/* * Generic hugetlb support. * (C) William Irwin, April 2004 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; static unsigned long nr_huge_pages, free_huge_pages, reserved_huge_pages; unsigned long max_huge_pages; static struct list_head hugepage_freelists[MAX_NUMNODES]; static unsigned int nr_huge_pages_node[MAX_NUMNODES]; static unsigned int free_huge_pages_node[MAX_NUMNODES]; /* * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages */ static DEFINE_SPINLOCK(hugetlb_lock); static void clear_huge_page(struct page *page, unsigned long addr) { int i; might_sleep(); for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) { cond_resched(); clear_user_highpage(page + i, addr); } } static void copy_huge_page(struct page *dst, struct page *src, unsigned long addr) { int i; might_sleep(); for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) { cond_resched(); copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE); } } static void enqueue_huge_page(struct page *page) { int nid = page_to_nid(page); list_add(&page->lru, &hugepage_freelists[nid]); free_huge_pages++; free_huge_pages_node[nid]++; } static struct page *dequeue_huge_page(struct vm_area_struct *vma, unsigned long address) { int nid = numa_node_id(); struct page *page = NULL; struct zonelist *zonelist = huge_zonelist(vma, address); struct zone **z; for (z = zonelist->zones; *z; z++) { nid = (*z)->zone_pgdat->node_id; if (cpuset_zone_allowed(*z, GFP_HIGHUSER) && !list_empty(&hugepage_freelists[nid])) break; } if (*z) { page = list_entry(hugepage_freelists[nid].next, struct page, lru); list_del(&page->lru); free_huge_pages--; free_huge_pages_node[nid]--; } return page; } static void free_huge_page(struct page *page) { BUG_ON(page_count(page)); INIT_LIST_HEAD(&page->lru); spin_lock(&hugetlb_lock); enqueue_huge_page(page); spin_unlock(&hugetlb_lock); } static int alloc_fresh_huge_page(void) { static int nid = 0; struct page *page; page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN, HUGETLB_PAGE_ORDER); nid = next_node(nid, node_online_map); if (nid == MAX_NUMNODES) nid = first_node(node_online_map); if (page) { page[1].lru.next = (void *)free_huge_page; /* dtor */ spin_lock(&hugetlb_lock); nr_huge_pages++; nr_huge_pages_node[page_to_nid(page)]++; spin_unlock(&hugetlb_lock); put_page(page); /* free it into the hugepage allocator */ return 1; } return 0; } static struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr) { struct inode *inode = vma->vm_file->f_dentry->d_inode; struct page *page; int use_reserve = 0; unsigned long idx; spin_lock(&hugetlb_lock); if (vma->vm_flags & VM_MAYSHARE) { /* idx = radix tree index, i.e. offset into file in * HPAGE_SIZE units */ idx = ((addr - vma->vm_start) >> HPAGE_SHIFT) + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT)); /* The hugetlbfs specific inode info stores the number * of "guaranteed available" (huge) pages. That is, * the first 'prereserved_hpages' pages of the inode * are either already instantiated, or have been * pre-reserved (by hugetlb_reserve_for_inode()). Here * we're in the process of instantiating the page, so * we use this to determine whether to draw from the * pre-reserved pool or the truly free pool. */ if (idx < HUGETLBFS_I(inode)->prereserved_hpages) use_reserve = 1; } if (!use_reserve) { if (free_huge_pages <= reserved_huge_pages) goto fail; } else { BUG_ON(reserved_huge_pages == 0); reserved_huge_pages--; } page = dequeue_huge_page(vma, addr); if (!page) goto fail; spin_unlock(&hugetlb_lock); set_page_refcounted(page); return page; fail: WARN_ON(use_reserve); /* reserved allocations shouldn't fail */ spin_unlock(&hugetlb_lock); return NULL; } /* hugetlb_extend_reservation() * * Ensure that at least 'atleast' hugepages are, and will remain, * available to instantiate the first 'atleast' pages of the given * inode. If the inode doesn't already have this many pages reserved * or instantiated, set aside some hugepages in the reserved pool to * satisfy later faults (or fail now if there aren't enough, rather * than getting the SIGBUS later). */ int hugetlb_extend_reservation(struct hugetlbfs_inode_info *info, unsigned long atleast) { struct inode *inode = &info->vfs_inode; unsigned long change_in_reserve = 0; int ret = 0; spin_lock(&hugetlb_lock); read_lock_irq(&inode->i_mapping->tree_lock); if (info->prereserved_hpages >= atleast) goto out; /* Because we always call this on shared mappings, none of the * pages beyond info->prereserved_hpages can have been * instantiated, so we need to reserve all of them now. */ change_in_reserve = atleast - info->prereserved_hpages; if ((reserved_huge_pages + change_in_reserve) > free_huge_pages) { ret = -ENOMEM; goto out; } reserved_huge_pages += change_in_reserve; info->prereserved_hpages = atleast; out: read_unlock_irq(&inode->i_mapping->tree_lock); spin_unlock(&hugetlb_lock); return ret; } /* hugetlb_truncate_reservation() * * This returns pages reserved for the given inode to the general free * hugepage pool. If the inode has any pages prereserved, but not * instantiated, beyond offset (atmost << HPAGE_SIZE), then release * them. */ void hugetlb_truncate_reservation(struct hugetlbfs_inode_info *info, unsigned long atmost) { struct inode *inode = &info->vfs_inode; struct address_space *mapping = inode->i_mapping; unsigned long idx; unsigned long change_in_reserve = 0; struct page *page; spin_lock(&hugetlb_lock); read_lock_irq(&inode->i_mapping->tree_lock); if (info->prereserved_hpages <= atmost) goto out; /* Count pages which were reserved, but not instantiated, and * which we can now release. */ for (idx = atmost; idx < info->prereserved_hpages; idx++) { page = radix_tree_lookup(&mapping->page_tree, idx); if (!page) /* Pages which are already instantiated can't * be unreserved (and in fact have already * been removed from the reserved pool) */ change_in_reserve++; } BUG_ON(reserved_huge_pages < change_in_reserve); reserved_huge_pages -= change_in_reserve; info->prereserved_hpages = atmost; out: read_unlock_irq(&inode->i_mapping->tree_lock); spin_unlock(&hugetlb_lock); } static int __init hugetlb_init(void) { unsigned long i; if (HPAGE_SHIFT == 0) return 0; for (i = 0; i < MAX_NUMNODES; ++i) INIT_LIST_HEAD(&hugepage_freelists[i]); for (i = 0; i < max_huge_pages; ++i) { if (!alloc_fresh_huge_page()) break; } max_huge_pages = free_huge_pages = nr_huge_pages = i; printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages); return 0; } module_init(hugetlb_init); static int __init hugetlb_setup(char *s) { if (sscanf(s, "%lu", &max_huge_pages) <= 0) max_huge_pages = 0; return 1; } __setup("hugepages=", hugetlb_setup); #ifdef CONFIG_SYSCTL static void update_and_free_page(struct page *page) { int i; nr_huge_pages--; nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--; for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) { page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved | 1 << PG_private | 1<< PG_writeback); } page[1].lru.next = NULL; set_page_refcounted(page); __free_pages(page, HUGETLB_PAGE_ORDER); } #ifdef CONFIG_HIGHMEM static void try_to_free_low(unsigned long count) { int i, nid; for (i = 0; i < MAX_NUMNODES; ++i) { struct page *page, *next; list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) { if (PageHighMem(page)) continue; list_del(&page->lru); update_and_free_page(page); nid = page_zone(page)->zone_pgdat->node_id; free_huge_pages--; free_huge_pages_node[nid]--; if (count >= nr_huge_pages) return; } } } #else static inline void try_to_free_low(unsigned long count) { } #endif static unsigned long set_max_huge_pages(unsigned long count) { while (count > nr_huge_pages) { if (!alloc_fresh_huge_page()) return nr_huge_pages; } if (count >= nr_huge_pages) return nr_huge_pages; spin_lock(&hugetlb_lock); count = max(count, reserved_huge_pages); try_to_free_low(count); while (count < nr_huge_pages) { struct page *page = dequeue_huge_page(NULL, 0); if (!page) break; update_and_free_page(page); } spin_unlock(&hugetlb_lock); return nr_huge_pages; } int hugetlb_sysctl_handler(struct ctl_table *table, int write, struct file *file, void __user *buffer, size_t *length, loff_t *ppos) { proc_doulongvec_minmax(table, write, file, buffer, length, ppos); max_huge_pages = set_max_huge_pages(max_huge_pages); return 0; } #endif /* CONFIG_SYSCTL */ int hugetlb_report_meminfo(char *buf) { return sprintf(buf, "HugePages_Total: %5lu\n" "HugePages_Free: %5lu\n" "HugePages_Rsvd: %5lu\n" "Hugepagesize: %5lu kB\n", nr_huge_pages, free_huge_pages, reserved_huge_pages, HPAGE_SIZE/1024); } int hugetlb_report_node_meminfo(int nid, char *buf) { return sprintf(buf, "Node %d HugePages_Total: %5u\n" "Node %d HugePages_Free: %5u\n", nid, nr_huge_pages_node[nid], nid, free_huge_pages_node[nid]); } /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ unsigned long hugetlb_total_pages(void) { return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE); } /* * We cannot handle pagefaults against hugetlb pages at all. They cause * handle_mm_fault() to try to instantiate regular-sized pages in the * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get * this far. */ static struct page *hugetlb_nopage(struct vm_area_struct *vma, unsigned long address, int *unused) { BUG(); return NULL; } struct vm_operations_struct hugetlb_vm_ops = { .nopage = hugetlb_nopage, }; static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, int writable) { pte_t entry; if (writable) { entry = pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); } else { entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot)); } entry = pte_mkyoung(entry); entry = pte_mkhuge(entry); return entry; } static void set_huge_ptep_writable(struct vm_area_struct *vma, unsigned long address, pte_t *ptep) { pte_t entry; entry = pte_mkwrite(pte_mkdirty(*ptep)); ptep_set_access_flags(vma, address, ptep, entry, 1); update_mmu_cache(vma, address, entry); lazy_mmu_prot_update(entry); } int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, struct vm_area_struct *vma) { pte_t *src_pte, *dst_pte, entry; struct page *ptepage; unsigned long addr; int cow; cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) { src_pte = huge_pte_offset(src, addr); if (!src_pte) continue; dst_pte = huge_pte_alloc(dst, addr); if (!dst_pte) goto nomem; spin_lock(&dst->page_table_lock); spin_lock(&src->page_table_lock); if (!pte_none(*src_pte)) { if (cow) ptep_set_wrprotect(src, addr, src_pte); entry = *src_pte; ptepage = pte_page(entry); get_page(ptepage); add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE); set_huge_pte_at(dst, addr, dst_pte, entry); } spin_unlock(&src->page_table_lock); spin_unlock(&dst->page_table_lock); } return 0; nomem: return -ENOMEM; } void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { struct mm_struct *mm = vma->vm_mm; unsigned long address; pte_t *ptep; pte_t pte; struct page *page; WARN_ON(!is_vm_hugetlb_page(vma)); BUG_ON(start & ~HPAGE_MASK); BUG_ON(end & ~HPAGE_MASK); spin_lock(&mm->page_table_lock); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); for (address = start; address < end; address += HPAGE_SIZE) { ptep = huge_pte_offset(mm, address); if (!ptep) continue; pte = huge_ptep_get_and_clear(mm, address, ptep); if (pte_none(pte)) continue; page = pte_page(pte); put_page(page); add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE)); } spin_unlock(&mm->page_table_lock); flush_tlb_range(vma, start, end); } static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t pte) { struct page *old_page, *new_page; int avoidcopy; old_page = pte_page(pte); /* If no-one else is actually using this page, avoid the copy * and just make the page writable */ avoidcopy = (page_count(old_page) == 1); if (avoidcopy) { set_huge_ptep_writable(vma, address, ptep); return VM_FAULT_MINOR; } page_cache_get(old_page); new_page = alloc_huge_page(vma, address); if (!new_page) { page_cache_release(old_page); return VM_FAULT_OOM; } spin_unlock(&mm->page_table_lock); copy_huge_page(new_page, old_page, address); spin_lock(&mm->page_table_lock); ptep = huge_pte_offset(mm, address & HPAGE_MASK); if (likely(pte_same(*ptep, pte))) { /* Break COW */ set_huge_pte_at(mm, address, ptep, make_huge_pte(vma, new_page, 1)); /* Make the old page be freed below */ new_page = old_page; } page_cache_release(new_page); page_cache_release(old_page); return VM_FAULT_MINOR; } int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, int write_access) { int ret = VM_FAULT_SIGBUS; unsigned long idx; unsigned long size; struct page *page; struct address_space *mapping; pte_t new_pte; mapping = vma->vm_file->f_mapping; idx = ((address - vma->vm_start) >> HPAGE_SHIFT) + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT)); /* * Use page lock to guard against racing truncation * before we get page_table_lock. */ retry: page = find_lock_page(mapping, idx); if (!page) { if (hugetlb_get_quota(mapping)) goto out; page = alloc_huge_page(vma, address); if (!page) { hugetlb_put_quota(mapping); ret = VM_FAULT_OOM; goto out; } clear_huge_page(page, address); if (vma->vm_flags & VM_SHARED) { int err; err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); if (err) { put_page(page); hugetlb_put_quota(mapping); if (err == -EEXIST) goto retry; goto out; } } else lock_page(page); } spin_lock(&mm->page_table_lock); size = i_size_read(mapping->host) >> HPAGE_SHIFT; if (idx >= size) goto backout; ret = VM_FAULT_MINOR; if (!pte_none(*ptep)) goto backout; add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE); new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) && (vma->vm_flags & VM_SHARED))); set_huge_pte_at(mm, address, ptep, new_pte); if (write_access && !(vma->vm_flags & VM_SHARED)) { /* Optimization, do the COW without a second fault */ ret = hugetlb_cow(mm, vma, address, ptep, new_pte); } spin_unlock(&mm->page_table_lock); unlock_page(page); out: return ret; backout: spin_unlock(&mm->page_table_lock); hugetlb_put_quota(mapping); unlock_page(page); put_page(page); goto out; } int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, int write_access) { pte_t *ptep; pte_t entry; int ret; static DEFINE_MUTEX(hugetlb_instantiation_mutex); ptep = huge_pte_alloc(mm, address); if (!ptep) return VM_FAULT_OOM; /* * Serialize hugepage allocation and instantiation, so that we don't * get spurious allocation failures if two CPUs race to instantiate * the same page in the page cache. */ mutex_lock(&hugetlb_instantiation_mutex); entry = *ptep; if (pte_none(entry)) { ret = hugetlb_no_page(mm, vma, address, ptep, write_access); mutex_unlock(&hugetlb_instantiation_mutex); return ret; } ret = VM_FAULT_MINOR; spin_lock(&mm->page_table_lock); /* Check for a racing update before calling hugetlb_cow */ if (likely(pte_same(entry, *ptep))) if (write_access && !pte_write(entry)) ret = hugetlb_cow(mm, vma, address, ptep, entry); spin_unlock(&mm->page_table_lock); mutex_unlock(&hugetlb_instantiation_mutex); return ret; } int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page **pages, struct vm_area_struct **vmas, unsigned long *position, int *length, int i) { unsigned long pfn_offset; unsigned long vaddr = *position; int remainder = *length; spin_lock(&mm->page_table_lock); while (vaddr < vma->vm_end && remainder) { pte_t *pte; struct page *page; /* * Some archs (sparc64, sh*) have multiple pte_ts to * each hugepage. We have to make * sure we get the * first, for the page indexing below to work. */ pte = huge_pte_offset(mm, vaddr & HPAGE_MASK); if (!pte || pte_none(*pte)) { int ret; spin_unlock(&mm->page_table_lock); ret = hugetlb_fault(mm, vma, vaddr, 0); spin_lock(&mm->page_table_lock); if (ret == VM_FAULT_MINOR) continue; remainder = 0; if (!i) i = -EFAULT; break; } pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT; page = pte_page(*pte); same_page: if (pages) { get_page(page); pages[i] = page + pfn_offset; } if (vmas) vmas[i] = vma; vaddr += PAGE_SIZE; ++pfn_offset; --remainder; ++i; if (vaddr < vma->vm_end && remainder && pfn_offset < HPAGE_SIZE/PAGE_SIZE) { /* * We use pfn_offset to avoid touching the pageframes * of this compound page. */ goto same_page; } } spin_unlock(&mm->page_table_lock); *length = remainder; *position = vaddr; return i; } void hugetlb_change_protection(struct vm_area_struct *vma, unsigned long address, unsigned long end, pgprot_t newprot) { struct mm_struct *mm = vma->vm_mm; unsigned long start = address; pte_t *ptep; pte_t pte; BUG_ON(address >= end); flush_cache_range(vma, address, end); spin_lock(&mm->page_table_lock); for (; address < end; address += HPAGE_SIZE) { ptep = huge_pte_offset(mm, address); if (!ptep) continue; if (!pte_none(*ptep)) { pte = huge_ptep_get_and_clear(mm, address, ptep); pte = pte_mkhuge(pte_modify(pte, newprot)); set_huge_pte_at(mm, address, ptep, pte); lazy_mmu_prot_update(pte); } } spin_unlock(&mm->page_table_lock); flush_tlb_range(vma, start, end); }