/* * 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 <asm/page.h> #include <asm/pgtable.h> #include <linux/hugetlb.h> const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; static unsigned long nr_huge_pages, free_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 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 struct page *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 = (nid + 1) % num_online_nodes(); if (page) { spin_lock(&hugetlb_lock); nr_huge_pages++; nr_huge_pages_node[page_to_nid(page)]++; spin_unlock(&hugetlb_lock); } return page; } void free_huge_page(struct page *page) { BUG_ON(page_count(page)); INIT_LIST_HEAD(&page->lru); page[1].mapping = NULL; spin_lock(&hugetlb_lock); enqueue_huge_page(page); spin_unlock(&hugetlb_lock); } struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr) { struct page *page; int i; spin_lock(&hugetlb_lock); page = dequeue_huge_page(vma, addr); if (!page) { spin_unlock(&hugetlb_lock); return NULL; } spin_unlock(&hugetlb_lock); set_page_count(page, 1); page[1].mapping = (void *)free_huge_page; for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i) clear_highpage(&page[i]); return page; } static int __init hugetlb_init(void) { unsigned long i; struct page *page; 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) { page = alloc_fresh_huge_page(); if (!page) break; spin_lock(&hugetlb_lock); enqueue_huge_page(page); spin_unlock(&hugetlb_lock); } 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); set_page_count(&page[i], 0); } set_page_count(page, 1); __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) { struct page *page = alloc_fresh_huge_page(); if (!page) return nr_huge_pages; spin_lock(&hugetlb_lock); enqueue_huge_page(page); spin_unlock(&hugetlb_lock); } if (count >= nr_huge_pages) return nr_huge_pages; spin_lock(&hugetlb_lock); 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" "Hugepagesize: %5lu kB\n", nr_huge_pages, free_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]); } int is_hugepage_mem_enough(size_t size) { return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages; } /* 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 i, 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); /* Logically this is OOM, not a SIGBUS, but an OOM * could cause the kernel to go killing other * processes which won't help the hugepage situation * at all (?) */ return VM_FAULT_SIGBUS; } spin_unlock(&mm->page_table_lock); for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) copy_user_highpage(new_page + i, old_page + i, address + i*PAGE_SIZE); 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); goto out; } 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; ptep = huge_pte_alloc(mm, address); if (!ptep) return VM_FAULT_OOM; entry = *ptep; if (pte_none(entry)) return hugetlb_no_page(mm, vma, address, ptep, write_access); 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); 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 vpfn, vaddr = *position; int remainder = *length; vpfn = vaddr/PAGE_SIZE; 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; } if (pages) { page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; get_page(page); pages[i] = page; } if (vmas) vmas[i] = vma; vaddr += PAGE_SIZE; ++vpfn; --remainder; ++i; } spin_unlock(&mm->page_table_lock); *length = remainder; *position = vaddr; return i; }