2 * Generic hugetlb support.
3 * (C) Nadia Yvette Chambers, April 2004
5 #include <linux/list.h>
6 #include <linux/init.h>
7 #include <linux/module.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>
29 #include <asm/pgtable.h>
33 #include <linux/hugetlb.h>
34 #include <linux/hugetlb_cgroup.h>
35 #include <linux/node.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 * Minimum page order among possible hugepage sizes, set to a proper value
47 static unsigned int minimum_order __read_mostly = UINT_MAX;
49 __initdata LIST_HEAD(huge_boot_pages);
51 /* for command line parsing */
52 static struct hstate * __initdata parsed_hstate;
53 static unsigned long __initdata default_hstate_max_huge_pages;
54 static unsigned long __initdata default_hstate_size;
57 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
58 * free_huge_pages, and surplus_huge_pages.
60 DEFINE_SPINLOCK(hugetlb_lock);
63 * Serializes faults on the same logical page. This is used to
64 * prevent spurious OOMs when the hugepage pool is fully utilized.
66 static int num_fault_mutexes;
67 struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
69 /* Forward declaration */
70 static int hugetlb_acct_memory(struct hstate *h, long delta);
72 static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
74 bool free = (spool->count == 0) && (spool->used_hpages == 0);
76 spin_unlock(&spool->lock);
78 /* If no pages are used, and no other handles to the subpool
79 * remain, give up any reservations mased on minimum size and
82 if (spool->min_hpages != -1)
83 hugetlb_acct_memory(spool->hstate,
89 struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
92 struct hugepage_subpool *spool;
94 spool = kzalloc(sizeof(*spool), GFP_KERNEL);
98 spin_lock_init(&spool->lock);
100 spool->max_hpages = max_hpages;
102 spool->min_hpages = min_hpages;
104 if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
108 spool->rsv_hpages = min_hpages;
113 void hugepage_put_subpool(struct hugepage_subpool *spool)
115 spin_lock(&spool->lock);
116 BUG_ON(!spool->count);
118 unlock_or_release_subpool(spool);
122 * Subpool accounting for allocating and reserving pages.
123 * Return -ENOMEM if there are not enough resources to satisfy the
124 * the request. Otherwise, return the number of pages by which the
125 * global pools must be adjusted (upward). The returned value may
126 * only be different than the passed value (delta) in the case where
127 * a subpool minimum size must be manitained.
129 static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
137 spin_lock(&spool->lock);
139 if (spool->max_hpages != -1) { /* maximum size accounting */
140 if ((spool->used_hpages + delta) <= spool->max_hpages)
141 spool->used_hpages += delta;
148 if (spool->min_hpages != -1) { /* minimum size accounting */
149 if (delta > spool->rsv_hpages) {
151 * Asking for more reserves than those already taken on
152 * behalf of subpool. Return difference.
154 ret = delta - spool->rsv_hpages;
155 spool->rsv_hpages = 0;
157 ret = 0; /* reserves already accounted for */
158 spool->rsv_hpages -= delta;
163 spin_unlock(&spool->lock);
168 * Subpool accounting for freeing and unreserving pages.
169 * Return the number of global page reservations that must be dropped.
170 * The return value may only be different than the passed value (delta)
171 * in the case where a subpool minimum size must be maintained.
173 static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
181 spin_lock(&spool->lock);
183 if (spool->max_hpages != -1) /* maximum size accounting */
184 spool->used_hpages -= delta;
186 if (spool->min_hpages != -1) { /* minimum size accounting */
187 if (spool->rsv_hpages + delta <= spool->min_hpages)
190 ret = spool->rsv_hpages + delta - spool->min_hpages;
192 spool->rsv_hpages += delta;
193 if (spool->rsv_hpages > spool->min_hpages)
194 spool->rsv_hpages = spool->min_hpages;
198 * If hugetlbfs_put_super couldn't free spool due to an outstanding
199 * quota reference, free it now.
201 unlock_or_release_subpool(spool);
206 static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
208 return HUGETLBFS_SB(inode->i_sb)->spool;
211 static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
213 return subpool_inode(file_inode(vma->vm_file));
217 * Region tracking -- allows tracking of reservations and instantiated pages
218 * across the pages in a mapping.
220 * The region data structures are embedded into a resv_map and protected
221 * by a resv_map's lock. The set of regions within the resv_map represent
222 * reservations for huge pages, or huge pages that have already been
223 * instantiated within the map. The from and to elements are huge page
224 * indicies into the associated mapping. from indicates the starting index
225 * of the region. to represents the first index past the end of the region.
227 * For example, a file region structure with from == 0 and to == 4 represents
228 * four huge pages in a mapping. It is important to note that the to element
229 * represents the first element past the end of the region. This is used in
230 * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
232 * Interval notation of the form [from, to) will be used to indicate that
233 * the endpoint from is inclusive and to is exclusive.
236 struct list_head link;
242 * Add the huge page range represented by [f, t) to the reserve
243 * map. In the normal case, existing regions will be expanded
244 * to accommodate the specified range. Sufficient regions should
245 * exist for expansion due to the previous call to region_chg
246 * with the same range. However, it is possible that region_del
247 * could have been called after region_chg and modifed the map
248 * in such a way that no region exists to be expanded. In this
249 * case, pull a region descriptor from the cache associated with
250 * the map and use that for the new range.
252 * Return the number of new huge pages added to the map. This
253 * number is greater than or equal to zero.
255 static long region_add(struct resv_map *resv, long f, long t)
257 struct list_head *head = &resv->regions;
258 struct file_region *rg, *nrg, *trg;
261 spin_lock(&resv->lock);
262 /* Locate the region we are either in or before. */
263 list_for_each_entry(rg, head, link)
268 * If no region exists which can be expanded to include the
269 * specified range, the list must have been modified by an
270 * interleving call to region_del(). Pull a region descriptor
271 * from the cache and use it for this range.
273 if (&rg->link == head || t < rg->from) {
274 VM_BUG_ON(resv->region_cache_count <= 0);
276 resv->region_cache_count--;
277 nrg = list_first_entry(&resv->region_cache, struct file_region,
279 list_del(&nrg->link);
283 list_add(&nrg->link, rg->link.prev);
289 /* Round our left edge to the current segment if it encloses us. */
293 /* Check for and consume any regions we now overlap with. */
295 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
296 if (&rg->link == head)
301 /* If this area reaches higher then extend our area to
302 * include it completely. If this is not the first area
303 * which we intend to reuse, free it. */
307 /* Decrement return value by the deleted range.
308 * Another range will span this area so that by
309 * end of routine add will be >= zero
311 add -= (rg->to - rg->from);
317 add += (nrg->from - f); /* Added to beginning of region */
319 add += t - nrg->to; /* Added to end of region */
323 resv->adds_in_progress--;
324 spin_unlock(&resv->lock);
330 * Examine the existing reserve map and determine how many
331 * huge pages in the specified range [f, t) are NOT currently
332 * represented. This routine is called before a subsequent
333 * call to region_add that will actually modify the reserve
334 * map to add the specified range [f, t). region_chg does
335 * not change the number of huge pages represented by the
336 * map. However, if the existing regions in the map can not
337 * be expanded to represent the new range, a new file_region
338 * structure is added to the map as a placeholder. This is
339 * so that the subsequent region_add call will have all the
340 * regions it needs and will not fail.
342 * Upon entry, region_chg will also examine the cache of region descriptors
343 * associated with the map. If there are not enough descriptors cached, one
344 * will be allocated for the in progress add operation.
346 * Returns the number of huge pages that need to be added to the existing
347 * reservation map for the range [f, t). This number is greater or equal to
348 * zero. -ENOMEM is returned if a new file_region structure or cache entry
349 * is needed and can not be allocated.
351 static long region_chg(struct resv_map *resv, long f, long t)
353 struct list_head *head = &resv->regions;
354 struct file_region *rg, *nrg = NULL;
358 spin_lock(&resv->lock);
360 resv->adds_in_progress++;
363 * Check for sufficient descriptors in the cache to accommodate
364 * the number of in progress add operations.
366 if (resv->adds_in_progress > resv->region_cache_count) {
367 struct file_region *trg;
369 VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
370 /* Must drop lock to allocate a new descriptor. */
371 resv->adds_in_progress--;
372 spin_unlock(&resv->lock);
374 trg = kmalloc(sizeof(*trg), GFP_KERNEL);
380 spin_lock(&resv->lock);
381 list_add(&trg->link, &resv->region_cache);
382 resv->region_cache_count++;
386 /* Locate the region we are before or in. */
387 list_for_each_entry(rg, head, link)
391 /* If we are below the current region then a new region is required.
392 * Subtle, allocate a new region at the position but make it zero
393 * size such that we can guarantee to record the reservation. */
394 if (&rg->link == head || t < rg->from) {
396 resv->adds_in_progress--;
397 spin_unlock(&resv->lock);
398 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
404 INIT_LIST_HEAD(&nrg->link);
408 list_add(&nrg->link, rg->link.prev);
413 /* Round our left edge to the current segment if it encloses us. */
418 /* Check for and consume any regions we now overlap with. */
419 list_for_each_entry(rg, rg->link.prev, link) {
420 if (&rg->link == head)
425 /* We overlap with this area, if it extends further than
426 * us then we must extend ourselves. Account for its
427 * existing reservation. */
432 chg -= rg->to - rg->from;
436 spin_unlock(&resv->lock);
437 /* We already know we raced and no longer need the new region */
441 spin_unlock(&resv->lock);
446 * Abort the in progress add operation. The adds_in_progress field
447 * of the resv_map keeps track of the operations in progress between
448 * calls to region_chg and region_add. Operations are sometimes
449 * aborted after the call to region_chg. In such cases, region_abort
450 * is called to decrement the adds_in_progress counter.
452 * NOTE: The range arguments [f, t) are not needed or used in this
453 * routine. They are kept to make reading the calling code easier as
454 * arguments will match the associated region_chg call.
456 static void region_abort(struct resv_map *resv, long f, long t)
458 spin_lock(&resv->lock);
459 VM_BUG_ON(!resv->region_cache_count);
460 resv->adds_in_progress--;
461 spin_unlock(&resv->lock);
465 * Delete the specified range [f, t) from the reserve map. If the
466 * t parameter is LONG_MAX, this indicates that ALL regions after f
467 * should be deleted. Locate the regions which intersect [f, t)
468 * and either trim, delete or split the existing regions.
470 * Returns the number of huge pages deleted from the reserve map.
471 * In the normal case, the return value is zero or more. In the
472 * case where a region must be split, a new region descriptor must
473 * be allocated. If the allocation fails, -ENOMEM will be returned.
474 * NOTE: If the parameter t == LONG_MAX, then we will never split
475 * a region and possibly return -ENOMEM. Callers specifying
476 * t == LONG_MAX do not need to check for -ENOMEM error.
478 static long region_del(struct resv_map *resv, long f, long t)
480 struct list_head *head = &resv->regions;
481 struct file_region *rg, *trg;
482 struct file_region *nrg = NULL;
486 spin_lock(&resv->lock);
487 list_for_each_entry_safe(rg, trg, head, link) {
489 * Skip regions before the range to be deleted. file_region
490 * ranges are normally of the form [from, to). However, there
491 * may be a "placeholder" entry in the map which is of the form
492 * (from, to) with from == to. Check for placeholder entries
493 * at the beginning of the range to be deleted.
495 if (rg->to <= f && (rg->to != rg->from || rg->to != f))
501 if (f > rg->from && t < rg->to) { /* Must split region */
503 * Check for an entry in the cache before dropping
504 * lock and attempting allocation.
507 resv->region_cache_count > resv->adds_in_progress) {
508 nrg = list_first_entry(&resv->region_cache,
511 list_del(&nrg->link);
512 resv->region_cache_count--;
516 spin_unlock(&resv->lock);
517 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
525 /* New entry for end of split region */
528 INIT_LIST_HEAD(&nrg->link);
530 /* Original entry is trimmed */
533 list_add(&nrg->link, &rg->link);
538 if (f <= rg->from && t >= rg->to) { /* Remove entire region */
539 del += rg->to - rg->from;
545 if (f <= rg->from) { /* Trim beginning of region */
548 } else { /* Trim end of region */
554 spin_unlock(&resv->lock);
560 * A rare out of memory error was encountered which prevented removal of
561 * the reserve map region for a page. The huge page itself was free'ed
562 * and removed from the page cache. This routine will adjust the subpool
563 * usage count, and the global reserve count if needed. By incrementing
564 * these counts, the reserve map entry which could not be deleted will
565 * appear as a "reserved" entry instead of simply dangling with incorrect
568 void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve)
570 struct hugepage_subpool *spool = subpool_inode(inode);
573 rsv_adjust = hugepage_subpool_get_pages(spool, 1);
574 if (restore_reserve && rsv_adjust) {
575 struct hstate *h = hstate_inode(inode);
577 hugetlb_acct_memory(h, 1);
582 * Count and return the number of huge pages in the reserve map
583 * that intersect with the range [f, t).
585 static long region_count(struct resv_map *resv, long f, long t)
587 struct list_head *head = &resv->regions;
588 struct file_region *rg;
591 spin_lock(&resv->lock);
592 /* Locate each segment we overlap with, and count that overlap. */
593 list_for_each_entry(rg, head, link) {
602 seg_from = max(rg->from, f);
603 seg_to = min(rg->to, t);
605 chg += seg_to - seg_from;
607 spin_unlock(&resv->lock);
613 * Convert the address within this vma to the page offset within
614 * the mapping, in pagecache page units; huge pages here.
616 static pgoff_t vma_hugecache_offset(struct hstate *h,
617 struct vm_area_struct *vma, unsigned long address)
619 return ((address - vma->vm_start) >> huge_page_shift(h)) +
620 (vma->vm_pgoff >> huge_page_order(h));
623 pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
624 unsigned long address)
626 return vma_hugecache_offset(hstate_vma(vma), vma, address);
630 * Return the size of the pages allocated when backing a VMA. In the majority
631 * cases this will be same size as used by the page table entries.
633 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
635 struct hstate *hstate;
637 if (!is_vm_hugetlb_page(vma))
640 hstate = hstate_vma(vma);
642 return 1UL << huge_page_shift(hstate);
644 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
647 * Return the page size being used by the MMU to back a VMA. In the majority
648 * of cases, the page size used by the kernel matches the MMU size. On
649 * architectures where it differs, an architecture-specific version of this
650 * function is required.
652 #ifndef vma_mmu_pagesize
653 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
655 return vma_kernel_pagesize(vma);
660 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
661 * bits of the reservation map pointer, which are always clear due to
664 #define HPAGE_RESV_OWNER (1UL << 0)
665 #define HPAGE_RESV_UNMAPPED (1UL << 1)
666 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
669 * These helpers are used to track how many pages are reserved for
670 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
671 * is guaranteed to have their future faults succeed.
673 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
674 * the reserve counters are updated with the hugetlb_lock held. It is safe
675 * to reset the VMA at fork() time as it is not in use yet and there is no
676 * chance of the global counters getting corrupted as a result of the values.
678 * The private mapping reservation is represented in a subtly different
679 * manner to a shared mapping. A shared mapping has a region map associated
680 * with the underlying file, this region map represents the backing file
681 * pages which have ever had a reservation assigned which this persists even
682 * after the page is instantiated. A private mapping has a region map
683 * associated with the original mmap which is attached to all VMAs which
684 * reference it, this region map represents those offsets which have consumed
685 * reservation ie. where pages have been instantiated.
687 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
689 return (unsigned long)vma->vm_private_data;
692 static void set_vma_private_data(struct vm_area_struct *vma,
695 vma->vm_private_data = (void *)value;
698 struct resv_map *resv_map_alloc(void)
700 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
701 struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
703 if (!resv_map || !rg) {
709 kref_init(&resv_map->refs);
710 spin_lock_init(&resv_map->lock);
711 INIT_LIST_HEAD(&resv_map->regions);
713 resv_map->adds_in_progress = 0;
715 INIT_LIST_HEAD(&resv_map->region_cache);
716 list_add(&rg->link, &resv_map->region_cache);
717 resv_map->region_cache_count = 1;
722 void resv_map_release(struct kref *ref)
724 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
725 struct list_head *head = &resv_map->region_cache;
726 struct file_region *rg, *trg;
728 /* Clear out any active regions before we release the map. */
729 region_del(resv_map, 0, LONG_MAX);
731 /* ... and any entries left in the cache */
732 list_for_each_entry_safe(rg, trg, head, link) {
737 VM_BUG_ON(resv_map->adds_in_progress);
742 static inline struct resv_map *inode_resv_map(struct inode *inode)
744 return inode->i_mapping->private_data;
747 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
749 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
750 if (vma->vm_flags & VM_MAYSHARE) {
751 struct address_space *mapping = vma->vm_file->f_mapping;
752 struct inode *inode = mapping->host;
754 return inode_resv_map(inode);
757 return (struct resv_map *)(get_vma_private_data(vma) &
762 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
764 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
765 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
767 set_vma_private_data(vma, (get_vma_private_data(vma) &
768 HPAGE_RESV_MASK) | (unsigned long)map);
771 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
773 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
774 VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
776 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
779 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
781 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
783 return (get_vma_private_data(vma) & flag) != 0;
786 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
787 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
789 VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
790 if (!(vma->vm_flags & VM_MAYSHARE))
791 vma->vm_private_data = (void *)0;
794 /* Returns true if the VMA has associated reserve pages */
795 static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
797 if (vma->vm_flags & VM_NORESERVE) {
799 * This address is already reserved by other process(chg == 0),
800 * so, we should decrement reserved count. Without decrementing,
801 * reserve count remains after releasing inode, because this
802 * allocated page will go into page cache and is regarded as
803 * coming from reserved pool in releasing step. Currently, we
804 * don't have any other solution to deal with this situation
805 * properly, so add work-around here.
807 if (vma->vm_flags & VM_MAYSHARE && chg == 0)
813 /* Shared mappings always use reserves */
814 if (vma->vm_flags & VM_MAYSHARE) {
816 * We know VM_NORESERVE is not set. Therefore, there SHOULD
817 * be a region map for all pages. The only situation where
818 * there is no region map is if a hole was punched via
819 * fallocate. In this case, there really are no reverves to
820 * use. This situation is indicated if chg != 0.
829 * Only the process that called mmap() has reserves for
832 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
838 static void enqueue_huge_page(struct hstate *h, struct page *page)
840 int nid = page_to_nid(page);
841 list_move(&page->lru, &h->hugepage_freelists[nid]);
842 h->free_huge_pages++;
843 h->free_huge_pages_node[nid]++;
846 static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
850 list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
851 if (!is_migrate_isolate_page(page))
854 * if 'non-isolated free hugepage' not found on the list,
855 * the allocation fails.
857 if (&h->hugepage_freelists[nid] == &page->lru)
859 list_move(&page->lru, &h->hugepage_activelist);
860 set_page_refcounted(page);
861 h->free_huge_pages--;
862 h->free_huge_pages_node[nid]--;
866 /* Movability of hugepages depends on migration support. */
867 static inline gfp_t htlb_alloc_mask(struct hstate *h)
869 if (hugepages_treat_as_movable || hugepage_migration_supported(h))
870 return GFP_HIGHUSER_MOVABLE;
875 static struct page *dequeue_huge_page_vma(struct hstate *h,
876 struct vm_area_struct *vma,
877 unsigned long address, int avoid_reserve,
880 struct page *page = NULL;
881 struct mempolicy *mpol;
882 nodemask_t *nodemask;
883 struct zonelist *zonelist;
886 unsigned int cpuset_mems_cookie;
889 * A child process with MAP_PRIVATE mappings created by their parent
890 * have no page reserves. This check ensures that reservations are
891 * not "stolen". The child may still get SIGKILLed
893 if (!vma_has_reserves(vma, chg) &&
894 h->free_huge_pages - h->resv_huge_pages == 0)
897 /* If reserves cannot be used, ensure enough pages are in the pool */
898 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
902 cpuset_mems_cookie = read_mems_allowed_begin();
903 zonelist = huge_zonelist(vma, address,
904 htlb_alloc_mask(h), &mpol, &nodemask);
906 for_each_zone_zonelist_nodemask(zone, z, zonelist,
907 MAX_NR_ZONES - 1, nodemask) {
908 if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
909 page = dequeue_huge_page_node(h, zone_to_nid(zone));
913 if (!vma_has_reserves(vma, chg))
916 SetPagePrivate(page);
917 h->resv_huge_pages--;
924 if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
933 * common helper functions for hstate_next_node_to_{alloc|free}.
934 * We may have allocated or freed a huge page based on a different
935 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
936 * be outside of *nodes_allowed. Ensure that we use an allowed
937 * node for alloc or free.
939 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
941 nid = next_node(nid, *nodes_allowed);
942 if (nid == MAX_NUMNODES)
943 nid = first_node(*nodes_allowed);
944 VM_BUG_ON(nid >= MAX_NUMNODES);
949 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
951 if (!node_isset(nid, *nodes_allowed))
952 nid = next_node_allowed(nid, nodes_allowed);
957 * returns the previously saved node ["this node"] from which to
958 * allocate a persistent huge page for the pool and advance the
959 * next node from which to allocate, handling wrap at end of node
962 static int hstate_next_node_to_alloc(struct hstate *h,
963 nodemask_t *nodes_allowed)
967 VM_BUG_ON(!nodes_allowed);
969 nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
970 h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
976 * helper for free_pool_huge_page() - return the previously saved
977 * node ["this node"] from which to free a huge page. Advance the
978 * next node id whether or not we find a free huge page to free so
979 * that the next attempt to free addresses the next node.
981 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
985 VM_BUG_ON(!nodes_allowed);
987 nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
988 h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
993 #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
994 for (nr_nodes = nodes_weight(*mask); \
996 ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \
999 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \
1000 for (nr_nodes = nodes_weight(*mask); \
1002 ((node = hstate_next_node_to_free(hs, mask)) || 1); \
1005 #if defined(CONFIG_CMA) && defined(CONFIG_X86_64)
1006 static void destroy_compound_gigantic_page(struct page *page,
1010 int nr_pages = 1 << order;
1011 struct page *p = page + 1;
1013 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1014 clear_compound_head(p);
1015 set_page_refcounted(p);
1018 set_compound_order(page, 0);
1019 __ClearPageHead(page);
1022 static void free_gigantic_page(struct page *page, unsigned int order)
1024 free_contig_range(page_to_pfn(page), 1 << order);
1027 static int __alloc_gigantic_page(unsigned long start_pfn,
1028 unsigned long nr_pages)
1030 unsigned long end_pfn = start_pfn + nr_pages;
1031 return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
1034 static bool pfn_range_valid_gigantic(unsigned long start_pfn,
1035 unsigned long nr_pages)
1037 unsigned long i, end_pfn = start_pfn + nr_pages;
1040 for (i = start_pfn; i < end_pfn; i++) {
1044 page = pfn_to_page(i);
1046 if (PageReserved(page))
1049 if (page_count(page) > 0)
1059 static bool zone_spans_last_pfn(const struct zone *zone,
1060 unsigned long start_pfn, unsigned long nr_pages)
1062 unsigned long last_pfn = start_pfn + nr_pages - 1;
1063 return zone_spans_pfn(zone, last_pfn);
1066 static struct page *alloc_gigantic_page(int nid, unsigned int order)
1068 unsigned long nr_pages = 1 << order;
1069 unsigned long ret, pfn, flags;
1072 z = NODE_DATA(nid)->node_zones;
1073 for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) {
1074 spin_lock_irqsave(&z->lock, flags);
1076 pfn = ALIGN(z->zone_start_pfn, nr_pages);
1077 while (zone_spans_last_pfn(z, pfn, nr_pages)) {
1078 if (pfn_range_valid_gigantic(pfn, nr_pages)) {
1080 * We release the zone lock here because
1081 * alloc_contig_range() will also lock the zone
1082 * at some point. If there's an allocation
1083 * spinning on this lock, it may win the race
1084 * and cause alloc_contig_range() to fail...
1086 spin_unlock_irqrestore(&z->lock, flags);
1087 ret = __alloc_gigantic_page(pfn, nr_pages);
1089 return pfn_to_page(pfn);
1090 spin_lock_irqsave(&z->lock, flags);
1095 spin_unlock_irqrestore(&z->lock, flags);
1101 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1102 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
1104 static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid)
1108 page = alloc_gigantic_page(nid, huge_page_order(h));
1110 prep_compound_gigantic_page(page, huge_page_order(h));
1111 prep_new_huge_page(h, page, nid);
1117 static int alloc_fresh_gigantic_page(struct hstate *h,
1118 nodemask_t *nodes_allowed)
1120 struct page *page = NULL;
1123 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1124 page = alloc_fresh_gigantic_page_node(h, node);
1132 static inline bool gigantic_page_supported(void) { return true; }
1134 static inline bool gigantic_page_supported(void) { return false; }
1135 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1136 static inline void destroy_compound_gigantic_page(struct page *page,
1137 unsigned int order) { }
1138 static inline int alloc_fresh_gigantic_page(struct hstate *h,
1139 nodemask_t *nodes_allowed) { return 0; }
1142 static void update_and_free_page(struct hstate *h, struct page *page)
1146 if (hstate_is_gigantic(h) && !gigantic_page_supported())
1150 h->nr_huge_pages_node[page_to_nid(page)]--;
1151 for (i = 0; i < pages_per_huge_page(h); i++) {
1152 page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1153 1 << PG_referenced | 1 << PG_dirty |
1154 1 << PG_active | 1 << PG_private |
1157 VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1158 set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1159 set_page_refcounted(page);
1160 if (hstate_is_gigantic(h)) {
1161 destroy_compound_gigantic_page(page, huge_page_order(h));
1162 free_gigantic_page(page, huge_page_order(h));
1164 __free_pages(page, huge_page_order(h));
1168 struct hstate *size_to_hstate(unsigned long size)
1172 for_each_hstate(h) {
1173 if (huge_page_size(h) == size)
1180 * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1181 * to hstate->hugepage_activelist.)
1183 * This function can be called for tail pages, but never returns true for them.
1185 bool page_huge_active(struct page *page)
1187 VM_BUG_ON_PAGE(!PageHuge(page), page);
1188 return PageHead(page) && PagePrivate(&page[1]);
1191 /* never called for tail page */
1192 static void set_page_huge_active(struct page *page)
1194 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1195 SetPagePrivate(&page[1]);
1198 static void clear_page_huge_active(struct page *page)
1200 VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1201 ClearPagePrivate(&page[1]);
1204 void free_huge_page(struct page *page)
1207 * Can't pass hstate in here because it is called from the
1208 * compound page destructor.
1210 struct hstate *h = page_hstate(page);
1211 int nid = page_to_nid(page);
1212 struct hugepage_subpool *spool =
1213 (struct hugepage_subpool *)page_private(page);
1214 bool restore_reserve;
1216 set_page_private(page, 0);
1217 page->mapping = NULL;
1218 BUG_ON(page_count(page));
1219 BUG_ON(page_mapcount(page));
1220 restore_reserve = PagePrivate(page);
1221 ClearPagePrivate(page);
1224 * A return code of zero implies that the subpool will be under its
1225 * minimum size if the reservation is not restored after page is free.
1226 * Therefore, force restore_reserve operation.
1228 if (hugepage_subpool_put_pages(spool, 1) == 0)
1229 restore_reserve = true;
1231 spin_lock(&hugetlb_lock);
1232 clear_page_huge_active(page);
1233 hugetlb_cgroup_uncharge_page(hstate_index(h),
1234 pages_per_huge_page(h), page);
1235 if (restore_reserve)
1236 h->resv_huge_pages++;
1238 if (h->surplus_huge_pages_node[nid]) {
1239 /* remove the page from active list */
1240 list_del(&page->lru);
1241 update_and_free_page(h, page);
1242 h->surplus_huge_pages--;
1243 h->surplus_huge_pages_node[nid]--;
1245 arch_clear_hugepage_flags(page);
1246 enqueue_huge_page(h, page);
1248 spin_unlock(&hugetlb_lock);
1251 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
1253 INIT_LIST_HEAD(&page->lru);
1254 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1255 spin_lock(&hugetlb_lock);
1256 set_hugetlb_cgroup(page, NULL);
1258 h->nr_huge_pages_node[nid]++;
1259 spin_unlock(&hugetlb_lock);
1260 put_page(page); /* free it into the hugepage allocator */
1263 static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1266 int nr_pages = 1 << order;
1267 struct page *p = page + 1;
1269 /* we rely on prep_new_huge_page to set the destructor */
1270 set_compound_order(page, order);
1271 __SetPageHead(page);
1272 __ClearPageReserved(page);
1273 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1275 * For gigantic hugepages allocated through bootmem at
1276 * boot, it's safer to be consistent with the not-gigantic
1277 * hugepages and clear the PG_reserved bit from all tail pages
1278 * too. Otherwse drivers using get_user_pages() to access tail
1279 * pages may get the reference counting wrong if they see
1280 * PG_reserved set on a tail page (despite the head page not
1281 * having PG_reserved set). Enforcing this consistency between
1282 * head and tail pages allows drivers to optimize away a check
1283 * on the head page when they need know if put_page() is needed
1284 * after get_user_pages().
1286 __ClearPageReserved(p);
1287 set_page_count(p, 0);
1288 set_compound_head(p, page);
1293 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1294 * transparent huge pages. See the PageTransHuge() documentation for more
1297 int PageHuge(struct page *page)
1299 if (!PageCompound(page))
1302 page = compound_head(page);
1303 return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1305 EXPORT_SYMBOL_GPL(PageHuge);
1308 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1309 * normal or transparent huge pages.
1311 int PageHeadHuge(struct page *page_head)
1313 if (!PageHead(page_head))
1316 return get_compound_page_dtor(page_head) == free_huge_page;
1319 pgoff_t __basepage_index(struct page *page)
1321 struct page *page_head = compound_head(page);
1322 pgoff_t index = page_index(page_head);
1323 unsigned long compound_idx;
1325 if (!PageHuge(page_head))
1326 return page_index(page);
1328 if (compound_order(page_head) >= MAX_ORDER)
1329 compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1331 compound_idx = page - page_head;
1333 return (index << compound_order(page_head)) + compound_idx;
1336 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
1340 page = __alloc_pages_node(nid,
1341 htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE|
1342 __GFP_REPEAT|__GFP_NOWARN,
1343 huge_page_order(h));
1345 prep_new_huge_page(h, page, nid);
1351 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
1357 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1358 page = alloc_fresh_huge_page_node(h, node);
1366 count_vm_event(HTLB_BUDDY_PGALLOC);
1368 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1374 * Free huge page from pool from next node to free.
1375 * Attempt to keep persistent huge pages more or less
1376 * balanced over allowed nodes.
1377 * Called with hugetlb_lock locked.
1379 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1385 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1387 * If we're returning unused surplus pages, only examine
1388 * nodes with surplus pages.
1390 if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1391 !list_empty(&h->hugepage_freelists[node])) {
1393 list_entry(h->hugepage_freelists[node].next,
1395 list_del(&page->lru);
1396 h->free_huge_pages--;
1397 h->free_huge_pages_node[node]--;
1399 h->surplus_huge_pages--;
1400 h->surplus_huge_pages_node[node]--;
1402 update_and_free_page(h, page);
1412 * Dissolve a given free hugepage into free buddy pages. This function does
1413 * nothing for in-use (including surplus) hugepages.
1415 static void dissolve_free_huge_page(struct page *page)
1417 spin_lock(&hugetlb_lock);
1418 if (PageHuge(page) && !page_count(page)) {
1419 struct page *head = compound_head(page);
1420 struct hstate *h = page_hstate(head);
1421 int nid = page_to_nid(head);
1422 list_del(&head->lru);
1423 h->free_huge_pages--;
1424 h->free_huge_pages_node[nid]--;
1425 update_and_free_page(h, head);
1427 spin_unlock(&hugetlb_lock);
1431 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1432 * make specified memory blocks removable from the system.
1433 * Note that this will dissolve a free gigantic hugepage completely, if any
1434 * part of it lies within the given range.
1436 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1440 if (!hugepages_supported())
1443 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
1444 dissolve_free_huge_page(pfn_to_page(pfn));
1448 * There are 3 ways this can get called:
1449 * 1. With vma+addr: we use the VMA's memory policy
1450 * 2. With !vma, but nid=NUMA_NO_NODE: We try to allocate a huge
1451 * page from any node, and let the buddy allocator itself figure
1453 * 3. With !vma, but nid!=NUMA_NO_NODE. We allocate a huge page
1454 * strictly from 'nid'
1456 static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
1457 struct vm_area_struct *vma, unsigned long addr, int nid)
1459 int order = huge_page_order(h);
1460 gfp_t gfp = htlb_alloc_mask(h)|__GFP_COMP|__GFP_REPEAT|__GFP_NOWARN;
1461 unsigned int cpuset_mems_cookie;
1464 * We need a VMA to get a memory policy. If we do not
1465 * have one, we use the 'nid' argument.
1467 * The mempolicy stuff below has some non-inlined bits
1468 * and calls ->vm_ops. That makes it hard to optimize at
1469 * compile-time, even when NUMA is off and it does
1470 * nothing. This helps the compiler optimize it out.
1472 if (!IS_ENABLED(CONFIG_NUMA) || !vma) {
1474 * If a specific node is requested, make sure to
1475 * get memory from there, but only when a node
1476 * is explicitly specified.
1478 if (nid != NUMA_NO_NODE)
1479 gfp |= __GFP_THISNODE;
1481 * Make sure to call something that can handle
1484 return alloc_pages_node(nid, gfp, order);
1488 * OK, so we have a VMA. Fetch the mempolicy and try to
1489 * allocate a huge page with it. We will only reach this
1490 * when CONFIG_NUMA=y.
1494 struct mempolicy *mpol;
1495 struct zonelist *zl;
1496 nodemask_t *nodemask;
1498 cpuset_mems_cookie = read_mems_allowed_begin();
1499 zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
1500 mpol_cond_put(mpol);
1501 page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
1504 } while (read_mems_allowed_retry(cpuset_mems_cookie));
1510 * There are two ways to allocate a huge page:
1511 * 1. When you have a VMA and an address (like a fault)
1512 * 2. When you have no VMA (like when setting /proc/.../nr_hugepages)
1514 * 'vma' and 'addr' are only for (1). 'nid' is always NUMA_NO_NODE in
1515 * this case which signifies that the allocation should be done with
1516 * respect for the VMA's memory policy.
1518 * For (2), we ignore 'vma' and 'addr' and use 'nid' exclusively. This
1519 * implies that memory policies will not be taken in to account.
1521 static struct page *__alloc_buddy_huge_page(struct hstate *h,
1522 struct vm_area_struct *vma, unsigned long addr, int nid)
1527 if (hstate_is_gigantic(h))
1531 * Make sure that anyone specifying 'nid' is not also specifying a VMA.
1532 * This makes sure the caller is picking _one_ of the modes with which
1533 * we can call this function, not both.
1535 if (vma || (addr != -1)) {
1536 VM_WARN_ON_ONCE(addr == -1);
1537 VM_WARN_ON_ONCE(nid != NUMA_NO_NODE);
1540 * Assume we will successfully allocate the surplus page to
1541 * prevent racing processes from causing the surplus to exceed
1544 * This however introduces a different race, where a process B
1545 * tries to grow the static hugepage pool while alloc_pages() is
1546 * called by process A. B will only examine the per-node
1547 * counters in determining if surplus huge pages can be
1548 * converted to normal huge pages in adjust_pool_surplus(). A
1549 * won't be able to increment the per-node counter, until the
1550 * lock is dropped by B, but B doesn't drop hugetlb_lock until
1551 * no more huge pages can be converted from surplus to normal
1552 * state (and doesn't try to convert again). Thus, we have a
1553 * case where a surplus huge page exists, the pool is grown, and
1554 * the surplus huge page still exists after, even though it
1555 * should just have been converted to a normal huge page. This
1556 * does not leak memory, though, as the hugepage will be freed
1557 * once it is out of use. It also does not allow the counters to
1558 * go out of whack in adjust_pool_surplus() as we don't modify
1559 * the node values until we've gotten the hugepage and only the
1560 * per-node value is checked there.
1562 spin_lock(&hugetlb_lock);
1563 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1564 spin_unlock(&hugetlb_lock);
1568 h->surplus_huge_pages++;
1570 spin_unlock(&hugetlb_lock);
1572 page = __hugetlb_alloc_buddy_huge_page(h, vma, addr, nid);
1574 spin_lock(&hugetlb_lock);
1576 INIT_LIST_HEAD(&page->lru);
1577 r_nid = page_to_nid(page);
1578 set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1579 set_hugetlb_cgroup(page, NULL);
1581 * We incremented the global counters already
1583 h->nr_huge_pages_node[r_nid]++;
1584 h->surplus_huge_pages_node[r_nid]++;
1585 __count_vm_event(HTLB_BUDDY_PGALLOC);
1588 h->surplus_huge_pages--;
1589 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
1591 spin_unlock(&hugetlb_lock);
1597 * Allocate a huge page from 'nid'. Note, 'nid' may be
1598 * NUMA_NO_NODE, which means that it may be allocated
1602 struct page *__alloc_buddy_huge_page_no_mpol(struct hstate *h, int nid)
1604 unsigned long addr = -1;
1606 return __alloc_buddy_huge_page(h, NULL, addr, nid);
1610 * Use the VMA's mpolicy to allocate a huge page from the buddy.
1613 struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
1614 struct vm_area_struct *vma, unsigned long addr)
1616 return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
1620 * This allocation function is useful in the context where vma is irrelevant.
1621 * E.g. soft-offlining uses this function because it only cares physical
1622 * address of error page.
1624 struct page *alloc_huge_page_node(struct hstate *h, int nid)
1626 struct page *page = NULL;
1628 spin_lock(&hugetlb_lock);
1629 if (h->free_huge_pages - h->resv_huge_pages > 0)
1630 page = dequeue_huge_page_node(h, nid);
1631 spin_unlock(&hugetlb_lock);
1634 page = __alloc_buddy_huge_page_no_mpol(h, nid);
1640 * Increase the hugetlb pool such that it can accommodate a reservation
1643 static int gather_surplus_pages(struct hstate *h, int delta)
1645 struct list_head surplus_list;
1646 struct page *page, *tmp;
1648 int needed, allocated;
1649 bool alloc_ok = true;
1651 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1653 h->resv_huge_pages += delta;
1658 INIT_LIST_HEAD(&surplus_list);
1662 spin_unlock(&hugetlb_lock);
1663 for (i = 0; i < needed; i++) {
1664 page = __alloc_buddy_huge_page_no_mpol(h, NUMA_NO_NODE);
1669 list_add(&page->lru, &surplus_list);
1674 * After retaking hugetlb_lock, we need to recalculate 'needed'
1675 * because either resv_huge_pages or free_huge_pages may have changed.
1677 spin_lock(&hugetlb_lock);
1678 needed = (h->resv_huge_pages + delta) -
1679 (h->free_huge_pages + allocated);
1684 * We were not able to allocate enough pages to
1685 * satisfy the entire reservation so we free what
1686 * we've allocated so far.
1691 * The surplus_list now contains _at_least_ the number of extra pages
1692 * needed to accommodate the reservation. Add the appropriate number
1693 * of pages to the hugetlb pool and free the extras back to the buddy
1694 * allocator. Commit the entire reservation here to prevent another
1695 * process from stealing the pages as they are added to the pool but
1696 * before they are reserved.
1698 needed += allocated;
1699 h->resv_huge_pages += delta;
1702 /* Free the needed pages to the hugetlb pool */
1703 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1707 * This page is now managed by the hugetlb allocator and has
1708 * no users -- drop the buddy allocator's reference.
1710 put_page_testzero(page);
1711 VM_BUG_ON_PAGE(page_count(page), page);
1712 enqueue_huge_page(h, page);
1715 spin_unlock(&hugetlb_lock);
1717 /* Free unnecessary surplus pages to the buddy allocator */
1718 list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1720 spin_lock(&hugetlb_lock);
1726 * This routine has two main purposes:
1727 * 1) Decrement the reservation count (resv_huge_pages) by the value passed
1728 * in unused_resv_pages. This corresponds to the prior adjustments made
1729 * to the associated reservation map.
1730 * 2) Free any unused surplus pages that may have been allocated to satisfy
1731 * the reservation. As many as unused_resv_pages may be freed.
1733 * Called with hugetlb_lock held. However, the lock could be dropped (and
1734 * reacquired) during calls to cond_resched_lock. Whenever dropping the lock,
1735 * we must make sure nobody else can claim pages we are in the process of
1736 * freeing. Do this by ensuring resv_huge_page always is greater than the
1737 * number of huge pages we plan to free when dropping the lock.
1739 static void return_unused_surplus_pages(struct hstate *h,
1740 unsigned long unused_resv_pages)
1742 unsigned long nr_pages;
1744 /* Cannot return gigantic pages currently */
1745 if (hstate_is_gigantic(h))
1749 * Part (or even all) of the reservation could have been backed
1750 * by pre-allocated pages. Only free surplus pages.
1752 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1755 * We want to release as many surplus pages as possible, spread
1756 * evenly across all nodes with memory. Iterate across these nodes
1757 * until we can no longer free unreserved surplus pages. This occurs
1758 * when the nodes with surplus pages have no free pages.
1759 * free_pool_huge_page() will balance the the freed pages across the
1760 * on-line nodes with memory and will handle the hstate accounting.
1762 * Note that we decrement resv_huge_pages as we free the pages. If
1763 * we drop the lock, resv_huge_pages will still be sufficiently large
1764 * to cover subsequent pages we may free.
1766 while (nr_pages--) {
1767 h->resv_huge_pages--;
1768 unused_resv_pages--;
1769 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1771 cond_resched_lock(&hugetlb_lock);
1775 /* Fully uncommit the reservation */
1776 h->resv_huge_pages -= unused_resv_pages;
1781 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1782 * are used by the huge page allocation routines to manage reservations.
1784 * vma_needs_reservation is called to determine if the huge page at addr
1785 * within the vma has an associated reservation. If a reservation is
1786 * needed, the value 1 is returned. The caller is then responsible for
1787 * managing the global reservation and subpool usage counts. After
1788 * the huge page has been allocated, vma_commit_reservation is called
1789 * to add the page to the reservation map. If the page allocation fails,
1790 * the reservation must be ended instead of committed. vma_end_reservation
1791 * is called in such cases.
1793 * In the normal case, vma_commit_reservation returns the same value
1794 * as the preceding vma_needs_reservation call. The only time this
1795 * is not the case is if a reserve map was changed between calls. It
1796 * is the responsibility of the caller to notice the difference and
1797 * take appropriate action.
1799 enum vma_resv_mode {
1804 static long __vma_reservation_common(struct hstate *h,
1805 struct vm_area_struct *vma, unsigned long addr,
1806 enum vma_resv_mode mode)
1808 struct resv_map *resv;
1812 resv = vma_resv_map(vma);
1816 idx = vma_hugecache_offset(h, vma, addr);
1818 case VMA_NEEDS_RESV:
1819 ret = region_chg(resv, idx, idx + 1);
1821 case VMA_COMMIT_RESV:
1822 ret = region_add(resv, idx, idx + 1);
1825 region_abort(resv, idx, idx + 1);
1832 if (vma->vm_flags & VM_MAYSHARE)
1835 return ret < 0 ? ret : 0;
1838 static long vma_needs_reservation(struct hstate *h,
1839 struct vm_area_struct *vma, unsigned long addr)
1841 return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1844 static long vma_commit_reservation(struct hstate *h,
1845 struct vm_area_struct *vma, unsigned long addr)
1847 return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1850 static void vma_end_reservation(struct hstate *h,
1851 struct vm_area_struct *vma, unsigned long addr)
1853 (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1856 struct page *alloc_huge_page(struct vm_area_struct *vma,
1857 unsigned long addr, int avoid_reserve)
1859 struct hugepage_subpool *spool = subpool_vma(vma);
1860 struct hstate *h = hstate_vma(vma);
1862 long map_chg, map_commit;
1865 struct hugetlb_cgroup *h_cg;
1867 idx = hstate_index(h);
1869 * Examine the region/reserve map to determine if the process
1870 * has a reservation for the page to be allocated. A return
1871 * code of zero indicates a reservation exists (no change).
1873 map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
1875 return ERR_PTR(-ENOMEM);
1878 * Processes that did not create the mapping will have no
1879 * reserves as indicated by the region/reserve map. Check
1880 * that the allocation will not exceed the subpool limit.
1881 * Allocations for MAP_NORESERVE mappings also need to be
1882 * checked against any subpool limit.
1884 if (map_chg || avoid_reserve) {
1885 gbl_chg = hugepage_subpool_get_pages(spool, 1);
1887 vma_end_reservation(h, vma, addr);
1888 return ERR_PTR(-ENOSPC);
1892 * Even though there was no reservation in the region/reserve
1893 * map, there could be reservations associated with the
1894 * subpool that can be used. This would be indicated if the
1895 * return value of hugepage_subpool_get_pages() is zero.
1896 * However, if avoid_reserve is specified we still avoid even
1897 * the subpool reservations.
1903 ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
1905 goto out_subpool_put;
1907 spin_lock(&hugetlb_lock);
1909 * glb_chg is passed to indicate whether or not a page must be taken
1910 * from the global free pool (global change). gbl_chg == 0 indicates
1911 * a reservation exists for the allocation.
1913 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
1915 spin_unlock(&hugetlb_lock);
1916 page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
1918 goto out_uncharge_cgroup;
1919 if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
1920 SetPagePrivate(page);
1921 h->resv_huge_pages--;
1923 spin_lock(&hugetlb_lock);
1924 list_move(&page->lru, &h->hugepage_activelist);
1927 hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
1928 spin_unlock(&hugetlb_lock);
1930 set_page_private(page, (unsigned long)spool);
1932 map_commit = vma_commit_reservation(h, vma, addr);
1933 if (unlikely(map_chg > map_commit)) {
1935 * The page was added to the reservation map between
1936 * vma_needs_reservation and vma_commit_reservation.
1937 * This indicates a race with hugetlb_reserve_pages.
1938 * Adjust for the subpool count incremented above AND
1939 * in hugetlb_reserve_pages for the same page. Also,
1940 * the reservation count added in hugetlb_reserve_pages
1941 * no longer applies.
1945 rsv_adjust = hugepage_subpool_put_pages(spool, 1);
1946 hugetlb_acct_memory(h, -rsv_adjust);
1950 out_uncharge_cgroup:
1951 hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
1953 if (map_chg || avoid_reserve)
1954 hugepage_subpool_put_pages(spool, 1);
1955 vma_end_reservation(h, vma, addr);
1956 return ERR_PTR(-ENOSPC);
1960 * alloc_huge_page()'s wrapper which simply returns the page if allocation
1961 * succeeds, otherwise NULL. This function is called from new_vma_page(),
1962 * where no ERR_VALUE is expected to be returned.
1964 struct page *alloc_huge_page_noerr(struct vm_area_struct *vma,
1965 unsigned long addr, int avoid_reserve)
1967 struct page *page = alloc_huge_page(vma, addr, avoid_reserve);
1973 int __weak alloc_bootmem_huge_page(struct hstate *h)
1975 struct huge_bootmem_page *m;
1978 for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
1981 addr = memblock_virt_alloc_try_nid_nopanic(
1982 huge_page_size(h), huge_page_size(h),
1983 0, BOOTMEM_ALLOC_ACCESSIBLE, node);
1986 * Use the beginning of the huge page to store the
1987 * huge_bootmem_page struct (until gather_bootmem
1988 * puts them into the mem_map).
1997 BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
1998 /* Put them into a private list first because mem_map is not up yet */
1999 list_add(&m->list, &huge_boot_pages);
2004 static void __init prep_compound_huge_page(struct page *page,
2007 if (unlikely(order > (MAX_ORDER - 1)))
2008 prep_compound_gigantic_page(page, order);
2010 prep_compound_page(page, order);
2013 /* Put bootmem huge pages into the standard lists after mem_map is up */
2014 static void __init gather_bootmem_prealloc(void)
2016 struct huge_bootmem_page *m;
2018 list_for_each_entry(m, &huge_boot_pages, list) {
2019 struct hstate *h = m->hstate;
2022 #ifdef CONFIG_HIGHMEM
2023 page = pfn_to_page(m->phys >> PAGE_SHIFT);
2024 memblock_free_late(__pa(m),
2025 sizeof(struct huge_bootmem_page));
2027 page = virt_to_page(m);
2029 WARN_ON(page_count(page) != 1);
2030 prep_compound_huge_page(page, h->order);
2031 WARN_ON(PageReserved(page));
2032 prep_new_huge_page(h, page, page_to_nid(page));
2034 * If we had gigantic hugepages allocated at boot time, we need
2035 * to restore the 'stolen' pages to totalram_pages in order to
2036 * fix confusing memory reports from free(1) and another
2037 * side-effects, like CommitLimit going negative.
2039 if (hstate_is_gigantic(h))
2040 adjust_managed_page_count(page, 1 << h->order);
2044 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2048 for (i = 0; i < h->max_huge_pages; ++i) {
2049 if (hstate_is_gigantic(h)) {
2050 if (!alloc_bootmem_huge_page(h))
2052 } else if (!alloc_fresh_huge_page(h,
2053 &node_states[N_MEMORY]))
2056 h->max_huge_pages = i;
2059 static void __init hugetlb_init_hstates(void)
2063 for_each_hstate(h) {
2064 if (minimum_order > huge_page_order(h))
2065 minimum_order = huge_page_order(h);
2067 /* oversize hugepages were init'ed in early boot */
2068 if (!hstate_is_gigantic(h))
2069 hugetlb_hstate_alloc_pages(h);
2071 VM_BUG_ON(minimum_order == UINT_MAX);
2074 static char * __init memfmt(char *buf, unsigned long n)
2076 if (n >= (1UL << 30))
2077 sprintf(buf, "%lu GB", n >> 30);
2078 else if (n >= (1UL << 20))
2079 sprintf(buf, "%lu MB", n >> 20);
2081 sprintf(buf, "%lu KB", n >> 10);
2085 static void __init report_hugepages(void)
2089 for_each_hstate(h) {
2091 pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2092 memfmt(buf, huge_page_size(h)),
2093 h->free_huge_pages);
2097 #ifdef CONFIG_HIGHMEM
2098 static void try_to_free_low(struct hstate *h, unsigned long count,
2099 nodemask_t *nodes_allowed)
2103 if (hstate_is_gigantic(h))
2106 for_each_node_mask(i, *nodes_allowed) {
2107 struct page *page, *next;
2108 struct list_head *freel = &h->hugepage_freelists[i];
2109 list_for_each_entry_safe(page, next, freel, lru) {
2110 if (count >= h->nr_huge_pages)
2112 if (PageHighMem(page))
2114 list_del(&page->lru);
2115 update_and_free_page(h, page);
2116 h->free_huge_pages--;
2117 h->free_huge_pages_node[page_to_nid(page)]--;
2122 static inline void try_to_free_low(struct hstate *h, unsigned long count,
2123 nodemask_t *nodes_allowed)
2129 * Increment or decrement surplus_huge_pages. Keep node-specific counters
2130 * balanced by operating on them in a round-robin fashion.
2131 * Returns 1 if an adjustment was made.
2133 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2138 VM_BUG_ON(delta != -1 && delta != 1);
2141 for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2142 if (h->surplus_huge_pages_node[node])
2146 for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2147 if (h->surplus_huge_pages_node[node] <
2148 h->nr_huge_pages_node[node])
2155 h->surplus_huge_pages += delta;
2156 h->surplus_huge_pages_node[node] += delta;
2160 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2161 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2162 nodemask_t *nodes_allowed)
2164 unsigned long min_count, ret;
2166 if (hstate_is_gigantic(h) && !gigantic_page_supported())
2167 return h->max_huge_pages;
2170 * Increase the pool size
2171 * First take pages out of surplus state. Then make up the
2172 * remaining difference by allocating fresh huge pages.
2174 * We might race with __alloc_buddy_huge_page() here and be unable
2175 * to convert a surplus huge page to a normal huge page. That is
2176 * not critical, though, it just means the overall size of the
2177 * pool might be one hugepage larger than it needs to be, but
2178 * within all the constraints specified by the sysctls.
2180 spin_lock(&hugetlb_lock);
2181 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2182 if (!adjust_pool_surplus(h, nodes_allowed, -1))
2186 while (count > persistent_huge_pages(h)) {
2188 * If this allocation races such that we no longer need the
2189 * page, free_huge_page will handle it by freeing the page
2190 * and reducing the surplus.
2192 spin_unlock(&hugetlb_lock);
2194 /* yield cpu to avoid soft lockup */
2197 if (hstate_is_gigantic(h))
2198 ret = alloc_fresh_gigantic_page(h, nodes_allowed);
2200 ret = alloc_fresh_huge_page(h, nodes_allowed);
2201 spin_lock(&hugetlb_lock);
2205 /* Bail for signals. Probably ctrl-c from user */
2206 if (signal_pending(current))
2211 * Decrease the pool size
2212 * First return free pages to the buddy allocator (being careful
2213 * to keep enough around to satisfy reservations). Then place
2214 * pages into surplus state as needed so the pool will shrink
2215 * to the desired size as pages become free.
2217 * By placing pages into the surplus state independent of the
2218 * overcommit value, we are allowing the surplus pool size to
2219 * exceed overcommit. There are few sane options here. Since
2220 * __alloc_buddy_huge_page() is checking the global counter,
2221 * though, we'll note that we're not allowed to exceed surplus
2222 * and won't grow the pool anywhere else. Not until one of the
2223 * sysctls are changed, or the surplus pages go out of use.
2225 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2226 min_count = max(count, min_count);
2227 try_to_free_low(h, min_count, nodes_allowed);
2228 while (min_count < persistent_huge_pages(h)) {
2229 if (!free_pool_huge_page(h, nodes_allowed, 0))
2231 cond_resched_lock(&hugetlb_lock);
2233 while (count < persistent_huge_pages(h)) {
2234 if (!adjust_pool_surplus(h, nodes_allowed, 1))
2238 ret = persistent_huge_pages(h);
2239 spin_unlock(&hugetlb_lock);
2243 #define HSTATE_ATTR_RO(_name) \
2244 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2246 #define HSTATE_ATTR(_name) \
2247 static struct kobj_attribute _name##_attr = \
2248 __ATTR(_name, 0644, _name##_show, _name##_store)
2250 static struct kobject *hugepages_kobj;
2251 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2253 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2255 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2259 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2260 if (hstate_kobjs[i] == kobj) {
2262 *nidp = NUMA_NO_NODE;
2266 return kobj_to_node_hstate(kobj, nidp);
2269 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2270 struct kobj_attribute *attr, char *buf)
2273 unsigned long nr_huge_pages;
2276 h = kobj_to_hstate(kobj, &nid);
2277 if (nid == NUMA_NO_NODE)
2278 nr_huge_pages = h->nr_huge_pages;
2280 nr_huge_pages = h->nr_huge_pages_node[nid];
2282 return sprintf(buf, "%lu\n", nr_huge_pages);
2285 static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2286 struct hstate *h, int nid,
2287 unsigned long count, size_t len)
2290 NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2292 if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2297 if (nid == NUMA_NO_NODE) {
2299 * global hstate attribute
2301 if (!(obey_mempolicy &&
2302 init_nodemask_of_mempolicy(nodes_allowed))) {
2303 NODEMASK_FREE(nodes_allowed);
2304 nodes_allowed = &node_states[N_MEMORY];
2306 } else if (nodes_allowed) {
2308 * per node hstate attribute: adjust count to global,
2309 * but restrict alloc/free to the specified node.
2311 count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2312 init_nodemask_of_node(nodes_allowed, nid);
2314 nodes_allowed = &node_states[N_MEMORY];
2316 h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2318 if (nodes_allowed != &node_states[N_MEMORY])
2319 NODEMASK_FREE(nodes_allowed);
2323 NODEMASK_FREE(nodes_allowed);
2327 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2328 struct kobject *kobj, const char *buf,
2332 unsigned long count;
2336 err = kstrtoul(buf, 10, &count);
2340 h = kobj_to_hstate(kobj, &nid);
2341 return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2344 static ssize_t nr_hugepages_show(struct kobject *kobj,
2345 struct kobj_attribute *attr, char *buf)
2347 return nr_hugepages_show_common(kobj, attr, buf);
2350 static ssize_t nr_hugepages_store(struct kobject *kobj,
2351 struct kobj_attribute *attr, const char *buf, size_t len)
2353 return nr_hugepages_store_common(false, kobj, buf, len);
2355 HSTATE_ATTR(nr_hugepages);
2360 * hstate attribute for optionally mempolicy-based constraint on persistent
2361 * huge page alloc/free.
2363 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2364 struct kobj_attribute *attr, char *buf)
2366 return nr_hugepages_show_common(kobj, attr, buf);
2369 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2370 struct kobj_attribute *attr, const char *buf, size_t len)
2372 return nr_hugepages_store_common(true, kobj, buf, len);
2374 HSTATE_ATTR(nr_hugepages_mempolicy);
2378 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2379 struct kobj_attribute *attr, char *buf)
2381 struct hstate *h = kobj_to_hstate(kobj, NULL);
2382 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2385 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2386 struct kobj_attribute *attr, const char *buf, size_t count)
2389 unsigned long input;
2390 struct hstate *h = kobj_to_hstate(kobj, NULL);
2392 if (hstate_is_gigantic(h))
2395 err = kstrtoul(buf, 10, &input);
2399 spin_lock(&hugetlb_lock);
2400 h->nr_overcommit_huge_pages = input;
2401 spin_unlock(&hugetlb_lock);
2405 HSTATE_ATTR(nr_overcommit_hugepages);
2407 static ssize_t free_hugepages_show(struct kobject *kobj,
2408 struct kobj_attribute *attr, char *buf)
2411 unsigned long free_huge_pages;
2414 h = kobj_to_hstate(kobj, &nid);
2415 if (nid == NUMA_NO_NODE)
2416 free_huge_pages = h->free_huge_pages;
2418 free_huge_pages = h->free_huge_pages_node[nid];
2420 return sprintf(buf, "%lu\n", free_huge_pages);
2422 HSTATE_ATTR_RO(free_hugepages);
2424 static ssize_t resv_hugepages_show(struct kobject *kobj,
2425 struct kobj_attribute *attr, char *buf)
2427 struct hstate *h = kobj_to_hstate(kobj, NULL);
2428 return sprintf(buf, "%lu\n", h->resv_huge_pages);
2430 HSTATE_ATTR_RO(resv_hugepages);
2432 static ssize_t surplus_hugepages_show(struct kobject *kobj,
2433 struct kobj_attribute *attr, char *buf)
2436 unsigned long surplus_huge_pages;
2439 h = kobj_to_hstate(kobj, &nid);
2440 if (nid == NUMA_NO_NODE)
2441 surplus_huge_pages = h->surplus_huge_pages;
2443 surplus_huge_pages = h->surplus_huge_pages_node[nid];
2445 return sprintf(buf, "%lu\n", surplus_huge_pages);
2447 HSTATE_ATTR_RO(surplus_hugepages);
2449 static struct attribute *hstate_attrs[] = {
2450 &nr_hugepages_attr.attr,
2451 &nr_overcommit_hugepages_attr.attr,
2452 &free_hugepages_attr.attr,
2453 &resv_hugepages_attr.attr,
2454 &surplus_hugepages_attr.attr,
2456 &nr_hugepages_mempolicy_attr.attr,
2461 static struct attribute_group hstate_attr_group = {
2462 .attrs = hstate_attrs,
2465 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2466 struct kobject **hstate_kobjs,
2467 struct attribute_group *hstate_attr_group)
2470 int hi = hstate_index(h);
2472 hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2473 if (!hstate_kobjs[hi])
2476 retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2478 kobject_put(hstate_kobjs[hi]);
2483 static void __init hugetlb_sysfs_init(void)
2488 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2489 if (!hugepages_kobj)
2492 for_each_hstate(h) {
2493 err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2494 hstate_kobjs, &hstate_attr_group);
2496 pr_err("Hugetlb: Unable to add hstate %s", h->name);
2503 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2504 * with node devices in node_devices[] using a parallel array. The array
2505 * index of a node device or _hstate == node id.
2506 * This is here to avoid any static dependency of the node device driver, in
2507 * the base kernel, on the hugetlb module.
2509 struct node_hstate {
2510 struct kobject *hugepages_kobj;
2511 struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2513 static struct node_hstate node_hstates[MAX_NUMNODES];
2516 * A subset of global hstate attributes for node devices
2518 static struct attribute *per_node_hstate_attrs[] = {
2519 &nr_hugepages_attr.attr,
2520 &free_hugepages_attr.attr,
2521 &surplus_hugepages_attr.attr,
2525 static struct attribute_group per_node_hstate_attr_group = {
2526 .attrs = per_node_hstate_attrs,
2530 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2531 * Returns node id via non-NULL nidp.
2533 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2537 for (nid = 0; nid < nr_node_ids; nid++) {
2538 struct node_hstate *nhs = &node_hstates[nid];
2540 for (i = 0; i < HUGE_MAX_HSTATE; i++)
2541 if (nhs->hstate_kobjs[i] == kobj) {
2553 * Unregister hstate attributes from a single node device.
2554 * No-op if no hstate attributes attached.
2556 static void hugetlb_unregister_node(struct node *node)
2559 struct node_hstate *nhs = &node_hstates[node->dev.id];
2561 if (!nhs->hugepages_kobj)
2562 return; /* no hstate attributes */
2564 for_each_hstate(h) {
2565 int idx = hstate_index(h);
2566 if (nhs->hstate_kobjs[idx]) {
2567 kobject_put(nhs->hstate_kobjs[idx]);
2568 nhs->hstate_kobjs[idx] = NULL;
2572 kobject_put(nhs->hugepages_kobj);
2573 nhs->hugepages_kobj = NULL;
2577 * hugetlb module exit: unregister hstate attributes from node devices
2580 static void hugetlb_unregister_all_nodes(void)
2585 * disable node device registrations.
2587 register_hugetlbfs_with_node(NULL, NULL);
2590 * remove hstate attributes from any nodes that have them.
2592 for (nid = 0; nid < nr_node_ids; nid++)
2593 hugetlb_unregister_node(node_devices[nid]);
2597 * Register hstate attributes for a single node device.
2598 * No-op if attributes already registered.
2600 static void hugetlb_register_node(struct node *node)
2603 struct node_hstate *nhs = &node_hstates[node->dev.id];
2606 if (nhs->hugepages_kobj)
2607 return; /* already allocated */
2609 nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2611 if (!nhs->hugepages_kobj)
2614 for_each_hstate(h) {
2615 err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2617 &per_node_hstate_attr_group);
2619 pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2620 h->name, node->dev.id);
2621 hugetlb_unregister_node(node);
2628 * hugetlb init time: register hstate attributes for all registered node
2629 * devices of nodes that have memory. All on-line nodes should have
2630 * registered their associated device by this time.
2632 static void __init hugetlb_register_all_nodes(void)
2636 for_each_node_state(nid, N_MEMORY) {
2637 struct node *node = node_devices[nid];
2638 if (node->dev.id == nid)
2639 hugetlb_register_node(node);
2643 * Let the node device driver know we're here so it can
2644 * [un]register hstate attributes on node hotplug.
2646 register_hugetlbfs_with_node(hugetlb_register_node,
2647 hugetlb_unregister_node);
2649 #else /* !CONFIG_NUMA */
2651 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2659 static void hugetlb_unregister_all_nodes(void) { }
2661 static void hugetlb_register_all_nodes(void) { }
2665 static void __exit hugetlb_exit(void)
2669 hugetlb_unregister_all_nodes();
2671 for_each_hstate(h) {
2672 kobject_put(hstate_kobjs[hstate_index(h)]);
2675 kobject_put(hugepages_kobj);
2676 kfree(hugetlb_fault_mutex_table);
2678 module_exit(hugetlb_exit);
2680 static int __init hugetlb_init(void)
2684 if (!hugepages_supported())
2687 if (!size_to_hstate(default_hstate_size)) {
2688 default_hstate_size = HPAGE_SIZE;
2689 if (!size_to_hstate(default_hstate_size))
2690 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2692 default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2693 if (default_hstate_max_huge_pages)
2694 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2696 hugetlb_init_hstates();
2697 gather_bootmem_prealloc();
2700 hugetlb_sysfs_init();
2701 hugetlb_register_all_nodes();
2702 hugetlb_cgroup_file_init();
2705 num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2707 num_fault_mutexes = 1;
2709 hugetlb_fault_mutex_table =
2710 kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
2711 BUG_ON(!hugetlb_fault_mutex_table);
2713 for (i = 0; i < num_fault_mutexes; i++)
2714 mutex_init(&hugetlb_fault_mutex_table[i]);
2717 module_init(hugetlb_init);
2719 /* Should be called on processing a hugepagesz=... option */
2720 void __init hugetlb_add_hstate(unsigned int order)
2725 if (size_to_hstate(PAGE_SIZE << order)) {
2726 pr_warning("hugepagesz= specified twice, ignoring\n");
2729 BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2731 h = &hstates[hugetlb_max_hstate++];
2733 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2734 h->nr_huge_pages = 0;
2735 h->free_huge_pages = 0;
2736 for (i = 0; i < MAX_NUMNODES; ++i)
2737 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2738 INIT_LIST_HEAD(&h->hugepage_activelist);
2739 h->next_nid_to_alloc = first_node(node_states[N_MEMORY]);
2740 h->next_nid_to_free = first_node(node_states[N_MEMORY]);
2741 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2742 huge_page_size(h)/1024);
2747 static int __init hugetlb_nrpages_setup(char *s)
2750 static unsigned long *last_mhp;
2753 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2754 * so this hugepages= parameter goes to the "default hstate".
2756 if (!hugetlb_max_hstate)
2757 mhp = &default_hstate_max_huge_pages;
2759 mhp = &parsed_hstate->max_huge_pages;
2761 if (mhp == last_mhp) {
2762 pr_warning("hugepages= specified twice without "
2763 "interleaving hugepagesz=, ignoring\n");
2767 if (sscanf(s, "%lu", mhp) <= 0)
2771 * Global state is always initialized later in hugetlb_init.
2772 * But we need to allocate >= MAX_ORDER hstates here early to still
2773 * use the bootmem allocator.
2775 if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2776 hugetlb_hstate_alloc_pages(parsed_hstate);
2782 __setup("hugepages=", hugetlb_nrpages_setup);
2784 static int __init hugetlb_default_setup(char *s)
2786 default_hstate_size = memparse(s, &s);
2789 __setup("default_hugepagesz=", hugetlb_default_setup);
2791 static unsigned int cpuset_mems_nr(unsigned int *array)
2794 unsigned int nr = 0;
2796 for_each_node_mask(node, cpuset_current_mems_allowed)
2802 #ifdef CONFIG_SYSCTL
2803 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2804 struct ctl_table *table, int write,
2805 void __user *buffer, size_t *length, loff_t *ppos)
2807 struct hstate *h = &default_hstate;
2808 unsigned long tmp = h->max_huge_pages;
2811 if (!hugepages_supported())
2815 table->maxlen = sizeof(unsigned long);
2816 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2821 ret = __nr_hugepages_store_common(obey_mempolicy, h,
2822 NUMA_NO_NODE, tmp, *length);
2827 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2828 void __user *buffer, size_t *length, loff_t *ppos)
2831 return hugetlb_sysctl_handler_common(false, table, write,
2832 buffer, length, ppos);
2836 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2837 void __user *buffer, size_t *length, loff_t *ppos)
2839 return hugetlb_sysctl_handler_common(true, table, write,
2840 buffer, length, ppos);
2842 #endif /* CONFIG_NUMA */
2844 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2845 void __user *buffer,
2846 size_t *length, loff_t *ppos)
2848 struct hstate *h = &default_hstate;
2852 if (!hugepages_supported())
2855 tmp = h->nr_overcommit_huge_pages;
2857 if (write && hstate_is_gigantic(h))
2861 table->maxlen = sizeof(unsigned long);
2862 ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2867 spin_lock(&hugetlb_lock);
2868 h->nr_overcommit_huge_pages = tmp;
2869 spin_unlock(&hugetlb_lock);
2875 #endif /* CONFIG_SYSCTL */
2877 void hugetlb_report_meminfo(struct seq_file *m)
2879 struct hstate *h = &default_hstate;
2880 if (!hugepages_supported())
2883 "HugePages_Total: %5lu\n"
2884 "HugePages_Free: %5lu\n"
2885 "HugePages_Rsvd: %5lu\n"
2886 "HugePages_Surp: %5lu\n"
2887 "Hugepagesize: %8lu kB\n",
2891 h->surplus_huge_pages,
2892 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2895 int hugetlb_report_node_meminfo(int nid, char *buf)
2897 struct hstate *h = &default_hstate;
2898 if (!hugepages_supported())
2901 "Node %d HugePages_Total: %5u\n"
2902 "Node %d HugePages_Free: %5u\n"
2903 "Node %d HugePages_Surp: %5u\n",
2904 nid, h->nr_huge_pages_node[nid],
2905 nid, h->free_huge_pages_node[nid],
2906 nid, h->surplus_huge_pages_node[nid]);
2909 void hugetlb_show_meminfo(void)
2914 if (!hugepages_supported())
2917 for_each_node_state(nid, N_MEMORY)
2919 pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
2921 h->nr_huge_pages_node[nid],
2922 h->free_huge_pages_node[nid],
2923 h->surplus_huge_pages_node[nid],
2924 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
2927 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
2929 seq_printf(m, "HugetlbPages:\t%8lu kB\n",
2930 atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
2933 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
2934 unsigned long hugetlb_total_pages(void)
2937 unsigned long nr_total_pages = 0;
2940 nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
2941 return nr_total_pages;
2944 static int hugetlb_acct_memory(struct hstate *h, long delta)
2948 spin_lock(&hugetlb_lock);
2950 * When cpuset is configured, it breaks the strict hugetlb page
2951 * reservation as the accounting is done on a global variable. Such
2952 * reservation is completely rubbish in the presence of cpuset because
2953 * the reservation is not checked against page availability for the
2954 * current cpuset. Application can still potentially OOM'ed by kernel
2955 * with lack of free htlb page in cpuset that the task is in.
2956 * Attempt to enforce strict accounting with cpuset is almost
2957 * impossible (or too ugly) because cpuset is too fluid that
2958 * task or memory node can be dynamically moved between cpusets.
2960 * The change of semantics for shared hugetlb mapping with cpuset is
2961 * undesirable. However, in order to preserve some of the semantics,
2962 * we fall back to check against current free page availability as
2963 * a best attempt and hopefully to minimize the impact of changing
2964 * semantics that cpuset has.
2967 if (gather_surplus_pages(h, delta) < 0)
2970 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
2971 return_unused_surplus_pages(h, delta);
2978 return_unused_surplus_pages(h, (unsigned long) -delta);
2981 spin_unlock(&hugetlb_lock);
2985 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2987 struct resv_map *resv = vma_resv_map(vma);
2990 * This new VMA should share its siblings reservation map if present.
2991 * The VMA will only ever have a valid reservation map pointer where
2992 * it is being copied for another still existing VMA. As that VMA
2993 * has a reference to the reservation map it cannot disappear until
2994 * after this open call completes. It is therefore safe to take a
2995 * new reference here without additional locking.
2997 if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
2998 kref_get(&resv->refs);
3001 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
3003 struct hstate *h = hstate_vma(vma);
3004 struct resv_map *resv = vma_resv_map(vma);
3005 struct hugepage_subpool *spool = subpool_vma(vma);
3006 unsigned long reserve, start, end;
3009 if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3012 start = vma_hugecache_offset(h, vma, vma->vm_start);
3013 end = vma_hugecache_offset(h, vma, vma->vm_end);
3015 reserve = (end - start) - region_count(resv, start, end);
3017 kref_put(&resv->refs, resv_map_release);
3021 * Decrement reserve counts. The global reserve count may be
3022 * adjusted if the subpool has a minimum size.
3024 gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
3025 hugetlb_acct_memory(h, -gbl_reserve);
3030 * We cannot handle pagefaults against hugetlb pages at all. They cause
3031 * handle_mm_fault() to try to instantiate regular-sized pages in the
3032 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
3035 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
3041 const struct vm_operations_struct hugetlb_vm_ops = {
3042 .fault = hugetlb_vm_op_fault,
3043 .open = hugetlb_vm_op_open,
3044 .close = hugetlb_vm_op_close,
3047 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3053 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3054 vma->vm_page_prot)));
3056 entry = huge_pte_wrprotect(mk_huge_pte(page,
3057 vma->vm_page_prot));
3059 entry = pte_mkyoung(entry);
3060 entry = pte_mkhuge(entry);
3061 entry = arch_make_huge_pte(entry, vma, page, writable);
3066 static void set_huge_ptep_writable(struct vm_area_struct *vma,
3067 unsigned long address, pte_t *ptep)
3071 entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3072 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3073 update_mmu_cache(vma, address, ptep);
3076 static int is_hugetlb_entry_migration(pte_t pte)
3080 if (huge_pte_none(pte) || pte_present(pte))
3082 swp = pte_to_swp_entry(pte);
3083 if (non_swap_entry(swp) && is_migration_entry(swp))
3089 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3093 if (huge_pte_none(pte) || pte_present(pte))
3095 swp = pte_to_swp_entry(pte);
3096 if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3102 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3103 struct vm_area_struct *vma)
3105 pte_t *src_pte, *dst_pte, entry;
3106 struct page *ptepage;
3109 struct hstate *h = hstate_vma(vma);
3110 unsigned long sz = huge_page_size(h);
3111 unsigned long mmun_start; /* For mmu_notifiers */
3112 unsigned long mmun_end; /* For mmu_notifiers */
3115 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3117 mmun_start = vma->vm_start;
3118 mmun_end = vma->vm_end;
3120 mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
3122 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
3123 spinlock_t *src_ptl, *dst_ptl;
3124 src_pte = huge_pte_offset(src, addr);
3127 dst_pte = huge_pte_alloc(dst, addr, sz);
3133 /* If the pagetables are shared don't copy or take references */
3134 if (dst_pte == src_pte)
3137 dst_ptl = huge_pte_lock(h, dst, dst_pte);
3138 src_ptl = huge_pte_lockptr(h, src, src_pte);
3139 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3140 entry = huge_ptep_get(src_pte);
3141 if (huge_pte_none(entry)) { /* skip none entry */
3143 } else if (unlikely(is_hugetlb_entry_migration(entry) ||
3144 is_hugetlb_entry_hwpoisoned(entry))) {
3145 swp_entry_t swp_entry = pte_to_swp_entry(entry);
3147 if (is_write_migration_entry(swp_entry) && cow) {
3149 * COW mappings require pages in both
3150 * parent and child to be set to read.
3152 make_migration_entry_read(&swp_entry);
3153 entry = swp_entry_to_pte(swp_entry);
3154 set_huge_pte_at(src, addr, src_pte, entry);
3156 set_huge_pte_at(dst, addr, dst_pte, entry);
3159 huge_ptep_set_wrprotect(src, addr, src_pte);
3160 mmu_notifier_invalidate_range(src, mmun_start,
3163 entry = huge_ptep_get(src_pte);
3164 ptepage = pte_page(entry);
3166 page_dup_rmap(ptepage);
3167 set_huge_pte_at(dst, addr, dst_pte, entry);
3168 hugetlb_count_add(pages_per_huge_page(h), dst);
3170 spin_unlock(src_ptl);
3171 spin_unlock(dst_ptl);
3175 mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
3180 void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3181 unsigned long start, unsigned long end,
3182 struct page *ref_page)
3184 int force_flush = 0;
3185 struct mm_struct *mm = vma->vm_mm;
3186 unsigned long address;
3191 struct hstate *h = hstate_vma(vma);
3192 unsigned long sz = huge_page_size(h);
3193 const unsigned long mmun_start = start; /* For mmu_notifiers */
3194 const unsigned long mmun_end = end; /* For mmu_notifiers */
3196 WARN_ON(!is_vm_hugetlb_page(vma));
3197 BUG_ON(start & ~huge_page_mask(h));
3198 BUG_ON(end & ~huge_page_mask(h));
3200 tlb_start_vma(tlb, vma);
3201 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3204 for (; address < end; address += sz) {
3205 ptep = huge_pte_offset(mm, address);
3209 ptl = huge_pte_lock(h, mm, ptep);
3210 if (huge_pmd_unshare(mm, &address, ptep))
3213 pte = huge_ptep_get(ptep);
3214 if (huge_pte_none(pte))
3218 * Migrating hugepage or HWPoisoned hugepage is already
3219 * unmapped and its refcount is dropped, so just clear pte here.
3221 if (unlikely(!pte_present(pte))) {
3222 huge_pte_clear(mm, address, ptep);
3226 page = pte_page(pte);
3228 * If a reference page is supplied, it is because a specific
3229 * page is being unmapped, not a range. Ensure the page we
3230 * are about to unmap is the actual page of interest.
3233 if (page != ref_page)
3237 * Mark the VMA as having unmapped its page so that
3238 * future faults in this VMA will fail rather than
3239 * looking like data was lost
3241 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
3244 pte = huge_ptep_get_and_clear(mm, address, ptep);
3245 tlb_remove_tlb_entry(tlb, ptep, address);
3246 if (huge_pte_dirty(pte))
3247 set_page_dirty(page);
3249 hugetlb_count_sub(pages_per_huge_page(h), mm);
3250 page_remove_rmap(page);
3251 force_flush = !__tlb_remove_page(tlb, page);
3257 /* Bail out after unmapping reference page if supplied */
3266 * mmu_gather ran out of room to batch pages, we break out of
3267 * the PTE lock to avoid doing the potential expensive TLB invalidate
3268 * and page-free while holding it.
3273 if (address < end && !ref_page)
3276 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3277 tlb_end_vma(tlb, vma);
3280 void __unmap_hugepage_range_final(struct mmu_gather *tlb,
3281 struct vm_area_struct *vma, unsigned long start,
3282 unsigned long end, struct page *ref_page)
3284 __unmap_hugepage_range(tlb, vma, start, end, ref_page);
3287 * Clear this flag so that x86's huge_pmd_share page_table_shareable
3288 * test will fail on a vma being torn down, and not grab a page table
3289 * on its way out. We're lucky that the flag has such an appropriate
3290 * name, and can in fact be safely cleared here. We could clear it
3291 * before the __unmap_hugepage_range above, but all that's necessary
3292 * is to clear it before releasing the i_mmap_rwsem. This works
3293 * because in the context this is called, the VMA is about to be
3294 * destroyed and the i_mmap_rwsem is held.
3296 vma->vm_flags &= ~VM_MAYSHARE;
3299 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3300 unsigned long end, struct page *ref_page)
3302 struct mm_struct *mm;
3303 struct mmu_gather tlb;
3307 tlb_gather_mmu(&tlb, mm, start, end);
3308 __unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3309 tlb_finish_mmu(&tlb, start, end);
3313 * This is called when the original mapper is failing to COW a MAP_PRIVATE
3314 * mappping it owns the reserve page for. The intention is to unmap the page
3315 * from other VMAs and let the children be SIGKILLed if they are faulting the
3318 static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
3319 struct page *page, unsigned long address)
3321 struct hstate *h = hstate_vma(vma);
3322 struct vm_area_struct *iter_vma;
3323 struct address_space *mapping;
3327 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
3328 * from page cache lookup which is in HPAGE_SIZE units.
3330 address = address & huge_page_mask(h);
3331 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
3333 mapping = file_inode(vma->vm_file)->i_mapping;
3336 * Take the mapping lock for the duration of the table walk. As
3337 * this mapping should be shared between all the VMAs,
3338 * __unmap_hugepage_range() is called as the lock is already held
3340 i_mmap_lock_write(mapping);
3341 vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3342 /* Do not unmap the current VMA */
3343 if (iter_vma == vma)
3347 * Shared VMAs have their own reserves and do not affect
3348 * MAP_PRIVATE accounting but it is possible that a shared
3349 * VMA is using the same page so check and skip such VMAs.
3351 if (iter_vma->vm_flags & VM_MAYSHARE)
3355 * Unmap the page from other VMAs without their own reserves.
3356 * They get marked to be SIGKILLed if they fault in these
3357 * areas. This is because a future no-page fault on this VMA
3358 * could insert a zeroed page instead of the data existing
3359 * from the time of fork. This would look like data corruption
3361 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3362 unmap_hugepage_range(iter_vma, address,
3363 address + huge_page_size(h), page);
3365 i_mmap_unlock_write(mapping);
3369 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3370 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
3371 * cannot race with other handlers or page migration.
3372 * Keep the pte_same checks anyway to make transition from the mutex easier.
3374 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3375 unsigned long address, pte_t *ptep, pte_t pte,
3376 struct page *pagecache_page, spinlock_t *ptl)
3378 struct hstate *h = hstate_vma(vma);
3379 struct page *old_page, *new_page;
3380 int ret = 0, outside_reserve = 0;
3381 unsigned long mmun_start; /* For mmu_notifiers */
3382 unsigned long mmun_end; /* For mmu_notifiers */
3384 old_page = pte_page(pte);
3387 /* If no-one else is actually using this page, avoid the copy
3388 * and just make the page writable */
3389 if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3390 page_move_anon_rmap(old_page, vma, address);
3391 set_huge_ptep_writable(vma, address, ptep);
3396 * If the process that created a MAP_PRIVATE mapping is about to
3397 * perform a COW due to a shared page count, attempt to satisfy
3398 * the allocation without using the existing reserves. The pagecache
3399 * page is used to determine if the reserve at this address was
3400 * consumed or not. If reserves were used, a partial faulted mapping
3401 * at the time of fork() could consume its reserves on COW instead
3402 * of the full address range.
3404 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3405 old_page != pagecache_page)
3406 outside_reserve = 1;
3408 page_cache_get(old_page);
3411 * Drop page table lock as buddy allocator may be called. It will
3412 * be acquired again before returning to the caller, as expected.
3415 new_page = alloc_huge_page(vma, address, outside_reserve);
3417 if (IS_ERR(new_page)) {
3419 * If a process owning a MAP_PRIVATE mapping fails to COW,
3420 * it is due to references held by a child and an insufficient
3421 * huge page pool. To guarantee the original mappers
3422 * reliability, unmap the page from child processes. The child
3423 * may get SIGKILLed if it later faults.
3425 if (outside_reserve) {
3426 page_cache_release(old_page);
3427 BUG_ON(huge_pte_none(pte));
3428 unmap_ref_private(mm, vma, old_page, address);
3429 BUG_ON(huge_pte_none(pte));
3431 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3433 pte_same(huge_ptep_get(ptep), pte)))
3434 goto retry_avoidcopy;
3436 * race occurs while re-acquiring page table
3437 * lock, and our job is done.
3442 ret = (PTR_ERR(new_page) == -ENOMEM) ?
3443 VM_FAULT_OOM : VM_FAULT_SIGBUS;
3444 goto out_release_old;
3448 * When the original hugepage is shared one, it does not have
3449 * anon_vma prepared.
3451 if (unlikely(anon_vma_prepare(vma))) {
3453 goto out_release_all;
3456 copy_user_huge_page(new_page, old_page, address, vma,
3457 pages_per_huge_page(h));
3458 __SetPageUptodate(new_page);
3459 set_page_huge_active(new_page);
3461 mmun_start = address & huge_page_mask(h);
3462 mmun_end = mmun_start + huge_page_size(h);
3463 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3466 * Retake the page table lock to check for racing updates
3467 * before the page tables are altered
3470 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
3471 if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3472 ClearPagePrivate(new_page);
3475 huge_ptep_clear_flush(vma, address, ptep);
3476 mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3477 set_huge_pte_at(mm, address, ptep,
3478 make_huge_pte(vma, new_page, 1));
3479 page_remove_rmap(old_page);
3480 hugepage_add_new_anon_rmap(new_page, vma, address);
3481 /* Make the old page be freed below */
3482 new_page = old_page;
3485 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3487 page_cache_release(new_page);
3489 page_cache_release(old_page);
3491 spin_lock(ptl); /* Caller expects lock to be held */
3495 /* Return the pagecache page at a given address within a VMA */
3496 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
3497 struct vm_area_struct *vma, unsigned long address)
3499 struct address_space *mapping;
3502 mapping = vma->vm_file->f_mapping;
3503 idx = vma_hugecache_offset(h, vma, address);
3505 return find_lock_page(mapping, idx);
3509 * Return whether there is a pagecache page to back given address within VMA.
3510 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
3512 static bool hugetlbfs_pagecache_present(struct hstate *h,
3513 struct vm_area_struct *vma, unsigned long address)
3515 struct address_space *mapping;
3519 mapping = vma->vm_file->f_mapping;
3520 idx = vma_hugecache_offset(h, vma, address);
3522 page = find_get_page(mapping, idx);
3525 return page != NULL;
3528 int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
3531 struct inode *inode = mapping->host;
3532 struct hstate *h = hstate_inode(inode);
3533 int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3537 ClearPagePrivate(page);
3539 spin_lock(&inode->i_lock);
3540 inode->i_blocks += blocks_per_huge_page(h);
3541 spin_unlock(&inode->i_lock);
3545 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3546 struct address_space *mapping, pgoff_t idx,
3547 unsigned long address, pte_t *ptep, unsigned int flags)
3549 struct hstate *h = hstate_vma(vma);
3550 int ret = VM_FAULT_SIGBUS;
3558 * Currently, we are forced to kill the process in the event the
3559 * original mapper has unmapped pages from the child due to a failed
3560 * COW. Warn that such a situation has occurred as it may not be obvious
3562 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3563 pr_warning("PID %d killed due to inadequate hugepage pool\n",
3569 * Use page lock to guard against racing truncation
3570 * before we get page_table_lock.
3573 page = find_lock_page(mapping, idx);
3575 size = i_size_read(mapping->host) >> huge_page_shift(h);
3578 page = alloc_huge_page(vma, address, 0);
3580 ret = PTR_ERR(page);
3584 ret = VM_FAULT_SIGBUS;
3587 clear_huge_page(page, address, pages_per_huge_page(h));
3588 __SetPageUptodate(page);
3589 set_page_huge_active(page);
3591 if (vma->vm_flags & VM_MAYSHARE) {
3592 int err = huge_add_to_page_cache(page, mapping, idx);
3601 if (unlikely(anon_vma_prepare(vma))) {
3603 goto backout_unlocked;
3609 * If memory error occurs between mmap() and fault, some process
3610 * don't have hwpoisoned swap entry for errored virtual address.
3611 * So we need to block hugepage fault by PG_hwpoison bit check.
3613 if (unlikely(PageHWPoison(page))) {
3614 ret = VM_FAULT_HWPOISON |
3615 VM_FAULT_SET_HINDEX(hstate_index(h));
3616 goto backout_unlocked;
3621 * If we are going to COW a private mapping later, we examine the
3622 * pending reservations for this page now. This will ensure that
3623 * any allocations necessary to record that reservation occur outside
3626 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3627 if (vma_needs_reservation(h, vma, address) < 0) {
3629 goto backout_unlocked;
3631 /* Just decrements count, does not deallocate */
3632 vma_end_reservation(h, vma, address);
3635 ptl = huge_pte_lockptr(h, mm, ptep);
3637 size = i_size_read(mapping->host) >> huge_page_shift(h);
3642 if (!huge_pte_none(huge_ptep_get(ptep)))
3646 ClearPagePrivate(page);
3647 hugepage_add_new_anon_rmap(page, vma, address);
3649 page_dup_rmap(page);
3650 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3651 && (vma->vm_flags & VM_SHARED)));
3652 set_huge_pte_at(mm, address, ptep, new_pte);
3654 hugetlb_count_add(pages_per_huge_page(h), mm);
3655 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3656 /* Optimization, do the COW without a second fault */
3657 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
3674 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3675 struct vm_area_struct *vma,
3676 struct address_space *mapping,
3677 pgoff_t idx, unsigned long address)
3679 unsigned long key[2];
3682 if (vma->vm_flags & VM_SHARED) {
3683 key[0] = (unsigned long) mapping;
3686 key[0] = (unsigned long) mm;
3687 key[1] = address >> huge_page_shift(h);
3690 hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3692 return hash & (num_fault_mutexes - 1);
3696 * For uniprocesor systems we always use a single mutex, so just
3697 * return 0 and avoid the hashing overhead.
3699 u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3700 struct vm_area_struct *vma,
3701 struct address_space *mapping,
3702 pgoff_t idx, unsigned long address)
3708 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3709 unsigned long address, unsigned int flags)
3716 struct page *page = NULL;
3717 struct page *pagecache_page = NULL;
3718 struct hstate *h = hstate_vma(vma);
3719 struct address_space *mapping;
3720 int need_wait_lock = 0;
3722 address &= huge_page_mask(h);
3724 ptep = huge_pte_offset(mm, address);
3726 entry = huge_ptep_get(ptep);
3727 if (unlikely(is_hugetlb_entry_migration(entry))) {
3728 migration_entry_wait_huge(vma, mm, ptep);
3730 } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3731 return VM_FAULT_HWPOISON_LARGE |
3732 VM_FAULT_SET_HINDEX(hstate_index(h));
3734 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3736 return VM_FAULT_OOM;
3739 mapping = vma->vm_file->f_mapping;
3740 idx = vma_hugecache_offset(h, vma, address);
3743 * Serialize hugepage allocation and instantiation, so that we don't
3744 * get spurious allocation failures if two CPUs race to instantiate
3745 * the same page in the page cache.
3747 hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
3748 mutex_lock(&hugetlb_fault_mutex_table[hash]);
3750 entry = huge_ptep_get(ptep);
3751 if (huge_pte_none(entry)) {
3752 ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3759 * entry could be a migration/hwpoison entry at this point, so this
3760 * check prevents the kernel from going below assuming that we have
3761 * a active hugepage in pagecache. This goto expects the 2nd page fault,
3762 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3765 if (!pte_present(entry))
3769 * If we are going to COW the mapping later, we examine the pending
3770 * reservations for this page now. This will ensure that any
3771 * allocations necessary to record that reservation occur outside the
3772 * spinlock. For private mappings, we also lookup the pagecache
3773 * page now as it is used to determine if a reservation has been
3776 if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3777 if (vma_needs_reservation(h, vma, address) < 0) {
3781 /* Just decrements count, does not deallocate */
3782 vma_end_reservation(h, vma, address);
3784 if (!(vma->vm_flags & VM_MAYSHARE))
3785 pagecache_page = hugetlbfs_pagecache_page(h,
3789 ptl = huge_pte_lock(h, mm, ptep);
3791 /* Check for a racing update before calling hugetlb_cow */
3792 if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3796 * hugetlb_cow() requires page locks of pte_page(entry) and
3797 * pagecache_page, so here we need take the former one
3798 * when page != pagecache_page or !pagecache_page.
3800 page = pte_page(entry);
3801 if (page != pagecache_page)
3802 if (!trylock_page(page)) {
3809 if (flags & FAULT_FLAG_WRITE) {
3810 if (!huge_pte_write(entry)) {
3811 ret = hugetlb_cow(mm, vma, address, ptep, entry,
3812 pagecache_page, ptl);
3815 entry = huge_pte_mkdirty(entry);
3817 entry = pte_mkyoung(entry);
3818 if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3819 flags & FAULT_FLAG_WRITE))
3820 update_mmu_cache(vma, address, ptep);
3822 if (page != pagecache_page)
3828 if (pagecache_page) {
3829 unlock_page(pagecache_page);
3830 put_page(pagecache_page);
3833 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3835 * Generally it's safe to hold refcount during waiting page lock. But
3836 * here we just wait to defer the next page fault to avoid busy loop and
3837 * the page is not used after unlocked before returning from the current
3838 * page fault. So we are safe from accessing freed page, even if we wait
3839 * here without taking refcount.
3842 wait_on_page_locked(page);
3846 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
3847 struct page **pages, struct vm_area_struct **vmas,
3848 unsigned long *position, unsigned long *nr_pages,
3849 long i, unsigned int flags)
3851 unsigned long pfn_offset;
3852 unsigned long vaddr = *position;
3853 unsigned long remainder = *nr_pages;
3854 struct hstate *h = hstate_vma(vma);
3856 while (vaddr < vma->vm_end && remainder) {
3858 spinlock_t *ptl = NULL;
3863 * If we have a pending SIGKILL, don't keep faulting pages and
3864 * potentially allocating memory.
3866 if (unlikely(fatal_signal_pending(current))) {
3872 * Some archs (sparc64, sh*) have multiple pte_ts to
3873 * each hugepage. We have to make sure we get the
3874 * first, for the page indexing below to work.
3876 * Note that page table lock is not held when pte is null.
3878 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
3880 ptl = huge_pte_lock(h, mm, pte);
3881 absent = !pte || huge_pte_none(huge_ptep_get(pte));
3884 * When coredumping, it suits get_dump_page if we just return
3885 * an error where there's an empty slot with no huge pagecache
3886 * to back it. This way, we avoid allocating a hugepage, and
3887 * the sparse dumpfile avoids allocating disk blocks, but its
3888 * huge holes still show up with zeroes where they need to be.
3890 if (absent && (flags & FOLL_DUMP) &&
3891 !hugetlbfs_pagecache_present(h, vma, vaddr)) {
3899 * We need call hugetlb_fault for both hugepages under migration
3900 * (in which case hugetlb_fault waits for the migration,) and
3901 * hwpoisoned hugepages (in which case we need to prevent the
3902 * caller from accessing to them.) In order to do this, we use
3903 * here is_swap_pte instead of is_hugetlb_entry_migration and
3904 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
3905 * both cases, and because we can't follow correct pages
3906 * directly from any kind of swap entries.
3908 if (absent || is_swap_pte(huge_ptep_get(pte)) ||
3909 ((flags & FOLL_WRITE) &&
3910 !huge_pte_write(huge_ptep_get(pte)))) {
3915 ret = hugetlb_fault(mm, vma, vaddr,
3916 (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
3917 if (!(ret & VM_FAULT_ERROR))
3924 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
3925 page = pte_page(huge_ptep_get(pte));
3928 pages[i] = mem_map_offset(page, pfn_offset);
3929 get_page_foll(pages[i]);
3939 if (vaddr < vma->vm_end && remainder &&
3940 pfn_offset < pages_per_huge_page(h)) {
3942 * We use pfn_offset to avoid touching the pageframes
3943 * of this compound page.
3949 *nr_pages = remainder;
3952 return i ? i : -EFAULT;
3955 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
3956 unsigned long address, unsigned long end, pgprot_t newprot)
3958 struct mm_struct *mm = vma->vm_mm;
3959 unsigned long start = address;
3962 struct hstate *h = hstate_vma(vma);
3963 unsigned long pages = 0;
3965 BUG_ON(address >= end);
3966 flush_cache_range(vma, address, end);
3968 mmu_notifier_invalidate_range_start(mm, start, end);
3969 i_mmap_lock_write(vma->vm_file->f_mapping);
3970 for (; address < end; address += huge_page_size(h)) {
3972 ptep = huge_pte_offset(mm, address);
3975 ptl = huge_pte_lock(h, mm, ptep);
3976 if (huge_pmd_unshare(mm, &address, ptep)) {
3981 pte = huge_ptep_get(ptep);
3982 if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
3986 if (unlikely(is_hugetlb_entry_migration(pte))) {
3987 swp_entry_t entry = pte_to_swp_entry(pte);
3989 if (is_write_migration_entry(entry)) {
3992 make_migration_entry_read(&entry);
3993 newpte = swp_entry_to_pte(entry);
3994 set_huge_pte_at(mm, address, ptep, newpte);
4000 if (!huge_pte_none(pte)) {
4001 pte = huge_ptep_get_and_clear(mm, address, ptep);
4002 pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4003 pte = arch_make_huge_pte(pte, vma, NULL, 0);
4004 set_huge_pte_at(mm, address, ptep, pte);
4010 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4011 * may have cleared our pud entry and done put_page on the page table:
4012 * once we release i_mmap_rwsem, another task can do the final put_page
4013 * and that page table be reused and filled with junk.
4015 flush_tlb_range(vma, start, end);
4016 mmu_notifier_invalidate_range(mm, start, end);
4017 i_mmap_unlock_write(vma->vm_file->f_mapping);
4018 mmu_notifier_invalidate_range_end(mm, start, end);
4020 return pages << h->order;
4023 int hugetlb_reserve_pages(struct inode *inode,
4025 struct vm_area_struct *vma,
4026 vm_flags_t vm_flags)
4029 struct hstate *h = hstate_inode(inode);
4030 struct hugepage_subpool *spool = subpool_inode(inode);
4031 struct resv_map *resv_map;
4035 * Only apply hugepage reservation if asked. At fault time, an
4036 * attempt will be made for VM_NORESERVE to allocate a page
4037 * without using reserves
4039 if (vm_flags & VM_NORESERVE)
4043 * Shared mappings base their reservation on the number of pages that
4044 * are already allocated on behalf of the file. Private mappings need
4045 * to reserve the full area even if read-only as mprotect() may be
4046 * called to make the mapping read-write. Assume !vma is a shm mapping
4048 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4049 resv_map = inode_resv_map(inode);
4051 chg = region_chg(resv_map, from, to);
4054 resv_map = resv_map_alloc();
4060 set_vma_resv_map(vma, resv_map);
4061 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
4070 * There must be enough pages in the subpool for the mapping. If
4071 * the subpool has a minimum size, there may be some global
4072 * reservations already in place (gbl_reserve).
4074 gbl_reserve = hugepage_subpool_get_pages(spool, chg);
4075 if (gbl_reserve < 0) {
4081 * Check enough hugepages are available for the reservation.
4082 * Hand the pages back to the subpool if there are not
4084 ret = hugetlb_acct_memory(h, gbl_reserve);
4086 /* put back original number of pages, chg */
4087 (void)hugepage_subpool_put_pages(spool, chg);
4092 * Account for the reservations made. Shared mappings record regions
4093 * that have reservations as they are shared by multiple VMAs.
4094 * When the last VMA disappears, the region map says how much
4095 * the reservation was and the page cache tells how much of
4096 * the reservation was consumed. Private mappings are per-VMA and
4097 * only the consumed reservations are tracked. When the VMA
4098 * disappears, the original reservation is the VMA size and the
4099 * consumed reservations are stored in the map. Hence, nothing
4100 * else has to be done for private mappings here
4102 if (!vma || vma->vm_flags & VM_MAYSHARE) {
4103 long add = region_add(resv_map, from, to);
4105 if (unlikely(chg > add)) {
4107 * pages in this range were added to the reserve
4108 * map between region_chg and region_add. This
4109 * indicates a race with alloc_huge_page. Adjust
4110 * the subpool and reserve counts modified above
4111 * based on the difference.
4115 rsv_adjust = hugepage_subpool_put_pages(spool,
4117 hugetlb_acct_memory(h, -rsv_adjust);
4122 if (!vma || vma->vm_flags & VM_MAYSHARE)
4123 region_abort(resv_map, from, to);
4124 if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
4125 kref_put(&resv_map->refs, resv_map_release);
4129 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
4132 struct hstate *h = hstate_inode(inode);
4133 struct resv_map *resv_map = inode_resv_map(inode);
4135 struct hugepage_subpool *spool = subpool_inode(inode);
4139 chg = region_del(resv_map, start, end);
4141 * region_del() can fail in the rare case where a region
4142 * must be split and another region descriptor can not be
4143 * allocated. If end == LONG_MAX, it will not fail.
4149 spin_lock(&inode->i_lock);
4150 inode->i_blocks -= (blocks_per_huge_page(h) * freed);
4151 spin_unlock(&inode->i_lock);
4154 * If the subpool has a minimum size, the number of global
4155 * reservations to be released may be adjusted.
4157 gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
4158 hugetlb_acct_memory(h, -gbl_reserve);
4163 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
4164 static unsigned long page_table_shareable(struct vm_area_struct *svma,
4165 struct vm_area_struct *vma,
4166 unsigned long addr, pgoff_t idx)
4168 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
4170 unsigned long sbase = saddr & PUD_MASK;
4171 unsigned long s_end = sbase + PUD_SIZE;
4173 /* Allow segments to share if only one is marked locked */
4174 unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
4175 unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4178 * match the virtual addresses, permission and the alignment of the
4181 if (pmd_index(addr) != pmd_index(saddr) ||
4182 vm_flags != svm_flags ||
4183 sbase < svma->vm_start || svma->vm_end < s_end)
4189 static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4191 unsigned long base = addr & PUD_MASK;
4192 unsigned long end = base + PUD_SIZE;
4195 * check on proper vm_flags and page table alignment
4197 if (vma->vm_flags & VM_MAYSHARE &&
4198 vma->vm_start <= base && end <= vma->vm_end)
4204 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
4205 * and returns the corresponding pte. While this is not necessary for the
4206 * !shared pmd case because we can allocate the pmd later as well, it makes the
4207 * code much cleaner. pmd allocation is essential for the shared case because
4208 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4209 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
4210 * bad pmd for sharing.
4212 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4214 struct vm_area_struct *vma = find_vma(mm, addr);
4215 struct address_space *mapping = vma->vm_file->f_mapping;
4216 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
4218 struct vm_area_struct *svma;
4219 unsigned long saddr;
4224 if (!vma_shareable(vma, addr))
4225 return (pte_t *)pmd_alloc(mm, pud, addr);
4227 i_mmap_lock_write(mapping);
4228 vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
4232 saddr = page_table_shareable(svma, vma, addr, idx);
4234 spte = huge_pte_offset(svma->vm_mm, saddr);
4236 get_page(virt_to_page(spte));
4245 ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
4247 if (pud_none(*pud)) {
4248 pud_populate(mm, pud,
4249 (pmd_t *)((unsigned long)spte & PAGE_MASK));
4252 put_page(virt_to_page(spte));
4256 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4257 i_mmap_unlock_write(mapping);
4262 * unmap huge page backed by shared pte.
4264 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
4265 * indicated by page_count > 1, unmap is achieved by clearing pud and
4266 * decrementing the ref count. If count == 1, the pte page is not shared.
4268 * called with page table lock held.
4270 * returns: 1 successfully unmapped a shared pte page
4271 * 0 the underlying pte page is not shared, or it is the last user
4273 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4275 pgd_t *pgd = pgd_offset(mm, *addr);
4276 pud_t *pud = pud_offset(pgd, *addr);
4278 BUG_ON(page_count(virt_to_page(ptep)) == 0);
4279 if (page_count(virt_to_page(ptep)) == 1)
4283 put_page(virt_to_page(ptep));
4285 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
4288 #define want_pmd_share() (1)
4289 #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4290 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
4295 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
4299 #define want_pmd_share() (0)
4300 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4302 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
4303 pte_t *huge_pte_alloc(struct mm_struct *mm,
4304 unsigned long addr, unsigned long sz)
4310 pgd = pgd_offset(mm, addr);
4311 pud = pud_alloc(mm, pgd, addr);
4313 if (sz == PUD_SIZE) {
4316 BUG_ON(sz != PMD_SIZE);
4317 if (want_pmd_share() && pud_none(*pud))
4318 pte = huge_pmd_share(mm, addr, pud);
4320 pte = (pte_t *)pmd_alloc(mm, pud, addr);
4323 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
4328 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
4334 pgd = pgd_offset(mm, addr);
4335 if (pgd_present(*pgd)) {
4336 pud = pud_offset(pgd, addr);
4337 if (pud_present(*pud)) {
4339 return (pte_t *)pud;
4340 pmd = pmd_offset(pud, addr);
4343 return (pte_t *) pmd;
4346 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
4349 * These functions are overwritable if your architecture needs its own
4352 struct page * __weak
4353 follow_huge_addr(struct mm_struct *mm, unsigned long address,
4356 return ERR_PTR(-EINVAL);
4359 struct page * __weak
4360 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4361 pmd_t *pmd, int flags)
4363 struct page *page = NULL;
4366 ptl = pmd_lockptr(mm, pmd);
4369 * make sure that the address range covered by this pmd is not
4370 * unmapped from other threads.
4372 if (!pmd_huge(*pmd))
4374 if (pmd_present(*pmd)) {
4375 page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4376 if (flags & FOLL_GET)
4379 if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
4381 __migration_entry_wait(mm, (pte_t *)pmd, ptl);
4385 * hwpoisoned entry is treated as no_page_table in
4386 * follow_page_mask().
4394 struct page * __weak
4395 follow_huge_pud(struct mm_struct *mm, unsigned long address,
4396 pud_t *pud, int flags)
4398 if (flags & FOLL_GET)
4401 return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
4404 #ifdef CONFIG_MEMORY_FAILURE
4407 * This function is called from memory failure code.
4408 * Assume the caller holds page lock of the head page.
4410 int dequeue_hwpoisoned_huge_page(struct page *hpage)
4412 struct hstate *h = page_hstate(hpage);
4413 int nid = page_to_nid(hpage);
4416 spin_lock(&hugetlb_lock);
4418 * Just checking !page_huge_active is not enough, because that could be
4419 * an isolated/hwpoisoned hugepage (which have >0 refcount).
4421 if (!page_huge_active(hpage) && !page_count(hpage)) {
4423 * Hwpoisoned hugepage isn't linked to activelist or freelist,
4424 * but dangling hpage->lru can trigger list-debug warnings
4425 * (this happens when we call unpoison_memory() on it),
4426 * so let it point to itself with list_del_init().
4428 list_del_init(&hpage->lru);
4429 set_page_refcounted(hpage);
4430 h->free_huge_pages--;
4431 h->free_huge_pages_node[nid]--;
4434 spin_unlock(&hugetlb_lock);
4439 bool isolate_huge_page(struct page *page, struct list_head *list)
4443 VM_BUG_ON_PAGE(!PageHead(page), page);
4444 spin_lock(&hugetlb_lock);
4445 if (!page_huge_active(page) || !get_page_unless_zero(page)) {
4449 clear_page_huge_active(page);
4450 list_move_tail(&page->lru, list);
4452 spin_unlock(&hugetlb_lock);
4456 void putback_active_hugepage(struct page *page)
4458 VM_BUG_ON_PAGE(!PageHead(page), page);
4459 spin_lock(&hugetlb_lock);
4460 set_page_huge_active(page);
4461 list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
4462 spin_unlock(&hugetlb_lock);