KVM: x86: Remove redundant definitions
[linux/fpc-iii.git] / mm / hugetlb.c
blob0a9ac6c268325a6ca9096bfc784cfbf68ac6a65e
1 /*
2 * Generic hugetlb support.
3 * (C) Nadia Yvette Chambers, April 2004
4 */
5 #include <linux/list.h>
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/mm.h>
9 #include <linux/seq_file.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/nodemask.h>
14 #include <linux/pagemap.h>
15 #include <linux/mempolicy.h>
16 #include <linux/compiler.h>
17 #include <linux/cpuset.h>
18 #include <linux/mutex.h>
19 #include <linux/bootmem.h>
20 #include <linux/sysfs.h>
21 #include <linux/slab.h>
22 #include <linux/rmap.h>
23 #include <linux/swap.h>
24 #include <linux/swapops.h>
25 #include <linux/page-isolation.h>
26 #include <linux/jhash.h>
28 #include <asm/page.h>
29 #include <asm/pgtable.h>
30 #include <asm/tlb.h>
32 #include <linux/io.h>
33 #include <linux/hugetlb.h>
34 #include <linux/hugetlb_cgroup.h>
35 #include <linux/node.h>
36 #include "internal.h"
38 int hugepages_treat_as_movable;
40 int hugetlb_max_hstate __read_mostly;
41 unsigned int default_hstate_idx;
42 struct hstate hstates[HUGE_MAX_HSTATE];
44 __initdata LIST_HEAD(huge_boot_pages);
46 /* for command line parsing */
47 static struct hstate * __initdata parsed_hstate;
48 static unsigned long __initdata default_hstate_max_huge_pages;
49 static unsigned long __initdata default_hstate_size;
52 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
53 * free_huge_pages, and surplus_huge_pages.
55 DEFINE_SPINLOCK(hugetlb_lock);
58 * Serializes faults on the same logical page. This is used to
59 * prevent spurious OOMs when the hugepage pool is fully utilized.
61 static int num_fault_mutexes;
62 static struct mutex *htlb_fault_mutex_table ____cacheline_aligned_in_smp;
64 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
66 bool free = (spool->count == 0) && (spool->used_hpages == 0);
68 spin_unlock(&spool->lock);
70 /* If no pages are used, and no other handles to the subpool
71 * remain, free the subpool the subpool remain */
72 if (free)
73 kfree(spool);
76 struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
78 struct hugepage_subpool *spool;
80 spool = kmalloc(sizeof(*spool), GFP_KERNEL);
81 if (!spool)
82 return NULL;
84 spin_lock_init(&spool->lock);
85 spool->count = 1;
86 spool->max_hpages = nr_blocks;
87 spool->used_hpages = 0;
89 return spool;
92 void hugepage_put_subpool(struct hugepage_subpool *spool)
94 spin_lock(&spool->lock);
95 BUG_ON(!spool->count);
96 spool->count--;
97 unlock_or_release_subpool(spool);
100 static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
101 long delta)
103 int ret = 0;
105 if (!spool)
106 return 0;
108 spin_lock(&spool->lock);
109 if ((spool->used_hpages + delta) <= spool->max_hpages) {
110 spool->used_hpages += delta;
111 } else {
112 ret = -ENOMEM;
114 spin_unlock(&spool->lock);
116 return ret;
119 static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
120 long delta)
122 if (!spool)
123 return;
125 spin_lock(&spool->lock);
126 spool->used_hpages -= delta;
127 /* If hugetlbfs_put_super couldn't free spool due to
128 * an outstanding quota reference, free it now. */
129 unlock_or_release_subpool(spool);
132 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
134 return HUGETLBFS_SB(inode->i_sb)->spool;
137 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
139 return subpool_inode(file_inode(vma->vm_file));
143 * Region tracking -- allows tracking of reservations and instantiated pages
144 * across the pages in a mapping.
146 * The region data structures are embedded into a resv_map and
147 * protected by a resv_map's lock
149 struct file_region {
150 struct list_head link;
151 long from;
152 long to;
155 static long region_add(struct resv_map *resv, long f, long t)
157 struct list_head *head = &resv->regions;
158 struct file_region *rg, *nrg, *trg;
160 spin_lock(&resv->lock);
161 /* Locate the region we are either in or before. */
162 list_for_each_entry(rg, head, link)
163 if (f <= rg->to)
164 break;
166 /* Round our left edge to the current segment if it encloses us. */
167 if (f > rg->from)
168 f = rg->from;
170 /* Check for and consume any regions we now overlap with. */
171 nrg = rg;
172 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
173 if (&rg->link == head)
174 break;
175 if (rg->from > t)
176 break;
178 /* If this area reaches higher then extend our area to
179 * include it completely. If this is not the first area
180 * which we intend to reuse, free it. */
181 if (rg->to > t)
182 t = rg->to;
183 if (rg != nrg) {
184 list_del(&rg->link);
185 kfree(rg);
188 nrg->from = f;
189 nrg->to = t;
190 spin_unlock(&resv->lock);
191 return 0;
194 static long region_chg(struct resv_map *resv, long f, long t)
196 struct list_head *head = &resv->regions;
197 struct file_region *rg, *nrg = NULL;
198 long chg = 0;
200 retry:
201 spin_lock(&resv->lock);
202 /* Locate the region we are before or in. */
203 list_for_each_entry(rg, head, link)
204 if (f <= rg->to)
205 break;
207 /* If we are below the current region then a new region is required.
208 * Subtle, allocate a new region at the position but make it zero
209 * size such that we can guarantee to record the reservation. */
210 if (&rg->link == head || t < rg->from) {
211 if (!nrg) {
212 spin_unlock(&resv->lock);
213 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
214 if (!nrg)
215 return -ENOMEM;
217 nrg->from = f;
218 nrg->to = f;
219 INIT_LIST_HEAD(&nrg->link);
220 goto retry;
223 list_add(&nrg->link, rg->link.prev);
224 chg = t - f;
225 goto out_nrg;
228 /* Round our left edge to the current segment if it encloses us. */
229 if (f > rg->from)
230 f = rg->from;
231 chg = t - f;
233 /* Check for and consume any regions we now overlap with. */
234 list_for_each_entry(rg, rg->link.prev, link) {
235 if (&rg->link == head)
236 break;
237 if (rg->from > t)
238 goto out;
240 /* We overlap with this area, if it extends further than
241 * us then we must extend ourselves. Account for its
242 * existing reservation. */
243 if (rg->to > t) {
244 chg += rg->to - t;
245 t = rg->to;
247 chg -= rg->to - rg->from;
250 out:
251 spin_unlock(&resv->lock);
252 /* We already know we raced and no longer need the new region */
253 kfree(nrg);
254 return chg;
255 out_nrg:
256 spin_unlock(&resv->lock);
257 return chg;
260 static long region_truncate(struct resv_map *resv, long end)
262 struct list_head *head = &resv->regions;
263 struct file_region *rg, *trg;
264 long chg = 0;
266 spin_lock(&resv->lock);
267 /* Locate the region we are either in or before. */
268 list_for_each_entry(rg, head, link)
269 if (end <= rg->to)
270 break;
271 if (&rg->link == head)
272 goto out;
274 /* If we are in the middle of a region then adjust it. */
275 if (end > rg->from) {
276 chg = rg->to - end;
277 rg->to = end;
278 rg = list_entry(rg->link.next, typeof(*rg), link);
281 /* Drop any remaining regions. */
282 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
283 if (&rg->link == head)
284 break;
285 chg += rg->to - rg->from;
286 list_del(&rg->link);
287 kfree(rg);
290 out:
291 spin_unlock(&resv->lock);
292 return chg;
295 static long region_count(struct resv_map *resv, long f, long t)
297 struct list_head *head = &resv->regions;
298 struct file_region *rg;
299 long chg = 0;
301 spin_lock(&resv->lock);
302 /* Locate each segment we overlap with, and count that overlap. */
303 list_for_each_entry(rg, head, link) {
304 long seg_from;
305 long seg_to;
307 if (rg->to <= f)
308 continue;
309 if (rg->from >= t)
310 break;
312 seg_from = max(rg->from, f);
313 seg_to = min(rg->to, t);
315 chg += seg_to - seg_from;
317 spin_unlock(&resv->lock);
319 return chg;
323 * Convert the address within this vma to the page offset within
324 * the mapping, in pagecache page units; huge pages here.
326 static pgoff_t vma_hugecache_offset(struct hstate *h,
327 struct vm_area_struct *vma, unsigned long address)
329 return ((address - vma->vm_start) >> huge_page_shift(h)) +
330 (vma->vm_pgoff >> huge_page_order(h));
333 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
334 unsigned long address)
336 return vma_hugecache_offset(hstate_vma(vma), vma, address);
340 * Return the size of the pages allocated when backing a VMA. In the majority
341 * cases this will be same size as used by the page table entries.
343 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
345 struct hstate *hstate;
347 if (!is_vm_hugetlb_page(vma))
348 return PAGE_SIZE;
350 hstate = hstate_vma(vma);
352 return 1UL << huge_page_shift(hstate);
354 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
357 * Return the page size being used by the MMU to back a VMA. In the majority
358 * of cases, the page size used by the kernel matches the MMU size. On
359 * architectures where it differs, an architecture-specific version of this
360 * function is required.
362 #ifndef vma_mmu_pagesize
363 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
365 return vma_kernel_pagesize(vma);
367 #endif
370 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
371 * bits of the reservation map pointer, which are always clear due to
372 * alignment.
374 #define HPAGE_RESV_OWNER (1UL << 0)
375 #define HPAGE_RESV_UNMAPPED (1UL << 1)
376 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
379 * These helpers are used to track how many pages are reserved for
380 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
381 * is guaranteed to have their future faults succeed.
383 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
384 * the reserve counters are updated with the hugetlb_lock held. It is safe
385 * to reset the VMA at fork() time as it is not in use yet and there is no
386 * chance of the global counters getting corrupted as a result of the values.
388 * The private mapping reservation is represented in a subtly different
389 * manner to a shared mapping. A shared mapping has a region map associated
390 * with the underlying file, this region map represents the backing file
391 * pages which have ever had a reservation assigned which this persists even
392 * after the page is instantiated. A private mapping has a region map
393 * associated with the original mmap which is attached to all VMAs which
394 * reference it, this region map represents those offsets which have consumed
395 * reservation ie. where pages have been instantiated.
397 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
399 return (unsigned long)vma->vm_private_data;
402 static void set_vma_private_data(struct vm_area_struct *vma,
403 unsigned long value)
405 vma->vm_private_data = (void *)value;
408 struct resv_map *resv_map_alloc(void)
410 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
411 if (!resv_map)
412 return NULL;
414 kref_init(&resv_map->refs);
415 spin_lock_init(&resv_map->lock);
416 INIT_LIST_HEAD(&resv_map->regions);
418 return resv_map;
421 void resv_map_release(struct kref *ref)
423 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
425 /* Clear out any active regions before we release the map. */
426 region_truncate(resv_map, 0);
427 kfree(resv_map);
430 static inline struct resv_map *inode_resv_map(struct inode *inode)
432 return inode->i_mapping->private_data;
435 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
437 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
438 if (vma->vm_flags & VM_MAYSHARE) {
439 struct address_space *mapping = vma->vm_file->f_mapping;
440 struct inode *inode = mapping->host;
442 return inode_resv_map(inode);
444 } else {
445 return (struct resv_map *)(get_vma_private_data(vma) &
446 ~HPAGE_RESV_MASK);
450 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
452 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
453 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
455 set_vma_private_data(vma, (get_vma_private_data(vma) &
456 HPAGE_RESV_MASK) | (unsigned long)map);
459 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
461 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
462 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
464 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
467 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
469 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
471 return (get_vma_private_data(vma) & flag) != 0;
474 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
475 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
477 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
478 if (!(vma->vm_flags & VM_MAYSHARE))
479 vma->vm_private_data = (void *)0;
482 /* Returns true if the VMA has associated reserve pages */
483 static int vma_has_reserves(struct vm_area_struct *vma, long chg)
485 if (vma->vm_flags & VM_NORESERVE) {
487 * This address is already reserved by other process(chg == 0),
488 * so, we should decrement reserved count. Without decrementing,
489 * reserve count remains after releasing inode, because this
490 * allocated page will go into page cache and is regarded as
491 * coming from reserved pool in releasing step. Currently, we
492 * don't have any other solution to deal with this situation
493 * properly, so add work-around here.
495 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
496 return 1;
497 else
498 return 0;
501 /* Shared mappings always use reserves */
502 if (vma->vm_flags & VM_MAYSHARE)
503 return 1;
506 * Only the process that called mmap() has reserves for
507 * private mappings.
509 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
510 return 1;
512 return 0;
515 static void enqueue_huge_page(struct hstate *h, struct page *page)
517 int nid = page_to_nid(page);
518 list_move(&page->lru, &h->hugepage_freelists[nid]);
519 h->free_huge_pages++;
520 h->free_huge_pages_node[nid]++;
523 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
525 struct page *page;
527 list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
528 if (!is_migrate_isolate_page(page))
529 break;
531 * if 'non-isolated free hugepage' not found on the list,
532 * the allocation fails.
534 if (&h->hugepage_freelists[nid] == &page->lru)
535 return NULL;
536 list_move(&page->lru, &h->hugepage_activelist);
537 set_page_refcounted(page);
538 h->free_huge_pages--;
539 h->free_huge_pages_node[nid]--;
540 return page;
543 /* Movability of hugepages depends on migration support. */
544 static inline gfp_t htlb_alloc_mask(struct hstate *h)
546 if (hugepages_treat_as_movable || hugepage_migration_supported(h))
547 return GFP_HIGHUSER_MOVABLE;
548 else
549 return GFP_HIGHUSER;
552 static struct page *dequeue_huge_page_vma(struct hstate *h,
553 struct vm_area_struct *vma,
554 unsigned long address, int avoid_reserve,
555 long chg)
557 struct page *page = NULL;
558 struct mempolicy *mpol;
559 nodemask_t *nodemask;
560 struct zonelist *zonelist;
561 struct zone *zone;
562 struct zoneref *z;
563 unsigned int cpuset_mems_cookie;
566 * A child process with MAP_PRIVATE mappings created by their parent
567 * have no page reserves. This check ensures that reservations are
568 * not "stolen". The child may still get SIGKILLed
570 if (!vma_has_reserves(vma, chg) &&
571 h->free_huge_pages - h->resv_huge_pages == 0)
572 goto err;
574 /* If reserves cannot be used, ensure enough pages are in the pool */
575 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
576 goto err;
578 retry_cpuset:
579 cpuset_mems_cookie = read_mems_allowed_begin();
580 zonelist = huge_zonelist(vma, address,
581 htlb_alloc_mask(h), &mpol, &nodemask);
583 for_each_zone_zonelist_nodemask(zone, z, zonelist,
584 MAX_NR_ZONES - 1, nodemask) {
585 if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
586 page = dequeue_huge_page_node(h, zone_to_nid(zone));
587 if (page) {
588 if (avoid_reserve)
589 break;
590 if (!vma_has_reserves(vma, chg))
591 break;
593 SetPagePrivate(page);
594 h->resv_huge_pages--;
595 break;
600 mpol_cond_put(mpol);
601 if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
602 goto retry_cpuset;
603 return page;
605 err:
606 return NULL;
610 * common helper functions for hstate_next_node_to_{alloc|free}.
611 * We may have allocated or freed a huge page based on a different
612 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
613 * be outside of *nodes_allowed. Ensure that we use an allowed
614 * node for alloc or free.
616 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
618 nid = next_node(nid, *nodes_allowed);
619 if (nid == MAX_NUMNODES)
620 nid = first_node(*nodes_allowed);
621 VM_BUG_ON(nid >= MAX_NUMNODES);
623 return nid;
626 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
628 if (!node_isset(nid, *nodes_allowed))
629 nid = next_node_allowed(nid, nodes_allowed);
630 return nid;
634 * returns the previously saved node ["this node"] from which to
635 * allocate a persistent huge page for the pool and advance the
636 * next node from which to allocate, handling wrap at end of node
637 * mask.
639 static int hstate_next_node_to_alloc(struct hstate *h,
640 nodemask_t *nodes_allowed)
642 int nid;
644 VM_BUG_ON(!nodes_allowed);
646 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
647 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
649 return nid;
653 * helper for free_pool_huge_page() - return the previously saved
654 * node ["this node"] from which to free a huge page. Advance the
655 * next node id whether or not we find a free huge page to free so
656 * that the next attempt to free addresses the next node.
658 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
660 int nid;
662 VM_BUG_ON(!nodes_allowed);
664 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
665 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
667 return nid;
670 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
671 for (nr_nodes = nodes_weight(*mask); \
672 nr_nodes > 0 && \
673 ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \
674 nr_nodes--)
676 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
677 for (nr_nodes = nodes_weight(*mask); \
678 nr_nodes > 0 && \
679 ((node = hstate_next_node_to_free(hs, mask)) || 1); \
680 nr_nodes--)
682 #if defined(CONFIG_CMA) && defined(CONFIG_X86_64)
683 static void destroy_compound_gigantic_page(struct page *page,
684 unsigned long order)
686 int i;
687 int nr_pages = 1 << order;
688 struct page *p = page + 1;
690 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
691 __ClearPageTail(p);
692 set_page_refcounted(p);
693 p->first_page = NULL;
696 set_compound_order(page, 0);
697 __ClearPageHead(page);
700 static void free_gigantic_page(struct page *page, unsigned order)
702 free_contig_range(page_to_pfn(page), 1 << order);
705 static int __alloc_gigantic_page(unsigned long start_pfn,
706 unsigned long nr_pages)
708 unsigned long end_pfn = start_pfn + nr_pages;
709 return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
712 static bool pfn_range_valid_gigantic(unsigned long start_pfn,
713 unsigned long nr_pages)
715 unsigned long i, end_pfn = start_pfn + nr_pages;
716 struct page *page;
718 for (i = start_pfn; i < end_pfn; i++) {
719 if (!pfn_valid(i))
720 return false;
722 page = pfn_to_page(i);
724 if (PageReserved(page))
725 return false;
727 if (page_count(page) > 0)
728 return false;
730 if (PageHuge(page))
731 return false;
734 return true;
737 static bool zone_spans_last_pfn(const struct zone *zone,
738 unsigned long start_pfn, unsigned long nr_pages)
740 unsigned long last_pfn = start_pfn + nr_pages - 1;
741 return zone_spans_pfn(zone, last_pfn);
744 static struct page *alloc_gigantic_page(int nid, unsigned order)
746 unsigned long nr_pages = 1 << order;
747 unsigned long ret, pfn, flags;
748 struct zone *z;
750 z = NODE_DATA(nid)->node_zones;
751 for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
752 spin_lock_irqsave(&z->lock, flags);
754 pfn = ALIGN(z->zone_start_pfn, nr_pages);
755 while (zone_spans_last_pfn(z, pfn, nr_pages)) {
756 if (pfn_range_valid_gigantic(pfn, nr_pages)) {
758 * We release the zone lock here because
759 * alloc_contig_range() will also lock the zone
760 * at some point. If there's an allocation
761 * spinning on this lock, it may win the race
762 * and cause alloc_contig_range() to fail...
764 spin_unlock_irqrestore(&z->lock, flags);
765 ret = __alloc_gigantic_page(pfn, nr_pages);
766 if (!ret)
767 return pfn_to_page(pfn);
768 spin_lock_irqsave(&z->lock, flags);
770 pfn += nr_pages;
773 spin_unlock_irqrestore(&z->lock, flags);
776 return NULL;
779 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
780 static void prep_compound_gigantic_page(struct page *page, unsigned long order);
782 static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
784 struct page *page;
786 page = alloc_gigantic_page(nid, huge_page_order(h));
787 if (page) {
788 prep_compound_gigantic_page(page, huge_page_order(h));
789 prep_new_huge_page(h, page, nid);
792 return page;
795 static int alloc_fresh_gigantic_page(struct hstate *h,
796 nodemask_t *nodes_allowed)
798 struct page *page = NULL;
799 int nr_nodes, node;
801 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
802 page = alloc_fresh_gigantic_page_node(h, node);
803 if (page)
804 return 1;
807 return 0;
810 static inline bool gigantic_page_supported(void) { return true; }
811 #else
812 static inline bool gigantic_page_supported(void) { return false; }
813 static inline void free_gigantic_page(struct page *page, unsigned order) { }
814 static inline void destroy_compound_gigantic_page(struct page *page,
815 unsigned long order) { }
816 static inline int alloc_fresh_gigantic_page(struct hstate *h,
817 nodemask_t *nodes_allowed) { return 0; }
818 #endif
820 static void update_and_free_page(struct hstate *h, struct page *page)
822 int i;
824 if (hstate_is_gigantic(h) && !gigantic_page_supported())
825 return;
827 h->nr_huge_pages--;
828 h->nr_huge_pages_node[page_to_nid(page)]--;
829 for (i = 0; i < pages_per_huge_page(h); i++) {
830 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
831 1 << PG_referenced | 1 << PG_dirty |
832 1 << PG_active | 1 << PG_private |
833 1 << PG_writeback);
835 VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
836 set_compound_page_dtor(page, NULL);
837 set_page_refcounted(page);
838 if (hstate_is_gigantic(h)) {
839 destroy_compound_gigantic_page(page, huge_page_order(h));
840 free_gigantic_page(page, huge_page_order(h));
841 } else {
842 arch_release_hugepage(page);
843 __free_pages(page, huge_page_order(h));
847 struct hstate *size_to_hstate(unsigned long size)
849 struct hstate *h;
851 for_each_hstate(h) {
852 if (huge_page_size(h) == size)
853 return h;
855 return NULL;
858 void free_huge_page(struct page *page)
861 * Can't pass hstate in here because it is called from the
862 * compound page destructor.
864 struct hstate *h = page_hstate(page);
865 int nid = page_to_nid(page);
866 struct hugepage_subpool *spool =
867 (struct hugepage_subpool *)page_private(page);
868 bool restore_reserve;
870 set_page_private(page, 0);
871 page->mapping = NULL;
872 BUG_ON(page_count(page));
873 BUG_ON(page_mapcount(page));
874 restore_reserve = PagePrivate(page);
875 ClearPagePrivate(page);
877 spin_lock(&hugetlb_lock);
878 hugetlb_cgroup_uncharge_page(hstate_index(h),
879 pages_per_huge_page(h), page);
880 if (restore_reserve)
881 h->resv_huge_pages++;
883 if (h->surplus_huge_pages_node[nid]) {
884 /* remove the page from active list */
885 list_del(&page->lru);
886 update_and_free_page(h, page);
887 h->surplus_huge_pages--;
888 h->surplus_huge_pages_node[nid]--;
889 } else {
890 arch_clear_hugepage_flags(page);
891 enqueue_huge_page(h, page);
893 spin_unlock(&hugetlb_lock);
894 hugepage_subpool_put_pages(spool, 1);
897 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
899 INIT_LIST_HEAD(&page->lru);
900 set_compound_page_dtor(page, free_huge_page);
901 spin_lock(&hugetlb_lock);
902 set_hugetlb_cgroup(page, NULL);
903 h->nr_huge_pages++;
904 h->nr_huge_pages_node[nid]++;
905 spin_unlock(&hugetlb_lock);
906 put_page(page); /* free it into the hugepage allocator */
909 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
911 int i;
912 int nr_pages = 1 << order;
913 struct page *p = page + 1;
915 /* we rely on prep_new_huge_page to set the destructor */
916 set_compound_order(page, order);
917 __SetPageHead(page);
918 __ClearPageReserved(page);
919 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
920 __SetPageTail(p);
922 * For gigantic hugepages allocated through bootmem at
923 * boot, it's safer to be consistent with the not-gigantic
924 * hugepages and clear the PG_reserved bit from all tail pages
925 * too. Otherwse drivers using get_user_pages() to access tail
926 * pages may get the reference counting wrong if they see
927 * PG_reserved set on a tail page (despite the head page not
928 * having PG_reserved set). Enforcing this consistency between
929 * head and tail pages allows drivers to optimize away a check
930 * on the head page when they need know if put_page() is needed
931 * after get_user_pages().
933 __ClearPageReserved(p);
934 set_page_count(p, 0);
935 p->first_page = page;
940 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
941 * transparent huge pages. See the PageTransHuge() documentation for more
942 * details.
944 int PageHuge(struct page *page)
946 if (!PageCompound(page))
947 return 0;
949 page = compound_head(page);
950 return get_compound_page_dtor(page) == free_huge_page;
952 EXPORT_SYMBOL_GPL(PageHuge);
955 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
956 * normal or transparent huge pages.
958 int PageHeadHuge(struct page *page_head)
960 if (!PageHead(page_head))
961 return 0;
963 return get_compound_page_dtor(page_head) == free_huge_page;
966 pgoff_t __basepage_index(struct page *page)
968 struct page *page_head = compound_head(page);
969 pgoff_t index = page_index(page_head);
970 unsigned long compound_idx;
972 if (!PageHuge(page_head))
973 return page_index(page);
975 if (compound_order(page_head) >= MAX_ORDER)
976 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
977 else
978 compound_idx = page - page_head;
980 return (index << compound_order(page_head)) + compound_idx;
983 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
985 struct page *page;
987 page = alloc_pages_exact_node(nid,
988 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
989 __GFP_REPEAT|__GFP_NOWARN,
990 huge_page_order(h));
991 if (page) {
992 if (arch_prepare_hugepage(page)) {
993 __free_pages(page, huge_page_order(h));
994 return NULL;
996 prep_new_huge_page(h, page, nid);
999 return page;
1002 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1004 struct page *page;
1005 int nr_nodes, node;
1006 int ret = 0;
1008 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1009 page = alloc_fresh_huge_page_node(h, node);
1010 if (page) {
1011 ret = 1;
1012 break;
1016 if (ret)
1017 count_vm_event(HTLB_BUDDY_PGALLOC);
1018 else
1019 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1021 return ret;
1025 * Free huge page from pool from next node to free.
1026 * Attempt to keep persistent huge pages more or less
1027 * balanced over allowed nodes.
1028 * Called with hugetlb_lock locked.
1030 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1031 bool acct_surplus)
1033 int nr_nodes, node;
1034 int ret = 0;
1036 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1038 * If we're returning unused surplus pages, only examine
1039 * nodes with surplus pages.
1041 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1042 !list_empty(&h->hugepage_freelists[node])) {
1043 struct page *page =
1044 list_entry(h->hugepage_freelists[node].next,
1045 struct page, lru);
1046 list_del(&page->lru);
1047 h->free_huge_pages--;
1048 h->free_huge_pages_node[node]--;
1049 if (acct_surplus) {
1050 h->surplus_huge_pages--;
1051 h->surplus_huge_pages_node[node]--;
1053 update_and_free_page(h, page);
1054 ret = 1;
1055 break;
1059 return ret;
1063 * Dissolve a given free hugepage into free buddy pages. This function does
1064 * nothing for in-use (including surplus) hugepages.
1066 static void dissolve_free_huge_page(struct page *page)
1068 spin_lock(&hugetlb_lock);
1069 if (PageHuge(page) && !page_count(page)) {
1070 struct hstate *h = page_hstate(page);
1071 int nid = page_to_nid(page);
1072 list_del(&page->lru);
1073 h->free_huge_pages--;
1074 h->free_huge_pages_node[nid]--;
1075 update_and_free_page(h, page);
1077 spin_unlock(&hugetlb_lock);
1081 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1082 * make specified memory blocks removable from the system.
1083 * Note that start_pfn should aligned with (minimum) hugepage size.
1085 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1087 unsigned int order = 8 * sizeof(void *);
1088 unsigned long pfn;
1089 struct hstate *h;
1091 if (!hugepages_supported())
1092 return;
1094 /* Set scan step to minimum hugepage size */
1095 for_each_hstate(h)
1096 if (order > huge_page_order(h))
1097 order = huge_page_order(h);
1098 VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order));
1099 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
1100 dissolve_free_huge_page(pfn_to_page(pfn));
1103 static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
1105 struct page *page;
1106 unsigned int r_nid;
1108 if (hstate_is_gigantic(h))
1109 return NULL;
1112 * Assume we will successfully allocate the surplus page to
1113 * prevent racing processes from causing the surplus to exceed
1114 * overcommit
1116 * This however introduces a different race, where a process B
1117 * tries to grow the static hugepage pool while alloc_pages() is
1118 * called by process A. B will only examine the per-node
1119 * counters in determining if surplus huge pages can be
1120 * converted to normal huge pages in adjust_pool_surplus(). A
1121 * won't be able to increment the per-node counter, until the
1122 * lock is dropped by B, but B doesn't drop hugetlb_lock until
1123 * no more huge pages can be converted from surplus to normal
1124 * state (and doesn't try to convert again). Thus, we have a
1125 * case where a surplus huge page exists, the pool is grown, and
1126 * the surplus huge page still exists after, even though it
1127 * should just have been converted to a normal huge page. This
1128 * does not leak memory, though, as the hugepage will be freed
1129 * once it is out of use. It also does not allow the counters to
1130 * go out of whack in adjust_pool_surplus() as we don't modify
1131 * the node values until we've gotten the hugepage and only the
1132 * per-node value is checked there.
1134 spin_lock(&hugetlb_lock);
1135 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1136 spin_unlock(&hugetlb_lock);
1137 return NULL;
1138 } else {
1139 h->nr_huge_pages++;
1140 h->surplus_huge_pages++;
1142 spin_unlock(&hugetlb_lock);
1144 if (nid == NUMA_NO_NODE)
1145 page = alloc_pages(htlb_alloc_mask(h)|__GFP_COMP|
1146 __GFP_REPEAT|__GFP_NOWARN,
1147 huge_page_order(h));
1148 else
1149 page = alloc_pages_exact_node(nid,
1150 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1151 __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
1153 if (page && arch_prepare_hugepage(page)) {
1154 __free_pages(page, huge_page_order(h));
1155 page = NULL;
1158 spin_lock(&hugetlb_lock);
1159 if (page) {
1160 INIT_LIST_HEAD(&page->lru);
1161 r_nid = page_to_nid(page);
1162 set_compound_page_dtor(page, free_huge_page);
1163 set_hugetlb_cgroup(page, NULL);
1165 * We incremented the global counters already
1167 h->nr_huge_pages_node[r_nid]++;
1168 h->surplus_huge_pages_node[r_nid]++;
1169 __count_vm_event(HTLB_BUDDY_PGALLOC);
1170 } else {
1171 h->nr_huge_pages--;
1172 h->surplus_huge_pages--;
1173 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1175 spin_unlock(&hugetlb_lock);
1177 return page;
1181 * This allocation function is useful in the context where vma is irrelevant.
1182 * E.g. soft-offlining uses this function because it only cares physical
1183 * address of error page.
1185 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1187 struct page *page = NULL;
1189 spin_lock(&hugetlb_lock);
1190 if (h->free_huge_pages - h->resv_huge_pages > 0)
1191 page = dequeue_huge_page_node(h, nid);
1192 spin_unlock(&hugetlb_lock);
1194 if (!page)
1195 page = alloc_buddy_huge_page(h, nid);
1197 return page;
1201 * Increase the hugetlb pool such that it can accommodate a reservation
1202 * of size 'delta'.
1204 static int gather_surplus_pages(struct hstate *h, int delta)
1206 struct list_head surplus_list;
1207 struct page *page, *tmp;
1208 int ret, i;
1209 int needed, allocated;
1210 bool alloc_ok = true;
1212 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1213 if (needed <= 0) {
1214 h->resv_huge_pages += delta;
1215 return 0;
1218 allocated = 0;
1219 INIT_LIST_HEAD(&surplus_list);
1221 ret = -ENOMEM;
1222 retry:
1223 spin_unlock(&hugetlb_lock);
1224 for (i = 0; i < needed; i++) {
1225 page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
1226 if (!page) {
1227 alloc_ok = false;
1228 break;
1230 list_add(&page->lru, &surplus_list);
1232 allocated += i;
1235 * After retaking hugetlb_lock, we need to recalculate 'needed'
1236 * because either resv_huge_pages or free_huge_pages may have changed.
1238 spin_lock(&hugetlb_lock);
1239 needed = (h->resv_huge_pages + delta) -
1240 (h->free_huge_pages + allocated);
1241 if (needed > 0) {
1242 if (alloc_ok)
1243 goto retry;
1245 * We were not able to allocate enough pages to
1246 * satisfy the entire reservation so we free what
1247 * we've allocated so far.
1249 goto free;
1252 * The surplus_list now contains _at_least_ the number of extra pages
1253 * needed to accommodate the reservation. Add the appropriate number
1254 * of pages to the hugetlb pool and free the extras back to the buddy
1255 * allocator. Commit the entire reservation here to prevent another
1256 * process from stealing the pages as they are added to the pool but
1257 * before they are reserved.
1259 needed += allocated;
1260 h->resv_huge_pages += delta;
1261 ret = 0;
1263 /* Free the needed pages to the hugetlb pool */
1264 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1265 if ((--needed) < 0)
1266 break;
1268 * This page is now managed by the hugetlb allocator and has
1269 * no users -- drop the buddy allocator's reference.
1271 put_page_testzero(page);
1272 VM_BUG_ON_PAGE(page_count(page), page);
1273 enqueue_huge_page(h, page);
1275 free:
1276 spin_unlock(&hugetlb_lock);
1278 /* Free unnecessary surplus pages to the buddy allocator */
1279 list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1280 put_page(page);
1281 spin_lock(&hugetlb_lock);
1283 return ret;
1287 * When releasing a hugetlb pool reservation, any surplus pages that were
1288 * allocated to satisfy the reservation must be explicitly freed if they were
1289 * never used.
1290 * Called with hugetlb_lock held.
1292 static void return_unused_surplus_pages(struct hstate *h,
1293 unsigned long unused_resv_pages)
1295 unsigned long nr_pages;
1297 /* Uncommit the reservation */
1298 h->resv_huge_pages -= unused_resv_pages;
1300 /* Cannot return gigantic pages currently */
1301 if (hstate_is_gigantic(h))
1302 return;
1304 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1307 * We want to release as many surplus pages as possible, spread
1308 * evenly across all nodes with memory. Iterate across these nodes
1309 * until we can no longer free unreserved surplus pages. This occurs
1310 * when the nodes with surplus pages have no free pages.
1311 * free_pool_huge_page() will balance the the freed pages across the
1312 * on-line nodes with memory and will handle the hstate accounting.
1314 while (nr_pages--) {
1315 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1316 break;
1317 cond_resched_lock(&hugetlb_lock);
1322 * Determine if the huge page at addr within the vma has an associated
1323 * reservation. Where it does not we will need to logically increase
1324 * reservation and actually increase subpool usage before an allocation
1325 * can occur. Where any new reservation would be required the
1326 * reservation change is prepared, but not committed. Once the page
1327 * has been allocated from the subpool and instantiated the change should
1328 * be committed via vma_commit_reservation. No action is required on
1329 * failure.
1331 static long vma_needs_reservation(struct hstate *h,
1332 struct vm_area_struct *vma, unsigned long addr)
1334 struct resv_map *resv;
1335 pgoff_t idx;
1336 long chg;
1338 resv = vma_resv_map(vma);
1339 if (!resv)
1340 return 1;
1342 idx = vma_hugecache_offset(h, vma, addr);
1343 chg = region_chg(resv, idx, idx + 1);
1345 if (vma->vm_flags & VM_MAYSHARE)
1346 return chg;
1347 else
1348 return chg < 0 ? chg : 0;
1350 static void vma_commit_reservation(struct hstate *h,
1351 struct vm_area_struct *vma, unsigned long addr)
1353 struct resv_map *resv;
1354 pgoff_t idx;
1356 resv = vma_resv_map(vma);
1357 if (!resv)
1358 return;
1360 idx = vma_hugecache_offset(h, vma, addr);
1361 region_add(resv, idx, idx + 1);
1364 static struct page *alloc_huge_page(struct vm_area_struct *vma,
1365 unsigned long addr, int avoid_reserve)
1367 struct hugepage_subpool *spool = subpool_vma(vma);
1368 struct hstate *h = hstate_vma(vma);
1369 struct page *page;
1370 long chg;
1371 int ret, idx;
1372 struct hugetlb_cgroup *h_cg;
1374 idx = hstate_index(h);
1376 * Processes that did not create the mapping will have no
1377 * reserves and will not have accounted against subpool
1378 * limit. Check that the subpool limit can be made before
1379 * satisfying the allocation MAP_NORESERVE mappings may also
1380 * need pages and subpool limit allocated allocated if no reserve
1381 * mapping overlaps.
1383 chg = vma_needs_reservation(h, vma, addr);
1384 if (chg < 0)
1385 return ERR_PTR(-ENOMEM);
1386 if (chg || avoid_reserve)
1387 if (hugepage_subpool_get_pages(spool, 1))
1388 return ERR_PTR(-ENOSPC);
1390 ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1391 if (ret)
1392 goto out_subpool_put;
1394 spin_lock(&hugetlb_lock);
1395 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
1396 if (!page) {
1397 spin_unlock(&hugetlb_lock);
1398 page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
1399 if (!page)
1400 goto out_uncharge_cgroup;
1402 spin_lock(&hugetlb_lock);
1403 list_move(&page->lru, &h->hugepage_activelist);
1404 /* Fall through */
1406 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
1407 spin_unlock(&hugetlb_lock);
1409 set_page_private(page, (unsigned long)spool);
1411 vma_commit_reservation(h, vma, addr);
1412 return page;
1414 out_uncharge_cgroup:
1415 hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
1416 out_subpool_put:
1417 if (chg || avoid_reserve)
1418 hugepage_subpool_put_pages(spool, 1);
1419 return ERR_PTR(-ENOSPC);
1423 * alloc_huge_page()'s wrapper which simply returns the page if allocation
1424 * succeeds, otherwise NULL. This function is called from new_vma_page(),
1425 * where no ERR_VALUE is expected to be returned.
1427 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
1428 unsigned long addr, int avoid_reserve)
1430 struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
1431 if (IS_ERR(page))
1432 page = NULL;
1433 return page;
1436 int __weak alloc_bootmem_huge_page(struct hstate *h)
1438 struct huge_bootmem_page *m;
1439 int nr_nodes, node;
1441 for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
1442 void *addr;
1444 addr = memblock_virt_alloc_try_nid_nopanic(
1445 huge_page_size(h), huge_page_size(h),
1446 0, BOOTMEM_ALLOC_ACCESSIBLE, node);
1447 if (addr) {
1449 * Use the beginning of the huge page to store the
1450 * huge_bootmem_page struct (until gather_bootmem
1451 * puts them into the mem_map).
1453 m = addr;
1454 goto found;
1457 return 0;
1459 found:
1460 BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
1461 /* Put them into a private list first because mem_map is not up yet */
1462 list_add(&m->list, &huge_boot_pages);
1463 m->hstate = h;
1464 return 1;
1467 static void __init prep_compound_huge_page(struct page *page, int order)
1469 if (unlikely(order > (MAX_ORDER - 1)))
1470 prep_compound_gigantic_page(page, order);
1471 else
1472 prep_compound_page(page, order);
1475 /* Put bootmem huge pages into the standard lists after mem_map is up */
1476 static void __init gather_bootmem_prealloc(void)
1478 struct huge_bootmem_page *m;
1480 list_for_each_entry(m, &huge_boot_pages, list) {
1481 struct hstate *h = m->hstate;
1482 struct page *page;
1484 #ifdef CONFIG_HIGHMEM
1485 page = pfn_to_page(m->phys >> PAGE_SHIFT);
1486 memblock_free_late(__pa(m),
1487 sizeof(struct huge_bootmem_page));
1488 #else
1489 page = virt_to_page(m);
1490 #endif
1491 WARN_ON(page_count(page) != 1);
1492 prep_compound_huge_page(page, h->order);
1493 WARN_ON(PageReserved(page));
1494 prep_new_huge_page(h, page, page_to_nid(page));
1496 * If we had gigantic hugepages allocated at boot time, we need
1497 * to restore the 'stolen' pages to totalram_pages in order to
1498 * fix confusing memory reports from free(1) and another
1499 * side-effects, like CommitLimit going negative.
1501 if (hstate_is_gigantic(h))
1502 adjust_managed_page_count(page, 1 << h->order);
1506 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1508 unsigned long i;
1510 for (i = 0; i < h->max_huge_pages; ++i) {
1511 if (hstate_is_gigantic(h)) {
1512 if (!alloc_bootmem_huge_page(h))
1513 break;
1514 } else if (!alloc_fresh_huge_page(h,
1515 &node_states[N_MEMORY]))
1516 break;
1518 h->max_huge_pages = i;
1521 static void __init hugetlb_init_hstates(void)
1523 struct hstate *h;
1525 for_each_hstate(h) {
1526 /* oversize hugepages were init'ed in early boot */
1527 if (!hstate_is_gigantic(h))
1528 hugetlb_hstate_alloc_pages(h);
1532 static char * __init memfmt(char *buf, unsigned long n)
1534 if (n >= (1UL << 30))
1535 sprintf(buf, "%lu GB", n >> 30);
1536 else if (n >= (1UL << 20))
1537 sprintf(buf, "%lu MB", n >> 20);
1538 else
1539 sprintf(buf, "%lu KB", n >> 10);
1540 return buf;
1543 static void __init report_hugepages(void)
1545 struct hstate *h;
1547 for_each_hstate(h) {
1548 char buf[32];
1549 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
1550 memfmt(buf, huge_page_size(h)),
1551 h->free_huge_pages);
1555 #ifdef CONFIG_HIGHMEM
1556 static void try_to_free_low(struct hstate *h, unsigned long count,
1557 nodemask_t *nodes_allowed)
1559 int i;
1561 if (hstate_is_gigantic(h))
1562 return;
1564 for_each_node_mask(i, *nodes_allowed) {
1565 struct page *page, *next;
1566 struct list_head *freel = &h->hugepage_freelists[i];
1567 list_for_each_entry_safe(page, next, freel, lru) {
1568 if (count >= h->nr_huge_pages)
1569 return;
1570 if (PageHighMem(page))
1571 continue;
1572 list_del(&page->lru);
1573 update_and_free_page(h, page);
1574 h->free_huge_pages--;
1575 h->free_huge_pages_node[page_to_nid(page)]--;
1579 #else
1580 static inline void try_to_free_low(struct hstate *h, unsigned long count,
1581 nodemask_t *nodes_allowed)
1584 #endif
1587 * Increment or decrement surplus_huge_pages. Keep node-specific counters
1588 * balanced by operating on them in a round-robin fashion.
1589 * Returns 1 if an adjustment was made.
1591 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1592 int delta)
1594 int nr_nodes, node;
1596 VM_BUG_ON(delta != -1 && delta != 1);
1598 if (delta < 0) {
1599 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1600 if (h->surplus_huge_pages_node[node])
1601 goto found;
1603 } else {
1604 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1605 if (h->surplus_huge_pages_node[node] <
1606 h->nr_huge_pages_node[node])
1607 goto found;
1610 return 0;
1612 found:
1613 h->surplus_huge_pages += delta;
1614 h->surplus_huge_pages_node[node] += delta;
1615 return 1;
1618 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1619 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1620 nodemask_t *nodes_allowed)
1622 unsigned long min_count, ret;
1624 if (hstate_is_gigantic(h) && !gigantic_page_supported())
1625 return h->max_huge_pages;
1628 * Increase the pool size
1629 * First take pages out of surplus state. Then make up the
1630 * remaining difference by allocating fresh huge pages.
1632 * We might race with alloc_buddy_huge_page() here and be unable
1633 * to convert a surplus huge page to a normal huge page. That is
1634 * not critical, though, it just means the overall size of the
1635 * pool might be one hugepage larger than it needs to be, but
1636 * within all the constraints specified by the sysctls.
1638 spin_lock(&hugetlb_lock);
1639 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1640 if (!adjust_pool_surplus(h, nodes_allowed, -1))
1641 break;
1644 while (count > persistent_huge_pages(h)) {
1646 * If this allocation races such that we no longer need the
1647 * page, free_huge_page will handle it by freeing the page
1648 * and reducing the surplus.
1650 spin_unlock(&hugetlb_lock);
1651 if (hstate_is_gigantic(h))
1652 ret = alloc_fresh_gigantic_page(h, nodes_allowed);
1653 else
1654 ret = alloc_fresh_huge_page(h, nodes_allowed);
1655 spin_lock(&hugetlb_lock);
1656 if (!ret)
1657 goto out;
1659 /* Bail for signals. Probably ctrl-c from user */
1660 if (signal_pending(current))
1661 goto out;
1665 * Decrease the pool size
1666 * First return free pages to the buddy allocator (being careful
1667 * to keep enough around to satisfy reservations). Then place
1668 * pages into surplus state as needed so the pool will shrink
1669 * to the desired size as pages become free.
1671 * By placing pages into the surplus state independent of the
1672 * overcommit value, we are allowing the surplus pool size to
1673 * exceed overcommit. There are few sane options here. Since
1674 * alloc_buddy_huge_page() is checking the global counter,
1675 * though, we'll note that we're not allowed to exceed surplus
1676 * and won't grow the pool anywhere else. Not until one of the
1677 * sysctls are changed, or the surplus pages go out of use.
1679 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1680 min_count = max(count, min_count);
1681 try_to_free_low(h, min_count, nodes_allowed);
1682 while (min_count < persistent_huge_pages(h)) {
1683 if (!free_pool_huge_page(h, nodes_allowed, 0))
1684 break;
1685 cond_resched_lock(&hugetlb_lock);
1687 while (count < persistent_huge_pages(h)) {
1688 if (!adjust_pool_surplus(h, nodes_allowed, 1))
1689 break;
1691 out:
1692 ret = persistent_huge_pages(h);
1693 spin_unlock(&hugetlb_lock);
1694 return ret;
1697 #define HSTATE_ATTR_RO(_name) \
1698 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1700 #define HSTATE_ATTR(_name) \
1701 static struct kobj_attribute _name##_attr = \
1702 __ATTR(_name, 0644, _name##_show, _name##_store)
1704 static struct kobject *hugepages_kobj;
1705 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1707 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1709 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1711 int i;
1713 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1714 if (hstate_kobjs[i] == kobj) {
1715 if (nidp)
1716 *nidp = NUMA_NO_NODE;
1717 return &hstates[i];
1720 return kobj_to_node_hstate(kobj, nidp);
1723 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1724 struct kobj_attribute *attr, char *buf)
1726 struct hstate *h;
1727 unsigned long nr_huge_pages;
1728 int nid;
1730 h = kobj_to_hstate(kobj, &nid);
1731 if (nid == NUMA_NO_NODE)
1732 nr_huge_pages = h->nr_huge_pages;
1733 else
1734 nr_huge_pages = h->nr_huge_pages_node[nid];
1736 return sprintf(buf, "%lu\n", nr_huge_pages);
1739 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
1740 struct hstate *h, int nid,
1741 unsigned long count, size_t len)
1743 int err;
1744 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1746 if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
1747 err = -EINVAL;
1748 goto out;
1751 if (nid == NUMA_NO_NODE) {
1753 * global hstate attribute
1755 if (!(obey_mempolicy &&
1756 init_nodemask_of_mempolicy(nodes_allowed))) {
1757 NODEMASK_FREE(nodes_allowed);
1758 nodes_allowed = &node_states[N_MEMORY];
1760 } else if (nodes_allowed) {
1762 * per node hstate attribute: adjust count to global,
1763 * but restrict alloc/free to the specified node.
1765 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1766 init_nodemask_of_node(nodes_allowed, nid);
1767 } else
1768 nodes_allowed = &node_states[N_MEMORY];
1770 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1772 if (nodes_allowed != &node_states[N_MEMORY])
1773 NODEMASK_FREE(nodes_allowed);
1775 return len;
1776 out:
1777 NODEMASK_FREE(nodes_allowed);
1778 return err;
1781 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1782 struct kobject *kobj, const char *buf,
1783 size_t len)
1785 struct hstate *h;
1786 unsigned long count;
1787 int nid;
1788 int err;
1790 err = kstrtoul(buf, 10, &count);
1791 if (err)
1792 return err;
1794 h = kobj_to_hstate(kobj, &nid);
1795 return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
1798 static ssize_t nr_hugepages_show(struct kobject *kobj,
1799 struct kobj_attribute *attr, char *buf)
1801 return nr_hugepages_show_common(kobj, attr, buf);
1804 static ssize_t nr_hugepages_store(struct kobject *kobj,
1805 struct kobj_attribute *attr, const char *buf, size_t len)
1807 return nr_hugepages_store_common(false, kobj, buf, len);
1809 HSTATE_ATTR(nr_hugepages);
1811 #ifdef CONFIG_NUMA
1814 * hstate attribute for optionally mempolicy-based constraint on persistent
1815 * huge page alloc/free.
1817 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1818 struct kobj_attribute *attr, char *buf)
1820 return nr_hugepages_show_common(kobj, attr, buf);
1823 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1824 struct kobj_attribute *attr, const char *buf, size_t len)
1826 return nr_hugepages_store_common(true, kobj, buf, len);
1828 HSTATE_ATTR(nr_hugepages_mempolicy);
1829 #endif
1832 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1833 struct kobj_attribute *attr, char *buf)
1835 struct hstate *h = kobj_to_hstate(kobj, NULL);
1836 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1839 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1840 struct kobj_attribute *attr, const char *buf, size_t count)
1842 int err;
1843 unsigned long input;
1844 struct hstate *h = kobj_to_hstate(kobj, NULL);
1846 if (hstate_is_gigantic(h))
1847 return -EINVAL;
1849 err = kstrtoul(buf, 10, &input);
1850 if (err)
1851 return err;
1853 spin_lock(&hugetlb_lock);
1854 h->nr_overcommit_huge_pages = input;
1855 spin_unlock(&hugetlb_lock);
1857 return count;
1859 HSTATE_ATTR(nr_overcommit_hugepages);
1861 static ssize_t free_hugepages_show(struct kobject *kobj,
1862 struct kobj_attribute *attr, char *buf)
1864 struct hstate *h;
1865 unsigned long free_huge_pages;
1866 int nid;
1868 h = kobj_to_hstate(kobj, &nid);
1869 if (nid == NUMA_NO_NODE)
1870 free_huge_pages = h->free_huge_pages;
1871 else
1872 free_huge_pages = h->free_huge_pages_node[nid];
1874 return sprintf(buf, "%lu\n", free_huge_pages);
1876 HSTATE_ATTR_RO(free_hugepages);
1878 static ssize_t resv_hugepages_show(struct kobject *kobj,
1879 struct kobj_attribute *attr, char *buf)
1881 struct hstate *h = kobj_to_hstate(kobj, NULL);
1882 return sprintf(buf, "%lu\n", h->resv_huge_pages);
1884 HSTATE_ATTR_RO(resv_hugepages);
1886 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1887 struct kobj_attribute *attr, char *buf)
1889 struct hstate *h;
1890 unsigned long surplus_huge_pages;
1891 int nid;
1893 h = kobj_to_hstate(kobj, &nid);
1894 if (nid == NUMA_NO_NODE)
1895 surplus_huge_pages = h->surplus_huge_pages;
1896 else
1897 surplus_huge_pages = h->surplus_huge_pages_node[nid];
1899 return sprintf(buf, "%lu\n", surplus_huge_pages);
1901 HSTATE_ATTR_RO(surplus_hugepages);
1903 static struct attribute *hstate_attrs[] = {
1904 &nr_hugepages_attr.attr,
1905 &nr_overcommit_hugepages_attr.attr,
1906 &free_hugepages_attr.attr,
1907 &resv_hugepages_attr.attr,
1908 &surplus_hugepages_attr.attr,
1909 #ifdef CONFIG_NUMA
1910 &nr_hugepages_mempolicy_attr.attr,
1911 #endif
1912 NULL,
1915 static struct attribute_group hstate_attr_group = {
1916 .attrs = hstate_attrs,
1919 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
1920 struct kobject **hstate_kobjs,
1921 struct attribute_group *hstate_attr_group)
1923 int retval;
1924 int hi = hstate_index(h);
1926 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1927 if (!hstate_kobjs[hi])
1928 return -ENOMEM;
1930 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1931 if (retval)
1932 kobject_put(hstate_kobjs[hi]);
1934 return retval;
1937 static void __init hugetlb_sysfs_init(void)
1939 struct hstate *h;
1940 int err;
1942 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1943 if (!hugepages_kobj)
1944 return;
1946 for_each_hstate(h) {
1947 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1948 hstate_kobjs, &hstate_attr_group);
1949 if (err)
1950 pr_err("Hugetlb: Unable to add hstate %s", h->name);
1954 #ifdef CONFIG_NUMA
1957 * node_hstate/s - associate per node hstate attributes, via their kobjects,
1958 * with node devices in node_devices[] using a parallel array. The array
1959 * index of a node device or _hstate == node id.
1960 * This is here to avoid any static dependency of the node device driver, in
1961 * the base kernel, on the hugetlb module.
1963 struct node_hstate {
1964 struct kobject *hugepages_kobj;
1965 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1967 struct node_hstate node_hstates[MAX_NUMNODES];
1970 * A subset of global hstate attributes for node devices
1972 static struct attribute *per_node_hstate_attrs[] = {
1973 &nr_hugepages_attr.attr,
1974 &free_hugepages_attr.attr,
1975 &surplus_hugepages_attr.attr,
1976 NULL,
1979 static struct attribute_group per_node_hstate_attr_group = {
1980 .attrs = per_node_hstate_attrs,
1984 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
1985 * Returns node id via non-NULL nidp.
1987 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1989 int nid;
1991 for (nid = 0; nid < nr_node_ids; nid++) {
1992 struct node_hstate *nhs = &node_hstates[nid];
1993 int i;
1994 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1995 if (nhs->hstate_kobjs[i] == kobj) {
1996 if (nidp)
1997 *nidp = nid;
1998 return &hstates[i];
2002 BUG();
2003 return NULL;
2007 * Unregister hstate attributes from a single node device.
2008 * No-op if no hstate attributes attached.
2010 static void hugetlb_unregister_node(struct node *node)
2012 struct hstate *h;
2013 struct node_hstate *nhs = &node_hstates[node->dev.id];
2015 if (!nhs->hugepages_kobj)
2016 return; /* no hstate attributes */
2018 for_each_hstate(h) {
2019 int idx = hstate_index(h);
2020 if (nhs->hstate_kobjs[idx]) {
2021 kobject_put(nhs->hstate_kobjs[idx]);
2022 nhs->hstate_kobjs[idx] = NULL;
2026 kobject_put(nhs->hugepages_kobj);
2027 nhs->hugepages_kobj = NULL;
2031 * hugetlb module exit: unregister hstate attributes from node devices
2032 * that have them.
2034 static void hugetlb_unregister_all_nodes(void)
2036 int nid;
2039 * disable node device registrations.
2041 register_hugetlbfs_with_node(NULL, NULL);
2044 * remove hstate attributes from any nodes that have them.
2046 for (nid = 0; nid < nr_node_ids; nid++)
2047 hugetlb_unregister_node(node_devices[nid]);
2051 * Register hstate attributes for a single node device.
2052 * No-op if attributes already registered.
2054 static void hugetlb_register_node(struct node *node)
2056 struct hstate *h;
2057 struct node_hstate *nhs = &node_hstates[node->dev.id];
2058 int err;
2060 if (nhs->hugepages_kobj)
2061 return; /* already allocated */
2063 nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2064 &node->dev.kobj);
2065 if (!nhs->hugepages_kobj)
2066 return;
2068 for_each_hstate(h) {
2069 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2070 nhs->hstate_kobjs,
2071 &per_node_hstate_attr_group);
2072 if (err) {
2073 pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2074 h->name, node->dev.id);
2075 hugetlb_unregister_node(node);
2076 break;
2082 * hugetlb init time: register hstate attributes for all registered node
2083 * devices of nodes that have memory. All on-line nodes should have
2084 * registered their associated device by this time.
2086 static void __init hugetlb_register_all_nodes(void)
2088 int nid;
2090 for_each_node_state(nid, N_MEMORY) {
2091 struct node *node = node_devices[nid];
2092 if (node->dev.id == nid)
2093 hugetlb_register_node(node);
2097 * Let the node device driver know we're here so it can
2098 * [un]register hstate attributes on node hotplug.
2100 register_hugetlbfs_with_node(hugetlb_register_node,
2101 hugetlb_unregister_node);
2103 #else /* !CONFIG_NUMA */
2105 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2107 BUG();
2108 if (nidp)
2109 *nidp = -1;
2110 return NULL;
2113 static void hugetlb_unregister_all_nodes(void) { }
2115 static void hugetlb_register_all_nodes(void) { }
2117 #endif
2119 static void __exit hugetlb_exit(void)
2121 struct hstate *h;
2123 hugetlb_unregister_all_nodes();
2125 for_each_hstate(h) {
2126 kobject_put(hstate_kobjs[hstate_index(h)]);
2129 kobject_put(hugepages_kobj);
2130 kfree(htlb_fault_mutex_table);
2132 module_exit(hugetlb_exit);
2134 static int __init hugetlb_init(void)
2136 int i;
2138 if (!hugepages_supported())
2139 return 0;
2141 if (!size_to_hstate(default_hstate_size)) {
2142 default_hstate_size = HPAGE_SIZE;
2143 if (!size_to_hstate(default_hstate_size))
2144 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2146 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2147 if (default_hstate_max_huge_pages)
2148 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2150 hugetlb_init_hstates();
2151 gather_bootmem_prealloc();
2152 report_hugepages();
2154 hugetlb_sysfs_init();
2155 hugetlb_register_all_nodes();
2156 hugetlb_cgroup_file_init();
2158 #ifdef CONFIG_SMP
2159 num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2160 #else
2161 num_fault_mutexes = 1;
2162 #endif
2163 htlb_fault_mutex_table =
2164 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2165 BUG_ON(!htlb_fault_mutex_table);
2167 for (i = 0; i < num_fault_mutexes; i++)
2168 mutex_init(&htlb_fault_mutex_table[i]);
2169 return 0;
2171 module_init(hugetlb_init);
2173 /* Should be called on processing a hugepagesz=... option */
2174 void __init hugetlb_add_hstate(unsigned order)
2176 struct hstate *h;
2177 unsigned long i;
2179 if (size_to_hstate(PAGE_SIZE << order)) {
2180 pr_warning("hugepagesz= specified twice, ignoring\n");
2181 return;
2183 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2184 BUG_ON(order == 0);
2185 h = &hstates[hugetlb_max_hstate++];
2186 h->order = order;
2187 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2188 h->nr_huge_pages = 0;
2189 h->free_huge_pages = 0;
2190 for (i = 0; i < MAX_NUMNODES; ++i)
2191 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2192 INIT_LIST_HEAD(&h->hugepage_activelist);
2193 h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
2194 h->next_nid_to_free = first_node(node_states[N_MEMORY]);
2195 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2196 huge_page_size(h)/1024);
2198 parsed_hstate = h;
2201 static int __init hugetlb_nrpages_setup(char *s)
2203 unsigned long *mhp;
2204 static unsigned long *last_mhp;
2207 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2208 * so this hugepages= parameter goes to the "default hstate".
2210 if (!hugetlb_max_hstate)
2211 mhp = &default_hstate_max_huge_pages;
2212 else
2213 mhp = &parsed_hstate->max_huge_pages;
2215 if (mhp == last_mhp) {
2216 pr_warning("hugepages= specified twice without "
2217 "interleaving hugepagesz=, ignoring\n");
2218 return 1;
2221 if (sscanf(s, "%lu", mhp) <= 0)
2222 *mhp = 0;
2225 * Global state is always initialized later in hugetlb_init.
2226 * But we need to allocate >= MAX_ORDER hstates here early to still
2227 * use the bootmem allocator.
2229 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2230 hugetlb_hstate_alloc_pages(parsed_hstate);
2232 last_mhp = mhp;
2234 return 1;
2236 __setup("hugepages=", hugetlb_nrpages_setup);
2238 static int __init hugetlb_default_setup(char *s)
2240 default_hstate_size = memparse(s, &s);
2241 return 1;
2243 __setup("default_hugepagesz=", hugetlb_default_setup);
2245 static unsigned int cpuset_mems_nr(unsigned int *array)
2247 int node;
2248 unsigned int nr = 0;
2250 for_each_node_mask(node, cpuset_current_mems_allowed)
2251 nr += array[node];
2253 return nr;
2256 #ifdef CONFIG_SYSCTL
2257 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2258 struct ctl_table *table, int write,
2259 void __user *buffer, size_t *length, loff_t *ppos)
2261 struct hstate *h = &default_hstate;
2262 unsigned long tmp = h->max_huge_pages;
2263 int ret;
2265 if (!hugepages_supported())
2266 return -ENOTSUPP;
2268 table->data = &tmp;
2269 table->maxlen = sizeof(unsigned long);
2270 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2271 if (ret)
2272 goto out;
2274 if (write)
2275 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2276 NUMA_NO_NODE, tmp, *length);
2277 out:
2278 return ret;
2281 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2282 void __user *buffer, size_t *length, loff_t *ppos)
2285 return hugetlb_sysctl_handler_common(false, table, write,
2286 buffer, length, ppos);
2289 #ifdef CONFIG_NUMA
2290 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2291 void __user *buffer, size_t *length, loff_t *ppos)
2293 return hugetlb_sysctl_handler_common(true, table, write,
2294 buffer, length, ppos);
2296 #endif /* CONFIG_NUMA */
2298 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2299 void __user *buffer,
2300 size_t *length, loff_t *ppos)
2302 struct hstate *h = &default_hstate;
2303 unsigned long tmp;
2304 int ret;
2306 if (!hugepages_supported())
2307 return -ENOTSUPP;
2309 tmp = h->nr_overcommit_huge_pages;
2311 if (write && hstate_is_gigantic(h))
2312 return -EINVAL;
2314 table->data = &tmp;
2315 table->maxlen = sizeof(unsigned long);
2316 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2317 if (ret)
2318 goto out;
2320 if (write) {
2321 spin_lock(&hugetlb_lock);
2322 h->nr_overcommit_huge_pages = tmp;
2323 spin_unlock(&hugetlb_lock);
2325 out:
2326 return ret;
2329 #endif /* CONFIG_SYSCTL */
2331 void hugetlb_report_meminfo(struct seq_file *m)
2333 struct hstate *h = &default_hstate;
2334 if (!hugepages_supported())
2335 return;
2336 seq_printf(m,
2337 "HugePages_Total: %5lu\n"
2338 "HugePages_Free: %5lu\n"
2339 "HugePages_Rsvd: %5lu\n"
2340 "HugePages_Surp: %5lu\n"
2341 "Hugepagesize: %8lu kB\n",
2342 h->nr_huge_pages,
2343 h->free_huge_pages,
2344 h->resv_huge_pages,
2345 h->surplus_huge_pages,
2346 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2349 int hugetlb_report_node_meminfo(int nid, char *buf)
2351 struct hstate *h = &default_hstate;
2352 if (!hugepages_supported())
2353 return 0;
2354 return sprintf(buf,
2355 "Node %d HugePages_Total: %5u\n"
2356 "Node %d HugePages_Free: %5u\n"
2357 "Node %d HugePages_Surp: %5u\n",
2358 nid, h->nr_huge_pages_node[nid],
2359 nid, h->free_huge_pages_node[nid],
2360 nid, h->surplus_huge_pages_node[nid]);
2363 void hugetlb_show_meminfo(void)
2365 struct hstate *h;
2366 int nid;
2368 if (!hugepages_supported())
2369 return;
2371 for_each_node_state(nid, N_MEMORY)
2372 for_each_hstate(h)
2373 pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
2374 nid,
2375 h->nr_huge_pages_node[nid],
2376 h->free_huge_pages_node[nid],
2377 h->surplus_huge_pages_node[nid],
2378 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2381 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2382 unsigned long hugetlb_total_pages(void)
2384 struct hstate *h;
2385 unsigned long nr_total_pages = 0;
2387 for_each_hstate(h)
2388 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
2389 return nr_total_pages;
2392 static int hugetlb_acct_memory(struct hstate *h, long delta)
2394 int ret = -ENOMEM;
2396 spin_lock(&hugetlb_lock);
2398 * When cpuset is configured, it breaks the strict hugetlb page
2399 * reservation as the accounting is done on a global variable. Such
2400 * reservation is completely rubbish in the presence of cpuset because
2401 * the reservation is not checked against page availability for the
2402 * current cpuset. Application can still potentially OOM'ed by kernel
2403 * with lack of free htlb page in cpuset that the task is in.
2404 * Attempt to enforce strict accounting with cpuset is almost
2405 * impossible (or too ugly) because cpuset is too fluid that
2406 * task or memory node can be dynamically moved between cpusets.
2408 * The change of semantics for shared hugetlb mapping with cpuset is
2409 * undesirable. However, in order to preserve some of the semantics,
2410 * we fall back to check against current free page availability as
2411 * a best attempt and hopefully to minimize the impact of changing
2412 * semantics that cpuset has.
2414 if (delta > 0) {
2415 if (gather_surplus_pages(h, delta) < 0)
2416 goto out;
2418 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2419 return_unused_surplus_pages(h, delta);
2420 goto out;
2424 ret = 0;
2425 if (delta < 0)
2426 return_unused_surplus_pages(h, (unsigned long) -delta);
2428 out:
2429 spin_unlock(&hugetlb_lock);
2430 return ret;
2433 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2435 struct resv_map *resv = vma_resv_map(vma);
2438 * This new VMA should share its siblings reservation map if present.
2439 * The VMA will only ever have a valid reservation map pointer where
2440 * it is being copied for another still existing VMA. As that VMA
2441 * has a reference to the reservation map it cannot disappear until
2442 * after this open call completes. It is therefore safe to take a
2443 * new reference here without additional locking.
2445 if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
2446 kref_get(&resv->refs);
2449 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2451 struct hstate *h = hstate_vma(vma);
2452 struct resv_map *resv = vma_resv_map(vma);
2453 struct hugepage_subpool *spool = subpool_vma(vma);
2454 unsigned long reserve, start, end;
2456 if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
2457 return;
2459 start = vma_hugecache_offset(h, vma, vma->vm_start);
2460 end = vma_hugecache_offset(h, vma, vma->vm_end);
2462 reserve = (end - start) - region_count(resv, start, end);
2464 kref_put(&resv->refs, resv_map_release);
2466 if (reserve) {
2467 hugetlb_acct_memory(h, -reserve);
2468 hugepage_subpool_put_pages(spool, reserve);
2473 * We cannot handle pagefaults against hugetlb pages at all. They cause
2474 * handle_mm_fault() to try to instantiate regular-sized pages in the
2475 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
2476 * this far.
2478 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2480 BUG();
2481 return 0;
2484 const struct vm_operations_struct hugetlb_vm_ops = {
2485 .fault = hugetlb_vm_op_fault,
2486 .open = hugetlb_vm_op_open,
2487 .close = hugetlb_vm_op_close,
2490 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2491 int writable)
2493 pte_t entry;
2495 if (writable) {
2496 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
2497 vma->vm_page_prot)));
2498 } else {
2499 entry = huge_pte_wrprotect(mk_huge_pte(page,
2500 vma->vm_page_prot));
2502 entry = pte_mkyoung(entry);
2503 entry = pte_mkhuge(entry);
2504 entry = arch_make_huge_pte(entry, vma, page, writable);
2506 return entry;
2509 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2510 unsigned long address, pte_t *ptep)
2512 pte_t entry;
2514 entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
2515 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
2516 update_mmu_cache(vma, address, ptep);
2519 static int is_hugetlb_entry_migration(pte_t pte)
2521 swp_entry_t swp;
2523 if (huge_pte_none(pte) || pte_present(pte))
2524 return 0;
2525 swp = pte_to_swp_entry(pte);
2526 if (non_swap_entry(swp) && is_migration_entry(swp))
2527 return 1;
2528 else
2529 return 0;
2532 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
2534 swp_entry_t swp;
2536 if (huge_pte_none(pte) || pte_present(pte))
2537 return 0;
2538 swp = pte_to_swp_entry(pte);
2539 if (non_swap_entry(swp) && is_hwpoison_entry(swp))
2540 return 1;
2541 else
2542 return 0;
2545 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2546 struct vm_area_struct *vma)
2548 pte_t *src_pte, *dst_pte, entry;
2549 struct page *ptepage;
2550 unsigned long addr;
2551 int cow;
2552 struct hstate *h = hstate_vma(vma);
2553 unsigned long sz = huge_page_size(h);
2554 unsigned long mmun_start; /* For mmu_notifiers */
2555 unsigned long mmun_end; /* For mmu_notifiers */
2556 int ret = 0;
2558 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2560 mmun_start = vma->vm_start;
2561 mmun_end = vma->vm_end;
2562 if (cow)
2563 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
2565 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2566 spinlock_t *src_ptl, *dst_ptl;
2567 src_pte = huge_pte_offset(src, addr);
2568 if (!src_pte)
2569 continue;
2570 dst_pte = huge_pte_alloc(dst, addr, sz);
2571 if (!dst_pte) {
2572 ret = -ENOMEM;
2573 break;
2576 /* If the pagetables are shared don't copy or take references */
2577 if (dst_pte == src_pte)
2578 continue;
2580 dst_ptl = huge_pte_lock(h, dst, dst_pte);
2581 src_ptl = huge_pte_lockptr(h, src, src_pte);
2582 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
2583 entry = huge_ptep_get(src_pte);
2584 if (huge_pte_none(entry)) { /* skip none entry */
2586 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
2587 is_hugetlb_entry_hwpoisoned(entry))) {
2588 swp_entry_t swp_entry = pte_to_swp_entry(entry);
2590 if (is_write_migration_entry(swp_entry) && cow) {
2592 * COW mappings require pages in both
2593 * parent and child to be set to read.
2595 make_migration_entry_read(&swp_entry);
2596 entry = swp_entry_to_pte(swp_entry);
2597 set_huge_pte_at(src, addr, src_pte, entry);
2599 set_huge_pte_at(dst, addr, dst_pte, entry);
2600 } else {
2601 if (cow) {
2602 huge_ptep_set_wrprotect(src, addr, src_pte);
2603 mmu_notifier_invalidate_range(src, mmun_start,
2604 mmun_end);
2606 entry = huge_ptep_get(src_pte);
2607 ptepage = pte_page(entry);
2608 get_page(ptepage);
2609 page_dup_rmap(ptepage);
2610 set_huge_pte_at(dst, addr, dst_pte, entry);
2612 spin_unlock(src_ptl);
2613 spin_unlock(dst_ptl);
2616 if (cow)
2617 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
2619 return ret;
2622 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
2623 unsigned long start, unsigned long end,
2624 struct page *ref_page)
2626 int force_flush = 0;
2627 struct mm_struct *mm = vma->vm_mm;
2628 unsigned long address;
2629 pte_t *ptep;
2630 pte_t pte;
2631 spinlock_t *ptl;
2632 struct page *page;
2633 struct hstate *h = hstate_vma(vma);
2634 unsigned long sz = huge_page_size(h);
2635 const unsigned long mmun_start = start; /* For mmu_notifiers */
2636 const unsigned long mmun_end = end; /* For mmu_notifiers */
2638 WARN_ON(!is_vm_hugetlb_page(vma));
2639 BUG_ON(start & ~huge_page_mask(h));
2640 BUG_ON(end & ~huge_page_mask(h));
2642 tlb_start_vma(tlb, vma);
2643 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2644 address = start;
2645 again:
2646 for (; address < end; address += sz) {
2647 ptep = huge_pte_offset(mm, address);
2648 if (!ptep)
2649 continue;
2651 ptl = huge_pte_lock(h, mm, ptep);
2652 if (huge_pmd_unshare(mm, &address, ptep))
2653 goto unlock;
2655 pte = huge_ptep_get(ptep);
2656 if (huge_pte_none(pte))
2657 goto unlock;
2660 * Migrating hugepage or HWPoisoned hugepage is already
2661 * unmapped and its refcount is dropped, so just clear pte here.
2663 if (unlikely(!pte_present(pte))) {
2664 huge_pte_clear(mm, address, ptep);
2665 goto unlock;
2668 page = pte_page(pte);
2670 * If a reference page is supplied, it is because a specific
2671 * page is being unmapped, not a range. Ensure the page we
2672 * are about to unmap is the actual page of interest.
2674 if (ref_page) {
2675 if (page != ref_page)
2676 goto unlock;
2679 * Mark the VMA as having unmapped its page so that
2680 * future faults in this VMA will fail rather than
2681 * looking like data was lost
2683 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2686 pte = huge_ptep_get_and_clear(mm, address, ptep);
2687 tlb_remove_tlb_entry(tlb, ptep, address);
2688 if (huge_pte_dirty(pte))
2689 set_page_dirty(page);
2691 page_remove_rmap(page);
2692 force_flush = !__tlb_remove_page(tlb, page);
2693 if (force_flush) {
2694 address += sz;
2695 spin_unlock(ptl);
2696 break;
2698 /* Bail out after unmapping reference page if supplied */
2699 if (ref_page) {
2700 spin_unlock(ptl);
2701 break;
2703 unlock:
2704 spin_unlock(ptl);
2707 * mmu_gather ran out of room to batch pages, we break out of
2708 * the PTE lock to avoid doing the potential expensive TLB invalidate
2709 * and page-free while holding it.
2711 if (force_flush) {
2712 force_flush = 0;
2713 tlb_flush_mmu(tlb);
2714 if (address < end && !ref_page)
2715 goto again;
2717 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2718 tlb_end_vma(tlb, vma);
2721 void __unmap_hugepage_range_final(struct mmu_gather *tlb,
2722 struct vm_area_struct *vma, unsigned long start,
2723 unsigned long end, struct page *ref_page)
2725 __unmap_hugepage_range(tlb, vma, start, end, ref_page);
2728 * Clear this flag so that x86's huge_pmd_share page_table_shareable
2729 * test will fail on a vma being torn down, and not grab a page table
2730 * on its way out. We're lucky that the flag has such an appropriate
2731 * name, and can in fact be safely cleared here. We could clear it
2732 * before the __unmap_hugepage_range above, but all that's necessary
2733 * is to clear it before releasing the i_mmap_rwsem. This works
2734 * because in the context this is called, the VMA is about to be
2735 * destroyed and the i_mmap_rwsem is held.
2737 vma->vm_flags &= ~VM_MAYSHARE;
2740 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2741 unsigned long end, struct page *ref_page)
2743 struct mm_struct *mm;
2744 struct mmu_gather tlb;
2746 mm = vma->vm_mm;
2748 tlb_gather_mmu(&tlb, mm, start, end);
2749 __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
2750 tlb_finish_mmu(&tlb, start, end);
2754 * This is called when the original mapper is failing to COW a MAP_PRIVATE
2755 * mappping it owns the reserve page for. The intention is to unmap the page
2756 * from other VMAs and let the children be SIGKILLed if they are faulting the
2757 * same region.
2759 static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2760 struct page *page, unsigned long address)
2762 struct hstate *h = hstate_vma(vma);
2763 struct vm_area_struct *iter_vma;
2764 struct address_space *mapping;
2765 pgoff_t pgoff;
2768 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2769 * from page cache lookup which is in HPAGE_SIZE units.
2771 address = address & huge_page_mask(h);
2772 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
2773 vma->vm_pgoff;
2774 mapping = file_inode(vma->vm_file)->i_mapping;
2777 * Take the mapping lock for the duration of the table walk. As
2778 * this mapping should be shared between all the VMAs,
2779 * __unmap_hugepage_range() is called as the lock is already held
2781 i_mmap_lock_write(mapping);
2782 vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
2783 /* Do not unmap the current VMA */
2784 if (iter_vma == vma)
2785 continue;
2788 * Unmap the page from other VMAs without their own reserves.
2789 * They get marked to be SIGKILLed if they fault in these
2790 * areas. This is because a future no-page fault on this VMA
2791 * could insert a zeroed page instead of the data existing
2792 * from the time of fork. This would look like data corruption
2794 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2795 unmap_hugepage_range(iter_vma, address,
2796 address + huge_page_size(h), page);
2798 i_mmap_unlock_write(mapping);
2802 * Hugetlb_cow() should be called with page lock of the original hugepage held.
2803 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
2804 * cannot race with other handlers or page migration.
2805 * Keep the pte_same checks anyway to make transition from the mutex easier.
2807 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2808 unsigned long address, pte_t *ptep, pte_t pte,
2809 struct page *pagecache_page, spinlock_t *ptl)
2811 struct hstate *h = hstate_vma(vma);
2812 struct page *old_page, *new_page;
2813 int ret = 0, outside_reserve = 0;
2814 unsigned long mmun_start; /* For mmu_notifiers */
2815 unsigned long mmun_end; /* For mmu_notifiers */
2817 old_page = pte_page(pte);
2819 retry_avoidcopy:
2820 /* If no-one else is actually using this page, avoid the copy
2821 * and just make the page writable */
2822 if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
2823 page_move_anon_rmap(old_page, vma, address);
2824 set_huge_ptep_writable(vma, address, ptep);
2825 return 0;
2829 * If the process that created a MAP_PRIVATE mapping is about to
2830 * perform a COW due to a shared page count, attempt to satisfy
2831 * the allocation without using the existing reserves. The pagecache
2832 * page is used to determine if the reserve at this address was
2833 * consumed or not. If reserves were used, a partial faulted mapping
2834 * at the time of fork() could consume its reserves on COW instead
2835 * of the full address range.
2837 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2838 old_page != pagecache_page)
2839 outside_reserve = 1;
2841 page_cache_get(old_page);
2844 * Drop page table lock as buddy allocator may be called. It will
2845 * be acquired again before returning to the caller, as expected.
2847 spin_unlock(ptl);
2848 new_page = alloc_huge_page(vma, address, outside_reserve);
2850 if (IS_ERR(new_page)) {
2852 * If a process owning a MAP_PRIVATE mapping fails to COW,
2853 * it is due to references held by a child and an insufficient
2854 * huge page pool. To guarantee the original mappers
2855 * reliability, unmap the page from child processes. The child
2856 * may get SIGKILLed if it later faults.
2858 if (outside_reserve) {
2859 page_cache_release(old_page);
2860 BUG_ON(huge_pte_none(pte));
2861 unmap_ref_private(mm, vma, old_page, address);
2862 BUG_ON(huge_pte_none(pte));
2863 spin_lock(ptl);
2864 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2865 if (likely(ptep &&
2866 pte_same(huge_ptep_get(ptep), pte)))
2867 goto retry_avoidcopy;
2869 * race occurs while re-acquiring page table
2870 * lock, and our job is done.
2872 return 0;
2875 ret = (PTR_ERR(new_page) == -ENOMEM) ?
2876 VM_FAULT_OOM : VM_FAULT_SIGBUS;
2877 goto out_release_old;
2881 * When the original hugepage is shared one, it does not have
2882 * anon_vma prepared.
2884 if (unlikely(anon_vma_prepare(vma))) {
2885 ret = VM_FAULT_OOM;
2886 goto out_release_all;
2889 copy_user_huge_page(new_page, old_page, address, vma,
2890 pages_per_huge_page(h));
2891 __SetPageUptodate(new_page);
2893 mmun_start = address & huge_page_mask(h);
2894 mmun_end = mmun_start + huge_page_size(h);
2895 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2898 * Retake the page table lock to check for racing updates
2899 * before the page tables are altered
2901 spin_lock(ptl);
2902 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2903 if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
2904 ClearPagePrivate(new_page);
2906 /* Break COW */
2907 huge_ptep_clear_flush(vma, address, ptep);
2908 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
2909 set_huge_pte_at(mm, address, ptep,
2910 make_huge_pte(vma, new_page, 1));
2911 page_remove_rmap(old_page);
2912 hugepage_add_new_anon_rmap(new_page, vma, address);
2913 /* Make the old page be freed below */
2914 new_page = old_page;
2916 spin_unlock(ptl);
2917 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2918 out_release_all:
2919 page_cache_release(new_page);
2920 out_release_old:
2921 page_cache_release(old_page);
2923 spin_lock(ptl); /* Caller expects lock to be held */
2924 return ret;
2927 /* Return the pagecache page at a given address within a VMA */
2928 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2929 struct vm_area_struct *vma, unsigned long address)
2931 struct address_space *mapping;
2932 pgoff_t idx;
2934 mapping = vma->vm_file->f_mapping;
2935 idx = vma_hugecache_offset(h, vma, address);
2937 return find_lock_page(mapping, idx);
2941 * Return whether there is a pagecache page to back given address within VMA.
2942 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2944 static bool hugetlbfs_pagecache_present(struct hstate *h,
2945 struct vm_area_struct *vma, unsigned long address)
2947 struct address_space *mapping;
2948 pgoff_t idx;
2949 struct page *page;
2951 mapping = vma->vm_file->f_mapping;
2952 idx = vma_hugecache_offset(h, vma, address);
2954 page = find_get_page(mapping, idx);
2955 if (page)
2956 put_page(page);
2957 return page != NULL;
2960 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2961 struct address_space *mapping, pgoff_t idx,
2962 unsigned long address, pte_t *ptep, unsigned int flags)
2964 struct hstate *h = hstate_vma(vma);
2965 int ret = VM_FAULT_SIGBUS;
2966 int anon_rmap = 0;
2967 unsigned long size;
2968 struct page *page;
2969 pte_t new_pte;
2970 spinlock_t *ptl;
2973 * Currently, we are forced to kill the process in the event the
2974 * original mapper has unmapped pages from the child due to a failed
2975 * COW. Warn that such a situation has occurred as it may not be obvious
2977 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2978 pr_warning("PID %d killed due to inadequate hugepage pool\n",
2979 current->pid);
2980 return ret;
2984 * Use page lock to guard against racing truncation
2985 * before we get page_table_lock.
2987 retry:
2988 page = find_lock_page(mapping, idx);
2989 if (!page) {
2990 size = i_size_read(mapping->host) >> huge_page_shift(h);
2991 if (idx >= size)
2992 goto out;
2993 page = alloc_huge_page(vma, address, 0);
2994 if (IS_ERR(page)) {
2995 ret = PTR_ERR(page);
2996 if (ret == -ENOMEM)
2997 ret = VM_FAULT_OOM;
2998 else
2999 ret = VM_FAULT_SIGBUS;
3000 goto out;
3002 clear_huge_page(page, address, pages_per_huge_page(h));
3003 __SetPageUptodate(page);
3005 if (vma->vm_flags & VM_MAYSHARE) {
3006 int err;
3007 struct inode *inode = mapping->host;
3009 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3010 if (err) {
3011 put_page(page);
3012 if (err == -EEXIST)
3013 goto retry;
3014 goto out;
3016 ClearPagePrivate(page);
3018 spin_lock(&inode->i_lock);
3019 inode->i_blocks += blocks_per_huge_page(h);
3020 spin_unlock(&inode->i_lock);
3021 } else {
3022 lock_page(page);
3023 if (unlikely(anon_vma_prepare(vma))) {
3024 ret = VM_FAULT_OOM;
3025 goto backout_unlocked;
3027 anon_rmap = 1;
3029 } else {
3031 * If memory error occurs between mmap() and fault, some process
3032 * don't have hwpoisoned swap entry for errored virtual address.
3033 * So we need to block hugepage fault by PG_hwpoison bit check.
3035 if (unlikely(PageHWPoison(page))) {
3036 ret = VM_FAULT_HWPOISON |
3037 VM_FAULT_SET_HINDEX(hstate_index(h));
3038 goto backout_unlocked;
3043 * If we are going to COW a private mapping later, we examine the
3044 * pending reservations for this page now. This will ensure that
3045 * any allocations necessary to record that reservation occur outside
3046 * the spinlock.
3048 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
3049 if (vma_needs_reservation(h, vma, address) < 0) {
3050 ret = VM_FAULT_OOM;
3051 goto backout_unlocked;
3054 ptl = huge_pte_lockptr(h, mm, ptep);
3055 spin_lock(ptl);
3056 size = i_size_read(mapping->host) >> huge_page_shift(h);
3057 if (idx >= size)
3058 goto backout;
3060 ret = 0;
3061 if (!huge_pte_none(huge_ptep_get(ptep)))
3062 goto backout;
3064 if (anon_rmap) {
3065 ClearPagePrivate(page);
3066 hugepage_add_new_anon_rmap(page, vma, address);
3067 } else
3068 page_dup_rmap(page);
3069 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3070 && (vma->vm_flags & VM_SHARED)));
3071 set_huge_pte_at(mm, address, ptep, new_pte);
3073 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3074 /* Optimization, do the COW without a second fault */
3075 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
3078 spin_unlock(ptl);
3079 unlock_page(page);
3080 out:
3081 return ret;
3083 backout:
3084 spin_unlock(ptl);
3085 backout_unlocked:
3086 unlock_page(page);
3087 put_page(page);
3088 goto out;
3091 #ifdef CONFIG_SMP
3092 static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3093 struct vm_area_struct *vma,
3094 struct address_space *mapping,
3095 pgoff_t idx, unsigned long address)
3097 unsigned long key[2];
3098 u32 hash;
3100 if (vma->vm_flags & VM_SHARED) {
3101 key[0] = (unsigned long) mapping;
3102 key[1] = idx;
3103 } else {
3104 key[0] = (unsigned long) mm;
3105 key[1] = address >> huge_page_shift(h);
3108 hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3110 return hash & (num_fault_mutexes - 1);
3112 #else
3114 * For uniprocesor systems we always use a single mutex, so just
3115 * return 0 and avoid the hashing overhead.
3117 static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3118 struct vm_area_struct *vma,
3119 struct address_space *mapping,
3120 pgoff_t idx, unsigned long address)
3122 return 0;
3124 #endif
3126 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3127 unsigned long address, unsigned int flags)
3129 pte_t *ptep, entry;
3130 spinlock_t *ptl;
3131 int ret;
3132 u32 hash;
3133 pgoff_t idx;
3134 struct page *page = NULL;
3135 struct page *pagecache_page = NULL;
3136 struct hstate *h = hstate_vma(vma);
3137 struct address_space *mapping;
3138 int need_wait_lock = 0;
3140 address &= huge_page_mask(h);
3142 ptep = huge_pte_offset(mm, address);
3143 if (ptep) {
3144 entry = huge_ptep_get(ptep);
3145 if (unlikely(is_hugetlb_entry_migration(entry))) {
3146 migration_entry_wait_huge(vma, mm, ptep);
3147 return 0;
3148 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3149 return VM_FAULT_HWPOISON_LARGE |
3150 VM_FAULT_SET_HINDEX(hstate_index(h));
3153 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3154 if (!ptep)
3155 return VM_FAULT_OOM;
3157 mapping = vma->vm_file->f_mapping;
3158 idx = vma_hugecache_offset(h, vma, address);
3161 * Serialize hugepage allocation and instantiation, so that we don't
3162 * get spurious allocation failures if two CPUs race to instantiate
3163 * the same page in the page cache.
3165 hash = fault_mutex_hash(h, mm, vma, mapping, idx, address);
3166 mutex_lock(&htlb_fault_mutex_table[hash]);
3168 entry = huge_ptep_get(ptep);
3169 if (huge_pte_none(entry)) {
3170 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3171 goto out_mutex;
3174 ret = 0;
3177 * entry could be a migration/hwpoison entry at this point, so this
3178 * check prevents the kernel from going below assuming that we have
3179 * a active hugepage in pagecache. This goto expects the 2nd page fault,
3180 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3181 * handle it.
3183 if (!pte_present(entry))
3184 goto out_mutex;
3187 * If we are going to COW the mapping later, we examine the pending
3188 * reservations for this page now. This will ensure that any
3189 * allocations necessary to record that reservation occur outside the
3190 * spinlock. For private mappings, we also lookup the pagecache
3191 * page now as it is used to determine if a reservation has been
3192 * consumed.
3194 if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3195 if (vma_needs_reservation(h, vma, address) < 0) {
3196 ret = VM_FAULT_OOM;
3197 goto out_mutex;
3200 if (!(vma->vm_flags & VM_MAYSHARE))
3201 pagecache_page = hugetlbfs_pagecache_page(h,
3202 vma, address);
3205 ptl = huge_pte_lock(h, mm, ptep);
3207 /* Check for a racing update before calling hugetlb_cow */
3208 if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3209 goto out_ptl;
3212 * hugetlb_cow() requires page locks of pte_page(entry) and
3213 * pagecache_page, so here we need take the former one
3214 * when page != pagecache_page or !pagecache_page.
3216 page = pte_page(entry);
3217 if (page != pagecache_page)
3218 if (!trylock_page(page)) {
3219 need_wait_lock = 1;
3220 goto out_ptl;
3223 get_page(page);
3225 if (flags & FAULT_FLAG_WRITE) {
3226 if (!huge_pte_write(entry)) {
3227 ret = hugetlb_cow(mm, vma, address, ptep, entry,
3228 pagecache_page, ptl);
3229 goto out_put_page;
3231 entry = huge_pte_mkdirty(entry);
3233 entry = pte_mkyoung(entry);
3234 if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3235 flags & FAULT_FLAG_WRITE))
3236 update_mmu_cache(vma, address, ptep);
3237 out_put_page:
3238 if (page != pagecache_page)
3239 unlock_page(page);
3240 put_page(page);
3241 out_ptl:
3242 spin_unlock(ptl);
3244 if (pagecache_page) {
3245 unlock_page(pagecache_page);
3246 put_page(pagecache_page);
3248 out_mutex:
3249 mutex_unlock(&htlb_fault_mutex_table[hash]);
3251 * Generally it's safe to hold refcount during waiting page lock. But
3252 * here we just wait to defer the next page fault to avoid busy loop and
3253 * the page is not used after unlocked before returning from the current
3254 * page fault. So we are safe from accessing freed page, even if we wait
3255 * here without taking refcount.
3257 if (need_wait_lock)
3258 wait_on_page_locked(page);
3259 return ret;
3262 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
3263 struct page **pages, struct vm_area_struct **vmas,
3264 unsigned long *position, unsigned long *nr_pages,
3265 long i, unsigned int flags)
3267 unsigned long pfn_offset;
3268 unsigned long vaddr = *position;
3269 unsigned long remainder = *nr_pages;
3270 struct hstate *h = hstate_vma(vma);
3272 while (vaddr < vma->vm_end && remainder) {
3273 pte_t *pte;
3274 spinlock_t *ptl = NULL;
3275 int absent;
3276 struct page *page;
3279 * Some archs (sparc64, sh*) have multiple pte_ts to
3280 * each hugepage. We have to make sure we get the
3281 * first, for the page indexing below to work.
3283 * Note that page table lock is not held when pte is null.
3285 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
3286 if (pte)
3287 ptl = huge_pte_lock(h, mm, pte);
3288 absent = !pte || huge_pte_none(huge_ptep_get(pte));
3291 * When coredumping, it suits get_dump_page if we just return
3292 * an error where there's an empty slot with no huge pagecache
3293 * to back it. This way, we avoid allocating a hugepage, and
3294 * the sparse dumpfile avoids allocating disk blocks, but its
3295 * huge holes still show up with zeroes where they need to be.
3297 if (absent && (flags & FOLL_DUMP) &&
3298 !hugetlbfs_pagecache_present(h, vma, vaddr)) {
3299 if (pte)
3300 spin_unlock(ptl);
3301 remainder = 0;
3302 break;
3306 * We need call hugetlb_fault for both hugepages under migration
3307 * (in which case hugetlb_fault waits for the migration,) and
3308 * hwpoisoned hugepages (in which case we need to prevent the
3309 * caller from accessing to them.) In order to do this, we use
3310 * here is_swap_pte instead of is_hugetlb_entry_migration and
3311 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
3312 * both cases, and because we can't follow correct pages
3313 * directly from any kind of swap entries.
3315 if (absent || is_swap_pte(huge_ptep_get(pte)) ||
3316 ((flags & FOLL_WRITE) &&
3317 !huge_pte_write(huge_ptep_get(pte)))) {
3318 int ret;
3320 if (pte)
3321 spin_unlock(ptl);
3322 ret = hugetlb_fault(mm, vma, vaddr,
3323 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
3324 if (!(ret & VM_FAULT_ERROR))
3325 continue;
3327 remainder = 0;
3328 break;
3331 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
3332 page = pte_page(huge_ptep_get(pte));
3333 same_page:
3334 if (pages) {
3335 pages[i] = mem_map_offset(page, pfn_offset);
3336 get_page_foll(pages[i]);
3339 if (vmas)
3340 vmas[i] = vma;
3342 vaddr += PAGE_SIZE;
3343 ++pfn_offset;
3344 --remainder;
3345 ++i;
3346 if (vaddr < vma->vm_end && remainder &&
3347 pfn_offset < pages_per_huge_page(h)) {
3349 * We use pfn_offset to avoid touching the pageframes
3350 * of this compound page.
3352 goto same_page;
3354 spin_unlock(ptl);
3356 *nr_pages = remainder;
3357 *position = vaddr;
3359 return i ? i : -EFAULT;
3362 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3363 unsigned long address, unsigned long end, pgprot_t newprot)
3365 struct mm_struct *mm = vma->vm_mm;
3366 unsigned long start = address;
3367 pte_t *ptep;
3368 pte_t pte;
3369 struct hstate *h = hstate_vma(vma);
3370 unsigned long pages = 0;
3372 BUG_ON(address >= end);
3373 flush_cache_range(vma, address, end);
3375 mmu_notifier_invalidate_range_start(mm, start, end);
3376 i_mmap_lock_write(vma->vm_file->f_mapping);
3377 for (; address < end; address += huge_page_size(h)) {
3378 spinlock_t *ptl;
3379 ptep = huge_pte_offset(mm, address);
3380 if (!ptep)
3381 continue;
3382 ptl = huge_pte_lock(h, mm, ptep);
3383 if (huge_pmd_unshare(mm, &address, ptep)) {
3384 pages++;
3385 spin_unlock(ptl);
3386 continue;
3388 pte = huge_ptep_get(ptep);
3389 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
3390 spin_unlock(ptl);
3391 continue;
3393 if (unlikely(is_hugetlb_entry_migration(pte))) {
3394 swp_entry_t entry = pte_to_swp_entry(pte);
3396 if (is_write_migration_entry(entry)) {
3397 pte_t newpte;
3399 make_migration_entry_read(&entry);
3400 newpte = swp_entry_to_pte(entry);
3401 set_huge_pte_at(mm, address, ptep, newpte);
3402 pages++;
3404 spin_unlock(ptl);
3405 continue;
3407 if (!huge_pte_none(pte)) {
3408 pte = huge_ptep_get_and_clear(mm, address, ptep);
3409 pte = pte_mkhuge(huge_pte_modify(pte, newprot));
3410 pte = arch_make_huge_pte(pte, vma, NULL, 0);
3411 set_huge_pte_at(mm, address, ptep, pte);
3412 pages++;
3414 spin_unlock(ptl);
3417 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
3418 * may have cleared our pud entry and done put_page on the page table:
3419 * once we release i_mmap_rwsem, another task can do the final put_page
3420 * and that page table be reused and filled with junk.
3422 flush_tlb_range(vma, start, end);
3423 mmu_notifier_invalidate_range(mm, start, end);
3424 i_mmap_unlock_write(vma->vm_file->f_mapping);
3425 mmu_notifier_invalidate_range_end(mm, start, end);
3427 return pages << h->order;
3430 int hugetlb_reserve_pages(struct inode *inode,
3431 long from, long to,
3432 struct vm_area_struct *vma,
3433 vm_flags_t vm_flags)
3435 long ret, chg;
3436 struct hstate *h = hstate_inode(inode);
3437 struct hugepage_subpool *spool = subpool_inode(inode);
3438 struct resv_map *resv_map;
3441 * Only apply hugepage reservation if asked. At fault time, an
3442 * attempt will be made for VM_NORESERVE to allocate a page
3443 * without using reserves
3445 if (vm_flags & VM_NORESERVE)
3446 return 0;
3449 * Shared mappings base their reservation on the number of pages that
3450 * are already allocated on behalf of the file. Private mappings need
3451 * to reserve the full area even if read-only as mprotect() may be
3452 * called to make the mapping read-write. Assume !vma is a shm mapping
3454 if (!vma || vma->vm_flags & VM_MAYSHARE) {
3455 resv_map = inode_resv_map(inode);
3457 chg = region_chg(resv_map, from, to);
3459 } else {
3460 resv_map = resv_map_alloc();
3461 if (!resv_map)
3462 return -ENOMEM;
3464 chg = to - from;
3466 set_vma_resv_map(vma, resv_map);
3467 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
3470 if (chg < 0) {
3471 ret = chg;
3472 goto out_err;
3475 /* There must be enough pages in the subpool for the mapping */
3476 if (hugepage_subpool_get_pages(spool, chg)) {
3477 ret = -ENOSPC;
3478 goto out_err;
3482 * Check enough hugepages are available for the reservation.
3483 * Hand the pages back to the subpool if there are not
3485 ret = hugetlb_acct_memory(h, chg);
3486 if (ret < 0) {
3487 hugepage_subpool_put_pages(spool, chg);
3488 goto out_err;
3492 * Account for the reservations made. Shared mappings record regions
3493 * that have reservations as they are shared by multiple VMAs.
3494 * When the last VMA disappears, the region map says how much
3495 * the reservation was and the page cache tells how much of
3496 * the reservation was consumed. Private mappings are per-VMA and
3497 * only the consumed reservations are tracked. When the VMA
3498 * disappears, the original reservation is the VMA size and the
3499 * consumed reservations are stored in the map. Hence, nothing
3500 * else has to be done for private mappings here
3502 if (!vma || vma->vm_flags & VM_MAYSHARE)
3503 region_add(resv_map, from, to);
3504 return 0;
3505 out_err:
3506 if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3507 kref_put(&resv_map->refs, resv_map_release);
3508 return ret;
3511 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
3513 struct hstate *h = hstate_inode(inode);
3514 struct resv_map *resv_map = inode_resv_map(inode);
3515 long chg = 0;
3516 struct hugepage_subpool *spool = subpool_inode(inode);
3518 if (resv_map)
3519 chg = region_truncate(resv_map, offset);
3520 spin_lock(&inode->i_lock);
3521 inode->i_blocks -= (blocks_per_huge_page(h) * freed);
3522 spin_unlock(&inode->i_lock);
3524 hugepage_subpool_put_pages(spool, (chg - freed));
3525 hugetlb_acct_memory(h, -(chg - freed));
3528 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
3529 static unsigned long page_table_shareable(struct vm_area_struct *svma,
3530 struct vm_area_struct *vma,
3531 unsigned long addr, pgoff_t idx)
3533 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
3534 svma->vm_start;
3535 unsigned long sbase = saddr & PUD_MASK;
3536 unsigned long s_end = sbase + PUD_SIZE;
3538 /* Allow segments to share if only one is marked locked */
3539 unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
3540 unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
3543 * match the virtual addresses, permission and the alignment of the
3544 * page table page.
3546 if (pmd_index(addr) != pmd_index(saddr) ||
3547 vm_flags != svm_flags ||
3548 sbase < svma->vm_start || svma->vm_end < s_end)
3549 return 0;
3551 return saddr;
3554 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
3556 unsigned long base = addr & PUD_MASK;
3557 unsigned long end = base + PUD_SIZE;
3560 * check on proper vm_flags and page table alignment
3562 if (vma->vm_flags & VM_MAYSHARE &&
3563 vma->vm_start <= base && end <= vma->vm_end)
3564 return 1;
3565 return 0;
3569 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
3570 * and returns the corresponding pte. While this is not necessary for the
3571 * !shared pmd case because we can allocate the pmd later as well, it makes the
3572 * code much cleaner. pmd allocation is essential for the shared case because
3573 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
3574 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
3575 * bad pmd for sharing.
3577 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
3579 struct vm_area_struct *vma = find_vma(mm, addr);
3580 struct address_space *mapping = vma->vm_file->f_mapping;
3581 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
3582 vma->vm_pgoff;
3583 struct vm_area_struct *svma;
3584 unsigned long saddr;
3585 pte_t *spte = NULL;
3586 pte_t *pte;
3587 spinlock_t *ptl;
3589 if (!vma_shareable(vma, addr))
3590 return (pte_t *)pmd_alloc(mm, pud, addr);
3592 i_mmap_lock_write(mapping);
3593 vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
3594 if (svma == vma)
3595 continue;
3597 saddr = page_table_shareable(svma, vma, addr, idx);
3598 if (saddr) {
3599 spte = huge_pte_offset(svma->vm_mm, saddr);
3600 if (spte) {
3601 mm_inc_nr_pmds(mm);
3602 get_page(virt_to_page(spte));
3603 break;
3608 if (!spte)
3609 goto out;
3611 ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
3612 spin_lock(ptl);
3613 if (pud_none(*pud)) {
3614 pud_populate(mm, pud,
3615 (pmd_t *)((unsigned long)spte & PAGE_MASK));
3616 } else {
3617 put_page(virt_to_page(spte));
3618 mm_inc_nr_pmds(mm);
3620 spin_unlock(ptl);
3621 out:
3622 pte = (pte_t *)pmd_alloc(mm, pud, addr);
3623 i_mmap_unlock_write(mapping);
3624 return pte;
3628 * unmap huge page backed by shared pte.
3630 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
3631 * indicated by page_count > 1, unmap is achieved by clearing pud and
3632 * decrementing the ref count. If count == 1, the pte page is not shared.
3634 * called with page table lock held.
3636 * returns: 1 successfully unmapped a shared pte page
3637 * 0 the underlying pte page is not shared, or it is the last user
3639 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
3641 pgd_t *pgd = pgd_offset(mm, *addr);
3642 pud_t *pud = pud_offset(pgd, *addr);
3644 BUG_ON(page_count(virt_to_page(ptep)) == 0);
3645 if (page_count(virt_to_page(ptep)) == 1)
3646 return 0;
3648 pud_clear(pud);
3649 put_page(virt_to_page(ptep));
3650 mm_dec_nr_pmds(mm);
3651 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
3652 return 1;
3654 #define want_pmd_share() (1)
3655 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
3656 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
3658 return NULL;
3660 #define want_pmd_share() (0)
3661 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
3663 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
3664 pte_t *huge_pte_alloc(struct mm_struct *mm,
3665 unsigned long addr, unsigned long sz)
3667 pgd_t *pgd;
3668 pud_t *pud;
3669 pte_t *pte = NULL;
3671 pgd = pgd_offset(mm, addr);
3672 pud = pud_alloc(mm, pgd, addr);
3673 if (pud) {
3674 if (sz == PUD_SIZE) {
3675 pte = (pte_t *)pud;
3676 } else {
3677 BUG_ON(sz != PMD_SIZE);
3678 if (want_pmd_share() && pud_none(*pud))
3679 pte = huge_pmd_share(mm, addr, pud);
3680 else
3681 pte = (pte_t *)pmd_alloc(mm, pud, addr);
3684 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
3686 return pte;
3689 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
3691 pgd_t *pgd;
3692 pud_t *pud;
3693 pmd_t *pmd = NULL;
3695 pgd = pgd_offset(mm, addr);
3696 if (pgd_present(*pgd)) {
3697 pud = pud_offset(pgd, addr);
3698 if (pud_present(*pud)) {
3699 if (pud_huge(*pud))
3700 return (pte_t *)pud;
3701 pmd = pmd_offset(pud, addr);
3704 return (pte_t *) pmd;
3707 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
3710 * These functions are overwritable if your architecture needs its own
3711 * behavior.
3713 struct page * __weak
3714 follow_huge_addr(struct mm_struct *mm, unsigned long address,
3715 int write)
3717 return ERR_PTR(-EINVAL);
3720 struct page * __weak
3721 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
3722 pmd_t *pmd, int flags)
3724 struct page *page = NULL;
3725 spinlock_t *ptl;
3726 retry:
3727 ptl = pmd_lockptr(mm, pmd);
3728 spin_lock(ptl);
3730 * make sure that the address range covered by this pmd is not
3731 * unmapped from other threads.
3733 if (!pmd_huge(*pmd))
3734 goto out;
3735 if (pmd_present(*pmd)) {
3736 page = pte_page(*(pte_t *)pmd) +
3737 ((address & ~PMD_MASK) >> PAGE_SHIFT);
3738 if (flags & FOLL_GET)
3739 get_page(page);
3740 } else {
3741 if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
3742 spin_unlock(ptl);
3743 __migration_entry_wait(mm, (pte_t *)pmd, ptl);
3744 goto retry;
3747 * hwpoisoned entry is treated as no_page_table in
3748 * follow_page_mask().
3751 out:
3752 spin_unlock(ptl);
3753 return page;
3756 struct page * __weak
3757 follow_huge_pud(struct mm_struct *mm, unsigned long address,
3758 pud_t *pud, int flags)
3760 if (flags & FOLL_GET)
3761 return NULL;
3763 return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
3766 #ifdef CONFIG_MEMORY_FAILURE
3768 /* Should be called in hugetlb_lock */
3769 static int is_hugepage_on_freelist(struct page *hpage)
3771 struct page *page;
3772 struct page *tmp;
3773 struct hstate *h = page_hstate(hpage);
3774 int nid = page_to_nid(hpage);
3776 list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
3777 if (page == hpage)
3778 return 1;
3779 return 0;
3783 * This function is called from memory failure code.
3784 * Assume the caller holds page lock of the head page.
3786 int dequeue_hwpoisoned_huge_page(struct page *hpage)
3788 struct hstate *h = page_hstate(hpage);
3789 int nid = page_to_nid(hpage);
3790 int ret = -EBUSY;
3792 spin_lock(&hugetlb_lock);
3793 if (is_hugepage_on_freelist(hpage)) {
3795 * Hwpoisoned hugepage isn't linked to activelist or freelist,
3796 * but dangling hpage->lru can trigger list-debug warnings
3797 * (this happens when we call unpoison_memory() on it),
3798 * so let it point to itself with list_del_init().
3800 list_del_init(&hpage->lru);
3801 set_page_refcounted(hpage);
3802 h->free_huge_pages--;
3803 h->free_huge_pages_node[nid]--;
3804 ret = 0;
3806 spin_unlock(&hugetlb_lock);
3807 return ret;
3809 #endif
3811 bool isolate_huge_page(struct page *page, struct list_head *list)
3813 VM_BUG_ON_PAGE(!PageHead(page), page);
3814 if (!get_page_unless_zero(page))
3815 return false;
3816 spin_lock(&hugetlb_lock);
3817 list_move_tail(&page->lru, list);
3818 spin_unlock(&hugetlb_lock);
3819 return true;
3822 void putback_active_hugepage(struct page *page)
3824 VM_BUG_ON_PAGE(!PageHead(page), page);
3825 spin_lock(&hugetlb_lock);
3826 list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
3827 spin_unlock(&hugetlb_lock);
3828 put_page(page);
3831 bool is_hugepage_active(struct page *page)
3833 VM_BUG_ON_PAGE(!PageHuge(page), page);
3835 * This function can be called for a tail page because the caller,
3836 * scan_movable_pages, scans through a given pfn-range which typically
3837 * covers one memory block. In systems using gigantic hugepage (1GB
3838 * for x86_64,) a hugepage is larger than a memory block, and we don't
3839 * support migrating such large hugepages for now, so return false
3840 * when called for tail pages.
3842 if (PageTail(page))
3843 return false;
3845 * Refcount of a hwpoisoned hugepages is 1, but they are not active,
3846 * so we should return false for them.
3848 if (unlikely(PageHWPoison(page)))
3849 return false;
3850 return page_count(page) > 0;