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);
43 #define HPAGE_RESV_OWNER (1UL << (BITS_PER_LONG - 1))
44 #define HPAGE_RESV_UNMAPPED (1UL << (BITS_PER_LONG - 2))
45 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
47 * These helpers are used to track how many pages are reserved for
48 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
49 * is guaranteed to have their future faults succeed.
51 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
52 * the reserve counters are updated with the hugetlb_lock held. It is safe
53 * to reset the VMA at fork() time as it is not in use yet and there is no
54 * chance of the global counters getting corrupted as a result of the values.
56 static unsigned long vma_resv_huge_pages(struct vm_area_struct *vma)
58 VM_BUG_ON(!is_vm_hugetlb_page(vma));
59 if (!(vma->vm_flags & VM_SHARED))
60 return (unsigned long)vma->vm_private_data & ~HPAGE_RESV_MASK;
64 static void set_vma_resv_huge_pages(struct vm_area_struct *vma,
65 unsigned long reserve)
68 VM_BUG_ON(!is_vm_hugetlb_page(vma));
69 VM_BUG_ON(vma->vm_flags & VM_SHARED);
71 flags = (unsigned long)vma->vm_private_data & HPAGE_RESV_MASK;
72 vma->vm_private_data = (void *)(reserve | flags);
75 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
77 unsigned long reserveflags = (unsigned long)vma->vm_private_data;
78 VM_BUG_ON(!is_vm_hugetlb_page(vma));
79 vma->vm_private_data = (void *)(reserveflags | flags);
82 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
84 VM_BUG_ON(!is_vm_hugetlb_page(vma));
85 return ((unsigned long)vma->vm_private_data & flag) != 0;
88 /* Decrement the reserved pages in the hugepage pool by one */
89 static void decrement_hugepage_resv_vma(struct vm_area_struct *vma)
91 if (vma->vm_flags & VM_SHARED) {
92 /* Shared mappings always use reserves */
96 * Only the process that called mmap() has reserves for
99 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
100 unsigned long flags, reserve;
102 flags = (unsigned long)vma->vm_private_data &
104 reserve = (unsigned long)vma->vm_private_data - 1;
105 vma->vm_private_data = (void *)(reserve | flags);
110 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
111 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
113 VM_BUG_ON(!is_vm_hugetlb_page(vma));
114 if (!(vma->vm_flags & VM_SHARED))
115 vma->vm_private_data = (void *)0;
118 /* Returns true if the VMA has associated reserve pages */
119 static int vma_has_private_reserves(struct vm_area_struct *vma)
121 if (vma->vm_flags & VM_SHARED)
123 if (!vma_resv_huge_pages(vma))
128 static void clear_huge_page(struct page *page, unsigned long addr)
133 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
135 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
139 static void copy_huge_page(struct page *dst, struct page *src,
140 unsigned long addr, struct vm_area_struct *vma)
145 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
147 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
151 static void enqueue_huge_page(struct page *page)
153 int nid = page_to_nid(page);
154 list_add(&page->lru, &hugepage_freelists[nid]);
156 free_huge_pages_node[nid]++;
159 static struct page *dequeue_huge_page(void)
162 struct page *page = NULL;
164 for (nid = 0; nid < MAX_NUMNODES; ++nid) {
165 if (!list_empty(&hugepage_freelists[nid])) {
166 page = list_entry(hugepage_freelists[nid].next,
168 list_del(&page->lru);
170 free_huge_pages_node[nid]--;
177 static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma,
178 unsigned long address, int avoid_reserve)
181 struct page *page = NULL;
182 struct mempolicy *mpol;
183 nodemask_t *nodemask;
184 struct zonelist *zonelist = huge_zonelist(vma, address,
185 htlb_alloc_mask, &mpol, &nodemask);
190 * A child process with MAP_PRIVATE mappings created by their parent
191 * have no page reserves. This check ensures that reservations are
192 * not "stolen". The child may still get SIGKILLed
194 if (!vma_has_private_reserves(vma) &&
195 free_huge_pages - resv_huge_pages == 0)
198 /* If reserves cannot be used, ensure enough pages are in the pool */
199 if (avoid_reserve && free_huge_pages - resv_huge_pages == 0)
202 for_each_zone_zonelist_nodemask(zone, z, zonelist,
203 MAX_NR_ZONES - 1, nodemask) {
204 nid = zone_to_nid(zone);
205 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
206 !list_empty(&hugepage_freelists[nid])) {
207 page = list_entry(hugepage_freelists[nid].next,
209 list_del(&page->lru);
211 free_huge_pages_node[nid]--;
214 decrement_hugepage_resv_vma(vma);
223 static void update_and_free_page(struct page *page)
227 nr_huge_pages_node[page_to_nid(page)]--;
228 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
229 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
230 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
231 1 << PG_private | 1<< PG_writeback);
233 set_compound_page_dtor(page, NULL);
234 set_page_refcounted(page);
235 arch_release_hugepage(page);
236 __free_pages(page, HUGETLB_PAGE_ORDER);
239 static void free_huge_page(struct page *page)
241 int nid = page_to_nid(page);
242 struct address_space *mapping;
244 mapping = (struct address_space *) page_private(page);
245 set_page_private(page, 0);
246 BUG_ON(page_count(page));
247 INIT_LIST_HEAD(&page->lru);
249 spin_lock(&hugetlb_lock);
250 if (surplus_huge_pages_node[nid]) {
251 update_and_free_page(page);
252 surplus_huge_pages--;
253 surplus_huge_pages_node[nid]--;
255 enqueue_huge_page(page);
257 spin_unlock(&hugetlb_lock);
259 hugetlb_put_quota(mapping, 1);
263 * Increment or decrement surplus_huge_pages. Keep node-specific counters
264 * balanced by operating on them in a round-robin fashion.
265 * Returns 1 if an adjustment was made.
267 static int adjust_pool_surplus(int delta)
273 VM_BUG_ON(delta != -1 && delta != 1);
275 nid = next_node(nid, node_online_map);
276 if (nid == MAX_NUMNODES)
277 nid = first_node(node_online_map);
279 /* To shrink on this node, there must be a surplus page */
280 if (delta < 0 && !surplus_huge_pages_node[nid])
282 /* Surplus cannot exceed the total number of pages */
283 if (delta > 0 && surplus_huge_pages_node[nid] >=
284 nr_huge_pages_node[nid])
287 surplus_huge_pages += delta;
288 surplus_huge_pages_node[nid] += delta;
291 } while (nid != prev_nid);
297 static struct page *alloc_fresh_huge_page_node(int nid)
301 page = alloc_pages_node(nid,
302 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
303 __GFP_REPEAT|__GFP_NOWARN,
306 if (arch_prepare_hugepage(page)) {
307 __free_pages(page, HUGETLB_PAGE_ORDER);
310 set_compound_page_dtor(page, free_huge_page);
311 spin_lock(&hugetlb_lock);
313 nr_huge_pages_node[nid]++;
314 spin_unlock(&hugetlb_lock);
315 put_page(page); /* free it into the hugepage allocator */
321 static int alloc_fresh_huge_page(void)
328 start_nid = hugetlb_next_nid;
331 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
335 * Use a helper variable to find the next node and then
336 * copy it back to hugetlb_next_nid afterwards:
337 * otherwise there's a window in which a racer might
338 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
339 * But we don't need to use a spin_lock here: it really
340 * doesn't matter if occasionally a racer chooses the
341 * same nid as we do. Move nid forward in the mask even
342 * if we just successfully allocated a hugepage so that
343 * the next caller gets hugepages on the next node.
345 next_nid = next_node(hugetlb_next_nid, node_online_map);
346 if (next_nid == MAX_NUMNODES)
347 next_nid = first_node(node_online_map);
348 hugetlb_next_nid = next_nid;
349 } while (!page && hugetlb_next_nid != start_nid);
352 count_vm_event(HTLB_BUDDY_PGALLOC);
354 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
359 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
360 unsigned long address)
366 * Assume we will successfully allocate the surplus page to
367 * prevent racing processes from causing the surplus to exceed
370 * This however introduces a different race, where a process B
371 * tries to grow the static hugepage pool while alloc_pages() is
372 * called by process A. B will only examine the per-node
373 * counters in determining if surplus huge pages can be
374 * converted to normal huge pages in adjust_pool_surplus(). A
375 * won't be able to increment the per-node counter, until the
376 * lock is dropped by B, but B doesn't drop hugetlb_lock until
377 * no more huge pages can be converted from surplus to normal
378 * state (and doesn't try to convert again). Thus, we have a
379 * case where a surplus huge page exists, the pool is grown, and
380 * the surplus huge page still exists after, even though it
381 * should just have been converted to a normal huge page. This
382 * does not leak memory, though, as the hugepage will be freed
383 * once it is out of use. It also does not allow the counters to
384 * go out of whack in adjust_pool_surplus() as we don't modify
385 * the node values until we've gotten the hugepage and only the
386 * per-node value is checked there.
388 spin_lock(&hugetlb_lock);
389 if (surplus_huge_pages >= nr_overcommit_huge_pages) {
390 spin_unlock(&hugetlb_lock);
394 surplus_huge_pages++;
396 spin_unlock(&hugetlb_lock);
398 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
399 __GFP_REPEAT|__GFP_NOWARN,
402 spin_lock(&hugetlb_lock);
405 * This page is now managed by the hugetlb allocator and has
406 * no users -- drop the buddy allocator's reference.
408 put_page_testzero(page);
409 VM_BUG_ON(page_count(page));
410 nid = page_to_nid(page);
411 set_compound_page_dtor(page, free_huge_page);
413 * We incremented the global counters already
415 nr_huge_pages_node[nid]++;
416 surplus_huge_pages_node[nid]++;
417 __count_vm_event(HTLB_BUDDY_PGALLOC);
420 surplus_huge_pages--;
421 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
423 spin_unlock(&hugetlb_lock);
429 * Increase the hugetlb pool such that it can accomodate a reservation
432 static int gather_surplus_pages(int delta)
434 struct list_head surplus_list;
435 struct page *page, *tmp;
437 int needed, allocated;
439 needed = (resv_huge_pages + delta) - free_huge_pages;
441 resv_huge_pages += delta;
446 INIT_LIST_HEAD(&surplus_list);
450 spin_unlock(&hugetlb_lock);
451 for (i = 0; i < needed; i++) {
452 page = alloc_buddy_huge_page(NULL, 0);
455 * We were not able to allocate enough pages to
456 * satisfy the entire reservation so we free what
457 * we've allocated so far.
459 spin_lock(&hugetlb_lock);
464 list_add(&page->lru, &surplus_list);
469 * After retaking hugetlb_lock, we need to recalculate 'needed'
470 * because either resv_huge_pages or free_huge_pages may have changed.
472 spin_lock(&hugetlb_lock);
473 needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
478 * The surplus_list now contains _at_least_ the number of extra pages
479 * needed to accomodate the reservation. Add the appropriate number
480 * of pages to the hugetlb pool and free the extras back to the buddy
481 * allocator. Commit the entire reservation here to prevent another
482 * process from stealing the pages as they are added to the pool but
483 * before they are reserved.
486 resv_huge_pages += delta;
489 /* Free the needed pages to the hugetlb pool */
490 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
493 list_del(&page->lru);
494 enqueue_huge_page(page);
497 /* Free unnecessary surplus pages to the buddy allocator */
498 if (!list_empty(&surplus_list)) {
499 spin_unlock(&hugetlb_lock);
500 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
501 list_del(&page->lru);
503 * The page has a reference count of zero already, so
504 * call free_huge_page directly instead of using
505 * put_page. This must be done with hugetlb_lock
506 * unlocked which is safe because free_huge_page takes
507 * hugetlb_lock before deciding how to free the page.
509 free_huge_page(page);
511 spin_lock(&hugetlb_lock);
518 * When releasing a hugetlb pool reservation, any surplus pages that were
519 * allocated to satisfy the reservation must be explicitly freed if they were
522 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
526 unsigned long nr_pages;
529 * We want to release as many surplus pages as possible, spread
530 * evenly across all nodes. Iterate across all nodes until we
531 * can no longer free unreserved surplus pages. This occurs when
532 * the nodes with surplus pages have no free pages.
534 unsigned long remaining_iterations = num_online_nodes();
536 /* Uncommit the reservation */
537 resv_huge_pages -= unused_resv_pages;
539 nr_pages = min(unused_resv_pages, surplus_huge_pages);
541 while (remaining_iterations-- && nr_pages) {
542 nid = next_node(nid, node_online_map);
543 if (nid == MAX_NUMNODES)
544 nid = first_node(node_online_map);
546 if (!surplus_huge_pages_node[nid])
549 if (!list_empty(&hugepage_freelists[nid])) {
550 page = list_entry(hugepage_freelists[nid].next,
552 list_del(&page->lru);
553 update_and_free_page(page);
555 free_huge_pages_node[nid]--;
556 surplus_huge_pages--;
557 surplus_huge_pages_node[nid]--;
559 remaining_iterations = num_online_nodes();
564 static struct page *alloc_huge_page(struct vm_area_struct *vma,
565 unsigned long addr, int avoid_reserve)
568 struct address_space *mapping = vma->vm_file->f_mapping;
569 struct inode *inode = mapping->host;
570 unsigned int chg = 0;
573 * Processes that did not create the mapping will have no reserves and
574 * will not have accounted against quota. Check that the quota can be
575 * made before satisfying the allocation
577 if (!(vma->vm_flags & VM_SHARED) &&
578 !is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
580 if (hugetlb_get_quota(inode->i_mapping, chg))
581 return ERR_PTR(-ENOSPC);
584 spin_lock(&hugetlb_lock);
585 page = dequeue_huge_page_vma(vma, addr, avoid_reserve);
586 spin_unlock(&hugetlb_lock);
589 page = alloc_buddy_huge_page(vma, addr);
591 hugetlb_put_quota(inode->i_mapping, chg);
592 return ERR_PTR(-VM_FAULT_OOM);
596 set_page_refcounted(page);
597 set_page_private(page, (unsigned long) mapping);
602 static int __init hugetlb_init(void)
606 if (HPAGE_SHIFT == 0)
609 for (i = 0; i < MAX_NUMNODES; ++i)
610 INIT_LIST_HEAD(&hugepage_freelists[i]);
612 hugetlb_next_nid = first_node(node_online_map);
614 for (i = 0; i < max_huge_pages; ++i) {
615 if (!alloc_fresh_huge_page())
618 max_huge_pages = free_huge_pages = nr_huge_pages = i;
619 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
622 module_init(hugetlb_init);
624 static int __init hugetlb_setup(char *s)
626 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
630 __setup("hugepages=", hugetlb_setup);
632 static unsigned int cpuset_mems_nr(unsigned int *array)
637 for_each_node_mask(node, cpuset_current_mems_allowed)
644 #ifdef CONFIG_HIGHMEM
645 static void try_to_free_low(unsigned long count)
649 for (i = 0; i < MAX_NUMNODES; ++i) {
650 struct page *page, *next;
651 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
652 if (count >= nr_huge_pages)
654 if (PageHighMem(page))
656 list_del(&page->lru);
657 update_and_free_page(page);
659 free_huge_pages_node[page_to_nid(page)]--;
664 static inline void try_to_free_low(unsigned long count)
669 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
670 static unsigned long set_max_huge_pages(unsigned long count)
672 unsigned long min_count, ret;
675 * Increase the pool size
676 * First take pages out of surplus state. Then make up the
677 * remaining difference by allocating fresh huge pages.
679 * We might race with alloc_buddy_huge_page() here and be unable
680 * to convert a surplus huge page to a normal huge page. That is
681 * not critical, though, it just means the overall size of the
682 * pool might be one hugepage larger than it needs to be, but
683 * within all the constraints specified by the sysctls.
685 spin_lock(&hugetlb_lock);
686 while (surplus_huge_pages && count > persistent_huge_pages) {
687 if (!adjust_pool_surplus(-1))
691 while (count > persistent_huge_pages) {
693 * If this allocation races such that we no longer need the
694 * page, free_huge_page will handle it by freeing the page
695 * and reducing the surplus.
697 spin_unlock(&hugetlb_lock);
698 ret = alloc_fresh_huge_page();
699 spin_lock(&hugetlb_lock);
706 * Decrease the pool size
707 * First return free pages to the buddy allocator (being careful
708 * to keep enough around to satisfy reservations). Then place
709 * pages into surplus state as needed so the pool will shrink
710 * to the desired size as pages become free.
712 * By placing pages into the surplus state independent of the
713 * overcommit value, we are allowing the surplus pool size to
714 * exceed overcommit. There are few sane options here. Since
715 * alloc_buddy_huge_page() is checking the global counter,
716 * though, we'll note that we're not allowed to exceed surplus
717 * and won't grow the pool anywhere else. Not until one of the
718 * sysctls are changed, or the surplus pages go out of use.
720 min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
721 min_count = max(count, min_count);
722 try_to_free_low(min_count);
723 while (min_count < persistent_huge_pages) {
724 struct page *page = dequeue_huge_page();
727 update_and_free_page(page);
729 while (count < persistent_huge_pages) {
730 if (!adjust_pool_surplus(1))
734 ret = persistent_huge_pages;
735 spin_unlock(&hugetlb_lock);
739 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
740 struct file *file, void __user *buffer,
741 size_t *length, loff_t *ppos)
743 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
744 max_huge_pages = set_max_huge_pages(max_huge_pages);
748 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
749 struct file *file, void __user *buffer,
750 size_t *length, loff_t *ppos)
752 proc_dointvec(table, write, file, buffer, length, ppos);
753 if (hugepages_treat_as_movable)
754 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
756 htlb_alloc_mask = GFP_HIGHUSER;
760 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
761 struct file *file, void __user *buffer,
762 size_t *length, loff_t *ppos)
764 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
765 spin_lock(&hugetlb_lock);
766 nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
767 spin_unlock(&hugetlb_lock);
771 #endif /* CONFIG_SYSCTL */
773 int hugetlb_report_meminfo(char *buf)
776 "HugePages_Total: %5lu\n"
777 "HugePages_Free: %5lu\n"
778 "HugePages_Rsvd: %5lu\n"
779 "HugePages_Surp: %5lu\n"
780 "Hugepagesize: %5lu kB\n",
788 int hugetlb_report_node_meminfo(int nid, char *buf)
791 "Node %d HugePages_Total: %5u\n"
792 "Node %d HugePages_Free: %5u\n"
793 "Node %d HugePages_Surp: %5u\n",
794 nid, nr_huge_pages_node[nid],
795 nid, free_huge_pages_node[nid],
796 nid, surplus_huge_pages_node[nid]);
799 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
800 unsigned long hugetlb_total_pages(void)
802 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
805 static int hugetlb_acct_memory(long delta)
809 spin_lock(&hugetlb_lock);
811 * When cpuset is configured, it breaks the strict hugetlb page
812 * reservation as the accounting is done on a global variable. Such
813 * reservation is completely rubbish in the presence of cpuset because
814 * the reservation is not checked against page availability for the
815 * current cpuset. Application can still potentially OOM'ed by kernel
816 * with lack of free htlb page in cpuset that the task is in.
817 * Attempt to enforce strict accounting with cpuset is almost
818 * impossible (or too ugly) because cpuset is too fluid that
819 * task or memory node can be dynamically moved between cpusets.
821 * The change of semantics for shared hugetlb mapping with cpuset is
822 * undesirable. However, in order to preserve some of the semantics,
823 * we fall back to check against current free page availability as
824 * a best attempt and hopefully to minimize the impact of changing
825 * semantics that cpuset has.
828 if (gather_surplus_pages(delta) < 0)
831 if (delta > cpuset_mems_nr(free_huge_pages_node)) {
832 return_unused_surplus_pages(delta);
839 return_unused_surplus_pages((unsigned long) -delta);
842 spin_unlock(&hugetlb_lock);
846 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
848 unsigned long reserve = vma_resv_huge_pages(vma);
850 hugetlb_acct_memory(-reserve);
854 * We cannot handle pagefaults against hugetlb pages at all. They cause
855 * handle_mm_fault() to try to instantiate regular-sized pages in the
856 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
859 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
865 struct vm_operations_struct hugetlb_vm_ops = {
866 .fault = hugetlb_vm_op_fault,
867 .close = hugetlb_vm_op_close,
870 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
877 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
879 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
881 entry = pte_mkyoung(entry);
882 entry = pte_mkhuge(entry);
887 static void set_huge_ptep_writable(struct vm_area_struct *vma,
888 unsigned long address, pte_t *ptep)
892 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
893 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
894 update_mmu_cache(vma, address, entry);
899 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
900 struct vm_area_struct *vma)
902 pte_t *src_pte, *dst_pte, entry;
903 struct page *ptepage;
907 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
909 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
910 src_pte = huge_pte_offset(src, addr);
913 dst_pte = huge_pte_alloc(dst, addr);
917 /* If the pagetables are shared don't copy or take references */
918 if (dst_pte == src_pte)
921 spin_lock(&dst->page_table_lock);
922 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
923 if (!huge_pte_none(huge_ptep_get(src_pte))) {
925 huge_ptep_set_wrprotect(src, addr, src_pte);
926 entry = huge_ptep_get(src_pte);
927 ptepage = pte_page(entry);
929 set_huge_pte_at(dst, addr, dst_pte, entry);
931 spin_unlock(&src->page_table_lock);
932 spin_unlock(&dst->page_table_lock);
940 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
941 unsigned long end, struct page *ref_page)
943 struct mm_struct *mm = vma->vm_mm;
944 unsigned long address;
950 * A page gathering list, protected by per file i_mmap_lock. The
951 * lock is used to avoid list corruption from multiple unmapping
952 * of the same page since we are using page->lru.
954 LIST_HEAD(page_list);
956 WARN_ON(!is_vm_hugetlb_page(vma));
957 BUG_ON(start & ~HPAGE_MASK);
958 BUG_ON(end & ~HPAGE_MASK);
960 spin_lock(&mm->page_table_lock);
961 for (address = start; address < end; address += HPAGE_SIZE) {
962 ptep = huge_pte_offset(mm, address);
966 if (huge_pmd_unshare(mm, &address, ptep))
970 * If a reference page is supplied, it is because a specific
971 * page is being unmapped, not a range. Ensure the page we
972 * are about to unmap is the actual page of interest.
975 pte = huge_ptep_get(ptep);
976 if (huge_pte_none(pte))
978 page = pte_page(pte);
979 if (page != ref_page)
983 * Mark the VMA as having unmapped its page so that
984 * future faults in this VMA will fail rather than
985 * looking like data was lost
987 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
990 pte = huge_ptep_get_and_clear(mm, address, ptep);
991 if (huge_pte_none(pte))
994 page = pte_page(pte);
996 set_page_dirty(page);
997 list_add(&page->lru, &page_list);
999 spin_unlock(&mm->page_table_lock);
1000 flush_tlb_range(vma, start, end);
1001 list_for_each_entry_safe(page, tmp, &page_list, lru) {
1002 list_del(&page->lru);
1007 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1008 unsigned long end, struct page *ref_page)
1011 * It is undesirable to test vma->vm_file as it should be non-null
1012 * for valid hugetlb area. However, vm_file will be NULL in the error
1013 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
1014 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
1015 * to clean up. Since no pte has actually been setup, it is safe to
1016 * do nothing in this case.
1019 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1020 __unmap_hugepage_range(vma, start, end, ref_page);
1021 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1026 * This is called when the original mapper is failing to COW a MAP_PRIVATE
1027 * mappping it owns the reserve page for. The intention is to unmap the page
1028 * from other VMAs and let the children be SIGKILLed if they are faulting the
1031 int unmap_ref_private(struct mm_struct *mm,
1032 struct vm_area_struct *vma,
1034 unsigned long address)
1036 struct vm_area_struct *iter_vma;
1037 struct address_space *mapping;
1038 struct prio_tree_iter iter;
1042 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1043 * from page cache lookup which is in HPAGE_SIZE units.
1045 address = address & huge_page_mask(hstate_vma(vma));
1046 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1047 + (vma->vm_pgoff >> PAGE_SHIFT);
1048 mapping = (struct address_space *)page_private(page);
1050 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1051 /* Do not unmap the current VMA */
1052 if (iter_vma == vma)
1056 * Unmap the page from other VMAs without their own reserves.
1057 * They get marked to be SIGKILLed if they fault in these
1058 * areas. This is because a future no-page fault on this VMA
1059 * could insert a zeroed page instead of the data existing
1060 * from the time of fork. This would look like data corruption
1062 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1063 unmap_hugepage_range(iter_vma,
1064 address, address + HPAGE_SIZE,
1071 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1072 unsigned long address, pte_t *ptep, pte_t pte,
1073 struct page *pagecache_page)
1075 struct page *old_page, *new_page;
1077 int outside_reserve = 0;
1079 old_page = pte_page(pte);
1082 /* If no-one else is actually using this page, avoid the copy
1083 * and just make the page writable */
1084 avoidcopy = (page_count(old_page) == 1);
1086 set_huge_ptep_writable(vma, address, ptep);
1091 * If the process that created a MAP_PRIVATE mapping is about to
1092 * perform a COW due to a shared page count, attempt to satisfy
1093 * the allocation without using the existing reserves. The pagecache
1094 * page is used to determine if the reserve at this address was
1095 * consumed or not. If reserves were used, a partial faulted mapping
1096 * at the time of fork() could consume its reserves on COW instead
1097 * of the full address range.
1099 if (!(vma->vm_flags & VM_SHARED) &&
1100 is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1101 old_page != pagecache_page)
1102 outside_reserve = 1;
1104 page_cache_get(old_page);
1105 new_page = alloc_huge_page(vma, address, outside_reserve);
1107 if (IS_ERR(new_page)) {
1108 page_cache_release(old_page);
1111 * If a process owning a MAP_PRIVATE mapping fails to COW,
1112 * it is due to references held by a child and an insufficient
1113 * huge page pool. To guarantee the original mappers
1114 * reliability, unmap the page from child processes. The child
1115 * may get SIGKILLed if it later faults.
1117 if (outside_reserve) {
1118 BUG_ON(huge_pte_none(pte));
1119 if (unmap_ref_private(mm, vma, old_page, address)) {
1120 BUG_ON(page_count(old_page) != 1);
1121 BUG_ON(huge_pte_none(pte));
1122 goto retry_avoidcopy;
1127 return -PTR_ERR(new_page);
1130 spin_unlock(&mm->page_table_lock);
1131 copy_huge_page(new_page, old_page, address, vma);
1132 __SetPageUptodate(new_page);
1133 spin_lock(&mm->page_table_lock);
1135 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
1136 if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1138 huge_ptep_clear_flush(vma, address, ptep);
1139 set_huge_pte_at(mm, address, ptep,
1140 make_huge_pte(vma, new_page, 1));
1141 /* Make the old page be freed below */
1142 new_page = old_page;
1144 page_cache_release(new_page);
1145 page_cache_release(old_page);
1149 /* Return the pagecache page at a given address within a VMA */
1150 static struct page *hugetlbfs_pagecache_page(struct vm_area_struct *vma,
1151 unsigned long address)
1153 struct address_space *mapping;
1156 mapping = vma->vm_file->f_mapping;
1157 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
1158 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
1160 return find_lock_page(mapping, idx);
1163 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1164 unsigned long address, pte_t *ptep, int write_access)
1166 int ret = VM_FAULT_SIGBUS;
1170 struct address_space *mapping;
1174 * Currently, we are forced to kill the process in the event the
1175 * original mapper has unmapped pages from the child due to a failed
1176 * COW. Warn that such a situation has occured as it may not be obvious
1178 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
1180 "PID %d killed due to inadequate hugepage pool\n",
1185 mapping = vma->vm_file->f_mapping;
1186 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
1187 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
1190 * Use page lock to guard against racing truncation
1191 * before we get page_table_lock.
1194 page = find_lock_page(mapping, idx);
1196 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
1199 page = alloc_huge_page(vma, address, 0);
1201 ret = -PTR_ERR(page);
1204 clear_huge_page(page, address);
1205 __SetPageUptodate(page);
1207 if (vma->vm_flags & VM_SHARED) {
1209 struct inode *inode = mapping->host;
1211 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
1219 spin_lock(&inode->i_lock);
1220 inode->i_blocks += BLOCKS_PER_HUGEPAGE;
1221 spin_unlock(&inode->i_lock);
1226 spin_lock(&mm->page_table_lock);
1227 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
1232 if (!huge_pte_none(huge_ptep_get(ptep)))
1235 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
1236 && (vma->vm_flags & VM_SHARED)));
1237 set_huge_pte_at(mm, address, ptep, new_pte);
1239 if (write_access && !(vma->vm_flags & VM_SHARED)) {
1240 /* Optimization, do the COW without a second fault */
1241 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
1244 spin_unlock(&mm->page_table_lock);
1250 spin_unlock(&mm->page_table_lock);
1256 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
1257 unsigned long address, int write_access)
1262 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
1264 ptep = huge_pte_alloc(mm, address);
1266 return VM_FAULT_OOM;
1269 * Serialize hugepage allocation and instantiation, so that we don't
1270 * get spurious allocation failures if two CPUs race to instantiate
1271 * the same page in the page cache.
1273 mutex_lock(&hugetlb_instantiation_mutex);
1274 entry = huge_ptep_get(ptep);
1275 if (huge_pte_none(entry)) {
1276 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1277 mutex_unlock(&hugetlb_instantiation_mutex);
1283 spin_lock(&mm->page_table_lock);
1284 /* Check for a racing update before calling hugetlb_cow */
1285 if (likely(pte_same(entry, huge_ptep_get(ptep))))
1286 if (write_access && !pte_write(entry)) {
1288 page = hugetlbfs_pagecache_page(vma, address);
1289 ret = hugetlb_cow(mm, vma, address, ptep, entry, page);
1295 spin_unlock(&mm->page_table_lock);
1296 mutex_unlock(&hugetlb_instantiation_mutex);
1301 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1302 struct page **pages, struct vm_area_struct **vmas,
1303 unsigned long *position, int *length, int i,
1306 unsigned long pfn_offset;
1307 unsigned long vaddr = *position;
1308 int remainder = *length;
1310 spin_lock(&mm->page_table_lock);
1311 while (vaddr < vma->vm_end && remainder) {
1316 * Some archs (sparc64, sh*) have multiple pte_ts to
1317 * each hugepage. We have to make * sure we get the
1318 * first, for the page indexing below to work.
1320 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
1322 if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
1323 (write && !pte_write(huge_ptep_get(pte)))) {
1326 spin_unlock(&mm->page_table_lock);
1327 ret = hugetlb_fault(mm, vma, vaddr, write);
1328 spin_lock(&mm->page_table_lock);
1329 if (!(ret & VM_FAULT_ERROR))
1338 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
1339 page = pte_page(huge_ptep_get(pte));
1343 pages[i] = page + pfn_offset;
1353 if (vaddr < vma->vm_end && remainder &&
1354 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1356 * We use pfn_offset to avoid touching the pageframes
1357 * of this compound page.
1362 spin_unlock(&mm->page_table_lock);
1363 *length = remainder;
1369 void hugetlb_change_protection(struct vm_area_struct *vma,
1370 unsigned long address, unsigned long end, pgprot_t newprot)
1372 struct mm_struct *mm = vma->vm_mm;
1373 unsigned long start = address;
1377 BUG_ON(address >= end);
1378 flush_cache_range(vma, address, end);
1380 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1381 spin_lock(&mm->page_table_lock);
1382 for (; address < end; address += HPAGE_SIZE) {
1383 ptep = huge_pte_offset(mm, address);
1386 if (huge_pmd_unshare(mm, &address, ptep))
1388 if (!huge_pte_none(huge_ptep_get(ptep))) {
1389 pte = huge_ptep_get_and_clear(mm, address, ptep);
1390 pte = pte_mkhuge(pte_modify(pte, newprot));
1391 set_huge_pte_at(mm, address, ptep, pte);
1394 spin_unlock(&mm->page_table_lock);
1395 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1397 flush_tlb_range(vma, start, end);
1400 struct file_region {
1401 struct list_head link;
1406 static long region_add(struct list_head *head, long f, long t)
1408 struct file_region *rg, *nrg, *trg;
1410 /* Locate the region we are either in or before. */
1411 list_for_each_entry(rg, head, link)
1415 /* Round our left edge to the current segment if it encloses us. */
1419 /* Check for and consume any regions we now overlap with. */
1421 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1422 if (&rg->link == head)
1427 /* If this area reaches higher then extend our area to
1428 * include it completely. If this is not the first area
1429 * which we intend to reuse, free it. */
1433 list_del(&rg->link);
1442 static long region_chg(struct list_head *head, long f, long t)
1444 struct file_region *rg, *nrg;
1447 /* Locate the region we are before or in. */
1448 list_for_each_entry(rg, head, link)
1452 /* If we are below the current region then a new region is required.
1453 * Subtle, allocate a new region at the position but make it zero
1454 * size such that we can guarantee to record the reservation. */
1455 if (&rg->link == head || t < rg->from) {
1456 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
1461 INIT_LIST_HEAD(&nrg->link);
1462 list_add(&nrg->link, rg->link.prev);
1467 /* Round our left edge to the current segment if it encloses us. */
1472 /* Check for and consume any regions we now overlap with. */
1473 list_for_each_entry(rg, rg->link.prev, link) {
1474 if (&rg->link == head)
1479 /* We overlap with this area, if it extends futher than
1480 * us then we must extend ourselves. Account for its
1481 * existing reservation. */
1486 chg -= rg->to - rg->from;
1491 static long region_truncate(struct list_head *head, long end)
1493 struct file_region *rg, *trg;
1496 /* Locate the region we are either in or before. */
1497 list_for_each_entry(rg, head, link)
1500 if (&rg->link == head)
1503 /* If we are in the middle of a region then adjust it. */
1504 if (end > rg->from) {
1507 rg = list_entry(rg->link.next, typeof(*rg), link);
1510 /* Drop any remaining regions. */
1511 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1512 if (&rg->link == head)
1514 chg += rg->to - rg->from;
1515 list_del(&rg->link);
1521 int hugetlb_reserve_pages(struct inode *inode,
1523 struct vm_area_struct *vma)
1528 * Shared mappings base their reservation on the number of pages that
1529 * are already allocated on behalf of the file. Private mappings need
1530 * to reserve the full area even if read-only as mprotect() may be
1531 * called to make the mapping read-write. Assume !vma is a shm mapping
1533 if (!vma || vma->vm_flags & VM_SHARED)
1534 chg = region_chg(&inode->i_mapping->private_list, from, to);
1537 set_vma_resv_huge_pages(vma, chg);
1538 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
1544 if (hugetlb_get_quota(inode->i_mapping, chg))
1546 ret = hugetlb_acct_memory(chg);
1548 hugetlb_put_quota(inode->i_mapping, chg);
1551 if (!vma || vma->vm_flags & VM_SHARED)
1552 region_add(&inode->i_mapping->private_list, from, to);
1556 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1558 long chg = region_truncate(&inode->i_mapping->private_list, offset);
1560 spin_lock(&inode->i_lock);
1561 inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1562 spin_unlock(&inode->i_lock);
1564 hugetlb_put_quota(inode->i_mapping, (chg - freed));
1565 hugetlb_acct_memory(-(chg - freed));