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, reserved_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];
31 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
33 static DEFINE_SPINLOCK(hugetlb_lock);
35 static void clear_huge_page(struct page *page, unsigned long addr)
40 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
42 clear_user_highpage(page + i, addr);
46 static void copy_huge_page(struct page *dst, struct page *src,
52 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
54 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE);
58 static void enqueue_huge_page(struct page *page)
60 int nid = page_to_nid(page);
61 list_add(&page->lru, &hugepage_freelists[nid]);
63 free_huge_pages_node[nid]++;
66 static struct page *dequeue_huge_page(struct vm_area_struct *vma,
67 unsigned long address)
69 int nid = numa_node_id();
70 struct page *page = NULL;
71 struct zonelist *zonelist = huge_zonelist(vma, address);
74 for (z = zonelist->zones; *z; z++) {
75 nid = (*z)->zone_pgdat->node_id;
76 if (cpuset_zone_allowed(*z, GFP_HIGHUSER) &&
77 !list_empty(&hugepage_freelists[nid]))
82 page = list_entry(hugepage_freelists[nid].next,
86 free_huge_pages_node[nid]--;
91 static void free_huge_page(struct page *page)
93 BUG_ON(page_count(page));
95 INIT_LIST_HEAD(&page->lru);
97 spin_lock(&hugetlb_lock);
98 enqueue_huge_page(page);
99 spin_unlock(&hugetlb_lock);
102 static int alloc_fresh_huge_page(void)
106 page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
108 nid = (nid + 1) % num_online_nodes();
110 page[1].lru.next = (void *)free_huge_page; /* dtor */
111 spin_lock(&hugetlb_lock);
113 nr_huge_pages_node[page_to_nid(page)]++;
114 spin_unlock(&hugetlb_lock);
115 put_page(page); /* free it into the hugepage allocator */
121 static struct page *alloc_huge_page(struct vm_area_struct *vma,
124 struct inode *inode = vma->vm_file->f_dentry->d_inode;
129 spin_lock(&hugetlb_lock);
131 if (vma->vm_flags & VM_MAYSHARE) {
133 /* idx = radix tree index, i.e. offset into file in
134 * HPAGE_SIZE units */
135 idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
136 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
138 /* The hugetlbfs specific inode info stores the number
139 * of "guaranteed available" (huge) pages. That is,
140 * the first 'prereserved_hpages' pages of the inode
141 * are either already instantiated, or have been
142 * pre-reserved (by hugetlb_reserve_for_inode()). Here
143 * we're in the process of instantiating the page, so
144 * we use this to determine whether to draw from the
145 * pre-reserved pool or the truly free pool. */
146 if (idx < HUGETLBFS_I(inode)->prereserved_hpages)
151 if (free_huge_pages <= reserved_huge_pages)
154 BUG_ON(reserved_huge_pages == 0);
155 reserved_huge_pages--;
158 page = dequeue_huge_page(vma, addr);
162 spin_unlock(&hugetlb_lock);
163 set_page_refcounted(page);
167 WARN_ON(use_reserve); /* reserved allocations shouldn't fail */
168 spin_unlock(&hugetlb_lock);
172 /* hugetlb_extend_reservation()
174 * Ensure that at least 'atleast' hugepages are, and will remain,
175 * available to instantiate the first 'atleast' pages of the given
176 * inode. If the inode doesn't already have this many pages reserved
177 * or instantiated, set aside some hugepages in the reserved pool to
178 * satisfy later faults (or fail now if there aren't enough, rather
179 * than getting the SIGBUS later).
181 int hugetlb_extend_reservation(struct hugetlbfs_inode_info *info,
182 unsigned long atleast)
184 struct inode *inode = &info->vfs_inode;
185 unsigned long change_in_reserve = 0;
188 spin_lock(&hugetlb_lock);
189 read_lock_irq(&inode->i_mapping->tree_lock);
191 if (info->prereserved_hpages >= atleast)
194 /* Because we always call this on shared mappings, none of the
195 * pages beyond info->prereserved_hpages can have been
196 * instantiated, so we need to reserve all of them now. */
197 change_in_reserve = atleast - info->prereserved_hpages;
199 if ((reserved_huge_pages + change_in_reserve) > free_huge_pages) {
204 reserved_huge_pages += change_in_reserve;
205 info->prereserved_hpages = atleast;
208 read_unlock_irq(&inode->i_mapping->tree_lock);
209 spin_unlock(&hugetlb_lock);
214 /* hugetlb_truncate_reservation()
216 * This returns pages reserved for the given inode to the general free
217 * hugepage pool. If the inode has any pages prereserved, but not
218 * instantiated, beyond offset (atmost << HPAGE_SIZE), then release
221 void hugetlb_truncate_reservation(struct hugetlbfs_inode_info *info,
222 unsigned long atmost)
224 struct inode *inode = &info->vfs_inode;
225 struct address_space *mapping = inode->i_mapping;
227 unsigned long change_in_reserve = 0;
230 spin_lock(&hugetlb_lock);
231 read_lock_irq(&inode->i_mapping->tree_lock);
233 if (info->prereserved_hpages <= atmost)
236 /* Count pages which were reserved, but not instantiated, and
237 * which we can now release. */
238 for (idx = atmost; idx < info->prereserved_hpages; idx++) {
239 page = radix_tree_lookup(&mapping->page_tree, idx);
241 /* Pages which are already instantiated can't
242 * be unreserved (and in fact have already
243 * been removed from the reserved pool) */
247 BUG_ON(reserved_huge_pages < change_in_reserve);
248 reserved_huge_pages -= change_in_reserve;
249 info->prereserved_hpages = atmost;
252 read_unlock_irq(&inode->i_mapping->tree_lock);
253 spin_unlock(&hugetlb_lock);
256 static int __init hugetlb_init(void)
260 if (HPAGE_SHIFT == 0)
263 for (i = 0; i < MAX_NUMNODES; ++i)
264 INIT_LIST_HEAD(&hugepage_freelists[i]);
266 for (i = 0; i < max_huge_pages; ++i) {
267 if (!alloc_fresh_huge_page())
270 max_huge_pages = free_huge_pages = nr_huge_pages = i;
271 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
274 module_init(hugetlb_init);
276 static int __init hugetlb_setup(char *s)
278 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
282 __setup("hugepages=", hugetlb_setup);
285 static void update_and_free_page(struct page *page)
289 nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
290 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
291 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
292 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
293 1 << PG_private | 1<< PG_writeback);
295 page[1].lru.next = NULL;
296 set_page_refcounted(page);
297 __free_pages(page, HUGETLB_PAGE_ORDER);
300 #ifdef CONFIG_HIGHMEM
301 static void try_to_free_low(unsigned long count)
304 for (i = 0; i < MAX_NUMNODES; ++i) {
305 struct page *page, *next;
306 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
307 if (PageHighMem(page))
309 list_del(&page->lru);
310 update_and_free_page(page);
311 nid = page_zone(page)->zone_pgdat->node_id;
313 free_huge_pages_node[nid]--;
314 if (count >= nr_huge_pages)
320 static inline void try_to_free_low(unsigned long count)
325 static unsigned long set_max_huge_pages(unsigned long count)
327 while (count > nr_huge_pages) {
328 if (!alloc_fresh_huge_page())
329 return nr_huge_pages;
331 if (count >= nr_huge_pages)
332 return nr_huge_pages;
334 spin_lock(&hugetlb_lock);
335 try_to_free_low(count);
336 while (count < nr_huge_pages) {
337 struct page *page = dequeue_huge_page(NULL, 0);
340 update_and_free_page(page);
342 spin_unlock(&hugetlb_lock);
343 return nr_huge_pages;
346 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
347 struct file *file, void __user *buffer,
348 size_t *length, loff_t *ppos)
350 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
351 max_huge_pages = set_max_huge_pages(max_huge_pages);
354 #endif /* CONFIG_SYSCTL */
356 int hugetlb_report_meminfo(char *buf)
359 "HugePages_Total: %5lu\n"
360 "HugePages_Free: %5lu\n"
361 "HugePages_Rsvd: %5lu\n"
362 "Hugepagesize: %5lu kB\n",
369 int hugetlb_report_node_meminfo(int nid, char *buf)
372 "Node %d HugePages_Total: %5u\n"
373 "Node %d HugePages_Free: %5u\n",
374 nid, nr_huge_pages_node[nid],
375 nid, free_huge_pages_node[nid]);
378 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
379 unsigned long hugetlb_total_pages(void)
381 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
385 * We cannot handle pagefaults against hugetlb pages at all. They cause
386 * handle_mm_fault() to try to instantiate regular-sized pages in the
387 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
390 static struct page *hugetlb_nopage(struct vm_area_struct *vma,
391 unsigned long address, int *unused)
397 struct vm_operations_struct hugetlb_vm_ops = {
398 .nopage = hugetlb_nopage,
401 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
408 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
410 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
412 entry = pte_mkyoung(entry);
413 entry = pte_mkhuge(entry);
418 static void set_huge_ptep_writable(struct vm_area_struct *vma,
419 unsigned long address, pte_t *ptep)
423 entry = pte_mkwrite(pte_mkdirty(*ptep));
424 ptep_set_access_flags(vma, address, ptep, entry, 1);
425 update_mmu_cache(vma, address, entry);
426 lazy_mmu_prot_update(entry);
430 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
431 struct vm_area_struct *vma)
433 pte_t *src_pte, *dst_pte, entry;
434 struct page *ptepage;
438 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
440 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
441 src_pte = huge_pte_offset(src, addr);
444 dst_pte = huge_pte_alloc(dst, addr);
447 spin_lock(&dst->page_table_lock);
448 spin_lock(&src->page_table_lock);
449 if (!pte_none(*src_pte)) {
451 ptep_set_wrprotect(src, addr, src_pte);
453 ptepage = pte_page(entry);
455 add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
456 set_huge_pte_at(dst, addr, dst_pte, entry);
458 spin_unlock(&src->page_table_lock);
459 spin_unlock(&dst->page_table_lock);
467 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
470 struct mm_struct *mm = vma->vm_mm;
471 unsigned long address;
476 WARN_ON(!is_vm_hugetlb_page(vma));
477 BUG_ON(start & ~HPAGE_MASK);
478 BUG_ON(end & ~HPAGE_MASK);
480 spin_lock(&mm->page_table_lock);
482 /* Update high watermark before we lower rss */
483 update_hiwater_rss(mm);
485 for (address = start; address < end; address += HPAGE_SIZE) {
486 ptep = huge_pte_offset(mm, address);
490 pte = huge_ptep_get_and_clear(mm, address, ptep);
494 page = pte_page(pte);
496 add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
499 spin_unlock(&mm->page_table_lock);
500 flush_tlb_range(vma, start, end);
503 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
504 unsigned long address, pte_t *ptep, pte_t pte)
506 struct page *old_page, *new_page;
509 old_page = pte_page(pte);
511 /* If no-one else is actually using this page, avoid the copy
512 * and just make the page writable */
513 avoidcopy = (page_count(old_page) == 1);
515 set_huge_ptep_writable(vma, address, ptep);
516 return VM_FAULT_MINOR;
519 page_cache_get(old_page);
520 new_page = alloc_huge_page(vma, address);
523 page_cache_release(old_page);
527 spin_unlock(&mm->page_table_lock);
528 copy_huge_page(new_page, old_page, address);
529 spin_lock(&mm->page_table_lock);
531 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
532 if (likely(pte_same(*ptep, pte))) {
534 set_huge_pte_at(mm, address, ptep,
535 make_huge_pte(vma, new_page, 1));
536 /* Make the old page be freed below */
539 page_cache_release(new_page);
540 page_cache_release(old_page);
541 return VM_FAULT_MINOR;
544 int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
545 unsigned long address, pte_t *ptep, int write_access)
547 int ret = VM_FAULT_SIGBUS;
551 struct address_space *mapping;
554 mapping = vma->vm_file->f_mapping;
555 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
556 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
559 * Use page lock to guard against racing truncation
560 * before we get page_table_lock.
563 page = find_lock_page(mapping, idx);
565 if (hugetlb_get_quota(mapping))
567 page = alloc_huge_page(vma, address);
569 hugetlb_put_quota(mapping);
573 clear_huge_page(page, address);
575 if (vma->vm_flags & VM_SHARED) {
578 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
581 hugetlb_put_quota(mapping);
590 spin_lock(&mm->page_table_lock);
591 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
595 ret = VM_FAULT_MINOR;
596 if (!pte_none(*ptep))
599 add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
600 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
601 && (vma->vm_flags & VM_SHARED)));
602 set_huge_pte_at(mm, address, ptep, new_pte);
604 if (write_access && !(vma->vm_flags & VM_SHARED)) {
605 /* Optimization, do the COW without a second fault */
606 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
609 spin_unlock(&mm->page_table_lock);
615 spin_unlock(&mm->page_table_lock);
616 hugetlb_put_quota(mapping);
622 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
623 unsigned long address, int write_access)
628 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
630 ptep = huge_pte_alloc(mm, address);
635 * Serialize hugepage allocation and instantiation, so that we don't
636 * get spurious allocation failures if two CPUs race to instantiate
637 * the same page in the page cache.
639 mutex_lock(&hugetlb_instantiation_mutex);
641 if (pte_none(entry)) {
642 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
643 mutex_unlock(&hugetlb_instantiation_mutex);
647 ret = VM_FAULT_MINOR;
649 spin_lock(&mm->page_table_lock);
650 /* Check for a racing update before calling hugetlb_cow */
651 if (likely(pte_same(entry, *ptep)))
652 if (write_access && !pte_write(entry))
653 ret = hugetlb_cow(mm, vma, address, ptep, entry);
654 spin_unlock(&mm->page_table_lock);
655 mutex_unlock(&hugetlb_instantiation_mutex);
660 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
661 struct page **pages, struct vm_area_struct **vmas,
662 unsigned long *position, int *length, int i)
664 unsigned long pfn_offset;
665 unsigned long vaddr = *position;
666 int remainder = *length;
668 spin_lock(&mm->page_table_lock);
669 while (vaddr < vma->vm_end && remainder) {
674 * Some archs (sparc64, sh*) have multiple pte_ts to
675 * each hugepage. We have to make * sure we get the
676 * first, for the page indexing below to work.
678 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
680 if (!pte || pte_none(*pte)) {
683 spin_unlock(&mm->page_table_lock);
684 ret = hugetlb_fault(mm, vma, vaddr, 0);
685 spin_lock(&mm->page_table_lock);
686 if (ret == VM_FAULT_MINOR)
695 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
696 page = pte_page(*pte);
700 pages[i] = page + pfn_offset;
709 if (vaddr < vma->vm_end && remainder &&
710 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
712 * We use pfn_offset to avoid touching the pageframes
713 * of this compound page.
718 spin_unlock(&mm->page_table_lock);
725 void hugetlb_change_protection(struct vm_area_struct *vma,
726 unsigned long address, unsigned long end, pgprot_t newprot)
728 struct mm_struct *mm = vma->vm_mm;
729 unsigned long start = address;
733 BUG_ON(address >= end);
734 flush_cache_range(vma, address, end);
736 spin_lock(&mm->page_table_lock);
737 for (; address < end; address += HPAGE_SIZE) {
738 ptep = huge_pte_offset(mm, address);
741 if (!pte_none(*ptep)) {
742 pte = huge_ptep_get_and_clear(mm, address, ptep);
743 pte = pte_mkhuge(pte_modify(pte, newprot));
744 set_huge_pte_at(mm, address, ptep, pte);
745 lazy_mmu_prot_update(pte);
748 spin_unlock(&mm->page_table_lock);
750 flush_tlb_range(vma, start, end);