/* * Generic hugetlb support. * (C) William Irwin, April 2004 */ #include <linux/gfp.h> #include <linux/list.h> #include <linux/init.h> #include <linux/module.h> #include <linux/mm.h> #include <linux/sysctl.h> #include <linux/highmem.h> #include <linux/nodemask.h> #include <linux/pagemap.h> #include <linux/mempolicy.h> #include <linux/cpuset.h> #include <linux/mutex.h> #include <asm/page.h> #include <asm/pgtable.h> #include <linux/hugetlb.h> #include "internal.h" const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; static unsigned long nr_huge_pages, free_huge_pages, resv_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, struct vm_area_struct *vma) { 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, vma); } } 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 = zone_to_nid(*z); if (cpuset_zone_allowed_softwall(*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) { set_compound_page_dtor(page, free_huge_page); 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 page *page; spin_lock(&hugetlb_lock); if (vma->vm_flags & VM_MAYSHARE) resv_huge_pages--; else if (free_huge_pages <= resv_huge_pages) goto fail; page = dequeue_huge_page(vma, addr); if (!page) goto fail; spin_unlock(&hugetlb_lock); set_page_refcounted(page); return page; fail: if (vma->vm_flags & VM_MAYSHARE) resv_huge_pages++; spin_unlock(&hugetlb_lock); return NULL; } 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); static unsigned int cpuset_mems_nr(unsigned int *array) { int node; unsigned int nr = 0; for_each_node_mask(node, cpuset_current_mems_allowed) nr += array[node]; return nr; } #ifdef CONFIG_SYSCTL static void update_and_free_page(struct page *page) { int i; nr_huge_pages--; nr_huge_pages_node[page_to_nid(page)]--; 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; 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); free_huge_pages--; free_huge_pages_node[page_to_nid(page)]--; 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, resv_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, resv_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); 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; struct page *tmp; /* * A page gathering list, protected by per file i_mmap_lock. The * lock is used to avoid list corruption from multiple unmapping * of the same page since we are using page->lru. */ LIST_HEAD(page_list); WARN_ON(!is_vm_hugetlb_page(vma)); BUG_ON(start & ~HPAGE_MASK); BUG_ON(end & ~HPAGE_MASK); spin_lock(&mm->page_table_lock); for (address = start; address < end; address += HPAGE_SIZE) { ptep = huge_pte_offset(mm, address); if (!ptep) continue; if (huge_pmd_unshare(mm, &address, ptep)) continue; pte = huge_ptep_get_and_clear(mm, address, ptep); if (pte_none(pte)) continue; page = pte_page(pte); if (pte_dirty(pte)) set_page_dirty(page); list_add(&page->lru, &page_list); } spin_unlock(&mm->page_table_lock); flush_tlb_range(vma, start, end); list_for_each_entry_safe(page, tmp, &page_list, lru) { list_del(&page->lru); put_page(page); } } void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { /* * It is undesirable to test vma->vm_file as it should be non-null * for valid hugetlb area. However, vm_file will be NULL in the error * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails, * do_mmap_pgoff() nullifies vma->vm_file before calling this function * to clean up. Since no pte has actually been setup, it is safe to * do nothing in this case. */ if (vma->vm_file) { spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); __unmap_hugepage_range(vma, start, end); spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); } } 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, vma); 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) { size = i_size_read(mapping->host) >> HPAGE_SHIFT; if (idx >= size) goto out; 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; 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(&vma->vm_file->f_mapping->i_mmap_lock); spin_lock(&mm->page_table_lock); for (; address < end; address += HPAGE_SIZE) { ptep = huge_pte_offset(mm, address); if (!ptep) continue; if (huge_pmd_unshare(mm, &address, 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); spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); flush_tlb_range(vma, start, end); } struct file_region { struct list_head link; long from; long to; }; static long region_add(struct list_head *head, long f, long t) { struct file_region *rg, *nrg, *trg; /* Locate the region we are either in or before. */ list_for_each_entry(rg, head, link) if (f <= rg->to) break; /* Round our left edge to the current segment if it encloses us. */ if (f > rg->from) f = rg->from; /* Check for and consume any regions we now overlap with. */ nrg = rg; list_for_each_entry_safe(rg, trg, rg->link.prev, link) { if (&rg->link == head) break; if (rg->from > t) break; /* If this area reaches higher then extend our area to * include it completely. If this is not the first area * which we intend to reuse, free it. */ if (rg->to > t) t = rg->to; if (rg != nrg) { list_del(&rg->link); kfree(rg); } } nrg->from = f; nrg->to = t; return 0; } static long region_chg(struct list_head *head, long f, long t) { struct file_region *rg, *nrg; long chg = 0; /* Locate the region we are before or in. */ list_for_each_entry(rg, head, link) if (f <= rg->to) break; /* If we are below the current region then a new region is required. * Subtle, allocate a new region at the position but make it zero * size such that we can guarentee to record the reservation. */ if (&rg->link == head || t < rg->from) { nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); if (nrg == 0) return -ENOMEM; nrg->from = f; nrg->to = f; INIT_LIST_HEAD(&nrg->link); list_add(&nrg->link, rg->link.prev); return t - f; } /* Round our left edge to the current segment if it encloses us. */ if (f > rg->from) f = rg->from; chg = t - f; /* Check for and consume any regions we now overlap with. */ list_for_each_entry(rg, rg->link.prev, link) { if (&rg->link == head) break; if (rg->from > t) return chg; /* We overlap with this area, if it extends futher than * us then we must extend ourselves. Account for its * existing reservation. */ if (rg->to > t) { chg += rg->to - t; t = rg->to; } chg -= rg->to - rg->from; } return chg; } static long region_truncate(struct list_head *head, long end) { struct file_region *rg, *trg; long chg = 0; /* Locate the region we are either in or before. */ list_for_each_entry(rg, head, link) if (end <= rg->to) break; if (&rg->link == head) return 0; /* If we are in the middle of a region then adjust it. */ if (end > rg->from) { chg = rg->to - end; rg->to = end; rg = list_entry(rg->link.next, typeof(*rg), link); } /* Drop any remaining regions. */ list_for_each_entry_safe(rg, trg, rg->link.prev, link) { if (&rg->link == head) break; chg += rg->to - rg->from; list_del(&rg->link); kfree(rg); } return chg; } static int hugetlb_acct_memory(long delta) { int ret = -ENOMEM; spin_lock(&hugetlb_lock); if ((delta + resv_huge_pages) <= free_huge_pages) { resv_huge_pages += delta; ret = 0; } spin_unlock(&hugetlb_lock); return ret; } int hugetlb_reserve_pages(struct inode *inode, long from, long to) { long ret, chg; chg = region_chg(&inode->i_mapping->private_list, from, to); if (chg < 0) return chg; /* * When cpuset is configured, it breaks the strict hugetlb page * reservation as the accounting is done on a global variable. Such * reservation is completely rubbish in the presence of cpuset because * the reservation is not checked against page availability for the * current cpuset. Application can still potentially OOM'ed by kernel * with lack of free htlb page in cpuset that the task is in. * Attempt to enforce strict accounting with cpuset is almost * impossible (or too ugly) because cpuset is too fluid that * task or memory node can be dynamically moved between cpusets. * * The change of semantics for shared hugetlb mapping with cpuset is * undesirable. However, in order to preserve some of the semantics, * we fall back to check against current free page availability as * a best attempt and hopefully to minimize the impact of changing * semantics that cpuset has. */ if (chg > cpuset_mems_nr(free_huge_pages_node)) return -ENOMEM; ret = hugetlb_acct_memory(chg); if (ret < 0) return ret; region_add(&inode->i_mapping->private_list, from, to); return 0; } void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) { long chg = region_truncate(&inode->i_mapping->private_list, offset); hugetlb_acct_memory(freed - chg); }