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>
19 #include <asm/pgtable.h>
21 #include <linux/hugetlb.h>
24 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
25 static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
26 static unsigned long surplus_huge_pages;
27 static unsigned long nr_overcommit_huge_pages;
28 unsigned long max_huge_pages;
29 unsigned long sysctl_overcommit_huge_pages;
30 static struct list_head hugepage_freelists[MAX_NUMNODES];
31 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
32 static unsigned int free_huge_pages_node[MAX_NUMNODES];
33 static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
34 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
35 unsigned long hugepages_treat_as_movable;
36 static int hugetlb_next_nid;
39 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
41 static DEFINE_SPINLOCK(hugetlb_lock);
44 * Region tracking -- allows tracking of reservations and instantiated pages
45 * across the pages in a mapping.
48 struct list_head link;
53 static long region_add(struct list_head *head, long f, long t)
55 struct file_region *rg, *nrg, *trg;
57 /* Locate the region we are either in or before. */
58 list_for_each_entry(rg, head, link)
62 /* Round our left edge to the current segment if it encloses us. */
66 /* Check for and consume any regions we now overlap with. */
68 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
69 if (&rg->link == head)
74 /* If this area reaches higher then extend our area to
75 * include it completely. If this is not the first area
76 * which we intend to reuse, free it. */
89 static long region_chg(struct list_head *head, long f, long t)
91 struct file_region *rg, *nrg;
94 /* Locate the region we are before or in. */
95 list_for_each_entry(rg, head, link)
99 /* If we are below the current region then a new region is required.
100 * Subtle, allocate a new region at the position but make it zero
101 * size such that we can guarantee to record the reservation. */
102 if (&rg->link == head || t < rg->from) {
103 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
108 INIT_LIST_HEAD(&nrg->link);
109 list_add(&nrg->link, rg->link.prev);
114 /* Round our left edge to the current segment if it encloses us. */
119 /* Check for and consume any regions we now overlap with. */
120 list_for_each_entry(rg, rg->link.prev, link) {
121 if (&rg->link == head)
126 /* We overlap with this area, if it extends futher than
127 * us then we must extend ourselves. Account for its
128 * existing reservation. */
133 chg -= rg->to - rg->from;
138 static long region_truncate(struct list_head *head, long end)
140 struct file_region *rg, *trg;
143 /* Locate the region we are either in or before. */
144 list_for_each_entry(rg, head, link)
147 if (&rg->link == head)
150 /* If we are in the middle of a region then adjust it. */
151 if (end > rg->from) {
154 rg = list_entry(rg->link.next, typeof(*rg), link);
157 /* Drop any remaining regions. */
158 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
159 if (&rg->link == head)
161 chg += rg->to - rg->from;
169 * Convert the address within this vma to the page offset within
170 * the mapping, in base page units.
172 static pgoff_t vma_page_offset(struct vm_area_struct *vma,
173 unsigned long address)
175 return ((address - vma->vm_start) >> PAGE_SHIFT) +
176 (vma->vm_pgoff >> PAGE_SHIFT);
180 * Convert the address within this vma to the page offset within
181 * the mapping, in pagecache page units; huge pages here.
183 static pgoff_t vma_pagecache_offset(struct vm_area_struct *vma,
184 unsigned long address)
186 return ((address - vma->vm_start) >> HPAGE_SHIFT) +
187 (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
190 #define HPAGE_RESV_OWNER (1UL << (BITS_PER_LONG - 1))
191 #define HPAGE_RESV_UNMAPPED (1UL << (BITS_PER_LONG - 2))
192 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
194 * These helpers are used to track how many pages are reserved for
195 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
196 * is guaranteed to have their future faults succeed.
198 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
199 * the reserve counters are updated with the hugetlb_lock held. It is safe
200 * to reset the VMA at fork() time as it is not in use yet and there is no
201 * chance of the global counters getting corrupted as a result of the values.
203 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
205 return (unsigned long)vma->vm_private_data;
208 static void set_vma_private_data(struct vm_area_struct *vma,
211 vma->vm_private_data = (void *)value;
214 static unsigned long vma_resv_huge_pages(struct vm_area_struct *vma)
216 VM_BUG_ON(!is_vm_hugetlb_page(vma));
217 if (!(vma->vm_flags & VM_SHARED))
218 return get_vma_private_data(vma) & ~HPAGE_RESV_MASK;
222 static void set_vma_resv_huge_pages(struct vm_area_struct *vma,
223 unsigned long reserve)
225 VM_BUG_ON(!is_vm_hugetlb_page(vma));
226 VM_BUG_ON(vma->vm_flags & VM_SHARED);
228 set_vma_private_data(vma,
229 (get_vma_private_data(vma) & HPAGE_RESV_MASK) | reserve);
232 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
234 VM_BUG_ON(!is_vm_hugetlb_page(vma));
235 VM_BUG_ON(vma->vm_flags & VM_SHARED);
237 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
240 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
242 VM_BUG_ON(!is_vm_hugetlb_page(vma));
244 return (get_vma_private_data(vma) & flag) != 0;
247 /* Decrement the reserved pages in the hugepage pool by one */
248 static void decrement_hugepage_resv_vma(struct vm_area_struct *vma)
250 if (vma->vm_flags & VM_SHARED) {
251 /* Shared mappings always use reserves */
255 * Only the process that called mmap() has reserves for
258 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
259 unsigned long flags, reserve;
261 flags = (unsigned long)vma->vm_private_data &
263 reserve = (unsigned long)vma->vm_private_data - 1;
264 vma->vm_private_data = (void *)(reserve | flags);
269 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
270 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
272 VM_BUG_ON(!is_vm_hugetlb_page(vma));
273 if (!(vma->vm_flags & VM_SHARED))
274 vma->vm_private_data = (void *)0;
277 /* Returns true if the VMA has associated reserve pages */
278 static int vma_has_private_reserves(struct vm_area_struct *vma)
280 if (vma->vm_flags & VM_SHARED)
282 if (!vma_resv_huge_pages(vma))
287 static void clear_huge_page(struct page *page, unsigned long addr)
292 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
294 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
298 static void copy_huge_page(struct page *dst, struct page *src,
299 unsigned long addr, struct vm_area_struct *vma)
304 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
306 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
310 static void enqueue_huge_page(struct page *page)
312 int nid = page_to_nid(page);
313 list_add(&page->lru, &hugepage_freelists[nid]);
315 free_huge_pages_node[nid]++;
318 static struct page *dequeue_huge_page(void)
321 struct page *page = NULL;
323 for (nid = 0; nid < MAX_NUMNODES; ++nid) {
324 if (!list_empty(&hugepage_freelists[nid])) {
325 page = list_entry(hugepage_freelists[nid].next,
327 list_del(&page->lru);
329 free_huge_pages_node[nid]--;
336 static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma,
337 unsigned long address, int avoid_reserve)
340 struct page *page = NULL;
341 struct mempolicy *mpol;
342 nodemask_t *nodemask;
343 struct zonelist *zonelist = huge_zonelist(vma, address,
344 htlb_alloc_mask, &mpol, &nodemask);
349 * A child process with MAP_PRIVATE mappings created by their parent
350 * have no page reserves. This check ensures that reservations are
351 * not "stolen". The child may still get SIGKILLed
353 if (!vma_has_private_reserves(vma) &&
354 free_huge_pages - resv_huge_pages == 0)
357 /* If reserves cannot be used, ensure enough pages are in the pool */
358 if (avoid_reserve && free_huge_pages - resv_huge_pages == 0)
361 for_each_zone_zonelist_nodemask(zone, z, zonelist,
362 MAX_NR_ZONES - 1, nodemask) {
363 nid = zone_to_nid(zone);
364 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
365 !list_empty(&hugepage_freelists[nid])) {
366 page = list_entry(hugepage_freelists[nid].next,
368 list_del(&page->lru);
370 free_huge_pages_node[nid]--;
373 decrement_hugepage_resv_vma(vma);
382 static void update_and_free_page(struct page *page)
386 nr_huge_pages_node[page_to_nid(page)]--;
387 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
388 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
389 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
390 1 << PG_private | 1<< PG_writeback);
392 set_compound_page_dtor(page, NULL);
393 set_page_refcounted(page);
394 arch_release_hugepage(page);
395 __free_pages(page, HUGETLB_PAGE_ORDER);
398 static void free_huge_page(struct page *page)
400 int nid = page_to_nid(page);
401 struct address_space *mapping;
403 mapping = (struct address_space *) page_private(page);
404 set_page_private(page, 0);
405 BUG_ON(page_count(page));
406 INIT_LIST_HEAD(&page->lru);
408 spin_lock(&hugetlb_lock);
409 if (surplus_huge_pages_node[nid]) {
410 update_and_free_page(page);
411 surplus_huge_pages--;
412 surplus_huge_pages_node[nid]--;
414 enqueue_huge_page(page);
416 spin_unlock(&hugetlb_lock);
418 hugetlb_put_quota(mapping, 1);
422 * Increment or decrement surplus_huge_pages. Keep node-specific counters
423 * balanced by operating on them in a round-robin fashion.
424 * Returns 1 if an adjustment was made.
426 static int adjust_pool_surplus(int delta)
432 VM_BUG_ON(delta != -1 && delta != 1);
434 nid = next_node(nid, node_online_map);
435 if (nid == MAX_NUMNODES)
436 nid = first_node(node_online_map);
438 /* To shrink on this node, there must be a surplus page */
439 if (delta < 0 && !surplus_huge_pages_node[nid])
441 /* Surplus cannot exceed the total number of pages */
442 if (delta > 0 && surplus_huge_pages_node[nid] >=
443 nr_huge_pages_node[nid])
446 surplus_huge_pages += delta;
447 surplus_huge_pages_node[nid] += delta;
450 } while (nid != prev_nid);
456 static struct page *alloc_fresh_huge_page_node(int nid)
460 page = alloc_pages_node(nid,
461 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
462 __GFP_REPEAT|__GFP_NOWARN,
465 if (arch_prepare_hugepage(page)) {
466 __free_pages(page, HUGETLB_PAGE_ORDER);
469 set_compound_page_dtor(page, free_huge_page);
470 spin_lock(&hugetlb_lock);
472 nr_huge_pages_node[nid]++;
473 spin_unlock(&hugetlb_lock);
474 put_page(page); /* free it into the hugepage allocator */
480 static int alloc_fresh_huge_page(void)
487 start_nid = hugetlb_next_nid;
490 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
494 * Use a helper variable to find the next node and then
495 * copy it back to hugetlb_next_nid afterwards:
496 * otherwise there's a window in which a racer might
497 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
498 * But we don't need to use a spin_lock here: it really
499 * doesn't matter if occasionally a racer chooses the
500 * same nid as we do. Move nid forward in the mask even
501 * if we just successfully allocated a hugepage so that
502 * the next caller gets hugepages on the next node.
504 next_nid = next_node(hugetlb_next_nid, node_online_map);
505 if (next_nid == MAX_NUMNODES)
506 next_nid = first_node(node_online_map);
507 hugetlb_next_nid = next_nid;
508 } while (!page && hugetlb_next_nid != start_nid);
511 count_vm_event(HTLB_BUDDY_PGALLOC);
513 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
518 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
519 unsigned long address)
525 * Assume we will successfully allocate the surplus page to
526 * prevent racing processes from causing the surplus to exceed
529 * This however introduces a different race, where a process B
530 * tries to grow the static hugepage pool while alloc_pages() is
531 * called by process A. B will only examine the per-node
532 * counters in determining if surplus huge pages can be
533 * converted to normal huge pages in adjust_pool_surplus(). A
534 * won't be able to increment the per-node counter, until the
535 * lock is dropped by B, but B doesn't drop hugetlb_lock until
536 * no more huge pages can be converted from surplus to normal
537 * state (and doesn't try to convert again). Thus, we have a
538 * case where a surplus huge page exists, the pool is grown, and
539 * the surplus huge page still exists after, even though it
540 * should just have been converted to a normal huge page. This
541 * does not leak memory, though, as the hugepage will be freed
542 * once it is out of use. It also does not allow the counters to
543 * go out of whack in adjust_pool_surplus() as we don't modify
544 * the node values until we've gotten the hugepage and only the
545 * per-node value is checked there.
547 spin_lock(&hugetlb_lock);
548 if (surplus_huge_pages >= nr_overcommit_huge_pages) {
549 spin_unlock(&hugetlb_lock);
553 surplus_huge_pages++;
555 spin_unlock(&hugetlb_lock);
557 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
558 __GFP_REPEAT|__GFP_NOWARN,
561 spin_lock(&hugetlb_lock);
564 * This page is now managed by the hugetlb allocator and has
565 * no users -- drop the buddy allocator's reference.
567 put_page_testzero(page);
568 VM_BUG_ON(page_count(page));
569 nid = page_to_nid(page);
570 set_compound_page_dtor(page, free_huge_page);
572 * We incremented the global counters already
574 nr_huge_pages_node[nid]++;
575 surplus_huge_pages_node[nid]++;
576 __count_vm_event(HTLB_BUDDY_PGALLOC);
579 surplus_huge_pages--;
580 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
582 spin_unlock(&hugetlb_lock);
588 * Increase the hugetlb pool such that it can accomodate a reservation
591 static int gather_surplus_pages(int delta)
593 struct list_head surplus_list;
594 struct page *page, *tmp;
596 int needed, allocated;
598 needed = (resv_huge_pages + delta) - free_huge_pages;
600 resv_huge_pages += delta;
605 INIT_LIST_HEAD(&surplus_list);
609 spin_unlock(&hugetlb_lock);
610 for (i = 0; i < needed; i++) {
611 page = alloc_buddy_huge_page(NULL, 0);
614 * We were not able to allocate enough pages to
615 * satisfy the entire reservation so we free what
616 * we've allocated so far.
618 spin_lock(&hugetlb_lock);
623 list_add(&page->lru, &surplus_list);
628 * After retaking hugetlb_lock, we need to recalculate 'needed'
629 * because either resv_huge_pages or free_huge_pages may have changed.
631 spin_lock(&hugetlb_lock);
632 needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
637 * The surplus_list now contains _at_least_ the number of extra pages
638 * needed to accomodate the reservation. Add the appropriate number
639 * of pages to the hugetlb pool and free the extras back to the buddy
640 * allocator. Commit the entire reservation here to prevent another
641 * process from stealing the pages as they are added to the pool but
642 * before they are reserved.
645 resv_huge_pages += delta;
648 /* Free the needed pages to the hugetlb pool */
649 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
652 list_del(&page->lru);
653 enqueue_huge_page(page);
656 /* Free unnecessary surplus pages to the buddy allocator */
657 if (!list_empty(&surplus_list)) {
658 spin_unlock(&hugetlb_lock);
659 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
660 list_del(&page->lru);
662 * The page has a reference count of zero already, so
663 * call free_huge_page directly instead of using
664 * put_page. This must be done with hugetlb_lock
665 * unlocked which is safe because free_huge_page takes
666 * hugetlb_lock before deciding how to free the page.
668 free_huge_page(page);
670 spin_lock(&hugetlb_lock);
677 * When releasing a hugetlb pool reservation, any surplus pages that were
678 * allocated to satisfy the reservation must be explicitly freed if they were
681 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
685 unsigned long nr_pages;
688 * We want to release as many surplus pages as possible, spread
689 * evenly across all nodes. Iterate across all nodes until we
690 * can no longer free unreserved surplus pages. This occurs when
691 * the nodes with surplus pages have no free pages.
693 unsigned long remaining_iterations = num_online_nodes();
695 /* Uncommit the reservation */
696 resv_huge_pages -= unused_resv_pages;
698 nr_pages = min(unused_resv_pages, surplus_huge_pages);
700 while (remaining_iterations-- && nr_pages) {
701 nid = next_node(nid, node_online_map);
702 if (nid == MAX_NUMNODES)
703 nid = first_node(node_online_map);
705 if (!surplus_huge_pages_node[nid])
708 if (!list_empty(&hugepage_freelists[nid])) {
709 page = list_entry(hugepage_freelists[nid].next,
711 list_del(&page->lru);
712 update_and_free_page(page);
714 free_huge_pages_node[nid]--;
715 surplus_huge_pages--;
716 surplus_huge_pages_node[nid]--;
718 remaining_iterations = num_online_nodes();
723 static struct page *alloc_huge_page(struct vm_area_struct *vma,
724 unsigned long addr, int avoid_reserve)
727 struct address_space *mapping = vma->vm_file->f_mapping;
728 struct inode *inode = mapping->host;
729 unsigned int chg = 0;
732 * Processes that did not create the mapping will have no reserves and
733 * will not have accounted against quota. Check that the quota can be
734 * made before satisfying the allocation
736 if (!(vma->vm_flags & VM_SHARED) &&
737 !is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
739 if (hugetlb_get_quota(inode->i_mapping, chg))
740 return ERR_PTR(-ENOSPC);
743 spin_lock(&hugetlb_lock);
744 page = dequeue_huge_page_vma(vma, addr, avoid_reserve);
745 spin_unlock(&hugetlb_lock);
748 page = alloc_buddy_huge_page(vma, addr);
750 hugetlb_put_quota(inode->i_mapping, chg);
751 return ERR_PTR(-VM_FAULT_OOM);
755 set_page_refcounted(page);
756 set_page_private(page, (unsigned long) mapping);
761 static int __init hugetlb_init(void)
765 if (HPAGE_SHIFT == 0)
768 for (i = 0; i < MAX_NUMNODES; ++i)
769 INIT_LIST_HEAD(&hugepage_freelists[i]);
771 hugetlb_next_nid = first_node(node_online_map);
773 for (i = 0; i < max_huge_pages; ++i) {
774 if (!alloc_fresh_huge_page())
777 max_huge_pages = free_huge_pages = nr_huge_pages = i;
778 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
781 module_init(hugetlb_init);
783 static int __init hugetlb_setup(char *s)
785 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
789 __setup("hugepages=", hugetlb_setup);
791 static unsigned int cpuset_mems_nr(unsigned int *array)
796 for_each_node_mask(node, cpuset_current_mems_allowed)
803 #ifdef CONFIG_HIGHMEM
804 static void try_to_free_low(unsigned long count)
808 for (i = 0; i < MAX_NUMNODES; ++i) {
809 struct page *page, *next;
810 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
811 if (count >= nr_huge_pages)
813 if (PageHighMem(page))
815 list_del(&page->lru);
816 update_and_free_page(page);
818 free_huge_pages_node[page_to_nid(page)]--;
823 static inline void try_to_free_low(unsigned long count)
828 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
829 static unsigned long set_max_huge_pages(unsigned long count)
831 unsigned long min_count, ret;
834 * Increase the pool size
835 * First take pages out of surplus state. Then make up the
836 * remaining difference by allocating fresh huge pages.
838 * We might race with alloc_buddy_huge_page() here and be unable
839 * to convert a surplus huge page to a normal huge page. That is
840 * not critical, though, it just means the overall size of the
841 * pool might be one hugepage larger than it needs to be, but
842 * within all the constraints specified by the sysctls.
844 spin_lock(&hugetlb_lock);
845 while (surplus_huge_pages && count > persistent_huge_pages) {
846 if (!adjust_pool_surplus(-1))
850 while (count > persistent_huge_pages) {
852 * If this allocation races such that we no longer need the
853 * page, free_huge_page will handle it by freeing the page
854 * and reducing the surplus.
856 spin_unlock(&hugetlb_lock);
857 ret = alloc_fresh_huge_page();
858 spin_lock(&hugetlb_lock);
865 * Decrease the pool size
866 * First return free pages to the buddy allocator (being careful
867 * to keep enough around to satisfy reservations). Then place
868 * pages into surplus state as needed so the pool will shrink
869 * to the desired size as pages become free.
871 * By placing pages into the surplus state independent of the
872 * overcommit value, we are allowing the surplus pool size to
873 * exceed overcommit. There are few sane options here. Since
874 * alloc_buddy_huge_page() is checking the global counter,
875 * though, we'll note that we're not allowed to exceed surplus
876 * and won't grow the pool anywhere else. Not until one of the
877 * sysctls are changed, or the surplus pages go out of use.
879 min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
880 min_count = max(count, min_count);
881 try_to_free_low(min_count);
882 while (min_count < persistent_huge_pages) {
883 struct page *page = dequeue_huge_page();
886 update_and_free_page(page);
888 while (count < persistent_huge_pages) {
889 if (!adjust_pool_surplus(1))
893 ret = persistent_huge_pages;
894 spin_unlock(&hugetlb_lock);
898 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
899 struct file *file, void __user *buffer,
900 size_t *length, loff_t *ppos)
902 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
903 max_huge_pages = set_max_huge_pages(max_huge_pages);
907 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
908 struct file *file, void __user *buffer,
909 size_t *length, loff_t *ppos)
911 proc_dointvec(table, write, file, buffer, length, ppos);
912 if (hugepages_treat_as_movable)
913 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
915 htlb_alloc_mask = GFP_HIGHUSER;
919 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
920 struct file *file, void __user *buffer,
921 size_t *length, loff_t *ppos)
923 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
924 spin_lock(&hugetlb_lock);
925 nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
926 spin_unlock(&hugetlb_lock);
930 #endif /* CONFIG_SYSCTL */
932 int hugetlb_report_meminfo(char *buf)
935 "HugePages_Total: %5lu\n"
936 "HugePages_Free: %5lu\n"
937 "HugePages_Rsvd: %5lu\n"
938 "HugePages_Surp: %5lu\n"
939 "Hugepagesize: %5lu kB\n",
947 int hugetlb_report_node_meminfo(int nid, char *buf)
950 "Node %d HugePages_Total: %5u\n"
951 "Node %d HugePages_Free: %5u\n"
952 "Node %d HugePages_Surp: %5u\n",
953 nid, nr_huge_pages_node[nid],
954 nid, free_huge_pages_node[nid],
955 nid, surplus_huge_pages_node[nid]);
958 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
959 unsigned long hugetlb_total_pages(void)
961 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
964 static int hugetlb_acct_memory(long delta)
968 spin_lock(&hugetlb_lock);
970 * When cpuset is configured, it breaks the strict hugetlb page
971 * reservation as the accounting is done on a global variable. Such
972 * reservation is completely rubbish in the presence of cpuset because
973 * the reservation is not checked against page availability for the
974 * current cpuset. Application can still potentially OOM'ed by kernel
975 * with lack of free htlb page in cpuset that the task is in.
976 * Attempt to enforce strict accounting with cpuset is almost
977 * impossible (or too ugly) because cpuset is too fluid that
978 * task or memory node can be dynamically moved between cpusets.
980 * The change of semantics for shared hugetlb mapping with cpuset is
981 * undesirable. However, in order to preserve some of the semantics,
982 * we fall back to check against current free page availability as
983 * a best attempt and hopefully to minimize the impact of changing
984 * semantics that cpuset has.
987 if (gather_surplus_pages(delta) < 0)
990 if (delta > cpuset_mems_nr(free_huge_pages_node)) {
991 return_unused_surplus_pages(delta);
998 return_unused_surplus_pages((unsigned long) -delta);
1001 spin_unlock(&hugetlb_lock);
1005 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
1007 unsigned long reserve = vma_resv_huge_pages(vma);
1009 hugetlb_acct_memory(-reserve);
1013 * We cannot handle pagefaults against hugetlb pages at all. They cause
1014 * handle_mm_fault() to try to instantiate regular-sized pages in the
1015 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
1018 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1024 struct vm_operations_struct hugetlb_vm_ops = {
1025 .fault = hugetlb_vm_op_fault,
1026 .close = hugetlb_vm_op_close,
1029 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
1036 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
1038 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
1040 entry = pte_mkyoung(entry);
1041 entry = pte_mkhuge(entry);
1046 static void set_huge_ptep_writable(struct vm_area_struct *vma,
1047 unsigned long address, pte_t *ptep)
1051 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
1052 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
1053 update_mmu_cache(vma, address, entry);
1058 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
1059 struct vm_area_struct *vma)
1061 pte_t *src_pte, *dst_pte, entry;
1062 struct page *ptepage;
1066 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
1068 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
1069 src_pte = huge_pte_offset(src, addr);
1072 dst_pte = huge_pte_alloc(dst, addr);
1076 /* If the pagetables are shared don't copy or take references */
1077 if (dst_pte == src_pte)
1080 spin_lock(&dst->page_table_lock);
1081 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
1082 if (!huge_pte_none(huge_ptep_get(src_pte))) {
1084 huge_ptep_set_wrprotect(src, addr, src_pte);
1085 entry = huge_ptep_get(src_pte);
1086 ptepage = pte_page(entry);
1088 set_huge_pte_at(dst, addr, dst_pte, entry);
1090 spin_unlock(&src->page_table_lock);
1091 spin_unlock(&dst->page_table_lock);
1099 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1100 unsigned long end, struct page *ref_page)
1102 struct mm_struct *mm = vma->vm_mm;
1103 unsigned long address;
1109 * A page gathering list, protected by per file i_mmap_lock. The
1110 * lock is used to avoid list corruption from multiple unmapping
1111 * of the same page since we are using page->lru.
1113 LIST_HEAD(page_list);
1115 WARN_ON(!is_vm_hugetlb_page(vma));
1116 BUG_ON(start & ~HPAGE_MASK);
1117 BUG_ON(end & ~HPAGE_MASK);
1119 spin_lock(&mm->page_table_lock);
1120 for (address = start; address < end; address += HPAGE_SIZE) {
1121 ptep = huge_pte_offset(mm, address);
1125 if (huge_pmd_unshare(mm, &address, ptep))
1129 * If a reference page is supplied, it is because a specific
1130 * page is being unmapped, not a range. Ensure the page we
1131 * are about to unmap is the actual page of interest.
1134 pte = huge_ptep_get(ptep);
1135 if (huge_pte_none(pte))
1137 page = pte_page(pte);
1138 if (page != ref_page)
1142 * Mark the VMA as having unmapped its page so that
1143 * future faults in this VMA will fail rather than
1144 * looking like data was lost
1146 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
1149 pte = huge_ptep_get_and_clear(mm, address, ptep);
1150 if (huge_pte_none(pte))
1153 page = pte_page(pte);
1155 set_page_dirty(page);
1156 list_add(&page->lru, &page_list);
1158 spin_unlock(&mm->page_table_lock);
1159 flush_tlb_range(vma, start, end);
1160 list_for_each_entry_safe(page, tmp, &page_list, lru) {
1161 list_del(&page->lru);
1166 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1167 unsigned long end, struct page *ref_page)
1170 * It is undesirable to test vma->vm_file as it should be non-null
1171 * for valid hugetlb area. However, vm_file will be NULL in the error
1172 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
1173 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
1174 * to clean up. Since no pte has actually been setup, it is safe to
1175 * do nothing in this case.
1178 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1179 __unmap_hugepage_range(vma, start, end, ref_page);
1180 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1185 * This is called when the original mapper is failing to COW a MAP_PRIVATE
1186 * mappping it owns the reserve page for. The intention is to unmap the page
1187 * from other VMAs and let the children be SIGKILLed if they are faulting the
1190 int unmap_ref_private(struct mm_struct *mm,
1191 struct vm_area_struct *vma,
1193 unsigned long address)
1195 struct vm_area_struct *iter_vma;
1196 struct address_space *mapping;
1197 struct prio_tree_iter iter;
1201 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1202 * from page cache lookup which is in HPAGE_SIZE units.
1204 address = address & huge_page_mask(hstate_vma(vma));
1205 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1206 + (vma->vm_pgoff >> PAGE_SHIFT);
1207 mapping = (struct address_space *)page_private(page);
1209 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1210 /* Do not unmap the current VMA */
1211 if (iter_vma == vma)
1215 * Unmap the page from other VMAs without their own reserves.
1216 * They get marked to be SIGKILLed if they fault in these
1217 * areas. This is because a future no-page fault on this VMA
1218 * could insert a zeroed page instead of the data existing
1219 * from the time of fork. This would look like data corruption
1221 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1222 unmap_hugepage_range(iter_vma,
1223 address, address + HPAGE_SIZE,
1230 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1231 unsigned long address, pte_t *ptep, pte_t pte,
1232 struct page *pagecache_page)
1234 struct page *old_page, *new_page;
1236 int outside_reserve = 0;
1238 old_page = pte_page(pte);
1241 /* If no-one else is actually using this page, avoid the copy
1242 * and just make the page writable */
1243 avoidcopy = (page_count(old_page) == 1);
1245 set_huge_ptep_writable(vma, address, ptep);
1250 * If the process that created a MAP_PRIVATE mapping is about to
1251 * perform a COW due to a shared page count, attempt to satisfy
1252 * the allocation without using the existing reserves. The pagecache
1253 * page is used to determine if the reserve at this address was
1254 * consumed or not. If reserves were used, a partial faulted mapping
1255 * at the time of fork() could consume its reserves on COW instead
1256 * of the full address range.
1258 if (!(vma->vm_flags & VM_SHARED) &&
1259 is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1260 old_page != pagecache_page)
1261 outside_reserve = 1;
1263 page_cache_get(old_page);
1264 new_page = alloc_huge_page(vma, address, outside_reserve);
1266 if (IS_ERR(new_page)) {
1267 page_cache_release(old_page);
1270 * If a process owning a MAP_PRIVATE mapping fails to COW,
1271 * it is due to references held by a child and an insufficient
1272 * huge page pool. To guarantee the original mappers
1273 * reliability, unmap the page from child processes. The child
1274 * may get SIGKILLed if it later faults.
1276 if (outside_reserve) {
1277 BUG_ON(huge_pte_none(pte));
1278 if (unmap_ref_private(mm, vma, old_page, address)) {
1279 BUG_ON(page_count(old_page) != 1);
1280 BUG_ON(huge_pte_none(pte));
1281 goto retry_avoidcopy;
1286 return -PTR_ERR(new_page);
1289 spin_unlock(&mm->page_table_lock);
1290 copy_huge_page(new_page, old_page, address, vma);
1291 __SetPageUptodate(new_page);
1292 spin_lock(&mm->page_table_lock);
1294 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
1295 if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1297 huge_ptep_clear_flush(vma, address, ptep);
1298 set_huge_pte_at(mm, address, ptep,
1299 make_huge_pte(vma, new_page, 1));
1300 /* Make the old page be freed below */
1301 new_page = old_page;
1303 page_cache_release(new_page);
1304 page_cache_release(old_page);
1308 /* Return the pagecache page at a given address within a VMA */
1309 static struct page *hugetlbfs_pagecache_page(struct vm_area_struct *vma,
1310 unsigned long address)
1312 struct address_space *mapping;
1315 mapping = vma->vm_file->f_mapping;
1316 idx = vma_pagecache_offset(vma, address);
1318 return find_lock_page(mapping, idx);
1321 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1322 unsigned long address, pte_t *ptep, int write_access)
1324 int ret = VM_FAULT_SIGBUS;
1328 struct address_space *mapping;
1332 * Currently, we are forced to kill the process in the event the
1333 * original mapper has unmapped pages from the child due to a failed
1334 * COW. Warn that such a situation has occured as it may not be obvious
1336 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
1338 "PID %d killed due to inadequate hugepage pool\n",
1343 mapping = vma->vm_file->f_mapping;
1344 idx = vma_pagecache_offset(vma, address);
1347 * Use page lock to guard against racing truncation
1348 * before we get page_table_lock.
1351 page = find_lock_page(mapping, idx);
1353 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
1356 page = alloc_huge_page(vma, address, 0);
1358 ret = -PTR_ERR(page);
1361 clear_huge_page(page, address);
1362 __SetPageUptodate(page);
1364 if (vma->vm_flags & VM_SHARED) {
1366 struct inode *inode = mapping->host;
1368 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
1376 spin_lock(&inode->i_lock);
1377 inode->i_blocks += BLOCKS_PER_HUGEPAGE;
1378 spin_unlock(&inode->i_lock);
1383 spin_lock(&mm->page_table_lock);
1384 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
1389 if (!huge_pte_none(huge_ptep_get(ptep)))
1392 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
1393 && (vma->vm_flags & VM_SHARED)));
1394 set_huge_pte_at(mm, address, ptep, new_pte);
1396 if (write_access && !(vma->vm_flags & VM_SHARED)) {
1397 /* Optimization, do the COW without a second fault */
1398 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
1401 spin_unlock(&mm->page_table_lock);
1407 spin_unlock(&mm->page_table_lock);
1413 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
1414 unsigned long address, int write_access)
1419 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
1421 ptep = huge_pte_alloc(mm, address);
1423 return VM_FAULT_OOM;
1426 * Serialize hugepage allocation and instantiation, so that we don't
1427 * get spurious allocation failures if two CPUs race to instantiate
1428 * the same page in the page cache.
1430 mutex_lock(&hugetlb_instantiation_mutex);
1431 entry = huge_ptep_get(ptep);
1432 if (huge_pte_none(entry)) {
1433 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1434 mutex_unlock(&hugetlb_instantiation_mutex);
1440 spin_lock(&mm->page_table_lock);
1441 /* Check for a racing update before calling hugetlb_cow */
1442 if (likely(pte_same(entry, huge_ptep_get(ptep))))
1443 if (write_access && !pte_write(entry)) {
1445 page = hugetlbfs_pagecache_page(vma, address);
1446 ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
1452 spin_unlock(&mm->page_table_lock);
1453 mutex_unlock(&hugetlb_instantiation_mutex);
1458 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1459 struct page **pages, struct vm_area_struct **vmas,
1460 unsigned long *position, int *length, int i,
1463 unsigned long pfn_offset;
1464 unsigned long vaddr = *position;
1465 int remainder = *length;
1467 spin_lock(&mm->page_table_lock);
1468 while (vaddr < vma->vm_end && remainder) {
1473 * Some archs (sparc64, sh*) have multiple pte_ts to
1474 * each hugepage. We have to make * sure we get the
1475 * first, for the page indexing below to work.
1477 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
1479 if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
1480 (write && !pte_write(huge_ptep_get(pte)))) {
1483 spin_unlock(&mm->page_table_lock);
1484 ret = hugetlb_fault(mm, vma, vaddr, write);
1485 spin_lock(&mm->page_table_lock);
1486 if (!(ret & VM_FAULT_ERROR))
1495 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
1496 page = pte_page(huge_ptep_get(pte));
1500 pages[i] = page + pfn_offset;
1510 if (vaddr < vma->vm_end && remainder &&
1511 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1513 * We use pfn_offset to avoid touching the pageframes
1514 * of this compound page.
1519 spin_unlock(&mm->page_table_lock);
1520 *length = remainder;
1526 void hugetlb_change_protection(struct vm_area_struct *vma,
1527 unsigned long address, unsigned long end, pgprot_t newprot)
1529 struct mm_struct *mm = vma->vm_mm;
1530 unsigned long start = address;
1534 BUG_ON(address >= end);
1535 flush_cache_range(vma, address, end);
1537 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1538 spin_lock(&mm->page_table_lock);
1539 for (; address < end; address += HPAGE_SIZE) {
1540 ptep = huge_pte_offset(mm, address);
1543 if (huge_pmd_unshare(mm, &address, ptep))
1545 if (!huge_pte_none(huge_ptep_get(ptep))) {
1546 pte = huge_ptep_get_and_clear(mm, address, ptep);
1547 pte = pte_mkhuge(pte_modify(pte, newprot));
1548 set_huge_pte_at(mm, address, ptep, pte);
1551 spin_unlock(&mm->page_table_lock);
1552 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1554 flush_tlb_range(vma, start, end);
1557 int hugetlb_reserve_pages(struct inode *inode,
1559 struct vm_area_struct *vma)
1564 * Shared mappings base their reservation on the number of pages that
1565 * are already allocated on behalf of the file. Private mappings need
1566 * to reserve the full area even if read-only as mprotect() may be
1567 * called to make the mapping read-write. Assume !vma is a shm mapping
1569 if (!vma || vma->vm_flags & VM_SHARED)
1570 chg = region_chg(&inode->i_mapping->private_list, from, to);
1573 set_vma_resv_huge_pages(vma, chg);
1574 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
1580 if (hugetlb_get_quota(inode->i_mapping, chg))
1582 ret = hugetlb_acct_memory(chg);
1584 hugetlb_put_quota(inode->i_mapping, chg);
1587 if (!vma || vma->vm_flags & VM_SHARED)
1588 region_add(&inode->i_mapping->private_list, from, to);
1592 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1594 long chg = region_truncate(&inode->i_mapping->private_list, offset);
1596 spin_lock(&inode->i_lock);
1597 inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1598 spin_unlock(&inode->i_lock);
1600 hugetlb_put_quota(inode->i_mapping, (chg - freed));
1601 hugetlb_acct_memory(-(chg - freed));