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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/mm.h>
8 #include <linux/seq_file.h>
9 #include <linux/sysctl.h>
10 #include <linux/highmem.h>
11 #include <linux/mmu_notifier.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/compiler.h>
16 #include <linux/cpuset.h>
17 #include <linux/mutex.h>
18 #include <linux/bootmem.h>
19 #include <linux/sysfs.h>
20 #include <linux/slab.h>
21 #include <linux/rmap.h>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24 #include <linux/page-isolation.h>
25 #include <linux/jhash.h>
26
27 #include <asm/page.h>
28 #include <asm/pgtable.h>
29 #include <asm/tlb.h>
30
31 #include <linux/io.h>
32 #include <linux/hugetlb.h>
33 #include <linux/hugetlb_cgroup.h>
34 #include <linux/node.h>
35 #include "internal.h"
36
37 int hugepages_treat_as_movable;
38
39 int hugetlb_max_hstate __read_mostly;
40 unsigned int default_hstate_idx;
41 struct hstate hstates[HUGE_MAX_HSTATE];
42 /*
43 * Minimum page order among possible hugepage sizes, set to a proper value
44 * at boot time.
45 */
46 static unsigned int minimum_order __read_mostly = UINT_MAX;
47
48 __initdata LIST_HEAD(huge_boot_pages);
49
50 /* for command line parsing */
51 static struct hstate * __initdata parsed_hstate;
52 static unsigned long __initdata default_hstate_max_huge_pages;
53 static unsigned long __initdata default_hstate_size;
54 static bool __initdata parsed_valid_hugepagesz = true;
55
56 /*
57 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
58 * free_huge_pages, and surplus_huge_pages.
59 */
60 DEFINE_SPINLOCK(hugetlb_lock);
61
62 /*
63 * Serializes faults on the same logical page. This is used to
64 * prevent spurious OOMs when the hugepage pool is fully utilized.
65 */
66 static int num_fault_mutexes;
67 struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
68
69 /* Forward declaration */
70 static int hugetlb_acct_memory(struct hstate *h, long delta);
71
72 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
73 {
74 bool free = (spool->count == 0) && (spool->used_hpages == 0);
75
76 spin_unlock(&spool->lock);
77
78 /* If no pages are used, and no other handles to the subpool
79 * remain, give up any reservations mased on minimum size and
80 * free the subpool */
81 if (free) {
82 if (spool->min_hpages != -1)
83 hugetlb_acct_memory(spool->hstate,
84 -spool->min_hpages);
85 kfree(spool);
86 }
87 }
88
89 struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
90 long min_hpages)
91 {
92 struct hugepage_subpool *spool;
93
94 spool = kzalloc(sizeof(*spool), GFP_KERNEL);
95 if (!spool)
96 return NULL;
97
98 spin_lock_init(&spool->lock);
99 spool->count = 1;
100 spool->max_hpages = max_hpages;
101 spool->hstate = h;
102 spool->min_hpages = min_hpages;
103
104 if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
105 kfree(spool);
106 return NULL;
107 }
108 spool->rsv_hpages = min_hpages;
109
110 return spool;
111 }
112
113 void hugepage_put_subpool(struct hugepage_subpool *spool)
114 {
115 spin_lock(&spool->lock);
116 BUG_ON(!spool->count);
117 spool->count--;
118 unlock_or_release_subpool(spool);
119 }
120
121 /*
122 * Subpool accounting for allocating and reserving pages.
123 * Return -ENOMEM if there are not enough resources to satisfy the
124 * the request. Otherwise, return the number of pages by which the
125 * global pools must be adjusted (upward). The returned value may
126 * only be different than the passed value (delta) in the case where
127 * a subpool minimum size must be manitained.
128 */
129 static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
130 long delta)
131 {
132 long ret = delta;
133
134 if (!spool)
135 return ret;
136
137 spin_lock(&spool->lock);
138
139 if (spool->max_hpages != -1) { /* maximum size accounting */
140 if ((spool->used_hpages + delta) <= spool->max_hpages)
141 spool->used_hpages += delta;
142 else {
143 ret = -ENOMEM;
144 goto unlock_ret;
145 }
146 }
147
148 /* minimum size accounting */
149 if (spool->min_hpages != -1 && spool->rsv_hpages) {
150 if (delta > spool->rsv_hpages) {
151 /*
152 * Asking for more reserves than those already taken on
153 * behalf of subpool. Return difference.
154 */
155 ret = delta - spool->rsv_hpages;
156 spool->rsv_hpages = 0;
157 } else {
158 ret = 0; /* reserves already accounted for */
159 spool->rsv_hpages -= delta;
160 }
161 }
162
163 unlock_ret:
164 spin_unlock(&spool->lock);
165 return ret;
166 }
167
168 /*
169 * Subpool accounting for freeing and unreserving pages.
170 * Return the number of global page reservations that must be dropped.
171 * The return value may only be different than the passed value (delta)
172 * in the case where a subpool minimum size must be maintained.
173 */
174 static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
175 long delta)
176 {
177 long ret = delta;
178
179 if (!spool)
180 return delta;
181
182 spin_lock(&spool->lock);
183
184 if (spool->max_hpages != -1) /* maximum size accounting */
185 spool->used_hpages -= delta;
186
187 /* minimum size accounting */
188 if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
189 if (spool->rsv_hpages + delta <= spool->min_hpages)
190 ret = 0;
191 else
192 ret = spool->rsv_hpages + delta - spool->min_hpages;
193
194 spool->rsv_hpages += delta;
195 if (spool->rsv_hpages > spool->min_hpages)
196 spool->rsv_hpages = spool->min_hpages;
197 }
198
199 /*
200 * If hugetlbfs_put_super couldn't free spool due to an outstanding
201 * quota reference, free it now.
202 */
203 unlock_or_release_subpool(spool);
204
205 return ret;
206 }
207
208 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
209 {
210 return HUGETLBFS_SB(inode->i_sb)->spool;
211 }
212
213 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
214 {
215 return subpool_inode(file_inode(vma->vm_file));
216 }
217
218 /*
219 * Region tracking -- allows tracking of reservations and instantiated pages
220 * across the pages in a mapping.
221 *
222 * The region data structures are embedded into a resv_map and protected
223 * by a resv_map's lock. The set of regions within the resv_map represent
224 * reservations for huge pages, or huge pages that have already been
225 * instantiated within the map. The from and to elements are huge page
226 * indicies into the associated mapping. from indicates the starting index
227 * of the region. to represents the first index past the end of the region.
228 *
229 * For example, a file region structure with from == 0 and to == 4 represents
230 * four huge pages in a mapping. It is important to note that the to element
231 * represents the first element past the end of the region. This is used in
232 * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
233 *
234 * Interval notation of the form [from, to) will be used to indicate that
235 * the endpoint from is inclusive and to is exclusive.
236 */
237 struct file_region {
238 struct list_head link;
239 long from;
240 long to;
241 };
242
243 /*
244 * Add the huge page range represented by [f, t) to the reserve
245 * map. In the normal case, existing regions will be expanded
246 * to accommodate the specified range. Sufficient regions should
247 * exist for expansion due to the previous call to region_chg
248 * with the same range. However, it is possible that region_del
249 * could have been called after region_chg and modifed the map
250 * in such a way that no region exists to be expanded. In this
251 * case, pull a region descriptor from the cache associated with
252 * the map and use that for the new range.
253 *
254 * Return the number of new huge pages added to the map. This
255 * number is greater than or equal to zero.
256 */
257 static long region_add(struct resv_map *resv, long f, long t)
258 {
259 struct list_head *head = &resv->regions;
260 struct file_region *rg, *nrg, *trg;
261 long add = 0;
262
263 spin_lock(&resv->lock);
264 /* Locate the region we are either in or before. */
265 list_for_each_entry(rg, head, link)
266 if (f <= rg->to)
267 break;
268
269 /*
270 * If no region exists which can be expanded to include the
271 * specified range, the list must have been modified by an
272 * interleving call to region_del(). Pull a region descriptor
273 * from the cache and use it for this range.
274 */
275 if (&rg->link == head || t < rg->from) {
276 VM_BUG_ON(resv->region_cache_count <= 0);
277
278 resv->region_cache_count--;
279 nrg = list_first_entry(&resv->region_cache, struct file_region,
280 link);
281 list_del(&nrg->link);
282
283 nrg->from = f;
284 nrg->to = t;
285 list_add(&nrg->link, rg->link.prev);
286
287 add += t - f;
288 goto out_locked;
289 }
290
291 /* Round our left edge to the current segment if it encloses us. */
292 if (f > rg->from)
293 f = rg->from;
294
295 /* Check for and consume any regions we now overlap with. */
296 nrg = rg;
297 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
298 if (&rg->link == head)
299 break;
300 if (rg->from > t)
301 break;
302
303 /* If this area reaches higher then extend our area to
304 * include it completely. If this is not the first area
305 * which we intend to reuse, free it. */
306 if (rg->to > t)
307 t = rg->to;
308 if (rg != nrg) {
309 /* Decrement return value by the deleted range.
310 * Another range will span this area so that by
311 * end of routine add will be >= zero
312 */
313 add -= (rg->to - rg->from);
314 list_del(&rg->link);
315 kfree(rg);
316 }
317 }
318
319 add += (nrg->from - f); /* Added to beginning of region */
320 nrg->from = f;
321 add += t - nrg->to; /* Added to end of region */
322 nrg->to = t;
323
324 out_locked:
325 resv->adds_in_progress--;
326 spin_unlock(&resv->lock);
327 VM_BUG_ON(add < 0);
328 return add;
329 }
330
331 /*
332 * Examine the existing reserve map and determine how many
333 * huge pages in the specified range [f, t) are NOT currently
334 * represented. This routine is called before a subsequent
335 * call to region_add that will actually modify the reserve
336 * map to add the specified range [f, t). region_chg does
337 * not change the number of huge pages represented by the
338 * map. However, if the existing regions in the map can not
339 * be expanded to represent the new range, a new file_region
340 * structure is added to the map as a placeholder. This is
341 * so that the subsequent region_add call will have all the
342 * regions it needs and will not fail.
343 *
344 * Upon entry, region_chg will also examine the cache of region descriptors
345 * associated with the map. If there are not enough descriptors cached, one
346 * will be allocated for the in progress add operation.
347 *
348 * Returns the number of huge pages that need to be added to the existing
349 * reservation map for the range [f, t). This number is greater or equal to
350 * zero. -ENOMEM is returned if a new file_region structure or cache entry
351 * is needed and can not be allocated.
352 */
353 static long region_chg(struct resv_map *resv, long f, long t)
354 {
355 struct list_head *head = &resv->regions;
356 struct file_region *rg, *nrg = NULL;
357 long chg = 0;
358
359 retry:
360 spin_lock(&resv->lock);
361 retry_locked:
362 resv->adds_in_progress++;
363
364 /*
365 * Check for sufficient descriptors in the cache to accommodate
366 * the number of in progress add operations.
367 */
368 if (resv->adds_in_progress > resv->region_cache_count) {
369 struct file_region *trg;
370
371 VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
372 /* Must drop lock to allocate a new descriptor. */
373 resv->adds_in_progress--;
374 spin_unlock(&resv->lock);
375
376 trg = kmalloc(sizeof(*trg), GFP_KERNEL);
377 if (!trg) {
378 kfree(nrg);
379 return -ENOMEM;
380 }
381
382 spin_lock(&resv->lock);
383 list_add(&trg->link, &resv->region_cache);
384 resv->region_cache_count++;
385 goto retry_locked;
386 }
387
388 /* Locate the region we are before or in. */
389 list_for_each_entry(rg, head, link)
390 if (f <= rg->to)
391 break;
392
393 /* If we are below the current region then a new region is required.
394 * Subtle, allocate a new region at the position but make it zero
395 * size such that we can guarantee to record the reservation. */
396 if (&rg->link == head || t < rg->from) {
397 if (!nrg) {
398 resv->adds_in_progress--;
399 spin_unlock(&resv->lock);
400 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
401 if (!nrg)
402 return -ENOMEM;
403
404 nrg->from = f;
405 nrg->to = f;
406 INIT_LIST_HEAD(&nrg->link);
407 goto retry;
408 }
409
410 list_add(&nrg->link, rg->link.prev);
411 chg = t - f;
412 goto out_nrg;
413 }
414
415 /* Round our left edge to the current segment if it encloses us. */
416 if (f > rg->from)
417 f = rg->from;
418 chg = t - f;
419
420 /* Check for and consume any regions we now overlap with. */
421 list_for_each_entry(rg, rg->link.prev, link) {
422 if (&rg->link == head)
423 break;
424 if (rg->from > t)
425 goto out;
426
427 /* We overlap with this area, if it extends further than
428 * us then we must extend ourselves. Account for its
429 * existing reservation. */
430 if (rg->to > t) {
431 chg += rg->to - t;
432 t = rg->to;
433 }
434 chg -= rg->to - rg->from;
435 }
436
437 out:
438 spin_unlock(&resv->lock);
439 /* We already know we raced and no longer need the new region */
440 kfree(nrg);
441 return chg;
442 out_nrg:
443 spin_unlock(&resv->lock);
444 return chg;
445 }
446
447 /*
448 * Abort the in progress add operation. The adds_in_progress field
449 * of the resv_map keeps track of the operations in progress between
450 * calls to region_chg and region_add. Operations are sometimes
451 * aborted after the call to region_chg. In such cases, region_abort
452 * is called to decrement the adds_in_progress counter.
453 *
454 * NOTE: The range arguments [f, t) are not needed or used in this
455 * routine. They are kept to make reading the calling code easier as
456 * arguments will match the associated region_chg call.
457 */
458 static void region_abort(struct resv_map *resv, long f, long t)
459 {
460 spin_lock(&resv->lock);
461 VM_BUG_ON(!resv->region_cache_count);
462 resv->adds_in_progress--;
463 spin_unlock(&resv->lock);
464 }
465
466 /*
467 * Delete the specified range [f, t) from the reserve map. If the
468 * t parameter is LONG_MAX, this indicates that ALL regions after f
469 * should be deleted. Locate the regions which intersect [f, t)
470 * and either trim, delete or split the existing regions.
471 *
472 * Returns the number of huge pages deleted from the reserve map.
473 * In the normal case, the return value is zero or more. In the
474 * case where a region must be split, a new region descriptor must
475 * be allocated. If the allocation fails, -ENOMEM will be returned.
476 * NOTE: If the parameter t == LONG_MAX, then we will never split
477 * a region and possibly return -ENOMEM. Callers specifying
478 * t == LONG_MAX do not need to check for -ENOMEM error.
479 */
480 static long region_del(struct resv_map *resv, long f, long t)
481 {
482 struct list_head *head = &resv->regions;
483 struct file_region *rg, *trg;
484 struct file_region *nrg = NULL;
485 long del = 0;
486
487 retry:
488 spin_lock(&resv->lock);
489 list_for_each_entry_safe(rg, trg, head, link) {
490 /*
491 * Skip regions before the range to be deleted. file_region
492 * ranges are normally of the form [from, to). However, there
493 * may be a "placeholder" entry in the map which is of the form
494 * (from, to) with from == to. Check for placeholder entries
495 * at the beginning of the range to be deleted.
496 */
497 if (rg->to <= f && (rg->to != rg->from || rg->to != f))
498 continue;
499
500 if (rg->from >= t)
501 break;
502
503 if (f > rg->from && t < rg->to) { /* Must split region */
504 /*
505 * Check for an entry in the cache before dropping
506 * lock and attempting allocation.
507 */
508 if (!nrg &&
509 resv->region_cache_count > resv->adds_in_progress) {
510 nrg = list_first_entry(&resv->region_cache,
511 struct file_region,
512 link);
513 list_del(&nrg->link);
514 resv->region_cache_count--;
515 }
516
517 if (!nrg) {
518 spin_unlock(&resv->lock);
519 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
520 if (!nrg)
521 return -ENOMEM;
522 goto retry;
523 }
524
525 del += t - f;
526
527 /* New entry for end of split region */
528 nrg->from = t;
529 nrg->to = rg->to;
530 INIT_LIST_HEAD(&nrg->link);
531
532 /* Original entry is trimmed */
533 rg->to = f;
534
535 list_add(&nrg->link, &rg->link);
536 nrg = NULL;
537 break;
538 }
539
540 if (f <= rg->from && t >= rg->to) { /* Remove entire region */
541 del += rg->to - rg->from;
542 list_del(&rg->link);
543 kfree(rg);
544 continue;
545 }
546
547 if (f <= rg->from) { /* Trim beginning of region */
548 del += t - rg->from;
549 rg->from = t;
550 } else { /* Trim end of region */
551 del += rg->to - f;
552 rg->to = f;
553 }
554 }
555
556 spin_unlock(&resv->lock);
557 kfree(nrg);
558 return del;
559 }
560
561 /*
562 * A rare out of memory error was encountered which prevented removal of
563 * the reserve map region for a page. The huge page itself was free'ed
564 * and removed from the page cache. This routine will adjust the subpool
565 * usage count, and the global reserve count if needed. By incrementing
566 * these counts, the reserve map entry which could not be deleted will
567 * appear as a "reserved" entry instead of simply dangling with incorrect
568 * counts.
569 */
570 void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve)
571 {
572 struct hugepage_subpool *spool = subpool_inode(inode);
573 long rsv_adjust;
574
575 rsv_adjust = hugepage_subpool_get_pages(spool, 1);
576 if (restore_reserve && rsv_adjust) {
577 struct hstate *h = hstate_inode(inode);
578
579 hugetlb_acct_memory(h, 1);
580 }
581 }
582
583 /*
584 * Count and return the number of huge pages in the reserve map
585 * that intersect with the range [f, t).
586 */
587 static long region_count(struct resv_map *resv, long f, long t)
588 {
589 struct list_head *head = &resv->regions;
590 struct file_region *rg;
591 long chg = 0;
592
593 spin_lock(&resv->lock);
594 /* Locate each segment we overlap with, and count that overlap. */
595 list_for_each_entry(rg, head, link) {
596 long seg_from;
597 long seg_to;
598
599 if (rg->to <= f)
600 continue;
601 if (rg->from >= t)
602 break;
603
604 seg_from = max(rg->from, f);
605 seg_to = min(rg->to, t);
606
607 chg += seg_to - seg_from;
608 }
609 spin_unlock(&resv->lock);
610
611 return chg;
612 }
613
614 /*
615 * Convert the address within this vma to the page offset within
616 * the mapping, in pagecache page units; huge pages here.
617 */
618 static pgoff_t vma_hugecache_offset(struct hstate *h,
619 struct vm_area_struct *vma, unsigned long address)
620 {
621 return ((address - vma->vm_start) >> huge_page_shift(h)) +
622 (vma->vm_pgoff >> huge_page_order(h));
623 }
624
625 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
626 unsigned long address)
627 {
628 return vma_hugecache_offset(hstate_vma(vma), vma, address);
629 }
630 EXPORT_SYMBOL_GPL(linear_hugepage_index);
631
632 /*
633 * Return the size of the pages allocated when backing a VMA. In the majority
634 * cases this will be same size as used by the page table entries.
635 */
636 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
637 {
638 struct hstate *hstate;
639
640 if (!is_vm_hugetlb_page(vma))
641 return PAGE_SIZE;
642
643 hstate = hstate_vma(vma);
644
645 return 1UL << huge_page_shift(hstate);
646 }
647 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
648
649 /*
650 * Return the page size being used by the MMU to back a VMA. In the majority
651 * of cases, the page size used by the kernel matches the MMU size. On
652 * architectures where it differs, an architecture-specific version of this
653 * function is required.
654 */
655 #ifndef vma_mmu_pagesize
656 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
657 {
658 return vma_kernel_pagesize(vma);
659 }
660 #endif
661
662 /*
663 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
664 * bits of the reservation map pointer, which are always clear due to
665 * alignment.
666 */
667 #define HPAGE_RESV_OWNER (1UL << 0)
668 #define HPAGE_RESV_UNMAPPED (1UL << 1)
669 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
670
671 /*
672 * These helpers are used to track how many pages are reserved for
673 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
674 * is guaranteed to have their future faults succeed.
675 *
676 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
677 * the reserve counters are updated with the hugetlb_lock held. It is safe
678 * to reset the VMA at fork() time as it is not in use yet and there is no
679 * chance of the global counters getting corrupted as a result of the values.
680 *
681 * The private mapping reservation is represented in a subtly different
682 * manner to a shared mapping. A shared mapping has a region map associated
683 * with the underlying file, this region map represents the backing file
684 * pages which have ever had a reservation assigned which this persists even
685 * after the page is instantiated. A private mapping has a region map
686 * associated with the original mmap which is attached to all VMAs which
687 * reference it, this region map represents those offsets which have consumed
688 * reservation ie. where pages have been instantiated.
689 */
690 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
691 {
692 return (unsigned long)vma->vm_private_data;
693 }
694
695 static void set_vma_private_data(struct vm_area_struct *vma,
696 unsigned long value)
697 {
698 vma->vm_private_data = (void *)value;
699 }
700
701 struct resv_map *resv_map_alloc(void)
702 {
703 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
704 struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
705
706 if (!resv_map || !rg) {
707 kfree(resv_map);
708 kfree(rg);
709 return NULL;
710 }
711
712 kref_init(&resv_map->refs);
713 spin_lock_init(&resv_map->lock);
714 INIT_LIST_HEAD(&resv_map->regions);
715
716 resv_map->adds_in_progress = 0;
717
718 INIT_LIST_HEAD(&resv_map->region_cache);
719 list_add(&rg->link, &resv_map->region_cache);
720 resv_map->region_cache_count = 1;
721
722 return resv_map;
723 }
724
725 void resv_map_release(struct kref *ref)
726 {
727 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
728 struct list_head *head = &resv_map->region_cache;
729 struct file_region *rg, *trg;
730
731 /* Clear out any active regions before we release the map. */
732 region_del(resv_map, 0, LONG_MAX);
733
734 /* ... and any entries left in the cache */
735 list_for_each_entry_safe(rg, trg, head, link) {
736 list_del(&rg->link);
737 kfree(rg);
738 }
739
740 VM_BUG_ON(resv_map->adds_in_progress);
741
742 kfree(resv_map);
743 }
744
745 static inline struct resv_map *inode_resv_map(struct inode *inode)
746 {
747 return inode->i_mapping->private_data;
748 }
749
750 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
751 {
752 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
753 if (vma->vm_flags & VM_MAYSHARE) {
754 struct address_space *mapping = vma->vm_file->f_mapping;
755 struct inode *inode = mapping->host;
756
757 return inode_resv_map(inode);
758
759 } else {
760 return (struct resv_map *)(get_vma_private_data(vma) &
761 ~HPAGE_RESV_MASK);
762 }
763 }
764
765 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
766 {
767 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
768 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
769
770 set_vma_private_data(vma, (get_vma_private_data(vma) &
771 HPAGE_RESV_MASK) | (unsigned long)map);
772 }
773
774 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
775 {
776 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
777 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
778
779 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
780 }
781
782 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
783 {
784 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
785
786 return (get_vma_private_data(vma) & flag) != 0;
787 }
788
789 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
790 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
791 {
792 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
793 if (!(vma->vm_flags & VM_MAYSHARE))
794 vma->vm_private_data = (void *)0;
795 }
796
797 /* Returns true if the VMA has associated reserve pages */
798 static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
799 {
800 if (vma->vm_flags & VM_NORESERVE) {
801 /*
802 * This address is already reserved by other process(chg == 0),
803 * so, we should decrement reserved count. Without decrementing,
804 * reserve count remains after releasing inode, because this
805 * allocated page will go into page cache and is regarded as
806 * coming from reserved pool in releasing step. Currently, we
807 * don't have any other solution to deal with this situation
808 * properly, so add work-around here.
809 */
810 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
811 return true;
812 else
813 return false;
814 }
815
816 /* Shared mappings always use reserves */
817 if (vma->vm_flags & VM_MAYSHARE) {
818 /*
819 * We know VM_NORESERVE is not set. Therefore, there SHOULD
820 * be a region map for all pages. The only situation where
821 * there is no region map is if a hole was punched via
822 * fallocate. In this case, there really are no reverves to
823 * use. This situation is indicated if chg != 0.
824 */
825 if (chg)
826 return false;
827 else
828 return true;
829 }
830
831 /*
832 * Only the process that called mmap() has reserves for
833 * private mappings.
834 */
835 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
836 /*
837 * Like the shared case above, a hole punch or truncate
838 * could have been performed on the private mapping.
839 * Examine the value of chg to determine if reserves
840 * actually exist or were previously consumed.
841 * Very Subtle - The value of chg comes from a previous
842 * call to vma_needs_reserves(). The reserve map for
843 * private mappings has different (opposite) semantics
844 * than that of shared mappings. vma_needs_reserves()
845 * has already taken this difference in semantics into
846 * account. Therefore, the meaning of chg is the same
847 * as in the shared case above. Code could easily be
848 * combined, but keeping it separate draws attention to
849 * subtle differences.
850 */
851 if (chg)
852 return false;
853 else
854 return true;
855 }
856
857 return false;
858 }
859
860 static void enqueue_huge_page(struct hstate *h, struct page *page)
861 {
862 int nid = page_to_nid(page);
863 list_move(&page->lru, &h->hugepage_freelists[nid]);
864 h->free_huge_pages++;
865 h->free_huge_pages_node[nid]++;
866 }
867
868 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
869 {
870 struct page *page;
871
872 list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
873 if (!is_migrate_isolate_page(page))
874 break;
875 /*
876 * if 'non-isolated free hugepage' not found on the list,
877 * the allocation fails.
878 */
879 if (&h->hugepage_freelists[nid] == &page->lru)
880 return NULL;
881 list_move(&page->lru, &h->hugepage_activelist);
882 set_page_refcounted(page);
883 h->free_huge_pages--;
884 h->free_huge_pages_node[nid]--;
885 return page;
886 }
887
888 /* Movability of hugepages depends on migration support. */
889 static inline gfp_t htlb_alloc_mask(struct hstate *h)
890 {
891 if (hugepages_treat_as_movable || hugepage_migration_supported(h))
892 return GFP_HIGHUSER_MOVABLE;
893 else
894 return GFP_HIGHUSER;
895 }
896
897 static struct page *dequeue_huge_page_vma(struct hstate *h,
898 struct vm_area_struct *vma,
899 unsigned long address, int avoid_reserve,
900 long chg)
901 {
902 struct page *page = NULL;
903 struct mempolicy *mpol;
904 nodemask_t *nodemask;
905 struct zonelist *zonelist;
906 struct zone *zone;
907 struct zoneref *z;
908 unsigned int cpuset_mems_cookie;
909
910 /*
911 * A child process with MAP_PRIVATE mappings created by their parent
912 * have no page reserves. This check ensures that reservations are
913 * not "stolen". The child may still get SIGKILLed
914 */
915 if (!vma_has_reserves(vma, chg) &&
916 h->free_huge_pages - h->resv_huge_pages == 0)
917 goto err;
918
919 /* If reserves cannot be used, ensure enough pages are in the pool */
920 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
921 goto err;
922
923 retry_cpuset:
924 cpuset_mems_cookie = read_mems_allowed_begin();
925 zonelist = huge_zonelist(vma, address,
926 htlb_alloc_mask(h), &mpol, &nodemask);
927
928 for_each_zone_zonelist_nodemask(zone, z, zonelist,
929 MAX_NR_ZONES - 1, nodemask) {
930 if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
931 page = dequeue_huge_page_node(h, zone_to_nid(zone));
932 if (page) {
933 if (avoid_reserve)
934 break;
935 if (!vma_has_reserves(vma, chg))
936 break;
937
938 SetPagePrivate(page);
939 h->resv_huge_pages--;
940 break;
941 }
942 }
943 }
944
945 mpol_cond_put(mpol);
946 if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
947 goto retry_cpuset;
948 return page;
949
950 err:
951 return NULL;
952 }
953
954 /*
955 * common helper functions for hstate_next_node_to_{alloc|free}.
956 * We may have allocated or freed a huge page based on a different
957 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
958 * be outside of *nodes_allowed. Ensure that we use an allowed
959 * node for alloc or free.
960 */
961 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
962 {
963 nid = next_node_in(nid, *nodes_allowed);
964 VM_BUG_ON(nid >= MAX_NUMNODES);
965
966 return nid;
967 }
968
969 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
970 {
971 if (!node_isset(nid, *nodes_allowed))
972 nid = next_node_allowed(nid, nodes_allowed);
973 return nid;
974 }
975
976 /*
977 * returns the previously saved node ["this node"] from which to
978 * allocate a persistent huge page for the pool and advance the
979 * next node from which to allocate, handling wrap at end of node
980 * mask.
981 */
982 static int hstate_next_node_to_alloc(struct hstate *h,
983 nodemask_t *nodes_allowed)
984 {
985 int nid;
986
987 VM_BUG_ON(!nodes_allowed);
988
989 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
990 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
991
992 return nid;
993 }
994
995 /*
996 * helper for free_pool_huge_page() - return the previously saved
997 * node ["this node"] from which to free a huge page. Advance the
998 * next node id whether or not we find a free huge page to free so
999 * that the next attempt to free addresses the next node.
1000 */
1001 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
1002 {
1003 int nid;
1004
1005 VM_BUG_ON(!nodes_allowed);
1006
1007 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
1008 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
1009
1010 return nid;
1011 }
1012
1013 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
1014 for (nr_nodes = nodes_weight(*mask); \
1015 nr_nodes > 0 && \
1016 ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \
1017 nr_nodes--)
1018
1019 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
1020 for (nr_nodes = nodes_weight(*mask); \
1021 nr_nodes > 0 && \
1022 ((node = hstate_next_node_to_free(hs, mask)) || 1); \
1023 nr_nodes--)
1024
1025 #if (defined(CONFIG_X86_64) || defined(CONFIG_S390)) && \
1026 ((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || \
1027 defined(CONFIG_CMA))
1028 static void destroy_compound_gigantic_page(struct page *page,
1029 unsigned int order)
1030 {
1031 int i;
1032 int nr_pages = 1 << order;
1033 struct page *p = page + 1;
1034
1035 atomic_set(compound_mapcount_ptr(page), 0);
1036 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1037 clear_compound_head(p);
1038 set_page_refcounted(p);
1039 }
1040
1041 set_compound_order(page, 0);
1042 __ClearPageHead(page);
1043 }
1044
1045 static void free_gigantic_page(struct page *page, unsigned int order)
1046 {
1047 free_contig_range(page_to_pfn(page), 1 << order);
1048 }
1049
1050 static int __alloc_gigantic_page(unsigned long start_pfn,
1051 unsigned long nr_pages)
1052 {
1053 unsigned long end_pfn = start_pfn + nr_pages;
1054 return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1055 }
1056
1057 static bool pfn_range_valid_gigantic(struct zone *z,
1058 unsigned long start_pfn, unsigned long nr_pages)
1059 {
1060 unsigned long i, end_pfn = start_pfn + nr_pages;
1061 struct page *page;
1062
1063 for (i = start_pfn; i < end_pfn; i++) {
1064 if (!pfn_valid(i))
1065 return false;
1066
1067 page = pfn_to_page(i);
1068
1069 if (page_zone(page) != z)
1070 return false;
1071
1072 if (PageReserved(page))
1073 return false;
1074
1075 if (page_count(page) > 0)
1076 return false;
1077
1078 if (PageHuge(page))
1079 return false;
1080 }
1081
1082 return true;
1083 }
1084
1085 static bool zone_spans_last_pfn(const struct zone *zone,
1086 unsigned long start_pfn, unsigned long nr_pages)
1087 {
1088 unsigned long last_pfn = start_pfn + nr_pages - 1;
1089 return zone_spans_pfn(zone, last_pfn);
1090 }
1091
1092 static struct page *alloc_gigantic_page(int nid, unsigned int order)
1093 {
1094 unsigned long nr_pages = 1 << order;
1095 unsigned long ret, pfn, flags;
1096 struct zone *z;
1097
1098 z = NODE_DATA(nid)->node_zones;
1099 for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
1100 spin_lock_irqsave(&z->lock, flags);
1101
1102 pfn = ALIGN(z->zone_start_pfn, nr_pages);
1103 while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1104 if (pfn_range_valid_gigantic(z, pfn, nr_pages)) {
1105 /*
1106 * We release the zone lock here because
1107 * alloc_contig_range() will also lock the zone
1108 * at some point. If there's an allocation
1109 * spinning on this lock, it may win the race
1110 * and cause alloc_contig_range() to fail...
1111 */
1112 spin_unlock_irqrestore(&z->lock, flags);
1113 ret = __alloc_gigantic_page(pfn, nr_pages);
1114 if (!ret)
1115 return pfn_to_page(pfn);
1116 spin_lock_irqsave(&z->lock, flags);
1117 }
1118 pfn += nr_pages;
1119 }
1120
1121 spin_unlock_irqrestore(&z->lock, flags);
1122 }
1123
1124 return NULL;
1125 }
1126
1127 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1128 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1129
1130 static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
1131 {
1132 struct page *page;
1133
1134 page = alloc_gigantic_page(nid, huge_page_order(h));
1135 if (page) {
1136 prep_compound_gigantic_page(page, huge_page_order(h));
1137 prep_new_huge_page(h, page, nid);
1138 }
1139
1140 return page;
1141 }
1142
1143 static int alloc_fresh_gigantic_page(struct hstate *h,
1144 nodemask_t *nodes_allowed)
1145 {
1146 struct page *page = NULL;
1147 int nr_nodes, node;
1148
1149 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1150 page = alloc_fresh_gigantic_page_node(h, node);
1151 if (page)
1152 return 1;
1153 }
1154
1155 return 0;
1156 }
1157
1158 static inline bool gigantic_page_supported(void) { return true; }
1159 #else
1160 static inline bool gigantic_page_supported(void) { return false; }
1161 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1162 static inline void destroy_compound_gigantic_page(struct page *page,
1163 unsigned int order) { }
1164 static inline int alloc_fresh_gigantic_page(struct hstate *h,
1165 nodemask_t *nodes_allowed) { return 0; }
1166 #endif
1167
1168 static void update_and_free_page(struct hstate *h, struct page *page)
1169 {
1170 int i;
1171
1172 if (hstate_is_gigantic(h) && !gigantic_page_supported())
1173 return;
1174
1175 h->nr_huge_pages--;
1176 h->nr_huge_pages_node[page_to_nid(page)]--;
1177 for (i = 0; i < pages_per_huge_page(h); i++) {
1178 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1179 1 << PG_referenced | 1 << PG_dirty |
1180 1 << PG_active | 1 << PG_private |
1181 1 << PG_writeback);
1182 }
1183 VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1184 set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1185 set_page_refcounted(page);
1186 if (hstate_is_gigantic(h)) {
1187 destroy_compound_gigantic_page(page, huge_page_order(h));
1188 free_gigantic_page(page, huge_page_order(h));
1189 } else {
1190 __free_pages(page, huge_page_order(h));
1191 }
1192 }
1193
1194 struct hstate *size_to_hstate(unsigned long size)
1195 {
1196 struct hstate *h;
1197
1198 for_each_hstate(h) {
1199 if (huge_page_size(h) == size)
1200 return h;
1201 }
1202 return NULL;
1203 }
1204
1205 /*
1206 * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1207 * to hstate->hugepage_activelist.)
1208 *
1209 * This function can be called for tail pages, but never returns true for them.
1210 */
1211 bool page_huge_active(struct page *page)
1212 {
1213 VM_BUG_ON_PAGE(!PageHuge(page), page);
1214 return PageHead(page) && PagePrivate(&page[1]);
1215 }
1216
1217 /* never called for tail page */
1218 static void set_page_huge_active(struct page *page)
1219 {
1220 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1221 SetPagePrivate(&page[1]);
1222 }
1223
1224 static void clear_page_huge_active(struct page *page)
1225 {
1226 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1227 ClearPagePrivate(&page[1]);
1228 }
1229
1230 void free_huge_page(struct page *page)
1231 {
1232 /*
1233 * Can't pass hstate in here because it is called from the
1234 * compound page destructor.
1235 */
1236 struct hstate *h = page_hstate(page);
1237 int nid = page_to_nid(page);
1238 struct hugepage_subpool *spool =
1239 (struct hugepage_subpool *)page_private(page);
1240 bool restore_reserve;
1241
1242 set_page_private(page, 0);
1243 page->mapping = NULL;
1244 VM_BUG_ON_PAGE(page_count(page), page);
1245 VM_BUG_ON_PAGE(page_mapcount(page), page);
1246 restore_reserve = PagePrivate(page);
1247 ClearPagePrivate(page);
1248
1249 /*
1250 * A return code of zero implies that the subpool will be under its
1251 * minimum size if the reservation is not restored after page is free.
1252 * Therefore, force restore_reserve operation.
1253 */
1254 if (hugepage_subpool_put_pages(spool, 1) == 0)
1255 restore_reserve = true;
1256
1257 spin_lock(&hugetlb_lock);
1258 clear_page_huge_active(page);
1259 hugetlb_cgroup_uncharge_page(hstate_index(h),
1260 pages_per_huge_page(h), page);
1261 if (restore_reserve)
1262 h->resv_huge_pages++;
1263
1264 if (h->surplus_huge_pages_node[nid]) {
1265 /* remove the page from active list */
1266 list_del(&page->lru);
1267 update_and_free_page(h, page);
1268 h->surplus_huge_pages--;
1269 h->surplus_huge_pages_node[nid]--;
1270 } else {
1271 arch_clear_hugepage_flags(page);
1272 enqueue_huge_page(h, page);
1273 }
1274 spin_unlock(&hugetlb_lock);
1275 }
1276
1277 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1278 {
1279 INIT_LIST_HEAD(&page->lru);
1280 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1281 spin_lock(&hugetlb_lock);
1282 set_hugetlb_cgroup(page, NULL);
1283 h->nr_huge_pages++;
1284 h->nr_huge_pages_node[nid]++;
1285 spin_unlock(&hugetlb_lock);
1286 put_page(page); /* free it into the hugepage allocator */
1287 }
1288
1289 static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1290 {
1291 int i;
1292 int nr_pages = 1 << order;
1293 struct page *p = page + 1;
1294
1295 /* we rely on prep_new_huge_page to set the destructor */
1296 set_compound_order(page, order);
1297 __ClearPageReserved(page);
1298 __SetPageHead(page);
1299 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1300 /*
1301 * For gigantic hugepages allocated through bootmem at
1302 * boot, it's safer to be consistent with the not-gigantic
1303 * hugepages and clear the PG_reserved bit from all tail pages
1304 * too. Otherwse drivers using get_user_pages() to access tail
1305 * pages may get the reference counting wrong if they see
1306 * PG_reserved set on a tail page (despite the head page not
1307 * having PG_reserved set). Enforcing this consistency between
1308 * head and tail pages allows drivers to optimize away a check
1309 * on the head page when they need know if put_page() is needed
1310 * after get_user_pages().
1311 */
1312 __ClearPageReserved(p);
1313 set_page_count(p, 0);
1314 set_compound_head(p, page);
1315 }
1316 atomic_set(compound_mapcount_ptr(page), -1);
1317 }
1318
1319 /*
1320 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1321 * transparent huge pages. See the PageTransHuge() documentation for more
1322 * details.
1323 */
1324 int PageHuge(struct page *page)
1325 {
1326 if (!PageCompound(page))
1327 return 0;
1328
1329 page = compound_head(page);
1330 return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1331 }
1332 EXPORT_SYMBOL_GPL(PageHuge);
1333
1334 /*
1335 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1336 * normal or transparent huge pages.
1337 */
1338 int PageHeadHuge(struct page *page_head)
1339 {
1340 if (!PageHead(page_head))
1341 return 0;
1342
1343 return get_compound_page_dtor(page_head) == free_huge_page;
1344 }
1345
1346 pgoff_t __basepage_index(struct page *page)
1347 {
1348 struct page *page_head = compound_head(page);
1349 pgoff_t index = page_index(page_head);
1350 unsigned long compound_idx;
1351
1352 if (!PageHuge(page_head))
1353 return page_index(page);
1354
1355 if (compound_order(page_head) >= MAX_ORDER)
1356 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1357 else
1358 compound_idx = page - page_head;
1359
1360 return (index << compound_order(page_head)) + compound_idx;
1361 }
1362
1363 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
1364 {
1365 struct page *page;
1366
1367 page = __alloc_pages_node(nid,
1368 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1369 __GFP_REPEAT|__GFP_NOWARN,
1370 huge_page_order(h));
1371 if (page) {
1372 prep_new_huge_page(h, page, nid);
1373 }
1374
1375 return page;
1376 }
1377
1378 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1379 {
1380 struct page *page;
1381 int nr_nodes, node;
1382 int ret = 0;
1383
1384 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1385 page = alloc_fresh_huge_page_node(h, node);
1386 if (page) {
1387 ret = 1;
1388 break;
1389 }
1390 }
1391
1392 if (ret)
1393 count_vm_event(HTLB_BUDDY_PGALLOC);
1394 else
1395 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1396
1397 return ret;
1398 }
1399
1400 /*
1401 * Free huge page from pool from next node to free.
1402 * Attempt to keep persistent huge pages more or less
1403 * balanced over allowed nodes.
1404 * Called with hugetlb_lock locked.
1405 */
1406 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1407 bool acct_surplus)
1408 {
1409 int nr_nodes, node;
1410 int ret = 0;
1411
1412 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1413 /*
1414 * If we're returning unused surplus pages, only examine
1415 * nodes with surplus pages.
1416 */
1417 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1418 !list_empty(&h->hugepage_freelists[node])) {
1419 struct page *page =
1420 list_entry(h->hugepage_freelists[node].next,
1421 struct page, lru);
1422 list_del(&page->lru);
1423 h->free_huge_pages--;
1424 h->free_huge_pages_node[node]--;
1425 if (acct_surplus) {
1426 h->surplus_huge_pages--;
1427 h->surplus_huge_pages_node[node]--;
1428 }
1429 update_and_free_page(h, page);
1430 ret = 1;
1431 break;
1432 }
1433 }
1434
1435 return ret;
1436 }
1437
1438 /*
1439 * Dissolve a given free hugepage into free buddy pages. This function does
1440 * nothing for in-use (including surplus) hugepages.
1441 */
1442 static void dissolve_free_huge_page(struct page *page)
1443 {
1444 spin_lock(&hugetlb_lock);
1445 if (PageHuge(page) && !page_count(page)) {
1446 struct hstate *h = page_hstate(page);
1447 int nid = page_to_nid(page);
1448 list_del(&page->lru);
1449 h->free_huge_pages--;
1450 h->free_huge_pages_node[nid]--;
1451 h->max_huge_pages--;
1452 update_and_free_page(h, page);
1453 }
1454 spin_unlock(&hugetlb_lock);
1455 }
1456
1457 /*
1458 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1459 * make specified memory blocks removable from the system.
1460 * Note that start_pfn should aligned with (minimum) hugepage size.
1461 */
1462 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1463 {
1464 unsigned long pfn;
1465
1466 if (!hugepages_supported())
1467 return;
1468
1469 VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << minimum_order));
1470 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
1471 dissolve_free_huge_page(pfn_to_page(pfn));
1472 }
1473
1474 /*
1475 * There are 3 ways this can get called:
1476 * 1. With vma+addr: we use the VMA's memory policy
1477 * 2. With !vma, but nid=NUMA_NO_NODE: We try to allocate a huge
1478 * page from any node, and let the buddy allocator itself figure
1479 * it out.
1480 * 3. With !vma, but nid!=NUMA_NO_NODE. We allocate a huge page
1481 * strictly from 'nid'
1482 */
1483 static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
1484 struct vm_area_struct *vma, unsigned long addr, int nid)
1485 {
1486 int order = huge_page_order(h);
1487 gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
1488 unsigned int cpuset_mems_cookie;
1489
1490 /*
1491 * We need a VMA to get a memory policy. If we do not
1492 * have one, we use the 'nid' argument.
1493 *
1494 * The mempolicy stuff below has some non-inlined bits
1495 * and calls ->vm_ops. That makes it hard to optimize at
1496 * compile-time, even when NUMA is off and it does
1497 * nothing. This helps the compiler optimize it out.
1498 */
1499 if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1500 /*
1501 * If a specific node is requested, make sure to
1502 * get memory from there, but only when a node
1503 * is explicitly specified.
1504 */
1505 if (nid != NUMA_NO_NODE)
1506 gfp |= __GFP_THISNODE;
1507 /*
1508 * Make sure to call something that can handle
1509 * nid=NUMA_NO_NODE
1510 */
1511 return alloc_pages_node(nid, gfp, order);
1512 }
1513
1514 /*
1515 * OK, so we have a VMA. Fetch the mempolicy and try to
1516 * allocate a huge page with it. We will only reach this
1517 * when CONFIG_NUMA=y.
1518 */
1519 do {
1520 struct page *page;
1521 struct mempolicy *mpol;
1522 struct zonelist *zl;
1523 nodemask_t *nodemask;
1524
1525 cpuset_mems_cookie = read_mems_allowed_begin();
1526 zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
1527 mpol_cond_put(mpol);
1528 page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
1529 if (page)
1530 return page;
1531 } while (read_mems_allowed_retry(cpuset_mems_cookie));
1532
1533 return NULL;
1534 }
1535
1536 /*
1537 * There are two ways to allocate a huge page:
1538 * 1. When you have a VMA and an address (like a fault)
1539 * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
1540 *
1541 * 'vma' and 'addr' are only for (1). 'nid' is always NUMA_NO_NODE in
1542 * this case which signifies that the allocation should be done with
1543 * respect for the VMA's memory policy.
1544 *
1545 * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
1546 * implies that memory policies will not be taken in to account.
1547 */
1548 static struct page *__alloc_buddy_huge_page(struct hstate *h,
1549 struct vm_area_struct *vma, unsigned long addr, int nid)
1550 {
1551 struct page *page;
1552 unsigned int r_nid;
1553
1554 if (hstate_is_gigantic(h))
1555 return NULL;
1556
1557 /*
1558 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
1559 * This makes sure the caller is picking _one_ of the modes with which
1560 * we can call this function, not both.
1561 */
1562 if (vma || (addr != -1)) {
1563 VM_WARN_ON_ONCE(addr == -1);
1564 VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1565 }
1566 /*
1567 * Assume we will successfully allocate the surplus page to
1568 * prevent racing processes from causing the surplus to exceed
1569 * overcommit
1570 *
1571 * This however introduces a different race, where a process B
1572 * tries to grow the static hugepage pool while alloc_pages() is
1573 * called by process A. B will only examine the per-node
1574 * counters in determining if surplus huge pages can be
1575 * converted to normal huge pages in adjust_pool_surplus(). A
1576 * won't be able to increment the per-node counter, until the
1577 * lock is dropped by B, but B doesn't drop hugetlb_lock until
1578 * no more huge pages can be converted from surplus to normal
1579 * state (and doesn't try to convert again). Thus, we have a
1580 * case where a surplus huge page exists, the pool is grown, and
1581 * the surplus huge page still exists after, even though it
1582 * should just have been converted to a normal huge page. This
1583 * does not leak memory, though, as the hugepage will be freed
1584 * once it is out of use. It also does not allow the counters to
1585 * go out of whack in adjust_pool_surplus() as we don't modify
1586 * the node values until we've gotten the hugepage and only the
1587 * per-node value is checked there.
1588 */
1589 spin_lock(&hugetlb_lock);
1590 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1591 spin_unlock(&hugetlb_lock);
1592 return NULL;
1593 } else {
1594 h->nr_huge_pages++;
1595 h->surplus_huge_pages++;
1596 }
1597 spin_unlock(&hugetlb_lock);
1598
1599 page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1600
1601 spin_lock(&hugetlb_lock);
1602 if (page) {
1603 INIT_LIST_HEAD(&page->lru);
1604 r_nid = page_to_nid(page);
1605 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1606 set_hugetlb_cgroup(page, NULL);
1607 /*
1608 * We incremented the global counters already
1609 */
1610 h->nr_huge_pages_node[r_nid]++;
1611 h->surplus_huge_pages_node[r_nid]++;
1612 __count_vm_event(HTLB_BUDDY_PGALLOC);
1613 } else {
1614 h->nr_huge_pages--;
1615 h->surplus_huge_pages--;
1616 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1617 }
1618 spin_unlock(&hugetlb_lock);
1619
1620 return page;
1621 }
1622
1623 /*
1624 * Allocate a huge page from 'nid'. Note, 'nid' may be
1625 * NUMA_NO_NODE, which means that it may be allocated
1626 * anywhere.
1627 */
1628 static
1629 struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
1630 {
1631 unsigned long addr = -1;
1632
1633 return __alloc_buddy_huge_page(h, NULL, addr, nid);
1634 }
1635
1636 /*
1637 * Use the VMA's mpolicy to allocate a huge page from the buddy.
1638 */
1639 static
1640 struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
1641 struct vm_area_struct *vma, unsigned long addr)
1642 {
1643 return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
1644 }
1645
1646 /*
1647 * This allocation function is useful in the context where vma is irrelevant.
1648 * E.g. soft-offlining uses this function because it only cares physical
1649 * address of error page.
1650 */
1651 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1652 {
1653 struct page *page = NULL;
1654
1655 spin_lock(&hugetlb_lock);
1656 if (h->free_huge_pages - h->resv_huge_pages > 0)
1657 page = dequeue_huge_page_node(h, nid);
1658 spin_unlock(&hugetlb_lock);
1659
1660 if (!page)
1661 page = __alloc_buddy_huge_page_no_mpol(h, nid);
1662
1663 return page;
1664 }
1665
1666 /*
1667 * Increase the hugetlb pool such that it can accommodate a reservation
1668 * of size 'delta'.
1669 */
1670 static int gather_surplus_pages(struct hstate *h, int delta)
1671 {
1672 struct list_head surplus_list;
1673 struct page *page, *tmp;
1674 int ret, i;
1675 int needed, allocated;
1676 bool alloc_ok = true;
1677
1678 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1679 if (needed <= 0) {
1680 h->resv_huge_pages += delta;
1681 return 0;
1682 }
1683
1684 allocated = 0;
1685 INIT_LIST_HEAD(&surplus_list);
1686
1687 ret = -ENOMEM;
1688 retry:
1689 spin_unlock(&hugetlb_lock);
1690 for (i = 0; i < needed; i++) {
1691 page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1692 if (!page) {
1693 alloc_ok = false;
1694 break;
1695 }
1696 list_add(&page->lru, &surplus_list);
1697 }
1698 allocated += i;
1699
1700 /*
1701 * After retaking hugetlb_lock, we need to recalculate 'needed'
1702 * because either resv_huge_pages or free_huge_pages may have changed.
1703 */
1704 spin_lock(&hugetlb_lock);
1705 needed = (h->resv_huge_pages + delta) -
1706 (h->free_huge_pages + allocated);
1707 if (needed > 0) {
1708 if (alloc_ok)
1709 goto retry;
1710 /*
1711 * We were not able to allocate enough pages to
1712 * satisfy the entire reservation so we free what
1713 * we've allocated so far.
1714 */
1715 goto free;
1716 }
1717 /*
1718 * The surplus_list now contains _at_least_ the number of extra pages
1719 * needed to accommodate the reservation. Add the appropriate number
1720 * of pages to the hugetlb pool and free the extras back to the buddy
1721 * allocator. Commit the entire reservation here to prevent another
1722 * process from stealing the pages as they are added to the pool but
1723 * before they are reserved.
1724 */
1725 needed += allocated;
1726 h->resv_huge_pages += delta;
1727 ret = 0;
1728
1729 /* Free the needed pages to the hugetlb pool */
1730 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1731 if ((--needed) < 0)
1732 break;
1733 /*
1734 * This page is now managed by the hugetlb allocator and has
1735 * no users -- drop the buddy allocator's reference.
1736 */
1737 put_page_testzero(page);
1738 VM_BUG_ON_PAGE(page_count(page), page);
1739 enqueue_huge_page(h, page);
1740 }
1741 free:
1742 spin_unlock(&hugetlb_lock);
1743
1744 /* Free unnecessary surplus pages to the buddy allocator */
1745 list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1746 put_page(page);
1747 spin_lock(&hugetlb_lock);
1748
1749 return ret;
1750 }
1751
1752 /*
1753 * When releasing a hugetlb pool reservation, any surplus pages that were
1754 * allocated to satisfy the reservation must be explicitly freed if they were
1755 * never used.
1756 * Called with hugetlb_lock held.
1757 */
1758 static void return_unused_surplus_pages(struct hstate *h,
1759 unsigned long unused_resv_pages)
1760 {
1761 unsigned long nr_pages;
1762
1763 /* Uncommit the reservation */
1764 h->resv_huge_pages -= unused_resv_pages;
1765
1766 /* Cannot return gigantic pages currently */
1767 if (hstate_is_gigantic(h))
1768 return;
1769
1770 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1771
1772 /*
1773 * We want to release as many surplus pages as possible, spread
1774 * evenly across all nodes with memory. Iterate across these nodes
1775 * until we can no longer free unreserved surplus pages. This occurs
1776 * when the nodes with surplus pages have no free pages.
1777 * free_pool_huge_page() will balance the the freed pages across the
1778 * on-line nodes with memory and will handle the hstate accounting.
1779 */
1780 while (nr_pages--) {
1781 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1782 break;
1783 cond_resched_lock(&hugetlb_lock);
1784 }
1785 }
1786
1787
1788 /*
1789 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1790 * are used by the huge page allocation routines to manage reservations.
1791 *
1792 * vma_needs_reservation is called to determine if the huge page at addr
1793 * within the vma has an associated reservation. If a reservation is
1794 * needed, the value 1 is returned. The caller is then responsible for
1795 * managing the global reservation and subpool usage counts. After
1796 * the huge page has been allocated, vma_commit_reservation is called
1797 * to add the page to the reservation map. If the page allocation fails,
1798 * the reservation must be ended instead of committed. vma_end_reservation
1799 * is called in such cases.
1800 *
1801 * In the normal case, vma_commit_reservation returns the same value
1802 * as the preceding vma_needs_reservation call. The only time this
1803 * is not the case is if a reserve map was changed between calls. It
1804 * is the responsibility of the caller to notice the difference and
1805 * take appropriate action.
1806 */
1807 enum vma_resv_mode {
1808 VMA_NEEDS_RESV,
1809 VMA_COMMIT_RESV,
1810 VMA_END_RESV,
1811 };
1812 static long __vma_reservation_common(struct hstate *h,
1813 struct vm_area_struct *vma, unsigned long addr,
1814 enum vma_resv_mode mode)
1815 {
1816 struct resv_map *resv;
1817 pgoff_t idx;
1818 long ret;
1819
1820 resv = vma_resv_map(vma);
1821 if (!resv)
1822 return 1;
1823
1824 idx = vma_hugecache_offset(h, vma, addr);
1825 switch (mode) {
1826 case VMA_NEEDS_RESV:
1827 ret = region_chg(resv, idx, idx + 1);
1828 break;
1829 case VMA_COMMIT_RESV:
1830 ret = region_add(resv, idx, idx + 1);
1831 break;
1832 case VMA_END_RESV:
1833 region_abort(resv, idx, idx + 1);
1834 ret = 0;
1835 break;
1836 default:
1837 BUG();
1838 }
1839
1840 if (vma->vm_flags & VM_MAYSHARE)
1841 return ret;
1842 else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
1843 /*
1844 * In most cases, reserves always exist for private mappings.
1845 * However, a file associated with mapping could have been
1846 * hole punched or truncated after reserves were consumed.
1847 * As subsequent fault on such a range will not use reserves.
1848 * Subtle - The reserve map for private mappings has the
1849 * opposite meaning than that of shared mappings. If NO
1850 * entry is in the reserve map, it means a reservation exists.
1851 * If an entry exists in the reserve map, it means the
1852 * reservation has already been consumed. As a result, the
1853 * return value of this routine is the opposite of the
1854 * value returned from reserve map manipulation routines above.
1855 */
1856 if (ret)
1857 return 0;
1858 else
1859 return 1;
1860 }
1861 else
1862 return ret < 0 ? ret : 0;
1863 }
1864
1865 static long vma_needs_reservation(struct hstate *h,
1866 struct vm_area_struct *vma, unsigned long addr)
1867 {
1868 return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1869 }
1870
1871 static long vma_commit_reservation(struct hstate *h,
1872 struct vm_area_struct *vma, unsigned long addr)
1873 {
1874 return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1875 }
1876
1877 static void vma_end_reservation(struct hstate *h,
1878 struct vm_area_struct *vma, unsigned long addr)
1879 {
1880 (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1881 }
1882
1883 struct page *alloc_huge_page(struct vm_area_struct *vma,
1884 unsigned long addr, int avoid_reserve)
1885 {
1886 struct hugepage_subpool *spool = subpool_vma(vma);
1887 struct hstate *h = hstate_vma(vma);
1888 struct page *page;
1889 long map_chg, map_commit;
1890 long gbl_chg;
1891 int ret, idx;
1892 struct hugetlb_cgroup *h_cg;
1893
1894 idx = hstate_index(h);
1895 /*
1896 * Examine the region/reserve map to determine if the process
1897 * has a reservation for the page to be allocated. A return
1898 * code of zero indicates a reservation exists (no change).
1899 */
1900 map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
1901 if (map_chg < 0)
1902 return ERR_PTR(-ENOMEM);
1903
1904 /*
1905 * Processes that did not create the mapping will have no
1906 * reserves as indicated by the region/reserve map. Check
1907 * that the allocation will not exceed the subpool limit.
1908 * Allocations for MAP_NORESERVE mappings also need to be
1909 * checked against any subpool limit.
1910 */
1911 if (map_chg || avoid_reserve) {
1912 gbl_chg = hugepage_subpool_get_pages(spool, 1);
1913 if (gbl_chg < 0) {
1914 vma_end_reservation(h, vma, addr);
1915 return ERR_PTR(-ENOSPC);
1916 }
1917
1918 /*
1919 * Even though there was no reservation in the region/reserve
1920 * map, there could be reservations associated with the
1921 * subpool that can be used. This would be indicated if the
1922 * return value of hugepage_subpool_get_pages() is zero.
1923 * However, if avoid_reserve is specified we still avoid even
1924 * the subpool reservations.
1925 */
1926 if (avoid_reserve)
1927 gbl_chg = 1;
1928 }
1929
1930 ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1931 if (ret)
1932 goto out_subpool_put;
1933
1934 spin_lock(&hugetlb_lock);
1935 /*
1936 * glb_chg is passed to indicate whether or not a page must be taken
1937 * from the global free pool (global change). gbl_chg == 0 indicates
1938 * a reservation exists for the allocation.
1939 */
1940 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
1941 if (!page) {
1942 spin_unlock(&hugetlb_lock);
1943 page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
1944 if (!page)
1945 goto out_uncharge_cgroup;
1946 if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
1947 SetPagePrivate(page);
1948 h->resv_huge_pages--;
1949 }
1950 spin_lock(&hugetlb_lock);
1951 list_move(&page->lru, &h->hugepage_activelist);
1952 /* Fall through */
1953 }
1954 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
1955 spin_unlock(&hugetlb_lock);
1956
1957 set_page_private(page, (unsigned long)spool);
1958
1959 map_commit = vma_commit_reservation(h, vma, addr);
1960 if (unlikely(map_chg > map_commit)) {
1961 /*
1962 * The page was added to the reservation map between
1963 * vma_needs_reservation and vma_commit_reservation.
1964 * This indicates a race with hugetlb_reserve_pages.
1965 * Adjust for the subpool count incremented above AND
1966 * in hugetlb_reserve_pages for the same page. Also,
1967 * the reservation count added in hugetlb_reserve_pages
1968 * no longer applies.
1969 */
1970 long rsv_adjust;
1971
1972 rsv_adjust = hugepage_subpool_put_pages(spool, 1);
1973 hugetlb_acct_memory(h, -rsv_adjust);
1974 }
1975 return page;
1976
1977 out_uncharge_cgroup:
1978 hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
1979 out_subpool_put:
1980 if (map_chg || avoid_reserve)
1981 hugepage_subpool_put_pages(spool, 1);
1982 vma_end_reservation(h, vma, addr);
1983 return ERR_PTR(-ENOSPC);
1984 }
1985
1986 /*
1987 * alloc_huge_page()'s wrapper which simply returns the page if allocation
1988 * succeeds, otherwise NULL. This function is called from new_vma_page(),
1989 * where no ERR_VALUE is expected to be returned.
1990 */
1991 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
1992 unsigned long addr, int avoid_reserve)
1993 {
1994 struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
1995 if (IS_ERR(page))
1996 page = NULL;
1997 return page;
1998 }
1999
2000 int __weak alloc_bootmem_huge_page(struct hstate *h)
2001 {
2002 struct huge_bootmem_page *m;
2003 int nr_nodes, node;
2004
2005 for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2006 void *addr;
2007
2008 addr = memblock_virt_alloc_try_nid_nopanic(
2009 huge_page_size(h), huge_page_size(h),
2010 0, BOOTMEM_ALLOC_ACCESSIBLE, node);
2011 if (addr) {
2012 /*
2013 * Use the beginning of the huge page to store the
2014 * huge_bootmem_page struct (until gather_bootmem
2015 * puts them into the mem_map).
2016 */
2017 m = addr;
2018 goto found;
2019 }
2020 }
2021 return 0;
2022
2023 found:
2024 BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2025 /* Put them into a private list first because mem_map is not up yet */
2026 list_add(&m->list, &huge_boot_pages);
2027 m->hstate = h;
2028 return 1;
2029 }
2030
2031 static void __init prep_compound_huge_page(struct page *page,
2032 unsigned int order)
2033 {
2034 if (unlikely(order > (MAX_ORDER - 1)))
2035 prep_compound_gigantic_page(page, order);
2036 else
2037 prep_compound_page(page, order);
2038 }
2039
2040 /* Put bootmem huge pages into the standard lists after mem_map is up */
2041 static void __init gather_bootmem_prealloc(void)
2042 {
2043 struct huge_bootmem_page *m;
2044
2045 list_for_each_entry(m, &huge_boot_pages, list) {
2046 struct hstate *h = m->hstate;
2047 struct page *page;
2048
2049 #ifdef CONFIG_HIGHMEM
2050 page = pfn_to_page(m->phys >> PAGE_SHIFT);
2051 memblock_free_late(__pa(m),
2052 sizeof(struct huge_bootmem_page));
2053 #else
2054 page = virt_to_page(m);
2055 #endif
2056 WARN_ON(page_count(page) != 1);
2057 prep_compound_huge_page(page, h->order);
2058 WARN_ON(PageReserved(page));
2059 prep_new_huge_page(h, page, page_to_nid(page));
2060 /*
2061 * If we had gigantic hugepages allocated at boot time, we need
2062 * to restore the 'stolen' pages to totalram_pages in order to
2063 * fix confusing memory reports from free(1) and another
2064 * side-effects, like CommitLimit going negative.
2065 */
2066 if (hstate_is_gigantic(h))
2067 adjust_managed_page_count(page, 1 << h->order);
2068 }
2069 }
2070
2071 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2072 {
2073 unsigned long i;
2074
2075 for (i = 0; i < h->max_huge_pages; ++i) {
2076 if (hstate_is_gigantic(h)) {
2077 if (!alloc_bootmem_huge_page(h))
2078 break;
2079 } else if (!alloc_fresh_huge_page(h,
2080 &node_states[N_MEMORY]))
2081 break;
2082 }
2083 h->max_huge_pages = i;
2084 }
2085
2086 static void __init hugetlb_init_hstates(void)
2087 {
2088 struct hstate *h;
2089
2090 for_each_hstate(h) {
2091 if (minimum_order > huge_page_order(h))
2092 minimum_order = huge_page_order(h);
2093
2094 /* oversize hugepages were init'ed in early boot */
2095 if (!hstate_is_gigantic(h))
2096 hugetlb_hstate_alloc_pages(h);
2097 }
2098 VM_BUG_ON(minimum_order == UINT_MAX);
2099 }
2100
2101 static char * __init memfmt(char *buf, unsigned long n)
2102 {
2103 if (n >= (1UL << 30))
2104 sprintf(buf, "%lu GB", n >> 30);
2105 else if (n >= (1UL << 20))
2106 sprintf(buf, "%lu MB", n >> 20);
2107 else
2108 sprintf(buf, "%lu KB", n >> 10);
2109 return buf;
2110 }
2111
2112 static void __init report_hugepages(void)
2113 {
2114 struct hstate *h;
2115
2116 for_each_hstate(h) {
2117 char buf[32];
2118 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2119 memfmt(buf, huge_page_size(h)),
2120 h->free_huge_pages);
2121 }
2122 }
2123
2124 #ifdef CONFIG_HIGHMEM
2125 static void try_to_free_low(struct hstate *h, unsigned long count,
2126 nodemask_t *nodes_allowed)
2127 {
2128 int i;
2129
2130 if (hstate_is_gigantic(h))
2131 return;
2132
2133 for_each_node_mask(i, *nodes_allowed) {
2134 struct page *page, *next;
2135 struct list_head *freel = &h->hugepage_freelists[i];
2136 list_for_each_entry_safe(page, next, freel, lru) {
2137 if (count >= h->nr_huge_pages)
2138 return;
2139 if (PageHighMem(page))
2140 continue;
2141 list_del(&page->lru);
2142 update_and_free_page(h, page);
2143 h->free_huge_pages--;
2144 h->free_huge_pages_node[page_to_nid(page)]--;
2145 }
2146 }
2147 }
2148 #else
2149 static inline void try_to_free_low(struct hstate *h, unsigned long count,
2150 nodemask_t *nodes_allowed)
2151 {
2152 }
2153 #endif
2154
2155 /*
2156 * Increment or decrement surplus_huge_pages. Keep node-specific counters
2157 * balanced by operating on them in a round-robin fashion.
2158 * Returns 1 if an adjustment was made.
2159 */
2160 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2161 int delta)
2162 {
2163 int nr_nodes, node;
2164
2165 VM_BUG_ON(delta != -1 && delta != 1);
2166
2167 if (delta < 0) {
2168 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2169 if (h->surplus_huge_pages_node[node])
2170 goto found;
2171 }
2172 } else {
2173 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2174 if (h->surplus_huge_pages_node[node] <
2175 h->nr_huge_pages_node[node])
2176 goto found;
2177 }
2178 }
2179 return 0;
2180
2181 found:
2182 h->surplus_huge_pages += delta;
2183 h->surplus_huge_pages_node[node] += delta;
2184 return 1;
2185 }
2186
2187 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2188 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2189 nodemask_t *nodes_allowed)
2190 {
2191 unsigned long min_count, ret;
2192
2193 if (hstate_is_gigantic(h) && !gigantic_page_supported())
2194 return h->max_huge_pages;
2195
2196 /*
2197 * Increase the pool size
2198 * First take pages out of surplus state. Then make up the
2199 * remaining difference by allocating fresh huge pages.
2200 *
2201 * We might race with __alloc_buddy_huge_page() here and be unable
2202 * to convert a surplus huge page to a normal huge page. That is
2203 * not critical, though, it just means the overall size of the
2204 * pool might be one hugepage larger than it needs to be, but
2205 * within all the constraints specified by the sysctls.
2206 */
2207 spin_lock(&hugetlb_lock);
2208 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2209 if (!adjust_pool_surplus(h, nodes_allowed, -1))
2210 break;
2211 }
2212
2213 while (count > persistent_huge_pages(h)) {
2214 /*
2215 * If this allocation races such that we no longer need the
2216 * page, free_huge_page will handle it by freeing the page
2217 * and reducing the surplus.
2218 */
2219 spin_unlock(&hugetlb_lock);
2220
2221 /* yield cpu to avoid soft lockup */
2222 cond_resched();
2223
2224 if (hstate_is_gigantic(h))
2225 ret = alloc_fresh_gigantic_page(h, nodes_allowed);
2226 else
2227 ret = alloc_fresh_huge_page(h, nodes_allowed);
2228 spin_lock(&hugetlb_lock);
2229 if (!ret)
2230 goto out;
2231
2232 /* Bail for signals. Probably ctrl-c from user */
2233 if (signal_pending(current))
2234 goto out;
2235 }
2236
2237 /*
2238 * Decrease the pool size
2239 * First return free pages to the buddy allocator (being careful
2240 * to keep enough around to satisfy reservations). Then place
2241 * pages into surplus state as needed so the pool will shrink
2242 * to the desired size as pages become free.
2243 *
2244 * By placing pages into the surplus state independent of the
2245 * overcommit value, we are allowing the surplus pool size to
2246 * exceed overcommit. There are few sane options here. Since
2247 * __alloc_buddy_huge_page() is checking the global counter,
2248 * though, we'll note that we're not allowed to exceed surplus
2249 * and won't grow the pool anywhere else. Not until one of the
2250 * sysctls are changed, or the surplus pages go out of use.
2251 */
2252 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2253 min_count = max(count, min_count);
2254 try_to_free_low(h, min_count, nodes_allowed);
2255 while (min_count < persistent_huge_pages(h)) {
2256 if (!free_pool_huge_page(h, nodes_allowed, 0))
2257 break;
2258 cond_resched_lock(&hugetlb_lock);
2259 }
2260 while (count < persistent_huge_pages(h)) {
2261 if (!adjust_pool_surplus(h, nodes_allowed, 1))
2262 break;
2263 }
2264 out:
2265 ret = persistent_huge_pages(h);
2266 spin_unlock(&hugetlb_lock);
2267 return ret;
2268 }
2269
2270 #define HSTATE_ATTR_RO(_name) \
2271 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2272
2273 #define HSTATE_ATTR(_name) \
2274 static struct kobj_attribute _name##_attr = \
2275 __ATTR(_name, 0644, _name##_show, _name##_store)
2276
2277 static struct kobject *hugepages_kobj;
2278 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2279
2280 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2281
2282 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2283 {
2284 int i;
2285
2286 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2287 if (hstate_kobjs[i] == kobj) {
2288 if (nidp)
2289 *nidp = NUMA_NO_NODE;
2290 return &hstates[i];
2291 }
2292
2293 return kobj_to_node_hstate(kobj, nidp);
2294 }
2295
2296 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2297 struct kobj_attribute *attr, char *buf)
2298 {
2299 struct hstate *h;
2300 unsigned long nr_huge_pages;
2301 int nid;
2302
2303 h = kobj_to_hstate(kobj, &nid);
2304 if (nid == NUMA_NO_NODE)
2305 nr_huge_pages = h->nr_huge_pages;
2306 else
2307 nr_huge_pages = h->nr_huge_pages_node[nid];
2308
2309 return sprintf(buf, "%lu\n", nr_huge_pages);
2310 }
2311
2312 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2313 struct hstate *h, int nid,
2314 unsigned long count, size_t len)
2315 {
2316 int err;
2317 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2318
2319 if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2320 err = -EINVAL;
2321 goto out;
2322 }
2323
2324 if (nid == NUMA_NO_NODE) {
2325 /*
2326 * global hstate attribute
2327 */
2328 if (!(obey_mempolicy &&
2329 init_nodemask_of_mempolicy(nodes_allowed))) {
2330 NODEMASK_FREE(nodes_allowed);
2331 nodes_allowed = &node_states[N_MEMORY];
2332 }
2333 } else if (nodes_allowed) {
2334 /*
2335 * per node hstate attribute: adjust count to global,
2336 * but restrict alloc/free to the specified node.
2337 */
2338 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2339 init_nodemask_of_node(nodes_allowed, nid);
2340 } else
2341 nodes_allowed = &node_states[N_MEMORY];
2342
2343 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2344
2345 if (nodes_allowed != &node_states[N_MEMORY])
2346 NODEMASK_FREE(nodes_allowed);
2347
2348 return len;
2349 out:
2350 NODEMASK_FREE(nodes_allowed);
2351 return err;
2352 }
2353
2354 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2355 struct kobject *kobj, const char *buf,
2356 size_t len)
2357 {
2358 struct hstate *h;
2359 unsigned long count;
2360 int nid;
2361 int err;
2362
2363 err = kstrtoul(buf, 10, &count);
2364 if (err)
2365 return err;
2366
2367 h = kobj_to_hstate(kobj, &nid);
2368 return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2369 }
2370
2371 static ssize_t nr_hugepages_show(struct kobject *kobj,
2372 struct kobj_attribute *attr, char *buf)
2373 {
2374 return nr_hugepages_show_common(kobj, attr, buf);
2375 }
2376
2377 static ssize_t nr_hugepages_store(struct kobject *kobj,
2378 struct kobj_attribute *attr, const char *buf, size_t len)
2379 {
2380 return nr_hugepages_store_common(false, kobj, buf, len);
2381 }
2382 HSTATE_ATTR(nr_hugepages);
2383
2384 #ifdef CONFIG_NUMA
2385
2386 /*
2387 * hstate attribute for optionally mempolicy-based constraint on persistent
2388 * huge page alloc/free.
2389 */
2390 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2391 struct kobj_attribute *attr, char *buf)
2392 {
2393 return nr_hugepages_show_common(kobj, attr, buf);
2394 }
2395
2396 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2397 struct kobj_attribute *attr, const char *buf, size_t len)
2398 {
2399 return nr_hugepages_store_common(true, kobj, buf, len);
2400 }
2401 HSTATE_ATTR(nr_hugepages_mempolicy);
2402 #endif
2403
2404
2405 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2406 struct kobj_attribute *attr, char *buf)
2407 {
2408 struct hstate *h = kobj_to_hstate(kobj, NULL);
2409 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2410 }
2411
2412 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2413 struct kobj_attribute *attr, const char *buf, size_t count)
2414 {
2415 int err;
2416 unsigned long input;
2417 struct hstate *h = kobj_to_hstate(kobj, NULL);
2418
2419 if (hstate_is_gigantic(h))
2420 return -EINVAL;
2421
2422 err = kstrtoul(buf, 10, &input);
2423 if (err)
2424 return err;
2425
2426 spin_lock(&hugetlb_lock);
2427 h->nr_overcommit_huge_pages = input;
2428 spin_unlock(&hugetlb_lock);
2429
2430 return count;
2431 }
2432 HSTATE_ATTR(nr_overcommit_hugepages);
2433
2434 static ssize_t free_hugepages_show(struct kobject *kobj,
2435 struct kobj_attribute *attr, char *buf)
2436 {
2437 struct hstate *h;
2438 unsigned long free_huge_pages;
2439 int nid;
2440
2441 h = kobj_to_hstate(kobj, &nid);
2442 if (nid == NUMA_NO_NODE)
2443 free_huge_pages = h->free_huge_pages;
2444 else
2445 free_huge_pages = h->free_huge_pages_node[nid];
2446
2447 return sprintf(buf, "%lu\n", free_huge_pages);
2448 }
2449 HSTATE_ATTR_RO(free_hugepages);
2450
2451 static ssize_t resv_hugepages_show(struct kobject *kobj,
2452 struct kobj_attribute *attr, char *buf)
2453 {
2454 struct hstate *h = kobj_to_hstate(kobj, NULL);
2455 return sprintf(buf, "%lu\n", h->resv_huge_pages);
2456 }
2457 HSTATE_ATTR_RO(resv_hugepages);
2458
2459 static ssize_t surplus_hugepages_show(struct kobject *kobj,
2460 struct kobj_attribute *attr, char *buf)
2461 {
2462 struct hstate *h;
2463 unsigned long surplus_huge_pages;
2464 int nid;
2465
2466 h = kobj_to_hstate(kobj, &nid);
2467 if (nid == NUMA_NO_NODE)
2468 surplus_huge_pages = h->surplus_huge_pages;
2469 else
2470 surplus_huge_pages = h->surplus_huge_pages_node[nid];
2471
2472 return sprintf(buf, "%lu\n", surplus_huge_pages);
2473 }
2474 HSTATE_ATTR_RO(surplus_hugepages);
2475
2476 static struct attribute *hstate_attrs[] = {
2477 &nr_hugepages_attr.attr,
2478 &nr_overcommit_hugepages_attr.attr,
2479 &free_hugepages_attr.attr,
2480 &resv_hugepages_attr.attr,
2481 &surplus_hugepages_attr.attr,
2482 #ifdef CONFIG_NUMA
2483 &nr_hugepages_mempolicy_attr.attr,
2484 #endif
2485 NULL,
2486 };
2487
2488 static struct attribute_group hstate_attr_group = {
2489 .attrs = hstate_attrs,
2490 };
2491
2492 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2493 struct kobject **hstate_kobjs,
2494 struct attribute_group *hstate_attr_group)
2495 {
2496 int retval;
2497 int hi = hstate_index(h);
2498
2499 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2500 if (!hstate_kobjs[hi])
2501 return -ENOMEM;
2502
2503 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2504 if (retval)
2505 kobject_put(hstate_kobjs[hi]);
2506
2507 return retval;
2508 }
2509
2510 static void __init hugetlb_sysfs_init(void)
2511 {
2512 struct hstate *h;
2513 int err;
2514
2515 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2516 if (!hugepages_kobj)
2517 return;
2518
2519 for_each_hstate(h) {
2520 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2521 hstate_kobjs, &hstate_attr_group);
2522 if (err)
2523 pr_err("Hugetlb: Unable to add hstate %s", h->name);
2524 }
2525 }
2526
2527 #ifdef CONFIG_NUMA
2528
2529 /*
2530 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2531 * with node devices in node_devices[] using a parallel array. The array
2532 * index of a node device or _hstate == node id.
2533 * This is here to avoid any static dependency of the node device driver, in
2534 * the base kernel, on the hugetlb module.
2535 */
2536 struct node_hstate {
2537 struct kobject *hugepages_kobj;
2538 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2539 };
2540 static struct node_hstate node_hstates[MAX_NUMNODES];
2541
2542 /*
2543 * A subset of global hstate attributes for node devices
2544 */
2545 static struct attribute *per_node_hstate_attrs[] = {
2546 &nr_hugepages_attr.attr,
2547 &free_hugepages_attr.attr,
2548 &surplus_hugepages_attr.attr,
2549 NULL,
2550 };
2551
2552 static struct attribute_group per_node_hstate_attr_group = {
2553 .attrs = per_node_hstate_attrs,
2554 };
2555
2556 /*
2557 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2558 * Returns node id via non-NULL nidp.
2559 */
2560 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2561 {
2562 int nid;
2563
2564 for (nid = 0; nid < nr_node_ids; nid++) {
2565 struct node_hstate *nhs = &node_hstates[nid];
2566 int i;
2567 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2568 if (nhs->hstate_kobjs[i] == kobj) {
2569 if (nidp)
2570 *nidp = nid;
2571 return &hstates[i];
2572 }
2573 }
2574
2575 BUG();
2576 return NULL;
2577 }
2578
2579 /*
2580 * Unregister hstate attributes from a single node device.
2581 * No-op if no hstate attributes attached.
2582 */
2583 static void hugetlb_unregister_node(struct node *node)
2584 {
2585 struct hstate *h;
2586 struct node_hstate *nhs = &node_hstates[node->dev.id];
2587
2588 if (!nhs->hugepages_kobj)
2589 return; /* no hstate attributes */
2590
2591 for_each_hstate(h) {
2592 int idx = hstate_index(h);
2593 if (nhs->hstate_kobjs[idx]) {
2594 kobject_put(nhs->hstate_kobjs[idx]);
2595 nhs->hstate_kobjs[idx] = NULL;
2596 }
2597 }
2598
2599 kobject_put(nhs->hugepages_kobj);
2600 nhs->hugepages_kobj = NULL;
2601 }
2602
2603
2604 /*
2605 * Register hstate attributes for a single node device.
2606 * No-op if attributes already registered.
2607 */
2608 static void hugetlb_register_node(struct node *node)
2609 {
2610 struct hstate *h;
2611 struct node_hstate *nhs = &node_hstates[node->dev.id];
2612 int err;
2613
2614 if (nhs->hugepages_kobj)
2615 return; /* already allocated */
2616
2617 nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2618 &node->dev.kobj);
2619 if (!nhs->hugepages_kobj)
2620 return;
2621
2622 for_each_hstate(h) {
2623 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2624 nhs->hstate_kobjs,
2625 &per_node_hstate_attr_group);
2626 if (err) {
2627 pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2628 h->name, node->dev.id);
2629 hugetlb_unregister_node(node);
2630 break;
2631 }
2632 }
2633 }
2634
2635 /*
2636 * hugetlb init time: register hstate attributes for all registered node
2637 * devices of nodes that have memory. All on-line nodes should have
2638 * registered their associated device by this time.
2639 */
2640 static void __init hugetlb_register_all_nodes(void)
2641 {
2642 int nid;
2643
2644 for_each_node_state(nid, N_MEMORY) {
2645 struct node *node = node_devices[nid];
2646 if (node->dev.id == nid)
2647 hugetlb_register_node(node);
2648 }
2649
2650 /*
2651 * Let the node device driver know we're here so it can
2652 * [un]register hstate attributes on node hotplug.
2653 */
2654 register_hugetlbfs_with_node(hugetlb_register_node,
2655 hugetlb_unregister_node);
2656 }
2657 #else /* !CONFIG_NUMA */
2658
2659 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2660 {
2661 BUG();
2662 if (nidp)
2663 *nidp = -1;
2664 return NULL;
2665 }
2666
2667 static void hugetlb_register_all_nodes(void) { }
2668
2669 #endif
2670
2671 static int __init hugetlb_init(void)
2672 {
2673 int i;
2674
2675 if (!hugepages_supported())
2676 return 0;
2677
2678 if (!size_to_hstate(default_hstate_size)) {
2679 default_hstate_size = HPAGE_SIZE;
2680 if (!size_to_hstate(default_hstate_size))
2681 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2682 }
2683 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2684 if (default_hstate_max_huge_pages) {
2685 if (!default_hstate.max_huge_pages)
2686 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2687 }
2688
2689 hugetlb_init_hstates();
2690 gather_bootmem_prealloc();
2691 report_hugepages();
2692
2693 hugetlb_sysfs_init();
2694 hugetlb_register_all_nodes();
2695 hugetlb_cgroup_file_init();
2696
2697 #ifdef CONFIG_SMP
2698 num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2699 #else
2700 num_fault_mutexes = 1;
2701 #endif
2702 hugetlb_fault_mutex_table =
2703 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2704 BUG_ON(!hugetlb_fault_mutex_table);
2705
2706 for (i = 0; i < num_fault_mutexes; i++)
2707 mutex_init(&hugetlb_fault_mutex_table[i]);
2708 return 0;
2709 }
2710 subsys_initcall(hugetlb_init);
2711
2712 /* Should be called on processing a hugepagesz=... option */
2713 void __init hugetlb_bad_size(void)
2714 {
2715 parsed_valid_hugepagesz = false;
2716 }
2717
2718 void __init hugetlb_add_hstate(unsigned int order)
2719 {
2720 struct hstate *h;
2721 unsigned long i;
2722
2723 if (size_to_hstate(PAGE_SIZE << order)) {
2724 pr_warn("hugepagesz= specified twice, ignoring\n");
2725 return;
2726 }
2727 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2728 BUG_ON(order == 0);
2729 h = &hstates[hugetlb_max_hstate++];
2730 h->order = order;
2731 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2732 h->nr_huge_pages = 0;
2733 h->free_huge_pages = 0;
2734 for (i = 0; i < MAX_NUMNODES; ++i)
2735 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2736 INIT_LIST_HEAD(&h->hugepage_activelist);
2737 h->next_nid_to_alloc = first_memory_node;
2738 h->next_nid_to_free = first_memory_node;
2739 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2740 huge_page_size(h)/1024);
2741
2742 parsed_hstate = h;
2743 }
2744
2745 static int __init hugetlb_nrpages_setup(char *s)
2746 {
2747 unsigned long *mhp;
2748 static unsigned long *last_mhp;
2749
2750 if (!parsed_valid_hugepagesz) {
2751 pr_warn("hugepages = %s preceded by "
2752 "an unsupported hugepagesz, ignoring\n", s);
2753 parsed_valid_hugepagesz = true;
2754 return 1;
2755 }
2756 /*
2757 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2758 * so this hugepages= parameter goes to the "default hstate".
2759 */
2760 else if (!hugetlb_max_hstate)
2761 mhp = &default_hstate_max_huge_pages;
2762 else
2763 mhp = &parsed_hstate->max_huge_pages;
2764
2765 if (mhp == last_mhp) {
2766 pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2767 return 1;
2768 }
2769
2770 if (sscanf(s, "%lu", mhp) <= 0)
2771 *mhp = 0;
2772
2773 /*
2774 * Global state is always initialized later in hugetlb_init.
2775 * But we need to allocate >= MAX_ORDER hstates here early to still
2776 * use the bootmem allocator.
2777 */
2778 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2779 hugetlb_hstate_alloc_pages(parsed_hstate);
2780
2781 last_mhp = mhp;
2782
2783 return 1;
2784 }
2785 __setup("hugepages=", hugetlb_nrpages_setup);
2786
2787 static int __init hugetlb_default_setup(char *s)
2788 {
2789 default_hstate_size = memparse(s, &s);
2790 return 1;
2791 }
2792 __setup("default_hugepagesz=", hugetlb_default_setup);
2793
2794 static unsigned int cpuset_mems_nr(unsigned int *array)
2795 {
2796 int node;
2797 unsigned int nr = 0;
2798
2799 for_each_node_mask(node, cpuset_current_mems_allowed)
2800 nr += array[node];
2801
2802 return nr;
2803 }
2804
2805 #ifdef CONFIG_SYSCTL
2806 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2807 struct ctl_table *table, int write,
2808 void __user *buffer, size_t *length, loff_t *ppos)
2809 {
2810 struct hstate *h = &default_hstate;
2811 unsigned long tmp = h->max_huge_pages;
2812 int ret;
2813
2814 if (!hugepages_supported())
2815 return -EOPNOTSUPP;
2816
2817 table->data = &tmp;
2818 table->maxlen = sizeof(unsigned long);
2819 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2820 if (ret)
2821 goto out;
2822
2823 if (write)
2824 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2825 NUMA_NO_NODE, tmp, *length);
2826 out:
2827 return ret;
2828 }
2829
2830 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2831 void __user *buffer, size_t *length, loff_t *ppos)
2832 {
2833
2834 return hugetlb_sysctl_handler_common(false, table, write,
2835 buffer, length, ppos);
2836 }
2837
2838 #ifdef CONFIG_NUMA
2839 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2840 void __user *buffer, size_t *length, loff_t *ppos)
2841 {
2842 return hugetlb_sysctl_handler_common(true, table, write,
2843 buffer, length, ppos);
2844 }
2845 #endif /* CONFIG_NUMA */
2846
2847 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2848 void __user *buffer,
2849 size_t *length, loff_t *ppos)
2850 {
2851 struct hstate *h = &default_hstate;
2852 unsigned long tmp;
2853 int ret;
2854
2855 if (!hugepages_supported())
2856 return -EOPNOTSUPP;
2857
2858 tmp = h->nr_overcommit_huge_pages;
2859
2860 if (write && hstate_is_gigantic(h))
2861 return -EINVAL;
2862
2863 table->data = &tmp;
2864 table->maxlen = sizeof(unsigned long);
2865 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2866 if (ret)
2867 goto out;
2868
2869 if (write) {
2870 spin_lock(&hugetlb_lock);
2871 h->nr_overcommit_huge_pages = tmp;
2872 spin_unlock(&hugetlb_lock);
2873 }
2874 out:
2875 return ret;
2876 }
2877
2878 #endif /* CONFIG_SYSCTL */
2879
2880 void hugetlb_report_meminfo(struct seq_file *m)
2881 {
2882 struct hstate *h = &default_hstate;
2883 if (!hugepages_supported())
2884 return;
2885 seq_printf(m,
2886 "HugePages_Total: %5lu\n"
2887 "HugePages_Free: %5lu\n"
2888 "HugePages_Rsvd: %5lu\n"
2889 "HugePages_Surp: %5lu\n"
2890 "Hugepagesize: %8lu kB\n",
2891 h->nr_huge_pages,
2892 h->free_huge_pages,
2893 h->resv_huge_pages,
2894 h->surplus_huge_pages,
2895 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2896 }
2897
2898 int hugetlb_report_node_meminfo(int nid, char *buf)
2899 {
2900 struct hstate *h = &default_hstate;
2901 if (!hugepages_supported())
2902 return 0;
2903 return sprintf(buf,
2904 "Node %d HugePages_Total: %5u\n"
2905 "Node %d HugePages_Free: %5u\n"
2906 "Node %d HugePages_Surp: %5u\n",
2907 nid, h->nr_huge_pages_node[nid],
2908 nid, h->free_huge_pages_node[nid],
2909 nid, h->surplus_huge_pages_node[nid]);
2910 }
2911
2912 void hugetlb_show_meminfo(void)
2913 {
2914 struct hstate *h;
2915 int nid;
2916
2917 if (!hugepages_supported())
2918 return;
2919
2920 for_each_node_state(nid, N_MEMORY)
2921 for_each_hstate(h)
2922 pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
2923 nid,
2924 h->nr_huge_pages_node[nid],
2925 h->free_huge_pages_node[nid],
2926 h->surplus_huge_pages_node[nid],
2927 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2928 }
2929
2930 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
2931 {
2932 seq_printf(m, "HugetlbPages:\t%8lu kB\n",
2933 atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
2934 }
2935
2936 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2937 unsigned long hugetlb_total_pages(void)
2938 {
2939 struct hstate *h;
2940 unsigned long nr_total_pages = 0;
2941
2942 for_each_hstate(h)
2943 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
2944 return nr_total_pages;
2945 }
2946
2947 static int hugetlb_acct_memory(struct hstate *h, long delta)
2948 {
2949 int ret = -ENOMEM;
2950
2951 spin_lock(&hugetlb_lock);
2952 /*
2953 * When cpuset is configured, it breaks the strict hugetlb page
2954 * reservation as the accounting is done on a global variable. Such
2955 * reservation is completely rubbish in the presence of cpuset because
2956 * the reservation is not checked against page availability for the
2957 * current cpuset. Application can still potentially OOM'ed by kernel
2958 * with lack of free htlb page in cpuset that the task is in.
2959 * Attempt to enforce strict accounting with cpuset is almost
2960 * impossible (or too ugly) because cpuset is too fluid that
2961 * task or memory node can be dynamically moved between cpusets.
2962 *
2963 * The change of semantics for shared hugetlb mapping with cpuset is
2964 * undesirable. However, in order to preserve some of the semantics,
2965 * we fall back to check against current free page availability as
2966 * a best attempt and hopefully to minimize the impact of changing
2967 * semantics that cpuset has.
2968 */
2969 if (delta > 0) {
2970 if (gather_surplus_pages(h, delta) < 0)
2971 goto out;
2972
2973 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2974 return_unused_surplus_pages(h, delta);
2975 goto out;
2976 }
2977 }
2978
2979 ret = 0;
2980 if (delta < 0)
2981 return_unused_surplus_pages(h, (unsigned long) -delta);
2982
2983 out:
2984 spin_unlock(&hugetlb_lock);
2985 return ret;
2986 }
2987
2988 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2989 {
2990 struct resv_map *resv = vma_resv_map(vma);
2991
2992 /*
2993 * This new VMA should share its siblings reservation map if present.
2994 * The VMA will only ever have a valid reservation map pointer where
2995 * it is being copied for another still existing VMA. As that VMA
2996 * has a reference to the reservation map it cannot disappear until
2997 * after this open call completes. It is therefore safe to take a
2998 * new reference here without additional locking.
2999 */
3000 if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3001 kref_get(&resv->refs);
3002 }
3003
3004 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
3005 {
3006 struct hstate *h = hstate_vma(vma);
3007 struct resv_map *resv = vma_resv_map(vma);
3008 struct hugepage_subpool *spool = subpool_vma(vma);
3009 unsigned long reserve, start, end;
3010 long gbl_reserve;
3011
3012 if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3013 return;
3014
3015 start = vma_hugecache_offset(h, vma, vma->vm_start);
3016 end = vma_hugecache_offset(h, vma, vma->vm_end);
3017
3018 reserve = (end - start) - region_count(resv, start, end);
3019
3020 kref_put(&resv->refs, resv_map_release);
3021
3022 if (reserve) {
3023 /*
3024 * Decrement reserve counts. The global reserve count may be
3025 * adjusted if the subpool has a minimum size.
3026 */
3027 gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
3028 hugetlb_acct_memory(h, -gbl_reserve);
3029 }
3030 }
3031
3032 /*
3033 * We cannot handle pagefaults against hugetlb pages at all. They cause
3034 * handle_mm_fault() to try to instantiate regular-sized pages in the
3035 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
3036 * this far.
3037 */
3038 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
3039 {
3040 BUG();
3041 return 0;
3042 }
3043
3044 const struct vm_operations_struct hugetlb_vm_ops = {
3045 .fault = hugetlb_vm_op_fault,
3046 .open = hugetlb_vm_op_open,
3047 .close = hugetlb_vm_op_close,
3048 };
3049
3050 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3051 int writable)
3052 {
3053 pte_t entry;
3054
3055 if (writable) {
3056 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3057 vma->vm_page_prot)));
3058 } else {
3059 entry = huge_pte_wrprotect(mk_huge_pte(page,
3060 vma->vm_page_prot));
3061 }
3062 entry = pte_mkyoung(entry);
3063 entry = pte_mkhuge(entry);
3064 entry = arch_make_huge_pte(entry, vma, page, writable);
3065
3066 return entry;
3067 }
3068
3069 static void set_huge_ptep_writable(struct vm_area_struct *vma,
3070 unsigned long address, pte_t *ptep)
3071 {
3072 pte_t entry;
3073
3074 entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3075 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3076 update_mmu_cache(vma, address, ptep);
3077 }
3078
3079 static int is_hugetlb_entry_migration(pte_t pte)
3080 {
3081 swp_entry_t swp;
3082
3083 if (huge_pte_none(pte) || pte_present(pte))
3084 return 0;
3085 swp = pte_to_swp_entry(pte);
3086 if (non_swap_entry(swp) && is_migration_entry(swp))
3087 return 1;
3088 else
3089 return 0;
3090 }
3091
3092 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3093 {
3094 swp_entry_t swp;
3095
3096 if (huge_pte_none(pte) || pte_present(pte))
3097 return 0;
3098 swp = pte_to_swp_entry(pte);
3099 if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3100 return 1;
3101 else
3102 return 0;
3103 }
3104
3105 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3106 struct vm_area_struct *vma)
3107 {
3108 pte_t *src_pte, *dst_pte, entry;
3109 struct page *ptepage;
3110 unsigned long addr;
3111 int cow;
3112 struct hstate *h = hstate_vma(vma);
3113 unsigned long sz = huge_page_size(h);
3114 unsigned long mmun_start; /* For mmu_notifiers */
3115 unsigned long mmun_end; /* For mmu_notifiers */
3116 int ret = 0;
3117
3118 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3119
3120 mmun_start = vma->vm_start;
3121 mmun_end = vma->vm_end;
3122 if (cow)
3123 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
3124
3125 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3126 spinlock_t *src_ptl, *dst_ptl;
3127 src_pte = huge_pte_offset(src, addr);
3128 if (!src_pte)
3129 continue;
3130 dst_pte = huge_pte_alloc(dst, addr, sz);
3131 if (!dst_pte) {
3132 ret = -ENOMEM;
3133 break;
3134 }
3135
3136 /* If the pagetables are shared don't copy or take references */
3137 if (dst_pte == src_pte)
3138 continue;
3139
3140 dst_ptl = huge_pte_lock(h, dst, dst_pte);
3141 src_ptl = huge_pte_lockptr(h, src, src_pte);
3142 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3143 entry = huge_ptep_get(src_pte);
3144 if (huge_pte_none(entry)) { /* skip none entry */
3145 ;
3146 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
3147 is_hugetlb_entry_hwpoisoned(entry))) {
3148 swp_entry_t swp_entry = pte_to_swp_entry(entry);
3149
3150 if (is_write_migration_entry(swp_entry) && cow) {
3151 /*
3152 * COW mappings require pages in both
3153 * parent and child to be set to read.
3154 */
3155 make_migration_entry_read(&swp_entry);
3156 entry = swp_entry_to_pte(swp_entry);
3157 set_huge_pte_at(src, addr, src_pte, entry);
3158 }
3159 set_huge_pte_at(dst, addr, dst_pte, entry);
3160 } else {
3161 if (cow) {
3162 huge_ptep_set_wrprotect(src, addr, src_pte);
3163 mmu_notifier_invalidate_range(src, mmun_start,
3164 mmun_end);
3165 }
3166 entry = huge_ptep_get(src_pte);
3167 ptepage = pte_page(entry);
3168 get_page(ptepage);
3169 page_dup_rmap(ptepage, true);
3170 set_huge_pte_at(dst, addr, dst_pte, entry);
3171 hugetlb_count_add(pages_per_huge_page(h), dst);
3172 }
3173 spin_unlock(src_ptl);
3174 spin_unlock(dst_ptl);
3175 }
3176
3177 if (cow)
3178 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
3179
3180 return ret;
3181 }
3182
3183 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3184 unsigned long start, unsigned long end,
3185 struct page *ref_page)
3186 {
3187 struct mm_struct *mm = vma->vm_mm;
3188 unsigned long address;
3189 pte_t *ptep;
3190 pte_t pte;
3191 spinlock_t *ptl;
3192 struct page *page;
3193 struct hstate *h = hstate_vma(vma);
3194 unsigned long sz = huge_page_size(h);
3195 const unsigned long mmun_start = start; /* For mmu_notifiers */
3196 const unsigned long mmun_end = end; /* For mmu_notifiers */
3197
3198 WARN_ON(!is_vm_hugetlb_page(vma));
3199 BUG_ON(start & ~huge_page_mask(h));
3200 BUG_ON(end & ~huge_page_mask(h));
3201
3202 tlb_start_vma(tlb, vma);
3203 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3204 address = start;
3205 for (; address < end; address += sz) {
3206 ptep = huge_pte_offset(mm, address);
3207 if (!ptep)
3208 continue;
3209
3210 ptl = huge_pte_lock(h, mm, ptep);
3211 if (huge_pmd_unshare(mm, &address, ptep)) {
3212 spin_unlock(ptl);
3213 continue;
3214 }
3215
3216 pte = huge_ptep_get(ptep);
3217 if (huge_pte_none(pte)) {
3218 spin_unlock(ptl);
3219 continue;
3220 }
3221
3222 /*
3223 * Migrating hugepage or HWPoisoned hugepage is already
3224 * unmapped and its refcount is dropped, so just clear pte here.
3225 */
3226 if (unlikely(!pte_present(pte))) {
3227 huge_pte_clear(mm, address, ptep);
3228 spin_unlock(ptl);
3229 continue;
3230 }
3231
3232 page = pte_page(pte);
3233 /*
3234 * If a reference page is supplied, it is because a specific
3235 * page is being unmapped, not a range. Ensure the page we
3236 * are about to unmap is the actual page of interest.
3237 */
3238 if (ref_page) {
3239 if (page != ref_page) {
3240 spin_unlock(ptl);
3241 continue;
3242 }
3243 /*
3244 * Mark the VMA as having unmapped its page so that
3245 * future faults in this VMA will fail rather than
3246 * looking like data was lost
3247 */
3248 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
3249 }
3250
3251 pte = huge_ptep_get_and_clear(mm, address, ptep);
3252 tlb_remove_tlb_entry(tlb, ptep, address);
3253 if (huge_pte_dirty(pte))
3254 set_page_dirty(page);
3255
3256 hugetlb_count_sub(pages_per_huge_page(h), mm);
3257 page_remove_rmap(page, true);
3258
3259 spin_unlock(ptl);
3260 tlb_remove_page_size(tlb, page, huge_page_size(h));
3261 /*
3262 * Bail out after unmapping reference page if supplied
3263 */
3264 if (ref_page)
3265 break;
3266 }
3267 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3268 tlb_end_vma(tlb, vma);
3269 }
3270
3271 void __unmap_hugepage_range_final(struct mmu_gather *tlb,
3272 struct vm_area_struct *vma, unsigned long start,
3273 unsigned long end, struct page *ref_page)
3274 {
3275 __unmap_hugepage_range(tlb, vma, start, end, ref_page);
3276
3277 /*
3278 * Clear this flag so that x86's huge_pmd_share page_table_shareable
3279 * test will fail on a vma being torn down, and not grab a page table
3280 * on its way out. We're lucky that the flag has such an appropriate
3281 * name, and can in fact be safely cleared here. We could clear it
3282 * before the __unmap_hugepage_range above, but all that's necessary
3283 * is to clear it before releasing the i_mmap_rwsem. This works
3284 * because in the context this is called, the VMA is about to be
3285 * destroyed and the i_mmap_rwsem is held.
3286 */
3287 vma->vm_flags &= ~VM_MAYSHARE;
3288 }
3289
3290 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3291 unsigned long end, struct page *ref_page)
3292 {
3293 struct mm_struct *mm;
3294 struct mmu_gather tlb;
3295
3296 mm = vma->vm_mm;
3297
3298 tlb_gather_mmu(&tlb, mm, start, end);
3299 __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3300 tlb_finish_mmu(&tlb, start, end);
3301 }
3302
3303 /*
3304 * This is called when the original mapper is failing to COW a MAP_PRIVATE
3305 * mappping it owns the reserve page for. The intention is to unmap the page
3306 * from other VMAs and let the children be SIGKILLed if they are faulting the
3307 * same region.
3308 */
3309 static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
3310 struct page *page, unsigned long address)
3311 {
3312 struct hstate *h = hstate_vma(vma);
3313 struct vm_area_struct *iter_vma;
3314 struct address_space *mapping;
3315 pgoff_t pgoff;
3316
3317 /*
3318 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
3319 * from page cache lookup which is in HPAGE_SIZE units.
3320 */
3321 address = address & huge_page_mask(h);
3322 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
3323 vma->vm_pgoff;
3324 mapping = vma->vm_file->f_mapping;
3325
3326 /*
3327 * Take the mapping lock for the duration of the table walk. As
3328 * this mapping should be shared between all the VMAs,
3329 * __unmap_hugepage_range() is called as the lock is already held
3330 */
3331 i_mmap_lock_write(mapping);
3332 vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3333 /* Do not unmap the current VMA */
3334 if (iter_vma == vma)
3335 continue;
3336
3337 /*
3338 * Shared VMAs have their own reserves and do not affect
3339 * MAP_PRIVATE accounting but it is possible that a shared
3340 * VMA is using the same page so check and skip such VMAs.
3341 */
3342 if (iter_vma->vm_flags & VM_MAYSHARE)
3343 continue;
3344
3345 /*
3346 * Unmap the page from other VMAs without their own reserves.
3347 * They get marked to be SIGKILLed if they fault in these
3348 * areas. This is because a future no-page fault on this VMA
3349 * could insert a zeroed page instead of the data existing
3350 * from the time of fork. This would look like data corruption
3351 */
3352 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3353 unmap_hugepage_range(iter_vma, address,
3354 address + huge_page_size(h), page);
3355 }
3356 i_mmap_unlock_write(mapping);
3357 }
3358
3359 /*
3360 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3361 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
3362 * cannot race with other handlers or page migration.
3363 * Keep the pte_same checks anyway to make transition from the mutex easier.
3364 */
3365 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3366 unsigned long address, pte_t *ptep, pte_t pte,
3367 struct page *pagecache_page, spinlock_t *ptl)
3368 {
3369 struct hstate *h = hstate_vma(vma);
3370 struct page *old_page, *new_page;
3371 int ret = 0, outside_reserve = 0;
3372 unsigned long mmun_start; /* For mmu_notifiers */
3373 unsigned long mmun_end; /* For mmu_notifiers */
3374
3375 old_page = pte_page(pte);
3376
3377 retry_avoidcopy:
3378 /* If no-one else is actually using this page, avoid the copy
3379 * and just make the page writable */
3380 if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3381 page_move_anon_rmap(old_page, vma);
3382 set_huge_ptep_writable(vma, address, ptep);
3383 return 0;
3384 }
3385
3386 /*
3387 * If the process that created a MAP_PRIVATE mapping is about to
3388 * perform a COW due to a shared page count, attempt to satisfy
3389 * the allocation without using the existing reserves. The pagecache
3390 * page is used to determine if the reserve at this address was
3391 * consumed or not. If reserves were used, a partial faulted mapping
3392 * at the time of fork() could consume its reserves on COW instead
3393 * of the full address range.
3394 */
3395 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3396 old_page != pagecache_page)
3397 outside_reserve = 1;
3398
3399 get_page(old_page);
3400
3401 /*
3402 * Drop page table lock as buddy allocator may be called. It will
3403 * be acquired again before returning to the caller, as expected.
3404 */
3405 spin_unlock(ptl);
3406 new_page = alloc_huge_page(vma, address, outside_reserve);
3407
3408 if (IS_ERR(new_page)) {
3409 /*
3410 * If a process owning a MAP_PRIVATE mapping fails to COW,
3411 * it is due to references held by a child and an insufficient
3412 * huge page pool. To guarantee the original mappers
3413 * reliability, unmap the page from child processes. The child
3414 * may get SIGKILLed if it later faults.
3415 */
3416 if (outside_reserve) {
3417 put_page(old_page);
3418 BUG_ON(huge_pte_none(pte));
3419 unmap_ref_private(mm, vma, old_page, address);
3420 BUG_ON(huge_pte_none(pte));
3421 spin_lock(ptl);
3422 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3423 if (likely(ptep &&
3424 pte_same(huge_ptep_get(ptep), pte)))
3425 goto retry_avoidcopy;
3426 /*
3427 * race occurs while re-acquiring page table
3428 * lock, and our job is done.
3429 */
3430 return 0;
3431 }
3432
3433 ret = (PTR_ERR(new_page) == -ENOMEM) ?
3434 VM_FAULT_OOM : VM_FAULT_SIGBUS;
3435 goto out_release_old;
3436 }
3437
3438 /*
3439 * When the original hugepage is shared one, it does not have
3440 * anon_vma prepared.
3441 */
3442 if (unlikely(anon_vma_prepare(vma))) {
3443 ret = VM_FAULT_OOM;
3444 goto out_release_all;
3445 }
3446
3447 copy_user_huge_page(new_page, old_page, address, vma,
3448 pages_per_huge_page(h));
3449 __SetPageUptodate(new_page);
3450 set_page_huge_active(new_page);
3451
3452 mmun_start = address & huge_page_mask(h);
3453 mmun_end = mmun_start + huge_page_size(h);
3454 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3455
3456 /*
3457 * Retake the page table lock to check for racing updates
3458 * before the page tables are altered
3459 */
3460 spin_lock(ptl);
3461 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3462 if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3463 ClearPagePrivate(new_page);
3464
3465 /* Break COW */
3466 huge_ptep_clear_flush(vma, address, ptep);
3467 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3468 set_huge_pte_at(mm, address, ptep,
3469 make_huge_pte(vma, new_page, 1));
3470 page_remove_rmap(old_page, true);
3471 hugepage_add_new_anon_rmap(new_page, vma, address);
3472 /* Make the old page be freed below */
3473 new_page = old_page;
3474 }
3475 spin_unlock(ptl);
3476 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3477 out_release_all:
3478 put_page(new_page);
3479 out_release_old:
3480 put_page(old_page);
3481
3482 spin_lock(ptl); /* Caller expects lock to be held */
3483 return ret;
3484 }
3485
3486 /* Return the pagecache page at a given address within a VMA */
3487 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
3488 struct vm_area_struct *vma, unsigned long address)
3489 {
3490 struct address_space *mapping;
3491 pgoff_t idx;
3492
3493 mapping = vma->vm_file->f_mapping;
3494 idx = vma_hugecache_offset(h, vma, address);
3495
3496 return find_lock_page(mapping, idx);
3497 }
3498
3499 /*
3500 * Return whether there is a pagecache page to back given address within VMA.
3501 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
3502 */
3503 static bool hugetlbfs_pagecache_present(struct hstate *h,
3504 struct vm_area_struct *vma, unsigned long address)
3505 {
3506 struct address_space *mapping;
3507 pgoff_t idx;
3508 struct page *page;
3509
3510 mapping = vma->vm_file->f_mapping;
3511 idx = vma_hugecache_offset(h, vma, address);
3512
3513 page = find_get_page(mapping, idx);
3514 if (page)
3515 put_page(page);
3516 return page != NULL;
3517 }
3518
3519 int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
3520 pgoff_t idx)
3521 {
3522 struct inode *inode = mapping->host;
3523 struct hstate *h = hstate_inode(inode);
3524 int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3525
3526 if (err)
3527 return err;
3528 ClearPagePrivate(page);
3529
3530 spin_lock(&inode->i_lock);
3531 inode->i_blocks += blocks_per_huge_page(h);
3532 spin_unlock(&inode->i_lock);
3533 return 0;
3534 }
3535
3536 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3537 struct address_space *mapping, pgoff_t idx,
3538 unsigned long address, pte_t *ptep, unsigned int flags)
3539 {
3540 struct hstate *h = hstate_vma(vma);
3541 int ret = VM_FAULT_SIGBUS;
3542 int anon_rmap = 0;
3543 unsigned long size;
3544 struct page *page;
3545 pte_t new_pte;
3546 spinlock_t *ptl;
3547
3548 /*
3549 * Currently, we are forced to kill the process in the event the
3550 * original mapper has unmapped pages from the child due to a failed
3551 * COW. Warn that such a situation has occurred as it may not be obvious
3552 */
3553 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3554 pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3555 current->pid);
3556 return ret;
3557 }
3558
3559 /*
3560 * Use page lock to guard against racing truncation
3561 * before we get page_table_lock.
3562 */
3563 retry:
3564 page = find_lock_page(mapping, idx);
3565 if (!page) {
3566 size = i_size_read(mapping->host) >> huge_page_shift(h);
3567 if (idx >= size)
3568 goto out;
3569 page = alloc_huge_page(vma, address, 0);
3570 if (IS_ERR(page)) {
3571 ret = PTR_ERR(page);
3572 if (ret == -ENOMEM)
3573 ret = VM_FAULT_OOM;
3574 else
3575 ret = VM_FAULT_SIGBUS;
3576 goto out;
3577 }
3578 clear_huge_page(page, address, pages_per_huge_page(h));
3579 __SetPageUptodate(page);
3580 set_page_huge_active(page);
3581
3582 if (vma->vm_flags & VM_MAYSHARE) {
3583 int err = huge_add_to_page_cache(page, mapping, idx);
3584 if (err) {
3585 put_page(page);
3586 if (err == -EEXIST)
3587 goto retry;
3588 goto out;
3589 }
3590 } else {
3591 lock_page(page);
3592 if (unlikely(anon_vma_prepare(vma))) {
3593 ret = VM_FAULT_OOM;
3594 goto backout_unlocked;
3595 }
3596 anon_rmap = 1;
3597 }
3598 } else {
3599 /*
3600 * If memory error occurs between mmap() and fault, some process
3601 * don't have hwpoisoned swap entry for errored virtual address.
3602 * So we need to block hugepage fault by PG_hwpoison bit check.
3603 */
3604 if (unlikely(PageHWPoison(page))) {
3605 ret = VM_FAULT_HWPOISON |
3606 VM_FAULT_SET_HINDEX(hstate_index(h));
3607 goto backout_unlocked;
3608 }
3609 }
3610
3611 /*
3612 * If we are going to COW a private mapping later, we examine the
3613 * pending reservations for this page now. This will ensure that
3614 * any allocations necessary to record that reservation occur outside
3615 * the spinlock.
3616 */
3617 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3618 if (vma_needs_reservation(h, vma, address) < 0) {
3619 ret = VM_FAULT_OOM;
3620 goto backout_unlocked;
3621 }
3622 /* Just decrements count, does not deallocate */
3623 vma_end_reservation(h, vma, address);
3624 }
3625
3626 ptl = huge_pte_lockptr(h, mm, ptep);
3627 spin_lock(ptl);
3628 size = i_size_read(mapping->host) >> huge_page_shift(h);
3629 if (idx >= size)
3630 goto backout;
3631
3632 ret = 0;
3633 if (!huge_pte_none(huge_ptep_get(ptep)))
3634 goto backout;
3635
3636 if (anon_rmap) {
3637 ClearPagePrivate(page);
3638 hugepage_add_new_anon_rmap(page, vma, address);
3639 } else
3640 page_dup_rmap(page, true);
3641 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3642 && (vma->vm_flags & VM_SHARED)));
3643 set_huge_pte_at(mm, address, ptep, new_pte);
3644
3645 hugetlb_count_add(pages_per_huge_page(h), mm);
3646 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3647 /* Optimization, do the COW without a second fault */
3648 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
3649 }
3650
3651 spin_unlock(ptl);
3652 unlock_page(page);
3653 out:
3654 return ret;
3655
3656 backout:
3657 spin_unlock(ptl);
3658 backout_unlocked:
3659 unlock_page(page);
3660 put_page(page);
3661 goto out;
3662 }
3663
3664 #ifdef CONFIG_SMP
3665 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3666 struct vm_area_struct *vma,
3667 struct address_space *mapping,
3668 pgoff_t idx, unsigned long address)
3669 {
3670 unsigned long key[2];
3671 u32 hash;
3672
3673 if (vma->vm_flags & VM_SHARED) {
3674 key[0] = (unsigned long) mapping;
3675 key[1] = idx;
3676 } else {
3677 key[0] = (unsigned long) mm;
3678 key[1] = address >> huge_page_shift(h);
3679 }
3680
3681 hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3682
3683 return hash & (num_fault_mutexes - 1);
3684 }
3685 #else
3686 /*
3687 * For uniprocesor systems we always use a single mutex, so just
3688 * return 0 and avoid the hashing overhead.
3689 */
3690 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3691 struct vm_area_struct *vma,
3692 struct address_space *mapping,
3693 pgoff_t idx, unsigned long address)
3694 {
3695 return 0;
3696 }
3697 #endif
3698
3699 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3700 unsigned long address, unsigned int flags)
3701 {
3702 pte_t *ptep, entry;
3703 spinlock_t *ptl;
3704 int ret;
3705 u32 hash;
3706 pgoff_t idx;
3707 struct page *page = NULL;
3708 struct page *pagecache_page = NULL;
3709 struct hstate *h = hstate_vma(vma);
3710 struct address_space *mapping;
3711 int need_wait_lock = 0;
3712
3713 address &= huge_page_mask(h);
3714
3715 ptep = huge_pte_offset(mm, address);
3716 if (ptep) {
3717 entry = huge_ptep_get(ptep);
3718 if (unlikely(is_hugetlb_entry_migration(entry))) {
3719 migration_entry_wait_huge(vma, mm, ptep);
3720 return 0;
3721 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3722 return VM_FAULT_HWPOISON_LARGE |
3723 VM_FAULT_SET_HINDEX(hstate_index(h));
3724 } else {
3725 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3726 if (!ptep)
3727 return VM_FAULT_OOM;
3728 }
3729
3730 mapping = vma->vm_file->f_mapping;
3731 idx = vma_hugecache_offset(h, vma, address);
3732
3733 /*
3734 * Serialize hugepage allocation and instantiation, so that we don't
3735 * get spurious allocation failures if two CPUs race to instantiate
3736 * the same page in the page cache.
3737 */
3738 hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
3739 mutex_lock(&hugetlb_fault_mutex_table[hash]);
3740
3741 entry = huge_ptep_get(ptep);
3742 if (huge_pte_none(entry)) {
3743 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3744 goto out_mutex;
3745 }
3746
3747 ret = 0;
3748
3749 /*
3750 * entry could be a migration/hwpoison entry at this point, so this
3751 * check prevents the kernel from going below assuming that we have
3752 * a active hugepage in pagecache. This goto expects the 2nd page fault,
3753 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3754 * handle it.
3755 */
3756 if (!pte_present(entry))
3757 goto out_mutex;
3758
3759 /*
3760 * If we are going to COW the mapping later, we examine the pending
3761 * reservations for this page now. This will ensure that any
3762 * allocations necessary to record that reservation occur outside the
3763 * spinlock. For private mappings, we also lookup the pagecache
3764 * page now as it is used to determine if a reservation has been
3765 * consumed.
3766 */
3767 if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3768 if (vma_needs_reservation(h, vma, address) < 0) {
3769 ret = VM_FAULT_OOM;
3770 goto out_mutex;
3771 }
3772 /* Just decrements count, does not deallocate */
3773 vma_end_reservation(h, vma, address);
3774
3775 if (!(vma->vm_flags & VM_MAYSHARE))
3776 pagecache_page = hugetlbfs_pagecache_page(h,
3777 vma, address);
3778 }
3779
3780 ptl = huge_pte_lock(h, mm, ptep);
3781
3782 /* Check for a racing update before calling hugetlb_cow */
3783 if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3784 goto out_ptl;
3785
3786 /*
3787 * hugetlb_cow() requires page locks of pte_page(entry) and
3788 * pagecache_page, so here we need take the former one
3789 * when page != pagecache_page or !pagecache_page.
3790 */
3791 page = pte_page(entry);
3792 if (page != pagecache_page)
3793 if (!trylock_page(page)) {
3794 need_wait_lock = 1;
3795 goto out_ptl;
3796 }
3797
3798 get_page(page);
3799
3800 if (flags & FAULT_FLAG_WRITE) {
3801 if (!huge_pte_write(entry)) {
3802 ret = hugetlb_cow(mm, vma, address, ptep, entry,
3803 pagecache_page, ptl);
3804 goto out_put_page;
3805 }
3806 entry = huge_pte_mkdirty(entry);
3807 }
3808 entry = pte_mkyoung(entry);
3809 if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3810 flags & FAULT_FLAG_WRITE))
3811 update_mmu_cache(vma, address, ptep);
3812 out_put_page:
3813 if (page != pagecache_page)
3814 unlock_page(page);
3815 put_page(page);
3816 out_ptl:
3817 spin_unlock(ptl);
3818
3819 if (pagecache_page) {
3820 unlock_page(pagecache_page);
3821 put_page(pagecache_page);
3822 }
3823 out_mutex:
3824 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3825 /*
3826 * Generally it's safe to hold refcount during waiting page lock. But
3827 * here we just wait to defer the next page fault to avoid busy loop and
3828 * the page is not used after unlocked before returning from the current
3829 * page fault. So we are safe from accessing freed page, even if we wait
3830 * here without taking refcount.
3831 */
3832 if (need_wait_lock)
3833 wait_on_page_locked(page);
3834 return ret;
3835 }
3836
3837 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
3838 struct page **pages, struct vm_area_struct **vmas,
3839 unsigned long *position, unsigned long *nr_pages,
3840 long i, unsigned int flags)
3841 {
3842 unsigned long pfn_offset;
3843 unsigned long vaddr = *position;
3844 unsigned long remainder = *nr_pages;
3845 struct hstate *h = hstate_vma(vma);
3846
3847 while (vaddr < vma->vm_end && remainder) {
3848 pte_t *pte;
3849 spinlock_t *ptl = NULL;
3850 int absent;
3851 struct page *page;
3852
3853 /*
3854 * If we have a pending SIGKILL, don't keep faulting pages and
3855 * potentially allocating memory.
3856 */
3857 if (unlikely(fatal_signal_pending(current))) {
3858 remainder = 0;
3859 break;
3860 }
3861
3862 /*
3863 * Some archs (sparc64, sh*) have multiple pte_ts to
3864 * each hugepage. We have to make sure we get the
3865 * first, for the page indexing below to work.
3866 *
3867 * Note that page table lock is not held when pte is null.
3868 */
3869 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
3870 if (pte)
3871 ptl = huge_pte_lock(h, mm, pte);
3872 absent = !pte || huge_pte_none(huge_ptep_get(pte));
3873
3874 /*
3875 * When coredumping, it suits get_dump_page if we just return
3876 * an error where there's an empty slot with no huge pagecache
3877 * to back it. This way, we avoid allocating a hugepage, and
3878 * the sparse dumpfile avoids allocating disk blocks, but its
3879 * huge holes still show up with zeroes where they need to be.
3880 */
3881 if (absent && (flags & FOLL_DUMP) &&
3882 !hugetlbfs_pagecache_present(h, vma, vaddr)) {
3883 if (pte)
3884 spin_unlock(ptl);
3885 remainder = 0;
3886 break;
3887 }
3888
3889 /*
3890 * We need call hugetlb_fault for both hugepages under migration
3891 * (in which case hugetlb_fault waits for the migration,) and
3892 * hwpoisoned hugepages (in which case we need to prevent the
3893 * caller from accessing to them.) In order to do this, we use
3894 * here is_swap_pte instead of is_hugetlb_entry_migration and
3895 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
3896 * both cases, and because we can't follow correct pages
3897 * directly from any kind of swap entries.
3898 */
3899 if (absent || is_swap_pte(huge_ptep_get(pte)) ||
3900 ((flags & FOLL_WRITE) &&
3901 !huge_pte_write(huge_ptep_get(pte)))) {
3902 int ret;
3903
3904 if (pte)
3905 spin_unlock(ptl);
3906 ret = hugetlb_fault(mm, vma, vaddr,
3907 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
3908 if (!(ret & VM_FAULT_ERROR))
3909 continue;
3910
3911 remainder = 0;
3912 break;
3913 }
3914
3915 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
3916 page = pte_page(huge_ptep_get(pte));
3917 same_page:
3918 if (pages) {
3919 pages[i] = mem_map_offset(page, pfn_offset);
3920 get_page(pages[i]);
3921 }
3922
3923 if (vmas)
3924 vmas[i] = vma;
3925
3926 vaddr += PAGE_SIZE;
3927 ++pfn_offset;
3928 --remainder;
3929 ++i;
3930 if (vaddr < vma->vm_end && remainder &&
3931 pfn_offset < pages_per_huge_page(h)) {
3932 /*
3933 * We use pfn_offset to avoid touching the pageframes
3934 * of this compound page.
3935 */
3936 goto same_page;
3937 }
3938 spin_unlock(ptl);
3939 }
3940 *nr_pages = remainder;
3941 *position = vaddr;
3942
3943 return i ? i : -EFAULT;
3944 }
3945
3946 #ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
3947 /*
3948 * ARCHes with special requirements for evicting HUGETLB backing TLB entries can
3949 * implement this.
3950 */
3951 #define flush_hugetlb_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end)
3952 #endif
3953
3954 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3955 unsigned long address, unsigned long end, pgprot_t newprot)
3956 {
3957 struct mm_struct *mm = vma->vm_mm;
3958 unsigned long start = address;
3959 pte_t *ptep;
3960 pte_t pte;
3961 struct hstate *h = hstate_vma(vma);
3962 unsigned long pages = 0;
3963
3964 BUG_ON(address >= end);
3965 flush_cache_range(vma, address, end);
3966
3967 mmu_notifier_invalidate_range_start(mm, start, end);
3968 i_mmap_lock_write(vma->vm_file->f_mapping);
3969 for (; address < end; address += huge_page_size(h)) {
3970 spinlock_t *ptl;
3971 ptep = huge_pte_offset(mm, address);
3972 if (!ptep)
3973 continue;
3974 ptl = huge_pte_lock(h, mm, ptep);
3975 if (huge_pmd_unshare(mm, &address, ptep)) {
3976 pages++;
3977 spin_unlock(ptl);
3978 continue;
3979 }
3980 pte = huge_ptep_get(ptep);
3981 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
3982 spin_unlock(ptl);
3983 continue;
3984 }
3985 if (unlikely(is_hugetlb_entry_migration(pte))) {
3986 swp_entry_t entry = pte_to_swp_entry(pte);
3987
3988 if (is_write_migration_entry(entry)) {
3989 pte_t newpte;
3990
3991 make_migration_entry_read(&entry);
3992 newpte = swp_entry_to_pte(entry);
3993 set_huge_pte_at(mm, address, ptep, newpte);
3994 pages++;
3995 }
3996 spin_unlock(ptl);
3997 continue;
3998 }
3999 if (!huge_pte_none(pte)) {
4000 pte = huge_ptep_get_and_clear(mm, address, ptep);
4001 pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4002 pte = arch_make_huge_pte(pte, vma, NULL, 0);
4003 set_huge_pte_at(mm, address, ptep, pte);
4004 pages++;
4005 }
4006 spin_unlock(ptl);
4007 }
4008 /*
4009 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4010 * may have cleared our pud entry and done put_page on the page table:
4011 * once we release i_mmap_rwsem, another task can do the final put_page
4012 * and that page table be reused and filled with junk.
4013 */
4014 flush_hugetlb_tlb_range(vma, start, end);
4015 mmu_notifier_invalidate_range(mm, start, end);
4016 i_mmap_unlock_write(vma->vm_file->f_mapping);
4017 mmu_notifier_invalidate_range_end(mm, start, end);
4018
4019 return pages << h->order;
4020 }
4021
4022 int hugetlb_reserve_pages(struct inode *inode,
4023 long from, long to,
4024 struct vm_area_struct *vma,
4025 vm_flags_t vm_flags)
4026 {
4027 long ret, chg;
4028 struct hstate *h = hstate_inode(inode);
4029 struct hugepage_subpool *spool = subpool_inode(inode);
4030 struct resv_map *resv_map;
4031 long gbl_reserve;
4032
4033 /*
4034 * Only apply hugepage reservation if asked. At fault time, an
4035 * attempt will be made for VM_NORESERVE to allocate a page
4036 * without using reserves
4037 */
4038 if (vm_flags & VM_NORESERVE)
4039 return 0;
4040
4041 /*
4042 * Shared mappings base their reservation on the number of pages that
4043 * are already allocated on behalf of the file. Private mappings need
4044 * to reserve the full area even if read-only as mprotect() may be
4045 * called to make the mapping read-write. Assume !vma is a shm mapping
4046 */
4047 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4048 resv_map = inode_resv_map(inode);
4049
4050 chg = region_chg(resv_map, from, to);
4051
4052 } else {
4053 resv_map = resv_map_alloc();
4054 if (!resv_map)
4055 return -ENOMEM;
4056
4057 chg = to - from;
4058
4059 set_vma_resv_map(vma, resv_map);
4060 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
4061 }
4062
4063 if (chg < 0) {
4064 ret = chg;
4065 goto out_err;
4066 }
4067
4068 /*
4069 * There must be enough pages in the subpool for the mapping. If
4070 * the subpool has a minimum size, there may be some global
4071 * reservations already in place (gbl_reserve).
4072 */
4073 gbl_reserve = hugepage_subpool_get_pages(spool, chg);
4074 if (gbl_reserve < 0) {
4075 ret = -ENOSPC;
4076 goto out_err;
4077 }
4078
4079 /*
4080 * Check enough hugepages are available for the reservation.
4081 * Hand the pages back to the subpool if there are not
4082 */
4083 ret = hugetlb_acct_memory(h, gbl_reserve);
4084 if (ret < 0) {
4085 /* put back original number of pages, chg */
4086 (void)hugepage_subpool_put_pages(spool, chg);
4087 goto out_err;
4088 }
4089
4090 /*
4091 * Account for the reservations made. Shared mappings record regions
4092 * that have reservations as they are shared by multiple VMAs.
4093 * When the last VMA disappears, the region map says how much
4094 * the reservation was and the page cache tells how much of
4095 * the reservation was consumed. Private mappings are per-VMA and
4096 * only the consumed reservations are tracked. When the VMA
4097 * disappears, the original reservation is the VMA size and the
4098 * consumed reservations are stored in the map. Hence, nothing
4099 * else has to be done for private mappings here
4100 */
4101 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4102 long add = region_add(resv_map, from, to);
4103
4104 if (unlikely(chg > add)) {
4105 /*
4106 * pages in this range were added to the reserve
4107 * map between region_chg and region_add. This
4108 * indicates a race with alloc_huge_page. Adjust
4109 * the subpool and reserve counts modified above
4110 * based on the difference.
4111 */
4112 long rsv_adjust;
4113
4114 rsv_adjust = hugepage_subpool_put_pages(spool,
4115 chg - add);
4116 hugetlb_acct_memory(h, -rsv_adjust);
4117 }
4118 }
4119 return 0;
4120 out_err:
4121 if (!vma || vma->vm_flags & VM_MAYSHARE)
4122 region_abort(resv_map, from, to);
4123 if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
4124 kref_put(&resv_map->refs, resv_map_release);
4125 return ret;
4126 }
4127
4128 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
4129 long freed)
4130 {
4131 struct hstate *h = hstate_inode(inode);
4132 struct resv_map *resv_map = inode_resv_map(inode);
4133 long chg = 0;
4134 struct hugepage_subpool *spool = subpool_inode(inode);
4135 long gbl_reserve;
4136
4137 if (resv_map) {
4138 chg = region_del(resv_map, start, end);
4139 /*
4140 * region_del() can fail in the rare case where a region
4141 * must be split and another region descriptor can not be
4142 * allocated. If end == LONG_MAX, it will not fail.
4143 */
4144 if (chg < 0)
4145 return chg;
4146 }
4147
4148 spin_lock(&inode->i_lock);
4149 inode->i_blocks -= (blocks_per_huge_page(h) * freed);
4150 spin_unlock(&inode->i_lock);
4151
4152 /*
4153 * If the subpool has a minimum size, the number of global
4154 * reservations to be released may be adjusted.
4155 */
4156 gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
4157 hugetlb_acct_memory(h, -gbl_reserve);
4158
4159 return 0;
4160 }
4161
4162 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
4163 static unsigned long page_table_shareable(struct vm_area_struct *svma,
4164 struct vm_area_struct *vma,
4165 unsigned long addr, pgoff_t idx)
4166 {
4167 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
4168 svma->vm_start;
4169 unsigned long sbase = saddr & PUD_MASK;
4170 unsigned long s_end = sbase + PUD_SIZE;
4171
4172 /* Allow segments to share if only one is marked locked */
4173 unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
4174 unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4175
4176 /*
4177 * match the virtual addresses, permission and the alignment of the
4178 * page table page.
4179 */
4180 if (pmd_index(addr) != pmd_index(saddr) ||
4181 vm_flags != svm_flags ||
4182 sbase < svma->vm_start || svma->vm_end < s_end)
4183 return 0;
4184
4185 return saddr;
4186 }
4187
4188 static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4189 {
4190 unsigned long base = addr & PUD_MASK;
4191 unsigned long end = base + PUD_SIZE;
4192
4193 /*
4194 * check on proper vm_flags and page table alignment
4195 */
4196 if (vma->vm_flags & VM_MAYSHARE &&
4197 vma->vm_start <= base && end <= vma->vm_end)
4198 return true;
4199 return false;
4200 }
4201
4202 /*
4203 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
4204 * and returns the corresponding pte. While this is not necessary for the
4205 * !shared pmd case because we can allocate the pmd later as well, it makes the
4206 * code much cleaner. pmd allocation is essential for the shared case because
4207 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4208 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
4209 * bad pmd for sharing.
4210 */
4211 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4212 {
4213 struct vm_area_struct *vma = find_vma(mm, addr);
4214 struct address_space *mapping = vma->vm_file->f_mapping;
4215 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
4216 vma->vm_pgoff;
4217 struct vm_area_struct *svma;
4218 unsigned long saddr;
4219 pte_t *spte = NULL;
4220 pte_t *pte;
4221 spinlock_t *ptl;
4222
4223 if (!vma_shareable(vma, addr))
4224 return (pte_t *)pmd_alloc(mm, pud, addr);
4225
4226 i_mmap_lock_write(mapping);
4227 vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
4228 if (svma == vma)
4229 continue;
4230
4231 saddr = page_table_shareable(svma, vma, addr, idx);
4232 if (saddr) {
4233 spte = huge_pte_offset(svma->vm_mm, saddr);
4234 if (spte) {
4235 get_page(virt_to_page(spte));
4236 break;
4237 }
4238 }
4239 }
4240
4241 if (!spte)
4242 goto out;
4243
4244 ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
4245 spin_lock(ptl);
4246 if (pud_none(*pud)) {
4247 pud_populate(mm, pud,
4248 (pmd_t *)((unsigned long)spte & PAGE_MASK));
4249 mm_inc_nr_pmds(mm);
4250 } else {
4251 put_page(virt_to_page(spte));
4252 }
4253 spin_unlock(ptl);
4254 out:
4255 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4256 i_mmap_unlock_write(mapping);
4257 return pte;
4258 }
4259
4260 /*
4261 * unmap huge page backed by shared pte.
4262 *
4263 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
4264 * indicated by page_count > 1, unmap is achieved by clearing pud and
4265 * decrementing the ref count. If count == 1, the pte page is not shared.
4266 *
4267 * called with page table lock held.
4268 *
4269 * returns: 1 successfully unmapped a shared pte page
4270 * 0 the underlying pte page is not shared, or it is the last user
4271 */
4272 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4273 {
4274 pgd_t *pgd = pgd_offset(mm, *addr);
4275 pud_t *pud = pud_offset(pgd, *addr);
4276
4277 BUG_ON(page_count(virt_to_page(ptep)) == 0);
4278 if (page_count(virt_to_page(ptep)) == 1)
4279 return 0;
4280
4281 pud_clear(pud);
4282 put_page(virt_to_page(ptep));
4283 mm_dec_nr_pmds(mm);
4284 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
4285 return 1;
4286 }
4287 #define want_pmd_share() (1)
4288 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4289 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4290 {
4291 return NULL;
4292 }
4293
4294 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4295 {
4296 return 0;
4297 }
4298 #define want_pmd_share() (0)
4299 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4300
4301 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
4302 pte_t *huge_pte_alloc(struct mm_struct *mm,
4303 unsigned long addr, unsigned long sz)
4304 {
4305 pgd_t *pgd;
4306 pud_t *pud;
4307 pte_t *pte = NULL;
4308
4309 pgd = pgd_offset(mm, addr);
4310 pud = pud_alloc(mm, pgd, addr);
4311 if (pud) {
4312 if (sz == PUD_SIZE) {
4313 pte = (pte_t *)pud;
4314 } else {
4315 BUG_ON(sz != PMD_SIZE);
4316 if (want_pmd_share() && pud_none(*pud))
4317 pte = huge_pmd_share(mm, addr, pud);
4318 else
4319 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4320 }
4321 }
4322 BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
4323
4324 return pte;
4325 }
4326
4327 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
4328 {
4329 pgd_t *pgd;
4330 pud_t *pud;
4331 pmd_t *pmd = NULL;
4332
4333 pgd = pgd_offset(mm, addr);
4334 if (pgd_present(*pgd)) {
4335 pud = pud_offset(pgd, addr);
4336 if (pud_present(*pud)) {
4337 if (pud_huge(*pud))
4338 return (pte_t *)pud;
4339 pmd = pmd_offset(pud, addr);
4340 }
4341 }
4342 return (pte_t *) pmd;
4343 }
4344
4345 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
4346
4347 /*
4348 * These functions are overwritable if your architecture needs its own
4349 * behavior.
4350 */
4351 struct page * __weak
4352 follow_huge_addr(struct mm_struct *mm, unsigned long address,
4353 int write)
4354 {
4355 return ERR_PTR(-EINVAL);
4356 }
4357
4358 struct page * __weak
4359 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4360 pmd_t *pmd, int flags)
4361 {
4362 struct page *page = NULL;
4363 spinlock_t *ptl;
4364 retry:
4365 ptl = pmd_lockptr(mm, pmd);
4366 spin_lock(ptl);
4367 /*
4368 * make sure that the address range covered by this pmd is not
4369 * unmapped from other threads.
4370 */
4371 if (!pmd_huge(*pmd))
4372 goto out;
4373 if (pmd_present(*pmd)) {
4374 page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4375 if (flags & FOLL_GET)
4376 get_page(page);
4377 } else {
4378 if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
4379 spin_unlock(ptl);
4380 __migration_entry_wait(mm, (pte_t *)pmd, ptl);
4381 goto retry;
4382 }
4383 /*
4384 * hwpoisoned entry is treated as no_page_table in
4385 * follow_page_mask().
4386 */
4387 }
4388 out:
4389 spin_unlock(ptl);
4390 return page;
4391 }
4392
4393 struct page * __weak
4394 follow_huge_pud(struct mm_struct *mm, unsigned long address,
4395 pud_t *pud, int flags)
4396 {
4397 if (flags & FOLL_GET)
4398 return NULL;
4399
4400 return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4401 }
4402
4403 #ifdef CONFIG_MEMORY_FAILURE
4404
4405 /*
4406 * This function is called from memory failure code.
4407 */
4408 int dequeue_hwpoisoned_huge_page(struct page *hpage)
4409 {
4410 struct hstate *h = page_hstate(hpage);
4411 int nid = page_to_nid(hpage);
4412 int ret = -EBUSY;
4413
4414 spin_lock(&hugetlb_lock);
4415 /*
4416 * Just checking !page_huge_active is not enough, because that could be
4417 * an isolated/hwpoisoned hugepage (which have >0 refcount).
4418 */
4419 if (!page_huge_active(hpage) && !page_count(hpage)) {
4420 /*
4421 * Hwpoisoned hugepage isn't linked to activelist or freelist,
4422 * but dangling hpage->lru can trigger list-debug warnings
4423 * (this happens when we call unpoison_memory() on it),
4424 * so let it point to itself with list_del_init().
4425 */
4426 list_del_init(&hpage->lru);
4427 set_page_refcounted(hpage);
4428 h->free_huge_pages--;
4429 h->free_huge_pages_node[nid]--;
4430 ret = 0;
4431 }
4432 spin_unlock(&hugetlb_lock);
4433 return ret;
4434 }
4435 #endif
4436
4437 bool isolate_huge_page(struct page *page, struct list_head *list)
4438 {
4439 bool ret = true;
4440
4441 VM_BUG_ON_PAGE(!PageHead(page), page);
4442 spin_lock(&hugetlb_lock);
4443 if (!page_huge_active(page) || !get_page_unless_zero(page)) {
4444 ret = false;
4445 goto unlock;
4446 }
4447 clear_page_huge_active(page);
4448 list_move_tail(&page->lru, list);
4449 unlock:
4450 spin_unlock(&hugetlb_lock);
4451 return ret;
4452 }
4453
4454 void putback_active_hugepage(struct page *page)
4455 {
4456 VM_BUG_ON_PAGE(!PageHead(page), page);
4457 spin_lock(&hugetlb_lock);
4458 set_page_huge_active(page);
4459 list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
4460 spin_unlock(&hugetlb_lock);
4461 put_page(page);
4462 }