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 unsigned long max_huge_pages;
27 static struct list_head hugepage_freelists[MAX_NUMNODES];
28 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
29 static unsigned int free_huge_pages_node[MAX_NUMNODES];
30 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
31 unsigned long hugepages_treat_as_movable;
34 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
36 static DEFINE_SPINLOCK(hugetlb_lock);
38 static void clear_huge_page(struct page *page, unsigned long addr)
43 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
45 clear_user_highpage(page + i, addr);
49 static void copy_huge_page(struct page *dst, struct page *src,
50 unsigned long addr, struct vm_area_struct *vma)
55 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
57 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
61 static void enqueue_huge_page(struct page *page)
63 int nid = page_to_nid(page);
64 list_add(&page->lru, &hugepage_freelists[nid]);
66 free_huge_pages_node[nid]++;
69 static struct page *dequeue_huge_page(struct vm_area_struct *vma,
70 unsigned long address)
73 struct page *page = NULL;
74 struct zonelist *zonelist = huge_zonelist(vma, address,
78 for (z = zonelist->zones; *z; z++) {
79 nid = zone_to_nid(*z);
80 if (cpuset_zone_allowed_softwall(*z, htlb_alloc_mask) &&
81 !list_empty(&hugepage_freelists[nid]))
86 page = list_entry(hugepage_freelists[nid].next,
90 free_huge_pages_node[nid]--;
95 static void free_huge_page(struct page *page)
97 BUG_ON(page_count(page));
99 INIT_LIST_HEAD(&page->lru);
101 spin_lock(&hugetlb_lock);
102 enqueue_huge_page(page);
103 spin_unlock(&hugetlb_lock);
106 static int alloc_fresh_huge_page(void)
110 static DEFINE_SPINLOCK(nid_lock);
113 spin_lock(&nid_lock);
114 nid = next_node(prev_nid, node_online_map);
115 if (nid == MAX_NUMNODES)
116 nid = first_node(node_online_map);
118 spin_unlock(&nid_lock);
120 page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
123 set_compound_page_dtor(page, free_huge_page);
124 spin_lock(&hugetlb_lock);
126 nr_huge_pages_node[page_to_nid(page)]++;
127 spin_unlock(&hugetlb_lock);
128 put_page(page); /* free it into the hugepage allocator */
134 static struct page *alloc_huge_page(struct vm_area_struct *vma,
139 spin_lock(&hugetlb_lock);
140 if (vma->vm_flags & VM_MAYSHARE)
142 else if (free_huge_pages <= resv_huge_pages)
145 page = dequeue_huge_page(vma, addr);
149 spin_unlock(&hugetlb_lock);
150 set_page_refcounted(page);
154 if (vma->vm_flags & VM_MAYSHARE)
156 spin_unlock(&hugetlb_lock);
160 static int __init hugetlb_init(void)
164 if (HPAGE_SHIFT == 0)
167 for (i = 0; i < MAX_NUMNODES; ++i)
168 INIT_LIST_HEAD(&hugepage_freelists[i]);
170 for (i = 0; i < max_huge_pages; ++i) {
171 if (!alloc_fresh_huge_page())
174 max_huge_pages = free_huge_pages = nr_huge_pages = i;
175 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
178 module_init(hugetlb_init);
180 static int __init hugetlb_setup(char *s)
182 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
186 __setup("hugepages=", hugetlb_setup);
188 static unsigned int cpuset_mems_nr(unsigned int *array)
193 for_each_node_mask(node, cpuset_current_mems_allowed)
200 static void update_and_free_page(struct page *page)
204 nr_huge_pages_node[page_to_nid(page)]--;
205 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
206 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
207 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
208 1 << PG_private | 1<< PG_writeback);
210 page[1].lru.next = NULL;
211 set_page_refcounted(page);
212 __free_pages(page, HUGETLB_PAGE_ORDER);
215 #ifdef CONFIG_HIGHMEM
216 static void try_to_free_low(unsigned long count)
220 for (i = 0; i < MAX_NUMNODES; ++i) {
221 struct page *page, *next;
222 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
223 if (PageHighMem(page))
225 list_del(&page->lru);
226 update_and_free_page(page);
228 free_huge_pages_node[page_to_nid(page)]--;
229 if (count >= nr_huge_pages)
235 static inline void try_to_free_low(unsigned long count)
240 static unsigned long set_max_huge_pages(unsigned long count)
242 while (count > nr_huge_pages) {
243 if (!alloc_fresh_huge_page())
244 return nr_huge_pages;
246 if (count >= nr_huge_pages)
247 return nr_huge_pages;
249 spin_lock(&hugetlb_lock);
250 count = max(count, resv_huge_pages);
251 try_to_free_low(count);
252 while (count < nr_huge_pages) {
253 struct page *page = dequeue_huge_page(NULL, 0);
256 update_and_free_page(page);
258 spin_unlock(&hugetlb_lock);
259 return nr_huge_pages;
262 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
263 struct file *file, void __user *buffer,
264 size_t *length, loff_t *ppos)
266 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
267 max_huge_pages = set_max_huge_pages(max_huge_pages);
271 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
272 struct file *file, void __user *buffer,
273 size_t *length, loff_t *ppos)
275 proc_dointvec(table, write, file, buffer, length, ppos);
276 if (hugepages_treat_as_movable)
277 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
279 htlb_alloc_mask = GFP_HIGHUSER;
283 #endif /* CONFIG_SYSCTL */
285 int hugetlb_report_meminfo(char *buf)
288 "HugePages_Total: %5lu\n"
289 "HugePages_Free: %5lu\n"
290 "HugePages_Rsvd: %5lu\n"
291 "Hugepagesize: %5lu kB\n",
298 int hugetlb_report_node_meminfo(int nid, char *buf)
301 "Node %d HugePages_Total: %5u\n"
302 "Node %d HugePages_Free: %5u\n",
303 nid, nr_huge_pages_node[nid],
304 nid, free_huge_pages_node[nid]);
307 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
308 unsigned long hugetlb_total_pages(void)
310 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
314 * We cannot handle pagefaults against hugetlb pages at all. They cause
315 * handle_mm_fault() to try to instantiate regular-sized pages in the
316 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
319 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
325 struct vm_operations_struct hugetlb_vm_ops = {
326 .fault = hugetlb_vm_op_fault,
329 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
336 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
338 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
340 entry = pte_mkyoung(entry);
341 entry = pte_mkhuge(entry);
346 static void set_huge_ptep_writable(struct vm_area_struct *vma,
347 unsigned long address, pte_t *ptep)
351 entry = pte_mkwrite(pte_mkdirty(*ptep));
352 if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
353 update_mmu_cache(vma, address, entry);
354 lazy_mmu_prot_update(entry);
359 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
360 struct vm_area_struct *vma)
362 pte_t *src_pte, *dst_pte, entry;
363 struct page *ptepage;
367 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
369 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
370 src_pte = huge_pte_offset(src, addr);
373 dst_pte = huge_pte_alloc(dst, addr);
376 spin_lock(&dst->page_table_lock);
377 spin_lock(&src->page_table_lock);
378 if (!pte_none(*src_pte)) {
380 ptep_set_wrprotect(src, addr, src_pte);
382 ptepage = pte_page(entry);
384 set_huge_pte_at(dst, addr, dst_pte, entry);
386 spin_unlock(&src->page_table_lock);
387 spin_unlock(&dst->page_table_lock);
395 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
398 struct mm_struct *mm = vma->vm_mm;
399 unsigned long address;
405 * A page gathering list, protected by per file i_mmap_lock. The
406 * lock is used to avoid list corruption from multiple unmapping
407 * of the same page since we are using page->lru.
409 LIST_HEAD(page_list);
411 WARN_ON(!is_vm_hugetlb_page(vma));
412 BUG_ON(start & ~HPAGE_MASK);
413 BUG_ON(end & ~HPAGE_MASK);
415 spin_lock(&mm->page_table_lock);
416 for (address = start; address < end; address += HPAGE_SIZE) {
417 ptep = huge_pte_offset(mm, address);
421 if (huge_pmd_unshare(mm, &address, ptep))
424 pte = huge_ptep_get_and_clear(mm, address, ptep);
428 page = pte_page(pte);
430 set_page_dirty(page);
431 list_add(&page->lru, &page_list);
433 spin_unlock(&mm->page_table_lock);
434 flush_tlb_range(vma, start, end);
435 list_for_each_entry_safe(page, tmp, &page_list, lru) {
436 list_del(&page->lru);
441 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
445 * It is undesirable to test vma->vm_file as it should be non-null
446 * for valid hugetlb area. However, vm_file will be NULL in the error
447 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
448 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
449 * to clean up. Since no pte has actually been setup, it is safe to
450 * do nothing in this case.
453 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
454 __unmap_hugepage_range(vma, start, end);
455 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
459 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
460 unsigned long address, pte_t *ptep, pte_t pte)
462 struct page *old_page, *new_page;
465 old_page = pte_page(pte);
467 /* If no-one else is actually using this page, avoid the copy
468 * and just make the page writable */
469 avoidcopy = (page_count(old_page) == 1);
471 set_huge_ptep_writable(vma, address, ptep);
475 page_cache_get(old_page);
476 new_page = alloc_huge_page(vma, address);
479 page_cache_release(old_page);
483 spin_unlock(&mm->page_table_lock);
484 copy_huge_page(new_page, old_page, address, vma);
485 spin_lock(&mm->page_table_lock);
487 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
488 if (likely(pte_same(*ptep, pte))) {
490 set_huge_pte_at(mm, address, ptep,
491 make_huge_pte(vma, new_page, 1));
492 /* Make the old page be freed below */
495 page_cache_release(new_page);
496 page_cache_release(old_page);
500 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
501 unsigned long address, pte_t *ptep, int write_access)
503 int ret = VM_FAULT_SIGBUS;
507 struct address_space *mapping;
510 mapping = vma->vm_file->f_mapping;
511 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
512 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
515 * Use page lock to guard against racing truncation
516 * before we get page_table_lock.
519 page = find_lock_page(mapping, idx);
521 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
524 if (hugetlb_get_quota(mapping))
526 page = alloc_huge_page(vma, address);
528 hugetlb_put_quota(mapping);
532 clear_huge_page(page, address);
534 if (vma->vm_flags & VM_SHARED) {
537 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
540 hugetlb_put_quota(mapping);
549 spin_lock(&mm->page_table_lock);
550 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
555 if (!pte_none(*ptep))
558 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
559 && (vma->vm_flags & VM_SHARED)));
560 set_huge_pte_at(mm, address, ptep, new_pte);
562 if (write_access && !(vma->vm_flags & VM_SHARED)) {
563 /* Optimization, do the COW without a second fault */
564 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
567 spin_unlock(&mm->page_table_lock);
573 spin_unlock(&mm->page_table_lock);
574 hugetlb_put_quota(mapping);
580 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
581 unsigned long address, int write_access)
586 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
588 ptep = huge_pte_alloc(mm, address);
593 * Serialize hugepage allocation and instantiation, so that we don't
594 * get spurious allocation failures if two CPUs race to instantiate
595 * the same page in the page cache.
597 mutex_lock(&hugetlb_instantiation_mutex);
599 if (pte_none(entry)) {
600 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
601 mutex_unlock(&hugetlb_instantiation_mutex);
607 spin_lock(&mm->page_table_lock);
608 /* Check for a racing update before calling hugetlb_cow */
609 if (likely(pte_same(entry, *ptep)))
610 if (write_access && !pte_write(entry))
611 ret = hugetlb_cow(mm, vma, address, ptep, entry);
612 spin_unlock(&mm->page_table_lock);
613 mutex_unlock(&hugetlb_instantiation_mutex);
618 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
619 struct page **pages, struct vm_area_struct **vmas,
620 unsigned long *position, int *length, int i)
622 unsigned long pfn_offset;
623 unsigned long vaddr = *position;
624 int remainder = *length;
626 spin_lock(&mm->page_table_lock);
627 while (vaddr < vma->vm_end && remainder) {
632 * Some archs (sparc64, sh*) have multiple pte_ts to
633 * each hugepage. We have to make * sure we get the
634 * first, for the page indexing below to work.
636 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
638 if (!pte || pte_none(*pte)) {
641 spin_unlock(&mm->page_table_lock);
642 ret = hugetlb_fault(mm, vma, vaddr, 0);
643 spin_lock(&mm->page_table_lock);
644 if (!(ret & VM_FAULT_MAJOR))
653 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
654 page = pte_page(*pte);
658 pages[i] = page + pfn_offset;
668 if (vaddr < vma->vm_end && remainder &&
669 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
671 * We use pfn_offset to avoid touching the pageframes
672 * of this compound page.
677 spin_unlock(&mm->page_table_lock);
684 void hugetlb_change_protection(struct vm_area_struct *vma,
685 unsigned long address, unsigned long end, pgprot_t newprot)
687 struct mm_struct *mm = vma->vm_mm;
688 unsigned long start = address;
692 BUG_ON(address >= end);
693 flush_cache_range(vma, address, end);
695 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
696 spin_lock(&mm->page_table_lock);
697 for (; address < end; address += HPAGE_SIZE) {
698 ptep = huge_pte_offset(mm, address);
701 if (huge_pmd_unshare(mm, &address, ptep))
703 if (!pte_none(*ptep)) {
704 pte = huge_ptep_get_and_clear(mm, address, ptep);
705 pte = pte_mkhuge(pte_modify(pte, newprot));
706 set_huge_pte_at(mm, address, ptep, pte);
707 lazy_mmu_prot_update(pte);
710 spin_unlock(&mm->page_table_lock);
711 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
713 flush_tlb_range(vma, start, end);
717 struct list_head link;
722 static long region_add(struct list_head *head, long f, long t)
724 struct file_region *rg, *nrg, *trg;
726 /* Locate the region we are either in or before. */
727 list_for_each_entry(rg, head, link)
731 /* Round our left edge to the current segment if it encloses us. */
735 /* Check for and consume any regions we now overlap with. */
737 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
738 if (&rg->link == head)
743 /* If this area reaches higher then extend our area to
744 * include it completely. If this is not the first area
745 * which we intend to reuse, free it. */
758 static long region_chg(struct list_head *head, long f, long t)
760 struct file_region *rg, *nrg;
763 /* Locate the region we are before or in. */
764 list_for_each_entry(rg, head, link)
768 /* If we are below the current region then a new region is required.
769 * Subtle, allocate a new region at the position but make it zero
770 * size such that we can guarentee to record the reservation. */
771 if (&rg->link == head || t < rg->from) {
772 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
777 INIT_LIST_HEAD(&nrg->link);
778 list_add(&nrg->link, rg->link.prev);
783 /* Round our left edge to the current segment if it encloses us. */
788 /* Check for and consume any regions we now overlap with. */
789 list_for_each_entry(rg, rg->link.prev, link) {
790 if (&rg->link == head)
795 /* We overlap with this area, if it extends futher than
796 * us then we must extend ourselves. Account for its
797 * existing reservation. */
802 chg -= rg->to - rg->from;
807 static long region_truncate(struct list_head *head, long end)
809 struct file_region *rg, *trg;
812 /* Locate the region we are either in or before. */
813 list_for_each_entry(rg, head, link)
816 if (&rg->link == head)
819 /* If we are in the middle of a region then adjust it. */
820 if (end > rg->from) {
823 rg = list_entry(rg->link.next, typeof(*rg), link);
826 /* Drop any remaining regions. */
827 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
828 if (&rg->link == head)
830 chg += rg->to - rg->from;
837 static int hugetlb_acct_memory(long delta)
841 spin_lock(&hugetlb_lock);
842 if ((delta + resv_huge_pages) <= free_huge_pages) {
843 resv_huge_pages += delta;
846 spin_unlock(&hugetlb_lock);
850 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
854 chg = region_chg(&inode->i_mapping->private_list, from, to);
858 * When cpuset is configured, it breaks the strict hugetlb page
859 * reservation as the accounting is done on a global variable. Such
860 * reservation is completely rubbish in the presence of cpuset because
861 * the reservation is not checked against page availability for the
862 * current cpuset. Application can still potentially OOM'ed by kernel
863 * with lack of free htlb page in cpuset that the task is in.
864 * Attempt to enforce strict accounting with cpuset is almost
865 * impossible (or too ugly) because cpuset is too fluid that
866 * task or memory node can be dynamically moved between cpusets.
868 * The change of semantics for shared hugetlb mapping with cpuset is
869 * undesirable. However, in order to preserve some of the semantics,
870 * we fall back to check against current free page availability as
871 * a best attempt and hopefully to minimize the impact of changing
872 * semantics that cpuset has.
874 if (chg > cpuset_mems_nr(free_huge_pages_node))
877 ret = hugetlb_acct_memory(chg);
880 region_add(&inode->i_mapping->private_list, from, to);
884 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
886 long chg = region_truncate(&inode->i_mapping->private_list, offset);
887 hugetlb_acct_memory(freed - chg);