huge_page will handle it by freeing the page
2170 * and reducing the surplus.
2171 */
2172 spin_unlock(&hugetlb_lock);
2173 if (hstate_is_gigantic(h))
2174 ret = alloc_fresh_gigantic_page(h, nodes_allowed);
2175 else
2176 ret = alloc_fresh_huge_page(h, nodes_allowed);
2177 spin_lock(&hugetlb_lock);
2178 if (!ret)
2179 goto out;
2180
2181 /* Bail for signals. Probably ctrl-c from user */
2182 if (signal_pending(current))
2183 goto out;
2184 }
2185
2186 /*
2187 * Decrease the pool size
2188 * First return free pages to the buddy allocator (being careful
2189 * to keep enough around to satisfy reservations). Then place
2190 * pages into surplus state as needed so the pool will shrink
2191 * to the desired size as pages become free.
2192 *
2193 * By placing pages into the surplus state independent of the
2194 * overcommit value, we are allowing the surplus pool size to
2195 * exceed overcommit. There are few sane options here. Since
2196 * __alloc_buddy_huge_page() is checking the global counter,
2197 * though, we'll note that we're not allowed to exceed surplus
2198 * and won't grow the pool anywhere else. Not until one of the
2199 * sysctls are changed, or the surplus pages go out of use.
2200 */
2201 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2202 min_count = max(count, min_count);
2203 try_to_free_low(h, min_count, nodes_allowed);
2204 while (min_count < persistent_huge_pages(h)) {
2205 if (!free_pool_huge_page(h, nodes_allowed, 0))
2206 break;
2207 cond_resched_lock(&hugetlb_lock);
2208 }
2209 while (count < persistent_huge_pages(h)) {
2210 if (!adjust_pool_surplus(h, nodes_allowed, 1))
2211 break;
2212 }
2213 out:
2214 ret = persistent_huge_pages(h);
2215 spin_unlock(&hugetlb_lock);
2216 return ret;
2217 }
2218
2219 #define HSTATE_ATTR_RO(_name) \
2220 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2221
2222 #define HSTATE_ATTR(_name) \
2223 static struct kobj_attribute _name##_attr = \
2224 __ATTR(_name, 0644, _name##_show, _name##_store)
2225
2226 static struct kobject *hugepages_kobj;
2227 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2228
2229 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2230
2231 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2232 {
2233 int i;
2234
2235 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2236 if (hstate_kobjs[i] == kobj) {
2237 if (nidp)
2238 *nidp = NUMA_NO_NODE;
2239 return &hstates[i];
2240 }
2241
2242 return kobj_to_node_hstate(kobj, nidp);
2243 }
2244
2245 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2246 struct kobj_attribute *attr, char *buf)
2247 {
2248 struct hstate *h;
2249 unsigned long nr_huge_pages;
2250 int nid;
2251
2252 h = kobj_to_hstate(kobj, &nid);
2253 if (nid == NUMA_NO_NODE)
2254 nr_huge_pages = h->nr_huge_pages;
2255 else
2256 nr_huge_pages = h->nr_huge_pages_node[nid];
2257
2258 return sprintf(buf, "%lu\n", nr_huge_pages);
2259 }
2260
2261 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2262 struct hstate *h, int nid,
2263 unsigned long count, size_t len)
2264 {
2265 int err;
2266 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2267
2268 if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2269 err = -EINVAL;
2270 goto out;
2271 }
2272
2273 if (nid == NUMA_NO_NODE) {
2274 /*
2275 * global hstate attribute
2276 */
2277 if (!(obey_mempolicy &&
2278 init_nodemask_of_mempolicy(nodes_allowed))) {
2279 NODEMASK_FREE(nodes_allowed);
2280 nodes_allowed = &node_states[N_MEMORY];
2281 }
2282 } else if (nodes_allowed) {
2283 /*
2284 * per node hstate attribute: adjust count to global,
2285 * but restrict alloc/free to the specified node.
2286 */
2287 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2288 init_nodemask_of_node(nodes_allowed, nid);
2289 } else
2290 nodes_allowed = &node_states[N_MEMORY];
2291
2292 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2293
2294 if (nodes_allowed != &node_states[N_MEMORY])
2295 NODEMASK_FREE(nodes_allowed);
2296
2297 return len;
2298 out:
2299 NODEMASK_FREE(nodes_allowed);
2300 return err;
2301 }
2302
2303 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2304 struct kobject *kobj, const char *buf,
2305 size_t len)
2306 {
2307 struct hstate *h;
2308 unsigned long count;
2309 int nid;
2310 int err;
2311
2312 err = kstrtoul(buf, 10, &count);
2313 if (err)
2314 return err;
2315
2316 h = kobj_to_hstate(kobj, &nid);
2317 return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2318 }
2319
2320 static ssize_t nr_hugepages_show(struct kobject *kobj,
2321 struct kobj_attribute *attr, char *buf)
2322 {
2323 return nr_hugepages_show_common(kobj, attr, buf);
2324 }
2325
2326 static ssize_t nr_hugepages_store(struct kobject *kobj,
2327 struct kobj_attribute *attr, const char *buf, size_t len)
2328 {
2329 return nr_hugepages_store_common(false, kobj, buf, len);
2330 }
2331 HSTATE_ATTR(nr_hugepages);
2332
2333 #ifdef CONFIG_NUMA
2334
2335 /*
2336 * hstate attribute for optionally mempolicy-based constraint on persistent
2337 * huge page alloc/free.
2338 */
2339 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2340 struct kobj_attribute *attr, char *buf)
2341 {
2342 return nr_hugepages_show_common(kobj, attr, buf);
2343 }
2344
2345 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2346 struct kobj_attribute *attr, const char *buf, size_t len)
2347 {
2348 return nr_hugepages_store_common(true, kobj, buf, len);
2349 }
2350 HSTATE_ATTR(nr_hugepages_mempolicy);
2351 #endif
2352
2353
2354 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2355 struct kobj_attribute *attr, char *buf)
2356 {
2357 struct hstate *h = kobj_to_hstate(kobj, NULL);
2358 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2359 }
2360
2361 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2362 struct kobj_attribute *attr, const char *buf, size_t count)
2363 {
2364 int err;
2365 unsigned long input;
2366 struct hstate *h = kobj_to_hstate(kobj, NULL);
2367
2368 if (hstate_is_gigantic(h))
2369 return -EINVAL;
2370
2371 err = kstrtoul(buf, 10, &input);
2372 if (err)
2373 return err;
2374
2375 spin_lock(&hugetlb_lock);
2376 h->nr_overcommit_huge_pages = input;
2377 spin_unlock(&hugetlb_lock);
2378
2379 return count;
2380 }
2381 HSTATE_ATTR(nr_overcommit_hugepages);
2382
2383 static ssize_t free_hugepages_show(struct kobject *kobj,
2384 struct kobj_attribute *attr, char *buf)
2385 {
2386 struct hstate *h;
2387 unsigned long free_huge_pages;
2388 int nid;
2389
2390 h = kobj_to_hstate(kobj, &nid);
2391 if (nid == NUMA_NO_NODE)
2392 free_huge_pages = h->free_huge_pages;
2393 else
2394 free_huge_pages = h->free_huge_pages_node[nid];
2395
2396 return sprintf(buf, "%lu\n", free_huge_pages);
2397 }
2398 HSTATE_ATTR_RO(free_hugepages);
2399
2400 static ssize_t resv_hugepages_show(struct kobject *kobj,
2401 struct kobj_attribute *attr, char *buf)
2402 {
2403 struct hstate *h = kobj_to_hstate(kobj, NULL);
2404 return sprintf(buf, "%lu\n", h->resv_huge_pages);
2405 }
2406 HSTATE_ATTR_RO(resv_hugepages);
2407
2408 static ssize_t surplus_hugepages_show(struct kobject *kobj,
2409 struct kobj_attribute *attr, char *buf)
2410 {
2411 struct hstate *h;
2412 unsigned long surplus_huge_pages;
2413 int nid;
2414
2415 h = kobj_to_hstate(kobj, &nid);
2416 if (nid == NUMA_NO_NODE)
2417 surplus_huge_pages = h->surplus_huge_pages;
2418 else
2419 surplus_huge_pages = h->surplus_huge_pages_node[nid];
2420
2421 return sprintf(buf, "%lu\n", surplus_huge_pages);
2422 }
2423 HSTATE_ATTR_RO(surplus_hugepages);
2424
2425 static struct attribute *hstate_attrs[] = {
2426 &nr_hugepages_attr.attr,
2427 &nr_overcommit_hugepages_attr.attr,
2428 &free_hugepages_attr.attr,
2429 &resv_hugepages_attr.attr,
2430 &surplus_hugepages_attr.attr,
2431 #ifdef CONFIG_NUMA
2432 &nr_hugepages_mempolicy_attr.attr,
2433 #endif
2434 NULL,
2435 };
2436
2437 static struct attribute_group hstate_attr_group = {
2438 .attrs = hstate_attrs,
2439 };
2440
2441 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2442 struct kobject **hstate_kobjs,
2443 struct attribute_group *hstate_attr_group)
2444 {
2445 int retval;
2446 int hi = hstate_index(h);
2447
2448 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2449 if (!hstate_kobjs[hi])
2450 return -ENOMEM;
2451
2452 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2453 if (retval)
2454 kobject_put(hstate_kobjs[hi]);
2455
2456 return retval;
2457 }
2458
2459 static void __init hugetlb_sysfs_init(void)
2460 {
2461 struct hstate *h;
2462 int err;
2463
2464 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2465 if (!hugepages_kobj)
2466 return;
2467
2468 for_each_hstate(h) {
2469 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2470 hstate_kobjs, &hstate_attr_group);
2471 if (err)
2472 pr_err("Hugetlb: Unable to add hstate %s", h->name);
2473 }
2474 }
2475
2476 #ifdef CONFIG_NUMA
2477
2478 /*
2479 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2480 * with node devices in node_devices[] using a parallel array. The array
2481 * index of a node device or _hstate == node id.
2482 * This is here to avoid any static dependency of the node device driver, in
2483 * the base kernel, on the hugetlb module.
2484 */
2485 struct node_hstate {
2486 struct kobject *hugepages_kobj;
2487 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2488 };
2489 static struct node_hstate node_hstates[MAX_NUMNODES];
2490
2491 /*
2492 * A subset of global hstate attributes for node devices
2493 */
2494 static struct attribute *per_node_hstate_attrs[] = {
2495 &nr_hugepages_attr.attr,
2496 &free_hugepages_attr.attr,
2497 &surplus_hugepages_attr.attr,
2498 NULL,
2499 };
2500
2501 static struct attribute_group per_node_hstate_attr_group = {
2502 .attrs = per_node_hstate_attrs,
2503 };
2504
2505 /*
2506 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2507 * Returns node id via non-NULL nidp.
2508 */
2509 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2510 {
2511 int nid;
2512
2513 for (nid = 0; nid < nr_node_ids; nid++) {
2514 struct node_hstate *nhs = &node_hstates[nid];
2515 int i;
2516 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2517 if (nhs->hstate_kobjs[i] == kobj) {
2518 if (nidp)
2519 *nidp = nid;
2520 return &hstates[i];
2521 }
2522 }
2523
2524 BUG();
2525 return NULL;
2526 }
2527
2528 /*
2529 * Unregister hstate attributes from a single node device.
2530 * No-op if no hstate attributes attached.
2531 */
2532 static void hugetlb_unregister_node(struct node *node)
2533 {
2534 struct hstate *h;
2535 struct node_hstate *nhs = &node_hstates[node->dev.id];
2536
2537 if (!nhs->hugepages_kobj)
2538 return; /* no hstate attributes */
2539
2540 for_each_hstate(h) {
2541 int idx = hstate_index(h);
2542 if (nhs->hstate_kobjs[idx]) {
2543 kobject_put(nhs->hstate_kobjs[idx]);
2544 nhs->hstate_kobjs[idx] = NULL;
2545 }
2546 }
2547
2548 kobject_put(nhs->hugepages_kobj);
2549 nhs->hugepages_kobj = NULL;
2550 }
2551
2552 /*
2553 * hugetlb module exit: unregister hstate attributes from node devices
2554 * that have them.
2555 */
2556 static void hugetlb_unregister_all_nodes(void)
2557 {
2558 int nid;
2559
2560 /*
2561 * disable node device registrations.
2562 */
2563 register_hugetlbfs_with_node(NULL, NULL);
2564
2565 /*
2566 * remove hstate attributes from any nodes that have them.
2567 */
2568 for (nid = 0; nid < nr_node_ids; nid++)
2569 hugetlb_unregister_node(node_devices[nid]);
2570 }
2571
2572 /*
2573 * Register hstate attributes for a single node device.
2574 * No-op if attributes already registered.
2575 */
2576 static void hugetlb_register_node(struct node *node)
2577 {
2578 struct hstate *h;
2579 struct node_hstate *nhs = &node_hstates[node->dev.id];
2580 int err;
2581
2582 if (nhs->hugepages_kobj)
2583 return; /* already allocated */
2584
2585 nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2586 &node->dev.kobj);
2587 if (!nhs->hugepages_kobj)
2588 return;
2589
2590 for_each_hstate(h) {
2591 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2592 nhs->hstate_kobjs,
2593 &per_node_hstate_attr_group);
2594 if (err) {
2595 pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2596 h->name, node->dev.id);
2597 hugetlb_unregister_node(node);
2598 break;
2599 }
2600 }
2601 }
2602
2603 /*
2604 * hugetlb init time: register hstate attributes for all registered node
2605 * devices of nodes that have memory. All on-line nodes should have
2606 * registered their associated device by this time.
2607 */
2608 static void __init hugetlb_register_all_nodes(void)
2609 {
2610 int nid;
2611
2612 for_each_node_state(nid, N_MEMORY) {
2613 struct node *node = node_devices[nid];
2614 if (node->dev.id == nid)
2615 hugetlb_register_node(node);
2616 }
2617
2618 /*
2619 * Let the node device driver know we're here so it can
2620 * [un]register hstate attributes on node hotplug.
2621 */
2622 register_hugetlbfs_with_node(hugetlb_register_node,
2623 hugetlb_unregister_node);
2624 }
2625 #else /* !CONFIG_NUMA */
2626
2627 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2628 {
2629 BUG();
2630 if (nidp)
2631 *nidp = -1;
2632 return NULL;
2633 }
2634
2635 static void hugetlb_unregister_all_nodes(void) { }
2636
2637 static void hugetlb_register_all_nodes(void) { }
2638
2639 #endif
2640
2641 static void __exit hugetlb_exit(void)
2642 {
2643 struct hstate *h;
2644
2645 hugetlb_unregister_all_nodes();
2646
2647 for_each_hstate(h) {
2648 kobject_put(hstate_kobjs[hstate_index(h)]);
2649 }
2650
2651 kobject_put(hugepages_kobj);
2652 kfree(hugetlb_fault_mutex_table);
2653 }
2654 module_exit(hugetlb_exit);
2655
2656 static int __init hugetlb_init(void)
2657 {
2658 int i;
2659
2660 if (!hugepages_supported())
2661 return 0;
2662
2663 if (!size_to_hstate(default_hstate_size)) {
2664 default_hstate_size = HPAGE_SIZE;
2665 if (!size_to_hstate(default_hstate_size))
2666 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2667 }
2668 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2669 if (default_hstate_max_huge_pages)
2670 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2671
2672 hugetlb_init_hstates();
2673 gather_bootmem_prealloc();
2674 report_hugepages();
2675
2676 hugetlb_sysfs_init();
2677 hugetlb_register_all_nodes();
2678 hugetlb_cgroup_file_init();
2679
2680 #ifdef CONFIG_SMP
2681 num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2682 #else
2683 num_fault_mutexes = 1;
2684 #endif
2685 hugetlb_fault_mutex_table =
2686 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2687 BUG_ON(!hugetlb_fault_mutex_table);
2688
2689 for (i = 0; i < num_fault_mutexes; i++)
2690 mutex_init(&hugetlb_fault_mutex_table[i]);
2691 return 0;
2692 }
2693 module_init(hugetlb_init);
2694
2695 /* Should be called on processing a hugepagesz=... option */
2696 void __init hugetlb_add_hstate(unsigned int order)
2697 {
2698 struct hstate *h;
2699 unsigned long i;
2700
2701 if (size_to_hstate(PAGE_SIZE << order)) {
2702 pr_warning("hugepagesz= specified twice, ignoring\n");
2703 return;
2704 }
2705 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2706 BUG_ON(order == 0);
2707 h = &hstates[hugetlb_max_hstate++];
2708 h->order = order;
2709 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2710 h->nr_huge_pages = 0;
2711 h->free_huge_pages = 0;
2712 for (i = 0; i < MAX_NUMNODES; ++i)
2713 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2714 INIT_LIST_HEAD(&h->hugepage_activelist);
2715 h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
2716 h->next_nid_to_free = first_node(node_states[N_MEMORY]);
2717 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2718 huge_page_size(h)/1024);
2719
2720 parsed_hstate = h;
2721 }
2722
2723 static int __init hugetlb_nrpages_setup(char *s)
2724 {
2725 unsigned long *mhp;
2726 static unsigned long *last_mhp;
2727
2728 /*
2729 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2730 * so this hugepages= parameter goes to the "default hstate".
2731 */
2732 if (!hugetlb_max_hstate)
2733 mhp = &default_hstate_max_huge_pages;
2734 else
2735 mhp = &parsed_hstate->max_huge_pages;
2736
2737 if (mhp == last_mhp) {
2738 pr_warning("hugepages= specified twice without "
2739 "interleaving hugepagesz=, ignoring\n");
2740 return 1;
2741 }
2742
2743 if (sscanf(s, "%lu", mhp) <= 0)
2744 *mhp = 0;
2745
2746 /*
2747 * Global state is always initialized later in hugetlb_init.
2748 * But we need to allocate >= MAX_ORDER hstates here early to still
2749 * use the bootmem allocator.
2750 */
2751 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2752 hugetlb_hstate_alloc_pages(parsed_hstate);
2753
2754 last_mhp = mhp;
2755
2756 return 1;
2757 }
2758 __setup("hugepages=", hugetlb_nrpages_setup);
2759
2760 static int __init hugetlb_default_setup(char *s)
2761 {
2762 default_hstate_size = memparse(s, &s);
2763 return 1;
2764 }
2765 __setup("default_hugepagesz=", hugetlb_default_setup);
2766
2767 static unsigned int cpuset_mems_nr(unsigned int *array)
2768 {
2769 int node;
2770 unsigned int nr = 0;
2771
2772 for_each_node_mask(node, cpuset_current_mems_allowed)
2773 nr += array[node];
2774
2775 return nr;
2776 }
2777
2778 #ifdef CONFIG_SYSCTL
2779 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2780 struct ctl_table *table, int write,
2781 void __user *buffer, size_t *length, loff_t *ppos)
2782 {
2783 struct hstate *h = &default_hstate;
2784 unsigned long tmp = h->max_huge_pages;
2785 int ret;
2786
2787 if (!hugepages_supported())
2788 return -ENOTSUPP;
2789
2790 table->data = &tmp;
2791 table->maxlen = sizeof(unsigned long);
2792 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2793 if (ret)
2794 goto out;
2795
2796 if (write)
2797 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2798 NUMA_NO_NODE, tmp, *length);
2799 out:
2800 return ret;
2801 }
2802
2803 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2804 void __user *buffer, size_t *length, loff_t *ppos)
2805 {
2806
2807 return hugetlb_sysctl_handler_common(false, table, write,
2808 buffer, length, ppos);
2809 }
2810
2811 #ifdef CONFIG_NUMA
2812 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2813 void __user *buffer, size_t *length, loff_t *ppos)
2814 {
2815 return hugetlb_sysctl_handler_common(true, table, write,
2816 buffer, length, ppos);
2817 }
2818 #endif /* CONFIG_NUMA */
2819
2820 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2821 void __user *buffer,
2822 size_t *length, loff_t *ppos)
2823 {
2824 struct hstate *h = &default_hstate;
2825 unsigned long tmp;
2826 int ret;
2827
2828 if (!hugepages_supported())
2829 return -ENOTSUPP;
2830
2831 tmp = h->nr_overcommit_huge_pages;
2832
2833 if (write && hstate_is_gigantic(h))
2834 return -EINVAL;
2835
2836 table->data = &tmp;
2837 table->maxlen = sizeof(unsigned long);
2838 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2839 if (ret)
2840 goto out;
2841
2842 if (write) {
2843 spin_lock(&hugetlb_lock);
2844 h->nr_overcommit_huge_pages = tmp;
2845 spin_unlock(&hugetlb_lock);
2846 }
2847 out:
2848 return ret;
2849 }
2850
2851 #endif /* CONFIG_SYSCTL */
2852
2853 void hugetlb_report_meminfo(struct seq_file *m)
2854 {
2855 struct hstate *h = &default_hstate;
2856 if (!hugepages_supported())
2857 return;
2858 seq_printf(m,
2859 "HugePages_Total: %5lu\n"
2860 "HugePages_Free: %5lu\n"
2861 "HugePages_Rsvd: %5lu\n"
2862 "HugePages_Surp: %5lu\n"
2863 "Hugepagesize: %8lu kB\n",
2864 h->nr_huge_pages,
2865 h->free_huge_pages,
2866 h->resv_huge_pages,
2867 h->surplus_huge_pages,
2868 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2869 }
2870
2871 int hugetlb_report_node_meminfo(int nid, char *buf)
2872 {
2873 struct hstate *h = &default_hstate;
2874 if (!hugepages_supported())
2875 return 0;
2876 return sprintf(buf,
2877 "Node %d HugePages_Total: %5u\n"
2878 "Node %d HugePages_Free: %5u\n"
2879 "Node %d HugePages_Surp: %5u\n",
2880 nid, h->nr_huge_pages_node[nid],
2881 nid, h->free_huge_pages_node[nid],
2882 nid, h->surplus_huge_pages_node[nid]);
2883 }
2884
2885 void hugetlb_show_meminfo(void)
2886 {
2887 struct hstate *h;
2888 int nid;
2889
2890 if (!hugepages_supported())
2891 return;
2892
2893 for_each_node_state(nid, N_MEMORY)
2894 for_each_hstate(h)
2895 pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
2896 nid,
2897 h->nr_huge_pages_node[nid],
2898 h->free_huge_pages_node[nid],
2899 h->surplus_huge_pages_node[nid],
2900 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2901 }
2902
2903 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
2904 {
2905 seq_printf(m, "HugetlbPages:\t%8lu kB\n",
2906 atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
2907 }
2908
2909 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2910 unsigned long hugetlb_total_pages(void)
2911 {
2912 struct hstate *h;
2913 unsigned long nr_total_pages = 0;
2914
2915 for_each_hstate(h)
2916 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
2917 return nr_total_pages;
2918 }
2919
2920 static int hugetlb_acct_memory(struct hstate *h, long delta)
2921 {
2922 int ret = -ENOMEM;
2923
2924 spin_lock(&hugetlb_lock);
2925 /*
2926 * When cpuset is configured, it breaks the strict hugetlb page
2927 * reservation as the accounting is done on a global variable. Such
2928 * reservation is completely rubbish in the presence of cpuset because
2929 * the reservation is not checked against page availability for the
2930 * current cpuset. Application can still potentially OOM'ed by kernel
2931 * with lack of free htlb page in cpuset that the task is in.
2932 * Attempt to enforce strict accounting with cpuset is almost
2933 * impossible (or too ugly) because cpuset is too fluid that
2934 * task or memory node can be dynamically moved between cpusets.
2935 *
2936 * The change of semantics for shared hugetlb mapping with cpuset is
2937 * undesirable. However, in order to preserve some of the semantics,
2938 * we fall back to check against current free page availability as
2939 * a best attempt and hopefully to minimize the impact of changing
2940 * semantics that cpuset has.
2941 */
2942 if (delta > 0) {
2943 if (gather_surplus_pages(h, delta) < 0)
2944 goto out;
2945
2946 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2947 return_unused_surplus_pages(h, delta);
2948 goto out;
2949 }
2950 }
2951
2952 ret = 0;
2953 if (delta < 0)
2954 return_unused_surplus_pages(h, (unsigned long) -delta);
2955
2956 out:
2957 spin_unlock(&hugetlb_lock);
2958 return ret;
2959 }
2960
2961 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2962 {
2963 struct resv_map *resv = vma_resv_map(vma);
2964
2965 /*
2966 * This new VMA should share its siblings reservation map if present.
2967 * The VMA will only ever have a valid reservation map pointer where
2968 * it is being copied for another still existing VMA. As that VMA
2969 * has a reference to the reservation map it cannot disappear until
2970 * after this open call completes. It is therefore safe to take a
2971 * new reference here without additional locking.
2972 */
2973 if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
2974 kref_get(&resv->refs);
2975 }
2976
2977 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2978 {
2979 struct hstate *h = hstate_vma(vma);
2980 struct resv_map *resv = vma_resv_map(vma);
2981 struct hugepage_subpool *spool = subpool_vma(vma);
2982 unsigned long reserve, start, end;
2983 long gbl_reserve;
2984
2985 if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
2986 return;
2987
2988 start = vma_hugecache_offset(h, vma, vma->vm_start);
2989 end = vma_hugecache_offset(h, vma, vma->vm_end);
2990
2991 reserve = (end - start) - region_count(resv, start, end);
2992
2993 kref_put(&resv->refs, resv_map_release);
2994
2995 if (reserve) {
2996 /*
2997 * Decrement reserve counts. The global reserve count may be
2998 * adjusted if the subpool has a minimum size.
2999 */
3000 gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
3001 hugetlb_acct_memory(h, -gbl_reserve);
3002 }
3003 }
3004
3005 /*
3006 * We cannot handle pagefaults against hugetlb pages at all. They cause
3007 * handle_mm_fault() to try to instantiate regular-sized pages in the
3008 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
3009 * this far.
3010 */
3011 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
3012 {
3013 BUG();
3014 return 0;
3015 }
3016
3017 const struct vm_operations_struct hugetlb_vm_ops = {
3018 .fault = hugetlb_vm_op_fault,
3019 .open = hugetlb_vm_op_open,
3020 .close = hugetlb_vm_op_close,
3021 };
3022
3023 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3024 int writable)
3025 {
3026 pte_t entry;
3027
3028 if (writable) {
3029 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3030 vma->vm_page_prot)));
3031 } else {
3032 entry = huge_pte_wrprotect(mk_huge_pte(page,
3033 vma->vm_page_prot));
3034 }
3035 entry = pte_mkyoung(entry);
3036 entry = pte_mkhuge(entry);
3037 entry = arch_make_huge_pte(entry, vma, page, writable);
3038
3039 return entry;
3040 }
3041
3042 static void set_huge_ptep_writable(struct vm_area_struct *vma,
3043 unsigned long address, pte_t *ptep)
3044 {
3045 pte_t entry;
3046
3047 entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3048 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3049 update_mmu_cache(vma, address, ptep);
3050 }
3051
3052 static int is_hugetlb_entry_migration(pte_t pte)
3053 {
3054 swp_entry_t swp;
3055
3056 if (huge_pte_none(pte) || pte_present(pte))
3057 return 0;
3058 swp = pte_to_swp_entry(pte);
3059 if (non_swap_entry(swp) && is_migration_entry(swp))
3060 return 1;
3061 else
3062 return 0;
3063 }
3064
3065 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3066 {
3067 swp_entry_t swp;
3068
3069 if (huge_pte_none(pte) || pte_present(pte))
3070 return 0;
3071 swp = pte_to_swp_entry(pte);
3072 if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3073 return 1;
3074 else
3075 return 0;
3076 }
3077
3078 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3079 struct vm_area_struct *vma)
3080 {
3081 pte_t *src_pte, *dst_pte, entry;
3082 struct page *ptepage;
3083 unsigned long addr;
3084 int cow;
3085 struct hstate *h = hstate_vma(vma);
3086 unsigned long sz = huge_page_size(h);
3087 unsigned long mmun_start; /* For mmu_notifiers */
3088 unsigned long mmun_end; /* For mmu_notifiers */
3089 int ret = 0;
3090
3091 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3092
3093 mmun_start = vma->vm_start;
3094 mmun_end = vma->vm_end;
3095 if (cow)
3096 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
3097
3098 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3099 spinlock_t *src_ptl, *dst_ptl;
3100 src_pte = huge_pte_offset(src, addr);
3101 if (!src_pte)
3102 continue;
3103 dst_pte = huge_pte_alloc(dst, addr, sz);
3104 if (!dst_pte) {
3105 ret = -ENOMEM;
3106 break;
3107 }
3108
3109 /* If the pagetables are shared don't copy or take references */
3110 if (dst_pte == src_pte)
3111 continue;
3112
3113 dst_ptl = huge_pte_lock(h, dst, dst_pte);
3114 src_ptl = huge_pte_lockptr(h, src, src_pte);
3115 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3116 entry = huge_ptep_get(src_pte);
3117 if (huge_pte_none(entry)) { /* skip none entry */
3118 ;
3119 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
3120 is_hugetlb_entry_hwpoisoned(entry))) {
3121 swp_entry_t swp_entry = pte_to_swp_entry(entry);
3122
3123 if (is_write_migration_entry(swp_entry) && cow) {
3124 /*
3125 * COW mappings require pages in both
3126 * parent and child to be set to read.
3127 */
3128 make_migration_entry_read(&swp_entry);
3129 entry = swp_entry_to_pte(swp_entry);
3130 set_huge_pte_at(src, addr, src_pte, entry);
3131 }
3132 set_huge_pte_at(dst, addr, dst_pte, entry);
3133 } else {
3134 if (cow) {
3135 huge_ptep_set_wrprotect(src, addr, src_pte);
3136 mmu_notifier_invalidate_range(src, mmun_start,
3137 mmun_end);
3138 }
3139 entry = huge_ptep_get(src_pte);
3140 ptepage = pte_page(entry);
3141 get_page(ptepage);
3142 page_dup_rmap(ptepage);
3143 set_huge_pte_at(dst, addr, dst_pte, entry);
3144 hugetlb_count_add(pages_per_huge_page(h), dst);
3145 }
3146 spin_unlock(src_ptl);
3147 spin_unlock(dst_ptl);
3148 }
3149
3150 if (cow)
3151 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
3152
3153 return ret;
3154 }
3155
3156 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3157 unsigned long start, unsigned long end,
3158 struct page *ref_page)
3159 {
3160 int force_flush = 0;
3161 struct mm_struct *mm = vma->vm_mm;
3162 unsigned long address;
3163 pte_t *ptep;
3164 pte_t pte;
3165 spinlock_t *ptl;
3166 struct page *page;
3167 struct hstate *h = hstate_vma(vma);
3168 unsigned long sz = huge_page_size(h);
3169 const unsigned long mmun_start = start; /* For mmu_notifiers */
3170 const unsigned long mmun_end = end; /* For mmu_notifiers */
3171
3172 WARN_ON(!is_vm_hugetlb_page(vma));
3173 BUG_ON(start & ~huge_page_mask(h));
3174 BUG_ON(end & ~huge_page_mask(h));
3175
3176 tlb_start_vma(tlb, vma);
3177 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3178 address = start;
3179 again:
3180 for (; address < end; address += sz) {
3181 ptep = huge_pte_offset(mm, address);
3182 if (!ptep)
3183 continue;
3184
3185 ptl = huge_pte_lock(h, mm, ptep);
3186 if (huge_pmd_unshare(mm, &address, ptep))
3187 goto unlock;
3188
3189 pte = huge_ptep_get(ptep);
3190 if (huge_pte_none(pte))
3191 goto unlock;
3192
3193 /*
3194 * Migrating hugepage or HWPoisoned hugepage is already
3195 * unmapped and its refcount is dropped, so just clear pte here.
3196 */
3197 if (unlikely(!pte_present(pte))) {
3198 huge_pte_clear(mm, address, ptep);
3199 goto unlock;
3200 }
3201
3202 page = pte_page(pte);
3203 /*
3204 * If a reference page is supplied, it is because a specific
3205 * page is being unmapped, not a range. Ensure the page we
3206 * are about to unmap is the actual page of interest.
3207 */
3208 if (ref_page) {
3209 if (page != ref_page)
3210 goto unlock;
3211
3212 /*
3213 * Mark the VMA as having unmapped its page so that
3214 * future faults in this VMA will fail rather than
3215 * looking like data was lost
3216 */
3217 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
3218 }
3219
3220 pte = huge_ptep_get_and_clear(mm, address, ptep);
3221 tlb_remove_tlb_entry(tlb, ptep, address);
3222 if (huge_pte_dirty(pte))
3223 set_page_dirty(page);
3224
3225 hugetlb_count_sub(pages_per_huge_page(h), mm);
3226 page_remove_rmap(page);
3227 force_flush = !__tlb_remove_page(tlb, page);
3228 if (force_flush) {
3229 address += sz;
3230 spin_unlock(ptl);
3231 break;
3232 }
3233 /* Bail out after unmapping reference page if supplied */
3234 if (ref_page) {
3235 spin_unlock(ptl);
3236 break;
3237 }
3238 unlock:
3239 spin_unlock(ptl);
3240 }
3241 /*
3242 * mmu_gather ran out of room to batch pages, we break out of
3243 * the PTE lock to avoid doing the potential expensive TLB invalidate
3244 * and page-free while holding it.
3245 */
3246 if (force_flush) {
3247 force_flush = 0;
3248 tlb_flush_mmu(tlb);
3249 if (address < end && !ref_page)
3250 goto again;
3251 }
3252 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3253 tlb_end_vma(tlb, vma);
3254 }
3255
3256 void __unmap_hugepage_range_final(struct mmu_gather *tlb,
3257 struct vm_area_struct *vma, unsigned long start,
3258 unsigned long end, struct page *ref_page)
3259 {
3260 __unmap_hugepage_range(tlb, vma, start, end, ref_page);
3261
3262 /*
3263 * Clear this flag so that x86's huge_pmd_share page_table_shareable
3264 * test will fail on a vma being torn down, and not grab a page table
3265 * on its way out. We're lucky that the flag has such an appropriate
3266 * name, and can in fact be safely cleared here. We could clear it
3267 * before the __unmap_hugepage_range above, but all that's necessary
3268 * is to clear it before releasing the i_mmap_rwsem. This works
3269 * because in the context this is called, the VMA is about to be
3270 * destroyed and the i_mmap_rwsem is held.
3271 */
3272 vma->vm_flags &= ~VM_MAYSHARE;
3273 }
3274
3275 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3276 unsigned long end, struct page *ref_page)
3277 {
3278 struct mm_struct *mm;
3279 struct mmu_gather tlb;
3280
3281 mm = vma->vm_mm;
3282
3283 tlb_gather_mmu(&tlb, mm, start, end);
3284 __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3285 tlb_finish_mmu(&tlb, start, end);
3286 }
3287
3288 /*
3289 * This is called when the original mapper is failing to COW a MAP_PRIVATE
3290 * mappping it owns the reserve page for. The intention is to unmap the page
3291 * from other VMAs and let the children be SIGKILLed if they are faulting the
3292 * same region.
3293 */
3294 static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
3295 struct page *page, unsigned long address)
3296 {
3297 struct hstate *h = hstate_vma(vma);
3298 struct vm_area_struct *iter_vma;
3299 struct address_space *mapping;
3300 pgoff_t pgoff;
3301
3302 /*
3303 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
3304 * from page cache lookup which is in HPAGE_SIZE units.
3305 */
3306 address = address & huge_page_mask(h);
3307 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
3308 vma->vm_pgoff;
3309 mapping = file_inode(vma->vm_file)->i_mapping;
3310
3311 /*
3312 * Take the mapping lock for the duration of the table walk. As
3313 * this mapping should be shared between all the VMAs,
3314 * __unmap_hugepage_range() is called as the lock is already held
3315 */
3316 i_mmap_lock_write(mapping);
3317 vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3318 /* Do not unmap the current VMA */
3319 if (iter_vma == vma)
3320 continue;
3321
3322 /*
3323 * Shared VMAs have their own reserves and do not affect
3324 * MAP_PRIVATE accounting but it is possible that a shared
3325 * VMA is using the same page so check and skip such VMAs.
3326 */
3327 if (iter_vma->vm_flags & VM_MAYSHARE)
3328 continue;
3329
3330 /*
3331 * Unmap the page from other VMAs without their own reserves.
3332 * They get marked to be SIGKILLed if they fault in these
3333 * areas. This is because a future no-page fault on this VMA
3334 * could insert a zeroed page instead of the data existing
3335 * from the time of fork. This would look like data corruption
3336 */
3337 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3338 unmap_hugepage_range(iter_vma, address,
3339 address + huge_page_size(h), page);
3340 }
3341 i_mmap_unlock_write(mapping);
3342 }
3343
3344 /*
3345 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3346 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
3347 * cannot race with other handlers or page migration.
3348 * Keep the pte_same checks anyway to make transition from the mutex easier.
3349 */
3350 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3351 unsigned long address, pte_t *ptep, pte_t pte,
3352 struct page *pagecache_page, spinlock_t *ptl)
3353 {
3354 struct hstate *h = hstate_vma(vma);
3355 struct page *old_page, *new_page;
3356 int ret = 0, outside_reserve = 0;
3357 unsigned long mmun_start; /* For mmu_notifiers */
3358 unsigned long mmun_end; /* For mmu_notifiers */
3359
3360 old_page = pte_page(pte);
3361
3362 retry_avoidcopy:
3363 /* If no-one else is actually using this page, avoid the copy
3364 * and just make the page writable */
3365 if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3366 page_move_anon_rmap(old_page, vma, address);
3367 set_huge_ptep_writable(vma, address, ptep);
3368 return 0;
3369 }
3370
3371 /*
3372 * If the process that created a MAP_PRIVATE mapping is about to
3373 * perform a COW due to a shared page count, attempt to satisfy
3374 * the allocation without using the existing reserves. The pagecache
3375 * page is used to determine if the reserve at this address was
3376 * consumed or not. If reserves were used, a partial faulted mapping
3377 * at the time of fork() could consume its reserves on COW instead
3378 * of the full address range.
3379 */
3380 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3381 old_page != pagecache_page)
3382 outside_reserve = 1;
3383
3384 page_cache_get(old_page);
3385
3386 /*
3387 * Drop page table lock as buddy allocator may be called. It will
3388 * be acquired again before returning to the caller, as expected.
3389 */
3390 spin_unlock(ptl);
3391 new_page = alloc_huge_page(vma, address, outside_reserve);
3392
3393 if (IS_ERR(new_page)) {
3394 /*
3395 * If a process owning a MAP_PRIVATE mapping fails to COW,
3396 * it is due to references held by a child and an insufficient
3397 * huge page pool. To guarantee the original mappers
3398 * reliability, unmap the page from child processes. The child
3399 * may get SIGKILLed if it later faults.
3400 */
3401 if (outside_reserve) {
3402 page_cache_release(old_page);
3403 BUG_ON(huge_pte_none(pte));
3404 unmap_ref_private(mm, vma, old_page, address);
3405 BUG_ON(huge_pte_none(pte));
3406 spin_lock(ptl);
3407 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3408 if (likely(ptep &&
3409 pte_same(huge_ptep_get(ptep), pte)))
3410 goto retry_avoidcopy;
3411 /*
3412 * race occurs while re-acquiring page table
3413 * lock, and our job is done.
3414 */
3415 return 0;
3416 }
3417
3418 ret = (PTR_ERR(new_page) == -ENOMEM) ?
3419 VM_FAULT_OOM : VM_FAULT_SIGBUS;
3420 goto out_release_old;
3421 }
3422
3423 /*
3424 * When the original hugepage is shared one, it does not have
3425 * anon_vma prepared.
3426 */
3427 if (unlikely(anon_vma_prepare(vma))) {
3428 ret = VM_FAULT_OOM;
3429 goto out_release_all;
3430 }
3431
3432 copy_user_huge_page(new_page, old_page, address, vma,
3433 pages_per_huge_page(h));
3434 __SetPageUptodate(new_page);
3435 set_page_huge_active(new_page);
3436
3437 mmun_start = address & huge_page_mask(h);
3438 mmun_end = mmun_start + huge_page_size(h);
3439 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3440
3441 /*
3442 * Retake the page table lock to check for racing updates
3443 * before the page tables are altered
3444 */
3445 spin_lock(ptl);
3446 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3447 if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3448 ClearPagePrivate(new_page);
3449
3450 /* Break COW */
3451 huge_ptep_clear_flush(vma, address, ptep);
3452 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3453 set_huge_pte_at(mm, address, ptep,
3454 make_huge_pte(vma, new_page, 1));
3455 page_remove_rmap(old_page);
3456 hugepage_add_new_anon_rmap(new_page, vma, address);
3457 /* Make the old page be freed below */
3458 new_page = old_page;
3459 }
3460 spin_unlock(ptl);
3461 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3462 out_release_all:
3463 page_cache_release(new_page);
3464 out_release_old:
3465 page_cache_release(old_page);
3466
3467 spin_lock(ptl); /* Caller expects lock to be held */
3468 return ret;
3469 }
3470
3471 /* Return the pagecache page at a given address within a VMA */
3472 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
3473 struct vm_area_struct *vma, unsigned long address)
3474 {
3475 struct address_space *mapping;
3476 pgoff_t idx;
3477
3478 mapping = vma->vm_file->f_mapping;
3479 idx = vma_hugecache_offset(h, vma, address);
3480
3481 return find_lock_page(mapping, idx);
3482 }
3483
3484 /*
3485 * Return whether there is a pagecache page to back given address within VMA.
3486 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
3487 */
3488 static bool hugetlbfs_pagecache_present(struct hstate *h,
3489 struct vm_area_struct *vma, unsigned long address)
3490 {
3491 struct address_space *mapping;
3492 pgoff_t idx;
3493 struct page *page;
3494
3495 mapping = vma->vm_file->f_mapping;
3496 idx = vma_hugecache_offset(h, vma, address);
3497
3498 page = find_get_page(mapping, idx);
3499 if (page)
3500 put_page(page);
3501 return page != NULL;
3502 }
3503
3504 int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
3505 pgoff_t idx)
3506 {
3507 struct inode *inode = mapping->host;
3508 struct hstate *h = hstate_inode(inode);
3509 int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3510
3511 if (err)
3512 return err;
3513 ClearPagePrivate(page);
3514
3515 spin_lock(&inode->i_lock);
3516 inode->i_blocks += blocks_per_huge_page(h);
3517 spin_unlock(&inode->i_lock);
3518 return 0;
3519 }
3520
3521 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3522 struct address_space *mapping, pgoff_t idx,
3523 unsigned long address, pte_t *ptep, unsigned int flags)
3524 {
3525 struct hstate *h = hstate_vma(vma);
3526 int ret = VM_FAULT_SIGBUS;
3527 int anon_rmap = 0;
3528 unsigned long size;
3529 struct page *page;
3530 pte_t new_pte;
3531 spinlock_t *ptl;
3532
3533 /*
3534 * Currently, we are forced to kill the process in the event the
3535 * original mapper has unmapped pages from the child due to a failed
3536 * COW. Warn that such a situation has occurred as it may not be obvious
3537 */
3538 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3539 pr_warning("PID %d killed due to inadequate hugepage pool\n",
3540 current->pid);
3541 return ret;
3542 }
3543
3544 /*
3545 * Use page lock to guard against racing truncation
3546 * before we get page_table_lock.
3547 */
3548 retry:
3549 page = find_lock_page(mapping, idx);
3550 if (!page) {
3551 size = i_size_read(mapping->host) >> huge_page_shift(h);
3552 if (idx >= size)
3553 goto out;
3554 page = alloc_huge_page(vma, address, 0);
3555 if (IS_ERR(page)) {
3556 ret = PTR_ERR(page);
3557 if (ret == -ENOMEM)
3558 ret = VM_FAULT_OOM;
3559 else
3560 ret = VM_FAULT_SIGBUS;
3561 goto out;
3562 }
3563 clear_huge_page(page, address, pages_per_huge_page(h));
3564 __SetPageUptodate(page);
3565 set_page_huge_active(page);
3566
3567 if (vma->vm_flags & VM_MAYSHARE) {
3568 int err = huge_add_to_page_cache(page, mapping, idx);
3569 if (err) {
3570 put_page(page);
3571 if (err == -EEXIST)
3572 goto retry;
3573 goto out;
3574 }
3575 } else {
3576 lock_page(page);
3577 if (unlikely(anon_vma_prepare(vma))) {
3578 ret = VM_FAULT_OOM;
3579 goto backout_unlocked;
3580 }
3581 anon_rmap = 1;
3582 }
3583 } else {
3584 /*
3585 * If memory error occurs between mmap() and fault, some process
3586 * don't have hwpoisoned swap entry for errored virtual address.
3587 * So we need to block hugepage fault by PG_hwpoison bit check.
3588 */
3589 if (unlikely(PageHWPoison(page))) {
3590 ret = VM_FAULT_HWPOISON |
3591 VM_FAULT_SET_HINDEX(hstate_index(h));
3592 goto backout_unlocked;
3593 }
3594 }
3595
3596 /*
3597 * If we are going to COW a private mapping later, we examine the
3598 * pending reservations for this page now. This will ensure that
3599 * any allocations necessary to record that reservation occur outside
3600 * the spinlock.
3601 */
3602 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3603 if (vma_needs_reservation(h, vma, address) < 0) {
3604 ret = VM_FAULT_OOM;
3605 goto backout_unlocked;
3606 }
3607 /* Just decrements count, does not deallocate */
3608 vma_end_reservation(h, vma, address);
3609 }
3610
3611 ptl = huge_pte_lockptr(h, mm, ptep);
3612 spin_lock(ptl);
3613 size = i_size_read(mapping->host) >> huge_page_shift(h);
3614 if (idx >= size)
3615 goto backout;
3616
3617 ret = 0;
3618 if (!huge_pte_none(huge_ptep_get(ptep)))
3619 goto backout;
3620
3621 if (anon_rmap) {
3622 ClearPagePrivate(page);
3623 hugepage_add_new_anon_rmap(page, vma, address);
3624 } else
3625 page_dup_rmap(page);
3626 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3627 && (vma->vm_flags & VM_SHARED)));
3628 set_huge_pte_at(mm, address, ptep, new_pte);
3629
3630 hugetlb_count_add(pages_per_huge_page(h), mm);
3631 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3632 /* Optimization, do the COW without a second fault */
3633 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
3634 }
3635
3636 spin_unlock(ptl);
3637 unlock_page(page);
3638 out:
3639 return ret;
3640
3641 backout:
3642 spin_unlock(ptl);
3643 backout_unlocked:
3644 unlock_page(page);
3645 put_page(page);
3646 goto out;
3647 }
3648
3649 #ifdef CONFIG_SMP
3650 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3651 struct vm_area_struct *vma,
3652 struct address_space *mapping,
3653 pgoff_t idx, unsigned long address)
3654 {
3655 unsigned long key[2];
3656 u32 hash;
3657
3658 if (vma->vm_flags & VM_SHARED) {
3659 key[0] = (unsigned long) mapping;
3660 key[1] = idx;
3661 } else {
3662 key[0] = (unsigned long) mm;
3663 key[1] = address >> huge_page_shift(h);
3664 }
3665
3666 hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3667
3668 return hash & (num_fault_mutexes - 1);
3669 }
3670 #else
3671 /*
3672 * For uniprocesor systems we always use a single mutex, so just
3673 * return 0 and avoid the hashing overhead.
3674 */
3675 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3676 struct vm_area_struct *vma,
3677 struct address_space *mapping,
3678 pgoff_t idx, unsigned long address)
3679 {
3680 return 0;
3681 }
3682 #endif
3683
3684 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3685 unsigned long address, unsigned int flags)
3686 {
3687 pte_t *ptep, entry;
3688 spinlock_t *ptl;
3689 int ret;
3690 u32 hash;
3691 pgoff_t idx;
3692 struct page *page = NULL;
3693 struct page *pagecache_page = NULL;
3694 struct hstate *h = hstate_vma(vma);
3695 struct address_space *mapping;
3696 int need_wait_lock = 0;
3697
3698 address &= huge_page_mask(h);
3699
3700 ptep = huge_pte_offset(mm, address);
3701 if (ptep) {
3702 entry = huge_ptep_get(ptep);
3703 if (unlikely(is_hugetlb_entry_migration(entry))) {
3704 migration_entry_wait_huge(vma, mm, ptep);
3705 return 0;
3706 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3707 return VM_FAULT_HWPOISON_LARGE |
3708 VM_FAULT_SET_HINDEX(hstate_index(h));
3709 } else {
3710 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3711 if (!ptep)
3712 return VM_FAULT_OOM;
3713 }
3714
3715 mapping = vma->vm_file->f_mapping;
3716 idx = vma_hugecache_offset(h, vma, address);
3717
3718 /*
3719 * Serialize hugepage allocation and instantiation, so that we don't
3720 * get spurious allocation failures if two CPUs race to instantiate
3721 * the same page in the page cache.
3722 */
3723 hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
3724 mutex_lock(&hugetlb_fault_mutex_table[hash]);
3725
3726 entry = huge_ptep_get(ptep);
3727 if (huge_pte_none(entry)) {
3728 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3729 goto out_mutex;
3730 }
3731
3732 ret = 0;
3733
3734 /*
3735 * entry could be a migration/hwpoison entry at this point, so this
3736 * check prevents the kernel from going below assuming that we have
3737 * a active hugepage in pagecache. This goto expects the 2nd page fault,
3738 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3739 * handle it.
3740 */
3741 if (!pte_present(entry))
3742 goto out_mutex;
3743
3744 /*
3745 * If we are going to COW the mapping later, we examine the pending
3746 * reservations for this page now. This will ensure that any
3747 * allocations necessary to record that reservation occur outside the
3748 * spinlock. For private mappings, we also lookup the pagecache
3749 * page now as it is used to determine if a reservation has been
3750 * consumed.
3751 */
3752 if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3753 if (vma_needs_reservation(h, vma, address) < 0) {
3754 ret = VM_FAULT_OOM;
3755 goto out_mutex;
3756 }
3757 /* Just decrements count, does not deallocate */
3758 vma_end_reservation(h, vma, address);
3759
3760 if (!(vma->vm_flags & VM_MAYSHARE))
3761 pagecache_page = hugetlbfs_pagecache_page(h,
3762 vma, address);
3763 }
3764
3765 ptl = huge_pte_lock(h, mm, ptep);
3766
3767 /* Check for a racing update before calling hugetlb_cow */
3768 if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3769 goto out_ptl;
3770
3771 /*
3772 * hugetlb_cow() requires page locks of pte_page(entry) and
3773 * pagecache_page, so here we need take the former one
3774 * when page != pagecache_page or !pagecache_page.
3775 */
3776 page = pte_page(entry);
3777 if (page != pagecache_page)
3778 if (!trylock_page(page)) {
3779 need_wait_lock = 1;
3780 goto out_ptl;
3781 }
3782
3783 get_page(page);
3784
3785 if (flags & FAULT_FLAG_WRITE) {
3786 if (!huge_pte_write(entry)) {
3787 ret = hugetlb_cow(mm, vma, address, ptep, entry,
3788 pagecache_page, ptl);
3789 goto out_put_page;
3790 }
3791 entry = huge_pte_mkdirty(entry);
3792 }
3793 entry = pte_mkyoung(entry);
3794 if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3795 flags & FAULT_FLAG_WRITE))
3796 update_mmu_cache(vma, address, ptep);
3797 out_put_page:
3798 if (page != pagecache_page)
3799 unlock_page(page);
3800 put_page(page);
3801 out_ptl:
3802 spin_unlock(ptl);
3803
3804 if (pagecache_page) {
3805 unlock_page(pagecache_page);
3806 put_page(pagecache_page);
3807 }
3808 out_mutex:
3809 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3810 /*
3811 * Generally it's safe to hold refcount during waiting page lock. But
3812 * here we just wait to defer the next page fault to avoid busy loop and
3813 * the page is not used after unlocked before returning from the current
3814 * page fault. So we are safe from accessing freed page, even if we wait
3815 * here without taking refcount.
3816 */
3817 if (need_wait_lock)
3818 wait_on_page_locked(page);
3819 return ret;
3820 }
3821
3822 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
3823 struct page **pages, struct vm_area_struct **vmas,
3824 unsigned long *position, unsigned long *nr_pages,
3825 long i, unsigned int flags)
3826 {
3827 unsigned long pfn_offset;
3828 unsigned long vaddr = *position;
3829 unsigned long remainder = *nr_pages;
3830 struct hstate *h = hstate_vma(vma);
3831
3832 while (vaddr < vma->vm_end && remainder) {
3833 pte_t *pte;
3834 spinlock_t *ptl = NULL;
3835 int absent;
3836 struct page *page;
3837
3838 /*
3839 * If we have a pending SIGKILL, don't keep faulting pages and
3840 * potentially allocating memory.
3841 */
3842 if (unlikely(fatal_signal_pending(current))) {
3843 remainder = 0;
3844 break;
3845 }
3846
3847 /*
3848 * Some archs (sparc64, sh*) have multiple pte_ts to
3849 * each hugepage. We have to make sure we get the
3850 * first, for the page indexing below to work.
3851 *
3852 * Note that page table lock is not held when pte is null.
3853 */
3854 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
3855 if (pte)
3856 ptl = huge_pte_lock(h, mm, pte);
3857 absent = !pte || huge_pte_none(huge_ptep_get(pte));
3858
3859 /*
3860 * When coredumping, it suits get_dump_page if we just return
3861 * an error where there's an empty slot with no huge pagecache
3862 * to back it. This way, we avoid allocating a hugepage, and
3863 * the sparse dumpfile avoids allocating disk blocks, but its
3864 * huge holes still show up with zeroes where they need to be.
3865 */
3866 if (absent && (flags & FOLL_DUMP) &&
3867 !hugetlbfs_pagecache_present(h, vma, vaddr)) {
3868 if (pte)
3869 spin_unlock(ptl);
3870 remainder = 0;
3871 break;
3872 }
3873
3874 /*
3875 * We need call hugetlb_fault for both hugepages under migration
3876 * (in which case hugetlb_fault waits for the migration,) and
3877 * hwpoisoned hugepages (in which case we need to prevent the
3878 * caller from accessing to them.) In order to do this, we use
3879 * here is_swap_pte instead of is_hugetlb_entry_migration and
3880 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
3881 * both cases, and because we can't follow correct pages
3882 * directly from any kind of swap entries.
3883 */
3884 if (absent || is_swap_pte(huge_ptep_get(pte)) ||
3885 ((flags & FOLL_WRITE) &&
3886 !huge_pte_write(huge_ptep_get(pte)))) {
3887 int ret;
3888
3889 if (pte)
3890 spin_unlock(ptl);
3891 ret = hugetlb_fault(mm, vma, vaddr,
3892 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
3893 if (!(ret & VM_FAULT_ERROR))
3894 continue;
3895
3896 remainder = 0;
3897 break;
3898 }
3899
3900 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
3901 page = pte_page(huge_ptep_get(pte));
3902 same_page:
3903 if (pages) {
3904 pages[i] = mem_map_offset(page, pfn_offset);
3905 get_page_foll(pages[i]);
3906 }
3907
3908 if (vmas)
3909 vmas[i] = vma;
3910
3911 vaddr += PAGE_SIZE;
3912 ++pfn_offset;
3913 --remainder;
3914 ++i;
3915 if (vaddr < vma->vm_end && remainder &&
3916 pfn_offset < pages_per_huge_page(h)) {
3917 /*
3918 * We use pfn_offset to avoid touching the pageframes
3919 * of this compound page.
3920 */
3921 goto same_page;
3922 }
3923 spin_unlock(ptl);
3924 }
3925 *nr_pages = remainder;
3926 *position = vaddr;
3927
3928 return i ? i : -EFAULT;
3929 }
3930
3931 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3932 unsigned long address, unsigned long end, pgprot_t newprot)
3933 {
3934 struct mm_struct *mm = vma->vm_mm;
3935 unsigned long start = address;
3936 pte_t *ptep;
3937 pte_t pte;
3938 struct hstate *h = hstate_vma(vma);
3939 unsigned long pages = 0;
3940
3941 BUG_ON(address >= end);
3942 flush_cache_range(vma, address, end);
3943
3944 mmu_notifier_invalidate_range_start(mm, start, end);
3945 i_mmap_lock_write(vma->vm_file->f_mapping);
3946 for (; address < end; address += huge_page_size(h)) {
3947 spinlock_t *ptl;
3948 ptep = huge_pte_offset(mm, address);
3949 if (!ptep)
3950 continue;
3951 ptl = huge_pte_lock(h, mm, ptep);
3952 if (huge_pmd_unshare(mm, &address, ptep)) {
3953 pages++;
3954 spin_unlock(ptl);
3955 continue;
3956 }
3957 pte = huge_ptep_get(ptep);
3958 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
3959 spin_unlock(ptl);
3960 continue;
3961 }
3962 if (unlikely(is_hugetlb_entry_migration(pte))) {
3963 swp_entry_t entry = pte_to_swp_entry(pte);
3964
3965 if (is_write_migration_entry(entry)) {
3966 pte_t newpte;
3967
3968 make_migration_entry_read(&entry);
3969 newpte = swp_entry_to_pte(entry);
3970 set_huge_pte_at(mm, address, ptep, newpte);
3971 pages++;
3972 }
3973 spin_unlock(ptl);
3974 continue;
3975 }
3976 if (!huge_pte_none(pte)) {
3977 pte = huge_ptep_get_and_clear(mm, address, ptep);
3978 pte = pte_mkhuge(huge_pte_modify(pte, newprot));
3979 pte = arch_make_huge_pte(pte, vma, NULL, 0);
3980 set_huge_pte_at(mm, address, ptep, pte);
3981 pages++;
3982 }
3983 spin_unlock(ptl);
3984 }
3985 /*
3986 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
3987 * may have cleared our pud entry and done put_page on the page table:
3988 * once we release i_mmap_rwsem, another task can do the final put_page
3989 * and that page table be reused and filled with junk.
3990 */
3991 flush_tlb_range(vma, start, end);
3992 mmu_notifier_invalidate_range(mm, start, end);
3993 i_mmap_unlock_write(vma->vm_file->f_mapping);
3994 mmu_notifier_invalidate_range_end(mm, start, end);
3995
3996 return pages << h->order;
3997 }
3998
3999 int hugetlb_reserve_pages(struct inode *inode,
4000 long from, long to,
4001 struct vm_area_struct *vma,
4002 vm_flags_t vm_flags)
4003 {
4004 long ret, chg;
4005 struct hstate *h = hstate_inode(inode);
4006 struct hugepage_subpool *spool = subpool_inode(inode);
4007 struct resv_map *resv_map;
4008 long gbl_reserve;
4009
4010 /*
4011 * Only apply hugepage reservation if asked. At fault time, an
4012 * attempt will be made for VM_NORESERVE to allocate a page
4013 * without using reserves
4014 */
4015 if (vm_flags & VM_NORESERVE)
4016 return 0;
4017
4018 /*
4019 * Shared mappings base their reservation on the number of pages that
4020 * are already allocated on behalf of the file. Private mappings need
4021 * to reserve the full area even if read-only as mprotect() may be
4022 * called to make the mapping read-write. Assume !vma is a shm mapping
4023 */
4024 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4025 resv_map = inode_resv_map(inode);
4026
4027 chg = region_chg(resv_map, from, to);
4028
4029 } else {
4030 resv_map = resv_map_alloc();
4031 if (!resv_map)
4032 return -ENOMEM;
4033
4034 chg = to - from;
4035
4036 set_vma_resv_map(vma, resv_map);
4037 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
4038 }
4039
4040 if (chg < 0) {
4041 ret = chg;
4042 goto out_err;
4043 }
4044
4045 /*
4046 * There must be enough pages in the subpool for the mapping. If
4047 * the subpool has a minimum size, there may be some global
4048 * reservations already in place (gbl_reserve).
4049 */
4050 gbl_reserve = hugepage_subpool_get_pages(spool, chg);
4051 if (gbl_reserve < 0) {
4052 ret = -ENOSPC;
4053 goto out_err;
4054 }
4055
4056 /*
4057 * Check enough hugepages are available for the reservation.
4058 * Hand the pages back to the subpool if there are not
4059 */
4060 ret = hugetlb_acct_memory(h, gbl_reserve);
4061 if (ret < 0) {
4062 /* put back original number of pages, chg */
4063 (void)hugepage_subpool_put_pages(spool, chg);
4064 goto out_err;
4065 }
4066
4067 /*
4068 * Account for the reservations made. Shared mappings record regions
4069 * that have reservations as they are shared by multiple VMAs.
4070 * When the last VMA disappears, the region map says how much
4071 * the reservation was and the page cache tells how much of
4072 * the reservation was consumed. Private mappings are per-VMA and
4073 * only the consumed reservations are tracked. When the VMA
4074 * disappears, the original reservation is the VMA size and the
4075 * consumed reservations are stored in the map. Hence, nothing
4076 * else has to be done for private mappings here
4077 */
4078 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4079 long add = region_add(resv_map, from, to);
4080
4081 if (unlikely(chg > add)) {
4082 /*
4083 * pages in this range were added to the reserve
4084 * map between region_chg and region_add. This
4085 * indicates a race with alloc_huge_page. Adjust
4086 * the subpool and reserve counts modified above
4087 * based on the difference.
4088 */
4089 long rsv_adjust;
4090
4091 rsv_adjust = hugepage_subpool_put_pages(spool,
4092 chg - add);
4093 hugetlb_acct_memory(h, -rsv_adjust);
4094 }
4095 }
4096 return 0;
4097 out_err:
4098 if (!vma || vma->vm_flags & VM_MAYSHARE)
4099 region_abort(resv_map, from, to);
4100 if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
4101 kref_put(&resv_map->refs, resv_map_release);
4102 return ret;
4103 }
4104
4105 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
4106 long freed)
4107 {
4108 struct hstate *h = hstate_inode(inode);
4109 struct resv_map *resv_map = inode_resv_map(inode);
4110 long chg = 0;
4111 struct hugepage_subpool *spool = subpool_inode(inode);
4112 long gbl_reserve;
4113
4114 if (resv_map) {
4115 chg = region_del(resv_map, start, end);
4116 /*
4117 * region_del() can fail in the rare case where a region
4118 * must be split and another region descriptor can not be
4119 * allocated. If end == LONG_MAX, it will not fail.
4120 */
4121 if (chg < 0)
4122 return chg;
4123 }
4124
4125 spin_lock(&inode->i_lock);
4126 inode->i_blocks -= (blocks_per_huge_page(h) * freed);
4127 spin_unlock(&inode->i_lock);
4128
4129 /*
4130 * If the subpool has a minimum size, the number of global
4131 * reservations to be released may be adjusted.
4132 */
4133 gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
4134 hugetlb_acct_memory(h, -gbl_reserve);
4135
4136 return 0;
4137 }
4138
4139 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
4140 static unsigned long page_table_shareable(struct vm_area_struct *svma,
4141 struct vm_area_struct *vma,
4142 unsigned long addr, pgoff_t idx)
4143 {
4144 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
4145 svma->vm_start;
4146 unsigned long sbase = saddr & PUD_MASK;
4147 unsigned long s_end = sbase + PUD_SIZE;
4148
4149 /* Allow segments to share if only one is marked locked */
4150 unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
4151 unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4152
4153 /*
4154 * match the virtual addresses, permission and the alignment of the
4155 * page table page.
4156 */
4157 if (pmd_index(addr) != pmd_index(saddr) ||
4158 vm_flags != svm_flags ||
4159 sbase < svma->vm_start || svma->vm_end < s_end)
4160 return 0;
4161
4162 return saddr;
4163 }
4164
4165 static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4166 {
4167 unsigned long base = addr & PUD_MASK;
4168 unsigned long end = base + PUD_SIZE;
4169
4170 /*
4171 * check on proper vm_flags and page table alignment
4172 */
4173 if (vma->vm_flags & VM_MAYSHARE &&
4174 vma->vm_start <= base && end <= vma->vm_end)
4175 return true;
4176 return false;
4177 }
4178
4179 /*
4180 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
4181 * and returns the corresponding pte. While this is not necessary for the
4182 * !shared pmd case because we can allocate the pmd later as well, it makes the
4183 * code much cleaner. pmd allocation is essential for the shared case because
4184 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4185 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
4186 * bad pmd for sharing.
4187 */
4188 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4189 {
4190 struct vm_area_struct *vma = find_vma(mm, addr);
4191 struct address_space *mapping = vma->vm_file->f_mapping;
4192 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
4193 vma->vm_pgoff;
4194 struct vm_area_struct *svma;
4195 unsigned long saddr;
4196 pte_t *spte = NULL;
4197 pte_t *pte;
4198 spinlock_t *ptl;
4199
4200 if (!vma_shareable(vma, addr))
4201 return (pte_t *)pmd_alloc(mm, pud, addr);
4202
4203 i_mmap_lock_write(mapping);
4204 vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
4205 if (svma == vma)
4206 continue;
4207
4208 saddr = page_table_shareable(svma, vma, addr, idx);
4209 if (saddr) {
4210 spte = huge_pte_offset(svma->vm_mm, saddr);
4211 if (spte) {
4212 mm_inc_nr_pmds(mm);
4213 get_page(virt_to_page(spte));
4214 break;
4215 }
4216 }
4217 }
4218
4219 if (!spte)
4220 goto out;
4221
4222 ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
4223 spin_lock(ptl);
4224 if (pud_none(*pud)) {
4225 pud_populate(mm, pud,
4226 (pmd_t *)((unsigned long)spte & PAGE_MASK));
4227 } else {
4228 put_page(virt_to_page(spte));
4229 mm_inc_nr_pmds(mm);
4230 }
4231 spin_unlock(ptl);
4232 out:
4233 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4234 i_mmap_unlock_write(mapping);
4235 return pte;
4236 }
4237
4238 /*
4239 * unmap huge page backed by shared pte.
4240 *
4241 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
4242 * indicated by page_count > 1, unmap is achieved by clearing pud and
4243 * decrementing the ref count. If count == 1, the pte page is not shared.
4244 *
4245 * called with page table lock held.
4246 *
4247 * returns: 1 successfully unmapped a shared pte page
4248 * 0 the underlying pte page is not shared, or it is the last user
4249 */
4250 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4251 {
4252 pgd_t *pgd = pgd_offset(mm, *addr);
4253 pud_t *pud = pud_offset(pgd, *addr);
4254
4255 BUG_ON(page_count(virt_to_page(ptep)) == 0);
4256 if (page_count(virt_to_page(ptep)) == 1)
4257 return 0;
4258
4259 pud_clear(pud);
4260 put_page(virt_to_page(ptep));
4261 mm_dec_nr_pmds(mm);
4262 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
4263 return 1;
4264 }
4265 #define want_pmd_share() (1)
4266 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4267 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4268 {
4269 return NULL;
4270 }
4271
4272 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4273 {
4274 return 0;
4275 }
4276 #define want_pmd_share() (0)
4277 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4278
4279 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
4280 pte_t *huge_pte_alloc(struct mm_struct *mm,
4281 unsigned long addr, unsigned long sz)
4282 {
4283 pgd_t *pgd;
4284 pud_t *pud;
4285 pte_t *pte = NULL;
4286
4287 pgd = pgd_offset(mm, addr);
4288 pud = pud_alloc(mm, pgd, addr);
4289 if (pud) {
4290 if (sz == PUD_SIZE) {
4291 pte = (pte_t *)pud;
4292 } else {
4293 BUG_ON(sz != PMD_SIZE);
4294 if (want_pmd_share() && pud_none(*pud))
4295 pte = huge_pmd_share(mm, addr, pud);
4296 else
4297 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4298 }
4299 }
4300 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
4301
4302 return pte;
4303 }
4304
4305 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
4306 {
4307 pgd_t *pgd;
4308 pud_t *pud;
4309 pmd_t *pmd = NULL;
4310
4311 pgd = pgd_offset(mm, addr);
4312 if (pgd_present(*pgd)) {
4313 pud = pud_offset(pgd, addr);
4314 if (pud_present(*pud)) {
4315 if (pud_huge(*pud))
4316 return (pte_t *)pud;
4317 pmd = pmd_offset(pud, addr);
4318 }
4319 }
4320 return (pte_t *) pmd;
4321 }
4322
4323 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
4324
4325 /*
4326 * These functions are overwritable if your architecture needs its own
4327 * behavior.
4328 */
4329 struct page * __weak
4330 follow_huge_addr(struct mm_struct *mm, unsigned long address,
4331 int write)
4332 {
4333 return ERR_PTR(-EINVAL);
4334 }
4335
4336 struct page * __weak
4337 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4338 pmd_t *pmd, int flags)
4339 {
4340 struct page *page = NULL;
4341 spinlock_t *ptl;
4342 retry:
4343 ptl = pmd_lockptr(mm, pmd);
4344 spin_lock(ptl);
4345 /*
4346 * make sure that the address range covered by this pmd is not
4347 * unmapped from other threads.
4348 */
4349 if (!pmd_huge(*pmd))
4350 goto out;
4351 if (pmd_present(*pmd)) {
4352 page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4353 if (flags & FOLL_GET)
4354 get_page(page);
4355 } else {
4356 if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
4357 spin_unlock(ptl);
4358 __migration_entry_wait(mm, (pte_t *)pmd, ptl);
4359 goto retry;
4360 }
4361 /*
4362 * hwpoisoned entry is treated as no_page_table in
4363 * follow_page_mask().
4364 */
4365 }
4366 out:
4367 spin_unlock(ptl);
4368 return page;
4369 }
4370
4371 struct page * __weak
4372 follow_huge_pud(struct mm_struct *mm, unsigned long address,
4373 pud_t *pud, int flags)
4374 {
4375 if (flags & FOLL_GET)
4376 return NULL;
4377
4378 return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4379 }
4380
4381 #ifdef CONFIG_MEMORY_FAILURE
4382
4383 /*
4384 * This function is called from memory failure code.
4385 * Assume the caller holds page lock of the head page.
4386 */
4387 int dequeue_hwpoisoned_huge_page(struct page *hpage)
4388 {
4389 struct hstate *h = page_hstate(hpage);
4390 int nid = page_to_nid(hpage);
4391 int ret = -EBUSY;
4392
4393 spin_lock(&hugetlb_lock);
4394 /*
4395 * Just checking !page_huge_active is not enough, because that could be
4396 * an isolated/hwpoisoned hugepage (which have >0 refcount).
4397 */
4398 if (!page_huge_active(hpage) && !page_count(hpage)) {
4399 /*
4400 * Hwpoisoned hugepage isn't linked to activelist or freelist,
4401 * but dangling hpage->lru can trigger list-debug warnings
4402 * (this happens when we call unpoison_memory() on it),
4403 * so let it point to itself with list_del_init().
4404 */
4405 list_del_init(&hpage->lru);
4406 set_page_refcounted(hpage);
4407 h->free_huge_pages--;
4408 h->free_huge_pages_node[nid]--;
4409 ret = 0;
4410 }
4411 spin_unlock(&hugetlb_lock);
4412 return ret;
4413 }
4414 #endif
4415
4416 bool isolate_huge_page(struct page *page, struct list_head *list)
4417 {
4418 bool ret = true;
4419
4420 VM_BUG_ON_PAGE(!PageHead(page), page);
4421 spin_lock(&hugetlb_lock);
4422 if (!page_huge_active(page) || !get_page_unless_zero(page)) {
4423 ret = false;
4424 goto unlock;
4425 }
4426 clear_page_huge_active(page);
4427 list_move_tail(&page->lru, list);
4428 unlock:
4429 spin_unlock(&hugetlb_lock);
4430 return ret;
4431 }
4432
4433 void putback_active_hugepage(struct page *page)
4434 {
4435 VM_BUG_ON_PAGE(!PageHead(page), page);
4436 spin_lock(&hugetlb_lock);
4437 set_page_huge_active(page);
4438 list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
4439 spin_unlock(&hugetlb_lock);
4440 put_page(page);
4441 }