2 * Generic hugetlb support.
3 * (C) William Irwin, April 2004
6 #include <linux/list.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/cpuset.h>
16 #include <linux/mutex.h>
17 #include <linux/bootmem.h>
18 #include <linux/sysfs.h>
21 #include <asm/pgtable.h>
23 #include <linux/hugetlb.h>
26 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
27 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
28 unsigned long hugepages_treat_as_movable;
30 static int max_hstate;
31 unsigned int default_hstate_idx;
32 struct hstate hstates[HUGE_MAX_HSTATE];
34 /* for command line parsing */
35 static struct hstate * __initdata parsed_hstate;
36 static unsigned long __initdata default_hstate_max_huge_pages;
38 #define for_each_hstate(h) \
39 for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
42 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
44 static DEFINE_SPINLOCK(hugetlb_lock);
47 * Region tracking -- allows tracking of reservations and instantiated pages
48 * across the pages in a mapping.
50 * The region data structures are protected by a combination of the mmap_sem
51 * and the hugetlb_instantion_mutex. To access or modify a region the caller
52 * must either hold the mmap_sem for write, or the mmap_sem for read and
53 * the hugetlb_instantiation mutex:
55 * down_write(&mm->mmap_sem);
57 * down_read(&mm->mmap_sem);
58 * mutex_lock(&hugetlb_instantiation_mutex);
61 struct list_head link;
66 static long region_add(struct list_head *head, long f, long t)
68 struct file_region *rg, *nrg, *trg;
70 /* Locate the region we are either in or before. */
71 list_for_each_entry(rg, head, link)
75 /* Round our left edge to the current segment if it encloses us. */
79 /* Check for and consume any regions we now overlap with. */
81 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
82 if (&rg->link == head)
87 /* If this area reaches higher then extend our area to
88 * include it completely. If this is not the first area
89 * which we intend to reuse, free it. */
102 static long region_chg(struct list_head *head, long f, long t)
104 struct file_region *rg, *nrg;
107 /* Locate the region we are before or in. */
108 list_for_each_entry(rg, head, link)
112 /* If we are below the current region then a new region is required.
113 * Subtle, allocate a new region at the position but make it zero
114 * size such that we can guarantee to record the reservation. */
115 if (&rg->link == head || t < rg->from) {
116 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
121 INIT_LIST_HEAD(&nrg->link);
122 list_add(&nrg->link, rg->link.prev);
127 /* Round our left edge to the current segment if it encloses us. */
132 /* Check for and consume any regions we now overlap with. */
133 list_for_each_entry(rg, rg->link.prev, link) {
134 if (&rg->link == head)
139 /* We overlap with this area, if it extends futher than
140 * us then we must extend ourselves. Account for its
141 * existing reservation. */
146 chg -= rg->to - rg->from;
151 static long region_truncate(struct list_head *head, long end)
153 struct file_region *rg, *trg;
156 /* Locate the region we are either in or before. */
157 list_for_each_entry(rg, head, link)
160 if (&rg->link == head)
163 /* If we are in the middle of a region then adjust it. */
164 if (end > rg->from) {
167 rg = list_entry(rg->link.next, typeof(*rg), link);
170 /* Drop any remaining regions. */
171 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
172 if (&rg->link == head)
174 chg += rg->to - rg->from;
181 static long region_count(struct list_head *head, long f, long t)
183 struct file_region *rg;
186 /* Locate each segment we overlap with, and count that overlap. */
187 list_for_each_entry(rg, head, link) {
196 seg_from = max(rg->from, f);
197 seg_to = min(rg->to, t);
199 chg += seg_to - seg_from;
206 * Convert the address within this vma to the page offset within
207 * the mapping, in pagecache page units; huge pages here.
209 static pgoff_t vma_hugecache_offset(struct hstate *h,
210 struct vm_area_struct *vma, unsigned long address)
212 return ((address - vma->vm_start) >> huge_page_shift(h)) +
213 (vma->vm_pgoff >> huge_page_order(h));
217 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
218 * bits of the reservation map pointer, which are always clear due to
221 #define HPAGE_RESV_OWNER (1UL << 0)
222 #define HPAGE_RESV_UNMAPPED (1UL << 1)
223 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
226 * These helpers are used to track how many pages are reserved for
227 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
228 * is guaranteed to have their future faults succeed.
230 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
231 * the reserve counters are updated with the hugetlb_lock held. It is safe
232 * to reset the VMA at fork() time as it is not in use yet and there is no
233 * chance of the global counters getting corrupted as a result of the values.
235 * The private mapping reservation is represented in a subtly different
236 * manner to a shared mapping. A shared mapping has a region map associated
237 * with the underlying file, this region map represents the backing file
238 * pages which have ever had a reservation assigned which this persists even
239 * after the page is instantiated. A private mapping has a region map
240 * associated with the original mmap which is attached to all VMAs which
241 * reference it, this region map represents those offsets which have consumed
242 * reservation ie. where pages have been instantiated.
244 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
246 return (unsigned long)vma->vm_private_data;
249 static void set_vma_private_data(struct vm_area_struct *vma,
252 vma->vm_private_data = (void *)value;
257 struct list_head regions;
260 struct resv_map *resv_map_alloc(void)
262 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
266 kref_init(&resv_map->refs);
267 INIT_LIST_HEAD(&resv_map->regions);
272 void resv_map_release(struct kref *ref)
274 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
276 /* Clear out any active regions before we release the map. */
277 region_truncate(&resv_map->regions, 0);
281 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
283 VM_BUG_ON(!is_vm_hugetlb_page(vma));
284 if (!(vma->vm_flags & VM_SHARED))
285 return (struct resv_map *)(get_vma_private_data(vma) &
290 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
292 VM_BUG_ON(!is_vm_hugetlb_page(vma));
293 VM_BUG_ON(vma->vm_flags & VM_SHARED);
295 set_vma_private_data(vma, (get_vma_private_data(vma) &
296 HPAGE_RESV_MASK) | (unsigned long)map);
299 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
301 VM_BUG_ON(!is_vm_hugetlb_page(vma));
302 VM_BUG_ON(vma->vm_flags & VM_SHARED);
304 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
307 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
309 VM_BUG_ON(!is_vm_hugetlb_page(vma));
311 return (get_vma_private_data(vma) & flag) != 0;
314 /* Decrement the reserved pages in the hugepage pool by one */
315 static void decrement_hugepage_resv_vma(struct hstate *h,
316 struct vm_area_struct *vma)
318 if (vma->vm_flags & VM_NORESERVE)
321 if (vma->vm_flags & VM_SHARED) {
322 /* Shared mappings always use reserves */
323 h->resv_huge_pages--;
324 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
326 * Only the process that called mmap() has reserves for
329 h->resv_huge_pages--;
333 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
334 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
336 VM_BUG_ON(!is_vm_hugetlb_page(vma));
337 if (!(vma->vm_flags & VM_SHARED))
338 vma->vm_private_data = (void *)0;
341 /* Returns true if the VMA has associated reserve pages */
342 static int vma_has_private_reserves(struct vm_area_struct *vma)
344 if (vma->vm_flags & VM_SHARED)
346 if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER))
351 static void clear_huge_page(struct page *page,
352 unsigned long addr, unsigned long sz)
357 for (i = 0; i < sz/PAGE_SIZE; i++) {
359 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
363 static void copy_huge_page(struct page *dst, struct page *src,
364 unsigned long addr, struct vm_area_struct *vma)
367 struct hstate *h = hstate_vma(vma);
370 for (i = 0; i < pages_per_huge_page(h); i++) {
372 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
376 static void enqueue_huge_page(struct hstate *h, struct page *page)
378 int nid = page_to_nid(page);
379 list_add(&page->lru, &h->hugepage_freelists[nid]);
380 h->free_huge_pages++;
381 h->free_huge_pages_node[nid]++;
384 static struct page *dequeue_huge_page(struct hstate *h)
387 struct page *page = NULL;
389 for (nid = 0; nid < MAX_NUMNODES; ++nid) {
390 if (!list_empty(&h->hugepage_freelists[nid])) {
391 page = list_entry(h->hugepage_freelists[nid].next,
393 list_del(&page->lru);
394 h->free_huge_pages--;
395 h->free_huge_pages_node[nid]--;
402 static struct page *dequeue_huge_page_vma(struct hstate *h,
403 struct vm_area_struct *vma,
404 unsigned long address, int avoid_reserve)
407 struct page *page = NULL;
408 struct mempolicy *mpol;
409 nodemask_t *nodemask;
410 struct zonelist *zonelist = huge_zonelist(vma, address,
411 htlb_alloc_mask, &mpol, &nodemask);
416 * A child process with MAP_PRIVATE mappings created by their parent
417 * have no page reserves. This check ensures that reservations are
418 * not "stolen". The child may still get SIGKILLed
420 if (!vma_has_private_reserves(vma) &&
421 h->free_huge_pages - h->resv_huge_pages == 0)
424 /* If reserves cannot be used, ensure enough pages are in the pool */
425 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
428 for_each_zone_zonelist_nodemask(zone, z, zonelist,
429 MAX_NR_ZONES - 1, nodemask) {
430 nid = zone_to_nid(zone);
431 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
432 !list_empty(&h->hugepage_freelists[nid])) {
433 page = list_entry(h->hugepage_freelists[nid].next,
435 list_del(&page->lru);
436 h->free_huge_pages--;
437 h->free_huge_pages_node[nid]--;
440 decrement_hugepage_resv_vma(h, vma);
449 static void update_and_free_page(struct hstate *h, struct page *page)
454 h->nr_huge_pages_node[page_to_nid(page)]--;
455 for (i = 0; i < pages_per_huge_page(h); i++) {
456 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
457 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
458 1 << PG_private | 1<< PG_writeback);
460 set_compound_page_dtor(page, NULL);
461 set_page_refcounted(page);
462 arch_release_hugepage(page);
463 __free_pages(page, huge_page_order(h));
466 struct hstate *size_to_hstate(unsigned long size)
471 if (huge_page_size(h) == size)
477 static void free_huge_page(struct page *page)
480 * Can't pass hstate in here because it is called from the
481 * compound page destructor.
483 struct hstate *h = page_hstate(page);
484 int nid = page_to_nid(page);
485 struct address_space *mapping;
487 mapping = (struct address_space *) page_private(page);
488 set_page_private(page, 0);
489 BUG_ON(page_count(page));
490 INIT_LIST_HEAD(&page->lru);
492 spin_lock(&hugetlb_lock);
493 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
494 update_and_free_page(h, page);
495 h->surplus_huge_pages--;
496 h->surplus_huge_pages_node[nid]--;
498 enqueue_huge_page(h, page);
500 spin_unlock(&hugetlb_lock);
502 hugetlb_put_quota(mapping, 1);
506 * Increment or decrement surplus_huge_pages. Keep node-specific counters
507 * balanced by operating on them in a round-robin fashion.
508 * Returns 1 if an adjustment was made.
510 static int adjust_pool_surplus(struct hstate *h, int delta)
516 VM_BUG_ON(delta != -1 && delta != 1);
518 nid = next_node(nid, node_online_map);
519 if (nid == MAX_NUMNODES)
520 nid = first_node(node_online_map);
522 /* To shrink on this node, there must be a surplus page */
523 if (delta < 0 && !h->surplus_huge_pages_node[nid])
525 /* Surplus cannot exceed the total number of pages */
526 if (delta > 0 && h->surplus_huge_pages_node[nid] >=
527 h->nr_huge_pages_node[nid])
530 h->surplus_huge_pages += delta;
531 h->surplus_huge_pages_node[nid] += delta;
534 } while (nid != prev_nid);
540 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
542 set_compound_page_dtor(page, free_huge_page);
543 spin_lock(&hugetlb_lock);
545 h->nr_huge_pages_node[nid]++;
546 spin_unlock(&hugetlb_lock);
547 put_page(page); /* free it into the hugepage allocator */
550 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
554 if (h->order >= MAX_ORDER)
557 page = alloc_pages_node(nid,
558 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
559 __GFP_REPEAT|__GFP_NOWARN,
562 if (arch_prepare_hugepage(page)) {
563 __free_pages(page, HUGETLB_PAGE_ORDER);
566 prep_new_huge_page(h, page, nid);
573 * Use a helper variable to find the next node and then
574 * copy it back to hugetlb_next_nid afterwards:
575 * otherwise there's a window in which a racer might
576 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
577 * But we don't need to use a spin_lock here: it really
578 * doesn't matter if occasionally a racer chooses the
579 * same nid as we do. Move nid forward in the mask even
580 * if we just successfully allocated a hugepage so that
581 * the next caller gets hugepages on the next node.
583 static int hstate_next_node(struct hstate *h)
586 next_nid = next_node(h->hugetlb_next_nid, node_online_map);
587 if (next_nid == MAX_NUMNODES)
588 next_nid = first_node(node_online_map);
589 h->hugetlb_next_nid = next_nid;
593 static int alloc_fresh_huge_page(struct hstate *h)
600 start_nid = h->hugetlb_next_nid;
603 page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
606 next_nid = hstate_next_node(h);
607 } while (!page && h->hugetlb_next_nid != start_nid);
610 count_vm_event(HTLB_BUDDY_PGALLOC);
612 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
617 static struct page *alloc_buddy_huge_page(struct hstate *h,
618 struct vm_area_struct *vma, unsigned long address)
623 if (h->order >= MAX_ORDER)
627 * Assume we will successfully allocate the surplus page to
628 * prevent racing processes from causing the surplus to exceed
631 * This however introduces a different race, where a process B
632 * tries to grow the static hugepage pool while alloc_pages() is
633 * called by process A. B will only examine the per-node
634 * counters in determining if surplus huge pages can be
635 * converted to normal huge pages in adjust_pool_surplus(). A
636 * won't be able to increment the per-node counter, until the
637 * lock is dropped by B, but B doesn't drop hugetlb_lock until
638 * no more huge pages can be converted from surplus to normal
639 * state (and doesn't try to convert again). Thus, we have a
640 * case where a surplus huge page exists, the pool is grown, and
641 * the surplus huge page still exists after, even though it
642 * should just have been converted to a normal huge page. This
643 * does not leak memory, though, as the hugepage will be freed
644 * once it is out of use. It also does not allow the counters to
645 * go out of whack in adjust_pool_surplus() as we don't modify
646 * the node values until we've gotten the hugepage and only the
647 * per-node value is checked there.
649 spin_lock(&hugetlb_lock);
650 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
651 spin_unlock(&hugetlb_lock);
655 h->surplus_huge_pages++;
657 spin_unlock(&hugetlb_lock);
659 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
660 __GFP_REPEAT|__GFP_NOWARN,
663 spin_lock(&hugetlb_lock);
666 * This page is now managed by the hugetlb allocator and has
667 * no users -- drop the buddy allocator's reference.
669 put_page_testzero(page);
670 VM_BUG_ON(page_count(page));
671 nid = page_to_nid(page);
672 set_compound_page_dtor(page, free_huge_page);
674 * We incremented the global counters already
676 h->nr_huge_pages_node[nid]++;
677 h->surplus_huge_pages_node[nid]++;
678 __count_vm_event(HTLB_BUDDY_PGALLOC);
681 h->surplus_huge_pages--;
682 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
684 spin_unlock(&hugetlb_lock);
690 * Increase the hugetlb pool such that it can accomodate a reservation
693 static int gather_surplus_pages(struct hstate *h, int delta)
695 struct list_head surplus_list;
696 struct page *page, *tmp;
698 int needed, allocated;
700 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
702 h->resv_huge_pages += delta;
707 INIT_LIST_HEAD(&surplus_list);
711 spin_unlock(&hugetlb_lock);
712 for (i = 0; i < needed; i++) {
713 page = alloc_buddy_huge_page(h, NULL, 0);
716 * We were not able to allocate enough pages to
717 * satisfy the entire reservation so we free what
718 * we've allocated so far.
720 spin_lock(&hugetlb_lock);
725 list_add(&page->lru, &surplus_list);
730 * After retaking hugetlb_lock, we need to recalculate 'needed'
731 * because either resv_huge_pages or free_huge_pages may have changed.
733 spin_lock(&hugetlb_lock);
734 needed = (h->resv_huge_pages + delta) -
735 (h->free_huge_pages + allocated);
740 * The surplus_list now contains _at_least_ the number of extra pages
741 * needed to accomodate the reservation. Add the appropriate number
742 * of pages to the hugetlb pool and free the extras back to the buddy
743 * allocator. Commit the entire reservation here to prevent another
744 * process from stealing the pages as they are added to the pool but
745 * before they are reserved.
748 h->resv_huge_pages += delta;
751 /* Free the needed pages to the hugetlb pool */
752 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
755 list_del(&page->lru);
756 enqueue_huge_page(h, page);
759 /* Free unnecessary surplus pages to the buddy allocator */
760 if (!list_empty(&surplus_list)) {
761 spin_unlock(&hugetlb_lock);
762 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
763 list_del(&page->lru);
765 * The page has a reference count of zero already, so
766 * call free_huge_page directly instead of using
767 * put_page. This must be done with hugetlb_lock
768 * unlocked which is safe because free_huge_page takes
769 * hugetlb_lock before deciding how to free the page.
771 free_huge_page(page);
773 spin_lock(&hugetlb_lock);
780 * When releasing a hugetlb pool reservation, any surplus pages that were
781 * allocated to satisfy the reservation must be explicitly freed if they were
784 static void return_unused_surplus_pages(struct hstate *h,
785 unsigned long unused_resv_pages)
789 unsigned long nr_pages;
792 * We want to release as many surplus pages as possible, spread
793 * evenly across all nodes. Iterate across all nodes until we
794 * can no longer free unreserved surplus pages. This occurs when
795 * the nodes with surplus pages have no free pages.
797 unsigned long remaining_iterations = num_online_nodes();
799 /* Uncommit the reservation */
800 h->resv_huge_pages -= unused_resv_pages;
802 /* Cannot return gigantic pages currently */
803 if (h->order >= MAX_ORDER)
806 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
808 while (remaining_iterations-- && nr_pages) {
809 nid = next_node(nid, node_online_map);
810 if (nid == MAX_NUMNODES)
811 nid = first_node(node_online_map);
813 if (!h->surplus_huge_pages_node[nid])
816 if (!list_empty(&h->hugepage_freelists[nid])) {
817 page = list_entry(h->hugepage_freelists[nid].next,
819 list_del(&page->lru);
820 update_and_free_page(h, page);
821 h->free_huge_pages--;
822 h->free_huge_pages_node[nid]--;
823 h->surplus_huge_pages--;
824 h->surplus_huge_pages_node[nid]--;
826 remaining_iterations = num_online_nodes();
832 * Determine if the huge page at addr within the vma has an associated
833 * reservation. Where it does not we will need to logically increase
834 * reservation and actually increase quota before an allocation can occur.
835 * Where any new reservation would be required the reservation change is
836 * prepared, but not committed. Once the page has been quota'd allocated
837 * an instantiated the change should be committed via vma_commit_reservation.
838 * No action is required on failure.
840 static int vma_needs_reservation(struct hstate *h,
841 struct vm_area_struct *vma, unsigned long addr)
843 struct address_space *mapping = vma->vm_file->f_mapping;
844 struct inode *inode = mapping->host;
846 if (vma->vm_flags & VM_SHARED) {
847 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
848 return region_chg(&inode->i_mapping->private_list,
851 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
856 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
857 struct resv_map *reservations = vma_resv_map(vma);
859 err = region_chg(&reservations->regions, idx, idx + 1);
865 static void vma_commit_reservation(struct hstate *h,
866 struct vm_area_struct *vma, unsigned long addr)
868 struct address_space *mapping = vma->vm_file->f_mapping;
869 struct inode *inode = mapping->host;
871 if (vma->vm_flags & VM_SHARED) {
872 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
873 region_add(&inode->i_mapping->private_list, idx, idx + 1);
875 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
876 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
877 struct resv_map *reservations = vma_resv_map(vma);
879 /* Mark this page used in the map. */
880 region_add(&reservations->regions, idx, idx + 1);
884 static struct page *alloc_huge_page(struct vm_area_struct *vma,
885 unsigned long addr, int avoid_reserve)
887 struct hstate *h = hstate_vma(vma);
889 struct address_space *mapping = vma->vm_file->f_mapping;
890 struct inode *inode = mapping->host;
894 * Processes that did not create the mapping will have no reserves and
895 * will not have accounted against quota. Check that the quota can be
896 * made before satisfying the allocation
897 * MAP_NORESERVE mappings may also need pages and quota allocated
898 * if no reserve mapping overlaps.
900 chg = vma_needs_reservation(h, vma, addr);
904 if (hugetlb_get_quota(inode->i_mapping, chg))
905 return ERR_PTR(-ENOSPC);
907 spin_lock(&hugetlb_lock);
908 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
909 spin_unlock(&hugetlb_lock);
912 page = alloc_buddy_huge_page(h, vma, addr);
914 hugetlb_put_quota(inode->i_mapping, chg);
915 return ERR_PTR(-VM_FAULT_OOM);
919 set_page_refcounted(page);
920 set_page_private(page, (unsigned long) mapping);
922 vma_commit_reservation(h, vma, addr);
927 static __initdata LIST_HEAD(huge_boot_pages);
929 struct huge_bootmem_page {
930 struct list_head list;
931 struct hstate *hstate;
934 static int __init alloc_bootmem_huge_page(struct hstate *h)
936 struct huge_bootmem_page *m;
937 int nr_nodes = nodes_weight(node_online_map);
942 addr = __alloc_bootmem_node_nopanic(
943 NODE_DATA(h->hugetlb_next_nid),
944 huge_page_size(h), huge_page_size(h), 0);
948 * Use the beginning of the huge page to store the
949 * huge_bootmem_page struct (until gather_bootmem
950 * puts them into the mem_map).
962 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
963 /* Put them into a private list first because mem_map is not up yet */
964 list_add(&m->list, &huge_boot_pages);
969 /* Put bootmem huge pages into the standard lists after mem_map is up */
970 static void __init gather_bootmem_prealloc(void)
972 struct huge_bootmem_page *m;
974 list_for_each_entry(m, &huge_boot_pages, list) {
975 struct page *page = virt_to_page(m);
976 struct hstate *h = m->hstate;
977 __ClearPageReserved(page);
978 WARN_ON(page_count(page) != 1);
979 prep_compound_page(page, h->order);
980 prep_new_huge_page(h, page, page_to_nid(page));
984 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
988 for (i = 0; i < h->max_huge_pages; ++i) {
989 if (h->order >= MAX_ORDER) {
990 if (!alloc_bootmem_huge_page(h))
992 } else if (!alloc_fresh_huge_page(h))
995 h->max_huge_pages = i;
998 static void __init hugetlb_init_hstates(void)
1002 for_each_hstate(h) {
1003 /* oversize hugepages were init'ed in early boot */
1004 if (h->order < MAX_ORDER)
1005 hugetlb_hstate_alloc_pages(h);
1009 static char * __init memfmt(char *buf, unsigned long n)
1011 if (n >= (1UL << 30))
1012 sprintf(buf, "%lu GB", n >> 30);
1013 else if (n >= (1UL << 20))
1014 sprintf(buf, "%lu MB", n >> 20);
1016 sprintf(buf, "%lu KB", n >> 10);
1020 static void __init report_hugepages(void)
1024 for_each_hstate(h) {
1026 printk(KERN_INFO "HugeTLB registered %s page size, "
1027 "pre-allocated %ld pages\n",
1028 memfmt(buf, huge_page_size(h)),
1029 h->free_huge_pages);
1033 #ifdef CONFIG_SYSCTL
1034 #ifdef CONFIG_HIGHMEM
1035 static void try_to_free_low(struct hstate *h, unsigned long count)
1039 if (h->order >= MAX_ORDER)
1042 for (i = 0; i < MAX_NUMNODES; ++i) {
1043 struct page *page, *next;
1044 struct list_head *freel = &h->hugepage_freelists[i];
1045 list_for_each_entry_safe(page, next, freel, lru) {
1046 if (count >= h->nr_huge_pages)
1048 if (PageHighMem(page))
1050 list_del(&page->lru);
1051 update_and_free_page(h, page);
1052 h->free_huge_pages--;
1053 h->free_huge_pages_node[page_to_nid(page)]--;
1058 static inline void try_to_free_low(struct hstate *h, unsigned long count)
1063 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1064 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
1066 unsigned long min_count, ret;
1068 if (h->order >= MAX_ORDER)
1069 return h->max_huge_pages;
1072 * Increase the pool size
1073 * First take pages out of surplus state. Then make up the
1074 * remaining difference by allocating fresh huge pages.
1076 * We might race with alloc_buddy_huge_page() here and be unable
1077 * to convert a surplus huge page to a normal huge page. That is
1078 * not critical, though, it just means the overall size of the
1079 * pool might be one hugepage larger than it needs to be, but
1080 * within all the constraints specified by the sysctls.
1082 spin_lock(&hugetlb_lock);
1083 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1084 if (!adjust_pool_surplus(h, -1))
1088 while (count > persistent_huge_pages(h)) {
1090 * If this allocation races such that we no longer need the
1091 * page, free_huge_page will handle it by freeing the page
1092 * and reducing the surplus.
1094 spin_unlock(&hugetlb_lock);
1095 ret = alloc_fresh_huge_page(h);
1096 spin_lock(&hugetlb_lock);
1103 * Decrease the pool size
1104 * First return free pages to the buddy allocator (being careful
1105 * to keep enough around to satisfy reservations). Then place
1106 * pages into surplus state as needed so the pool will shrink
1107 * to the desired size as pages become free.
1109 * By placing pages into the surplus state independent of the
1110 * overcommit value, we are allowing the surplus pool size to
1111 * exceed overcommit. There are few sane options here. Since
1112 * alloc_buddy_huge_page() is checking the global counter,
1113 * though, we'll note that we're not allowed to exceed surplus
1114 * and won't grow the pool anywhere else. Not until one of the
1115 * sysctls are changed, or the surplus pages go out of use.
1117 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1118 min_count = max(count, min_count);
1119 try_to_free_low(h, min_count);
1120 while (min_count < persistent_huge_pages(h)) {
1121 struct page *page = dequeue_huge_page(h);
1124 update_and_free_page(h, page);
1126 while (count < persistent_huge_pages(h)) {
1127 if (!adjust_pool_surplus(h, 1))
1131 ret = persistent_huge_pages(h);
1132 spin_unlock(&hugetlb_lock);
1136 #define HSTATE_ATTR_RO(_name) \
1137 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1139 #define HSTATE_ATTR(_name) \
1140 static struct kobj_attribute _name##_attr = \
1141 __ATTR(_name, 0644, _name##_show, _name##_store)
1143 static struct kobject *hugepages_kobj;
1144 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1146 static struct hstate *kobj_to_hstate(struct kobject *kobj)
1149 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1150 if (hstate_kobjs[i] == kobj)
1156 static ssize_t nr_hugepages_show(struct kobject *kobj,
1157 struct kobj_attribute *attr, char *buf)
1159 struct hstate *h = kobj_to_hstate(kobj);
1160 return sprintf(buf, "%lu\n", h->nr_huge_pages);
1162 static ssize_t nr_hugepages_store(struct kobject *kobj,
1163 struct kobj_attribute *attr, const char *buf, size_t count)
1166 unsigned long input;
1167 struct hstate *h = kobj_to_hstate(kobj);
1169 err = strict_strtoul(buf, 10, &input);
1173 h->max_huge_pages = set_max_huge_pages(h, input);
1177 HSTATE_ATTR(nr_hugepages);
1179 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1180 struct kobj_attribute *attr, char *buf)
1182 struct hstate *h = kobj_to_hstate(kobj);
1183 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1185 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1186 struct kobj_attribute *attr, const char *buf, size_t count)
1189 unsigned long input;
1190 struct hstate *h = kobj_to_hstate(kobj);
1192 err = strict_strtoul(buf, 10, &input);
1196 spin_lock(&hugetlb_lock);
1197 h->nr_overcommit_huge_pages = input;
1198 spin_unlock(&hugetlb_lock);
1202 HSTATE_ATTR(nr_overcommit_hugepages);
1204 static ssize_t free_hugepages_show(struct kobject *kobj,
1205 struct kobj_attribute *attr, char *buf)
1207 struct hstate *h = kobj_to_hstate(kobj);
1208 return sprintf(buf, "%lu\n", h->free_huge_pages);
1210 HSTATE_ATTR_RO(free_hugepages);
1212 static ssize_t resv_hugepages_show(struct kobject *kobj,
1213 struct kobj_attribute *attr, char *buf)
1215 struct hstate *h = kobj_to_hstate(kobj);
1216 return sprintf(buf, "%lu\n", h->resv_huge_pages);
1218 HSTATE_ATTR_RO(resv_hugepages);
1220 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1221 struct kobj_attribute *attr, char *buf)
1223 struct hstate *h = kobj_to_hstate(kobj);
1224 return sprintf(buf, "%lu\n", h->surplus_huge_pages);
1226 HSTATE_ATTR_RO(surplus_hugepages);
1228 static struct attribute *hstate_attrs[] = {
1229 &nr_hugepages_attr.attr,
1230 &nr_overcommit_hugepages_attr.attr,
1231 &free_hugepages_attr.attr,
1232 &resv_hugepages_attr.attr,
1233 &surplus_hugepages_attr.attr,
1237 static struct attribute_group hstate_attr_group = {
1238 .attrs = hstate_attrs,
1241 static int __init hugetlb_sysfs_add_hstate(struct hstate *h)
1245 hstate_kobjs[h - hstates] = kobject_create_and_add(h->name,
1247 if (!hstate_kobjs[h - hstates])
1250 retval = sysfs_create_group(hstate_kobjs[h - hstates],
1251 &hstate_attr_group);
1253 kobject_put(hstate_kobjs[h - hstates]);
1258 static void __init hugetlb_sysfs_init(void)
1263 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1264 if (!hugepages_kobj)
1267 for_each_hstate(h) {
1268 err = hugetlb_sysfs_add_hstate(h);
1270 printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1275 static void __exit hugetlb_exit(void)
1279 for_each_hstate(h) {
1280 kobject_put(hstate_kobjs[h - hstates]);
1283 kobject_put(hugepages_kobj);
1285 module_exit(hugetlb_exit);
1287 static int __init hugetlb_init(void)
1289 BUILD_BUG_ON(HPAGE_SHIFT == 0);
1291 if (!size_to_hstate(HPAGE_SIZE)) {
1292 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1293 parsed_hstate->max_huge_pages = default_hstate_max_huge_pages;
1295 default_hstate_idx = size_to_hstate(HPAGE_SIZE) - hstates;
1297 hugetlb_init_hstates();
1299 gather_bootmem_prealloc();
1303 hugetlb_sysfs_init();
1307 module_init(hugetlb_init);
1309 /* Should be called on processing a hugepagesz=... option */
1310 void __init hugetlb_add_hstate(unsigned order)
1315 if (size_to_hstate(PAGE_SIZE << order)) {
1316 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1319 BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1321 h = &hstates[max_hstate++];
1323 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1324 h->nr_huge_pages = 0;
1325 h->free_huge_pages = 0;
1326 for (i = 0; i < MAX_NUMNODES; ++i)
1327 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1328 h->hugetlb_next_nid = first_node(node_online_map);
1329 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1330 huge_page_size(h)/1024);
1335 static int __init hugetlb_setup(char *s)
1338 static unsigned long *last_mhp;
1341 * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1342 * so this hugepages= parameter goes to the "default hstate".
1345 mhp = &default_hstate_max_huge_pages;
1347 mhp = &parsed_hstate->max_huge_pages;
1349 if (mhp == last_mhp) {
1350 printk(KERN_WARNING "hugepages= specified twice without "
1351 "interleaving hugepagesz=, ignoring\n");
1355 if (sscanf(s, "%lu", mhp) <= 0)
1359 * Global state is always initialized later in hugetlb_init.
1360 * But we need to allocate >= MAX_ORDER hstates here early to still
1361 * use the bootmem allocator.
1363 if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1364 hugetlb_hstate_alloc_pages(parsed_hstate);
1370 __setup("hugepages=", hugetlb_setup);
1372 static unsigned int cpuset_mems_nr(unsigned int *array)
1375 unsigned int nr = 0;
1377 for_each_node_mask(node, cpuset_current_mems_allowed)
1383 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1384 struct file *file, void __user *buffer,
1385 size_t *length, loff_t *ppos)
1387 struct hstate *h = &default_hstate;
1391 tmp = h->max_huge_pages;
1394 table->maxlen = sizeof(unsigned long);
1395 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1398 h->max_huge_pages = set_max_huge_pages(h, tmp);
1403 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1404 struct file *file, void __user *buffer,
1405 size_t *length, loff_t *ppos)
1407 proc_dointvec(table, write, file, buffer, length, ppos);
1408 if (hugepages_treat_as_movable)
1409 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1411 htlb_alloc_mask = GFP_HIGHUSER;
1415 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1416 struct file *file, void __user *buffer,
1417 size_t *length, loff_t *ppos)
1419 struct hstate *h = &default_hstate;
1423 tmp = h->nr_overcommit_huge_pages;
1426 table->maxlen = sizeof(unsigned long);
1427 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1430 spin_lock(&hugetlb_lock);
1431 h->nr_overcommit_huge_pages = tmp;
1432 spin_unlock(&hugetlb_lock);
1438 #endif /* CONFIG_SYSCTL */
1440 int hugetlb_report_meminfo(char *buf)
1442 struct hstate *h = &default_hstate;
1444 "HugePages_Total: %5lu\n"
1445 "HugePages_Free: %5lu\n"
1446 "HugePages_Rsvd: %5lu\n"
1447 "HugePages_Surp: %5lu\n"
1448 "Hugepagesize: %5lu kB\n",
1452 h->surplus_huge_pages,
1453 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1456 int hugetlb_report_node_meminfo(int nid, char *buf)
1458 struct hstate *h = &default_hstate;
1460 "Node %d HugePages_Total: %5u\n"
1461 "Node %d HugePages_Free: %5u\n"
1462 "Node %d HugePages_Surp: %5u\n",
1463 nid, h->nr_huge_pages_node[nid],
1464 nid, h->free_huge_pages_node[nid],
1465 nid, h->surplus_huge_pages_node[nid]);
1468 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1469 unsigned long hugetlb_total_pages(void)
1471 struct hstate *h = &default_hstate;
1472 return h->nr_huge_pages * pages_per_huge_page(h);
1475 static int hugetlb_acct_memory(struct hstate *h, long delta)
1479 spin_lock(&hugetlb_lock);
1481 * When cpuset is configured, it breaks the strict hugetlb page
1482 * reservation as the accounting is done on a global variable. Such
1483 * reservation is completely rubbish in the presence of cpuset because
1484 * the reservation is not checked against page availability for the
1485 * current cpuset. Application can still potentially OOM'ed by kernel
1486 * with lack of free htlb page in cpuset that the task is in.
1487 * Attempt to enforce strict accounting with cpuset is almost
1488 * impossible (or too ugly) because cpuset is too fluid that
1489 * task or memory node can be dynamically moved between cpusets.
1491 * The change of semantics for shared hugetlb mapping with cpuset is
1492 * undesirable. However, in order to preserve some of the semantics,
1493 * we fall back to check against current free page availability as
1494 * a best attempt and hopefully to minimize the impact of changing
1495 * semantics that cpuset has.
1498 if (gather_surplus_pages(h, delta) < 0)
1501 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1502 return_unused_surplus_pages(h, delta);
1509 return_unused_surplus_pages(h, (unsigned long) -delta);
1512 spin_unlock(&hugetlb_lock);
1516 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
1518 struct resv_map *reservations = vma_resv_map(vma);
1521 * This new VMA should share its siblings reservation map if present.
1522 * The VMA will only ever have a valid reservation map pointer where
1523 * it is being copied for another still existing VMA. As that VMA
1524 * has a reference to the reservation map it cannot dissappear until
1525 * after this open call completes. It is therefore safe to take a
1526 * new reference here without additional locking.
1529 kref_get(&reservations->refs);
1532 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
1534 struct hstate *h = hstate_vma(vma);
1535 struct resv_map *reservations = vma_resv_map(vma);
1536 unsigned long reserve;
1537 unsigned long start;
1541 start = vma_hugecache_offset(h, vma, vma->vm_start);
1542 end = vma_hugecache_offset(h, vma, vma->vm_end);
1544 reserve = (end - start) -
1545 region_count(&reservations->regions, start, end);
1547 kref_put(&reservations->refs, resv_map_release);
1550 hugetlb_acct_memory(h, -reserve);
1555 * We cannot handle pagefaults against hugetlb pages at all. They cause
1556 * handle_mm_fault() to try to instantiate regular-sized pages in the
1557 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
1560 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1566 struct vm_operations_struct hugetlb_vm_ops = {
1567 .fault = hugetlb_vm_op_fault,
1568 .open = hugetlb_vm_op_open,
1569 .close = hugetlb_vm_op_close,
1572 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
1579 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
1581 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
1583 entry = pte_mkyoung(entry);
1584 entry = pte_mkhuge(entry);
1589 static void set_huge_ptep_writable(struct vm_area_struct *vma,
1590 unsigned long address, pte_t *ptep)
1594 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
1595 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
1596 update_mmu_cache(vma, address, entry);
1601 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
1602 struct vm_area_struct *vma)
1604 pte_t *src_pte, *dst_pte, entry;
1605 struct page *ptepage;
1608 struct hstate *h = hstate_vma(vma);
1609 unsigned long sz = huge_page_size(h);
1611 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
1613 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
1614 src_pte = huge_pte_offset(src, addr);
1617 dst_pte = huge_pte_alloc(dst, addr, sz);
1621 /* If the pagetables are shared don't copy or take references */
1622 if (dst_pte == src_pte)
1625 spin_lock(&dst->page_table_lock);
1626 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
1627 if (!huge_pte_none(huge_ptep_get(src_pte))) {
1629 huge_ptep_set_wrprotect(src, addr, src_pte);
1630 entry = huge_ptep_get(src_pte);
1631 ptepage = pte_page(entry);
1633 set_huge_pte_at(dst, addr, dst_pte, entry);
1635 spin_unlock(&src->page_table_lock);
1636 spin_unlock(&dst->page_table_lock);
1644 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1645 unsigned long end, struct page *ref_page)
1647 struct mm_struct *mm = vma->vm_mm;
1648 unsigned long address;
1653 struct hstate *h = hstate_vma(vma);
1654 unsigned long sz = huge_page_size(h);
1657 * A page gathering list, protected by per file i_mmap_lock. The
1658 * lock is used to avoid list corruption from multiple unmapping
1659 * of the same page since we are using page->lru.
1661 LIST_HEAD(page_list);
1663 WARN_ON(!is_vm_hugetlb_page(vma));
1664 BUG_ON(start & ~huge_page_mask(h));
1665 BUG_ON(end & ~huge_page_mask(h));
1667 spin_lock(&mm->page_table_lock);
1668 for (address = start; address < end; address += sz) {
1669 ptep = huge_pte_offset(mm, address);
1673 if (huge_pmd_unshare(mm, &address, ptep))
1677 * If a reference page is supplied, it is because a specific
1678 * page is being unmapped, not a range. Ensure the page we
1679 * are about to unmap is the actual page of interest.
1682 pte = huge_ptep_get(ptep);
1683 if (huge_pte_none(pte))
1685 page = pte_page(pte);
1686 if (page != ref_page)
1690 * Mark the VMA as having unmapped its page so that
1691 * future faults in this VMA will fail rather than
1692 * looking like data was lost
1694 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
1697 pte = huge_ptep_get_and_clear(mm, address, ptep);
1698 if (huge_pte_none(pte))
1701 page = pte_page(pte);
1703 set_page_dirty(page);
1704 list_add(&page->lru, &page_list);
1706 spin_unlock(&mm->page_table_lock);
1707 flush_tlb_range(vma, start, end);
1708 list_for_each_entry_safe(page, tmp, &page_list, lru) {
1709 list_del(&page->lru);
1714 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1715 unsigned long end, struct page *ref_page)
1717 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1718 __unmap_hugepage_range(vma, start, end, ref_page);
1719 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1723 * This is called when the original mapper is failing to COW a MAP_PRIVATE
1724 * mappping it owns the reserve page for. The intention is to unmap the page
1725 * from other VMAs and let the children be SIGKILLed if they are faulting the
1728 int unmap_ref_private(struct mm_struct *mm,
1729 struct vm_area_struct *vma,
1731 unsigned long address)
1733 struct vm_area_struct *iter_vma;
1734 struct address_space *mapping;
1735 struct prio_tree_iter iter;
1739 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1740 * from page cache lookup which is in HPAGE_SIZE units.
1742 address = address & huge_page_mask(hstate_vma(vma));
1743 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1744 + (vma->vm_pgoff >> PAGE_SHIFT);
1745 mapping = (struct address_space *)page_private(page);
1747 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1748 /* Do not unmap the current VMA */
1749 if (iter_vma == vma)
1753 * Unmap the page from other VMAs without their own reserves.
1754 * They get marked to be SIGKILLed if they fault in these
1755 * areas. This is because a future no-page fault on this VMA
1756 * could insert a zeroed page instead of the data existing
1757 * from the time of fork. This would look like data corruption
1759 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1760 unmap_hugepage_range(iter_vma,
1761 address, address + HPAGE_SIZE,
1768 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1769 unsigned long address, pte_t *ptep, pte_t pte,
1770 struct page *pagecache_page)
1772 struct hstate *h = hstate_vma(vma);
1773 struct page *old_page, *new_page;
1775 int outside_reserve = 0;
1777 old_page = pte_page(pte);
1780 /* If no-one else is actually using this page, avoid the copy
1781 * and just make the page writable */
1782 avoidcopy = (page_count(old_page) == 1);
1784 set_huge_ptep_writable(vma, address, ptep);
1789 * If the process that created a MAP_PRIVATE mapping is about to
1790 * perform a COW due to a shared page count, attempt to satisfy
1791 * the allocation without using the existing reserves. The pagecache
1792 * page is used to determine if the reserve at this address was
1793 * consumed or not. If reserves were used, a partial faulted mapping
1794 * at the time of fork() could consume its reserves on COW instead
1795 * of the full address range.
1797 if (!(vma->vm_flags & VM_SHARED) &&
1798 is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1799 old_page != pagecache_page)
1800 outside_reserve = 1;
1802 page_cache_get(old_page);
1803 new_page = alloc_huge_page(vma, address, outside_reserve);
1805 if (IS_ERR(new_page)) {
1806 page_cache_release(old_page);
1809 * If a process owning a MAP_PRIVATE mapping fails to COW,
1810 * it is due to references held by a child and an insufficient
1811 * huge page pool. To guarantee the original mappers
1812 * reliability, unmap the page from child processes. The child
1813 * may get SIGKILLed if it later faults.
1815 if (outside_reserve) {
1816 BUG_ON(huge_pte_none(pte));
1817 if (unmap_ref_private(mm, vma, old_page, address)) {
1818 BUG_ON(page_count(old_page) != 1);
1819 BUG_ON(huge_pte_none(pte));
1820 goto retry_avoidcopy;
1825 return -PTR_ERR(new_page);
1828 spin_unlock(&mm->page_table_lock);
1829 copy_huge_page(new_page, old_page, address, vma);
1830 __SetPageUptodate(new_page);
1831 spin_lock(&mm->page_table_lock);
1833 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
1834 if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1836 huge_ptep_clear_flush(vma, address, ptep);
1837 set_huge_pte_at(mm, address, ptep,
1838 make_huge_pte(vma, new_page, 1));
1839 /* Make the old page be freed below */
1840 new_page = old_page;
1842 page_cache_release(new_page);
1843 page_cache_release(old_page);
1847 /* Return the pagecache page at a given address within a VMA */
1848 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
1849 struct vm_area_struct *vma, unsigned long address)
1851 struct address_space *mapping;
1854 mapping = vma->vm_file->f_mapping;
1855 idx = vma_hugecache_offset(h, vma, address);
1857 return find_lock_page(mapping, idx);
1860 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1861 unsigned long address, pte_t *ptep, int write_access)
1863 struct hstate *h = hstate_vma(vma);
1864 int ret = VM_FAULT_SIGBUS;
1868 struct address_space *mapping;
1872 * Currently, we are forced to kill the process in the event the
1873 * original mapper has unmapped pages from the child due to a failed
1874 * COW. Warn that such a situation has occured as it may not be obvious
1876 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
1878 "PID %d killed due to inadequate hugepage pool\n",
1883 mapping = vma->vm_file->f_mapping;
1884 idx = vma_hugecache_offset(h, vma, address);
1887 * Use page lock to guard against racing truncation
1888 * before we get page_table_lock.
1891 page = find_lock_page(mapping, idx);
1893 size = i_size_read(mapping->host) >> huge_page_shift(h);
1896 page = alloc_huge_page(vma, address, 0);
1898 ret = -PTR_ERR(page);
1901 clear_huge_page(page, address, huge_page_size(h));
1902 __SetPageUptodate(page);
1904 if (vma->vm_flags & VM_SHARED) {
1906 struct inode *inode = mapping->host;
1908 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
1916 spin_lock(&inode->i_lock);
1917 inode->i_blocks += blocks_per_huge_page(h);
1918 spin_unlock(&inode->i_lock);
1923 spin_lock(&mm->page_table_lock);
1924 size = i_size_read(mapping->host) >> huge_page_shift(h);
1929 if (!huge_pte_none(huge_ptep_get(ptep)))
1932 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
1933 && (vma->vm_flags & VM_SHARED)));
1934 set_huge_pte_at(mm, address, ptep, new_pte);
1936 if (write_access && !(vma->vm_flags & VM_SHARED)) {
1937 /* Optimization, do the COW without a second fault */
1938 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
1941 spin_unlock(&mm->page_table_lock);
1947 spin_unlock(&mm->page_table_lock);
1953 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
1954 unsigned long address, int write_access)
1959 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
1960 struct hstate *h = hstate_vma(vma);
1962 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
1964 return VM_FAULT_OOM;
1967 * Serialize hugepage allocation and instantiation, so that we don't
1968 * get spurious allocation failures if two CPUs race to instantiate
1969 * the same page in the page cache.
1971 mutex_lock(&hugetlb_instantiation_mutex);
1972 entry = huge_ptep_get(ptep);
1973 if (huge_pte_none(entry)) {
1974 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1975 mutex_unlock(&hugetlb_instantiation_mutex);
1981 spin_lock(&mm->page_table_lock);
1982 /* Check for a racing update before calling hugetlb_cow */
1983 if (likely(pte_same(entry, huge_ptep_get(ptep))))
1984 if (write_access && !pte_write(entry)) {
1986 page = hugetlbfs_pagecache_page(h, vma, address);
1987 ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
1993 spin_unlock(&mm->page_table_lock);
1994 mutex_unlock(&hugetlb_instantiation_mutex);
1999 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2000 struct page **pages, struct vm_area_struct **vmas,
2001 unsigned long *position, int *length, int i,
2004 unsigned long pfn_offset;
2005 unsigned long vaddr = *position;
2006 int remainder = *length;
2007 struct hstate *h = hstate_vma(vma);
2009 spin_lock(&mm->page_table_lock);
2010 while (vaddr < vma->vm_end && remainder) {
2015 * Some archs (sparc64, sh*) have multiple pte_ts to
2016 * each hugepage. We have to make * sure we get the
2017 * first, for the page indexing below to work.
2019 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2021 if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
2022 (write && !pte_write(huge_ptep_get(pte)))) {
2025 spin_unlock(&mm->page_table_lock);
2026 ret = hugetlb_fault(mm, vma, vaddr, write);
2027 spin_lock(&mm->page_table_lock);
2028 if (!(ret & VM_FAULT_ERROR))
2037 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2038 page = pte_page(huge_ptep_get(pte));
2042 pages[i] = page + pfn_offset;
2052 if (vaddr < vma->vm_end && remainder &&
2053 pfn_offset < pages_per_huge_page(h)) {
2055 * We use pfn_offset to avoid touching the pageframes
2056 * of this compound page.
2061 spin_unlock(&mm->page_table_lock);
2062 *length = remainder;
2068 void hugetlb_change_protection(struct vm_area_struct *vma,
2069 unsigned long address, unsigned long end, pgprot_t newprot)
2071 struct mm_struct *mm = vma->vm_mm;
2072 unsigned long start = address;
2075 struct hstate *h = hstate_vma(vma);
2077 BUG_ON(address >= end);
2078 flush_cache_range(vma, address, end);
2080 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2081 spin_lock(&mm->page_table_lock);
2082 for (; address < end; address += huge_page_size(h)) {
2083 ptep = huge_pte_offset(mm, address);
2086 if (huge_pmd_unshare(mm, &address, ptep))
2088 if (!huge_pte_none(huge_ptep_get(ptep))) {
2089 pte = huge_ptep_get_and_clear(mm, address, ptep);
2090 pte = pte_mkhuge(pte_modify(pte, newprot));
2091 set_huge_pte_at(mm, address, ptep, pte);
2094 spin_unlock(&mm->page_table_lock);
2095 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2097 flush_tlb_range(vma, start, end);
2100 int hugetlb_reserve_pages(struct inode *inode,
2102 struct vm_area_struct *vma)
2105 struct hstate *h = hstate_inode(inode);
2107 if (vma && vma->vm_flags & VM_NORESERVE)
2111 * Shared mappings base their reservation on the number of pages that
2112 * are already allocated on behalf of the file. Private mappings need
2113 * to reserve the full area even if read-only as mprotect() may be
2114 * called to make the mapping read-write. Assume !vma is a shm mapping
2116 if (!vma || vma->vm_flags & VM_SHARED)
2117 chg = region_chg(&inode->i_mapping->private_list, from, to);
2119 struct resv_map *resv_map = resv_map_alloc();
2125 set_vma_resv_map(vma, resv_map);
2126 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2132 if (hugetlb_get_quota(inode->i_mapping, chg))
2134 ret = hugetlb_acct_memory(h, chg);
2136 hugetlb_put_quota(inode->i_mapping, chg);
2139 if (!vma || vma->vm_flags & VM_SHARED)
2140 region_add(&inode->i_mapping->private_list, from, to);
2144 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2146 struct hstate *h = hstate_inode(inode);
2147 long chg = region_truncate(&inode->i_mapping->private_list, offset);
2149 spin_lock(&inode->i_lock);
2150 inode->i_blocks -= blocks_per_huge_page(h);
2151 spin_unlock(&inode->i_lock);
2153 hugetlb_put_quota(inode->i_mapping, (chg - freed));
2154 hugetlb_acct_memory(h, -(chg - freed));