diff options
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 3094 |
1 files changed, 3094 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c new file mode 100644 index 00000000..263e1770 --- /dev/null +++ b/mm/hugetlb.c @@ -0,0 +1,3094 @@ +/* + * Generic hugetlb support. + * (C) William Irwin, April 2004 + */ +#include <linux/list.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mm.h> +#include <linux/seq_file.h> +#include <linux/sysctl.h> +#include <linux/highmem.h> +#include <linux/mmu_notifier.h> +#include <linux/nodemask.h> +#include <linux/pagemap.h> +#include <linux/mempolicy.h> +#include <linux/cpuset.h> +#include <linux/mutex.h> +#include <linux/bootmem.h> +#include <linux/sysfs.h> +#include <linux/slab.h> +#include <linux/rmap.h> +#include <linux/swap.h> +#include <linux/swapops.h> + +#include <asm/page.h> +#include <asm/pgtable.h> +#include <linux/io.h> + +#include <linux/hugetlb.h> +#include <linux/node.h> +#include "internal.h" + +const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; +static gfp_t htlb_alloc_mask = GFP_HIGHUSER; +unsigned long hugepages_treat_as_movable; + +static int max_hstate; +unsigned int default_hstate_idx; +struct hstate hstates[HUGE_MAX_HSTATE]; + +__initdata LIST_HEAD(huge_boot_pages); + +/* for command line parsing */ +static struct hstate * __initdata parsed_hstate; +static unsigned long __initdata default_hstate_max_huge_pages; +static unsigned long __initdata default_hstate_size; + +#define for_each_hstate(h) \ + for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++) + +/* + * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages + */ +static DEFINE_SPINLOCK(hugetlb_lock); + +static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) +{ + bool free = (spool->count == 0) && (spool->used_hpages == 0); + + spin_unlock(&spool->lock); + + /* If no pages are used, and no other handles to the subpool + * remain, free the subpool the subpool remain */ + if (free) + kfree(spool); +} + +struct hugepage_subpool *hugepage_new_subpool(long nr_blocks) +{ + struct hugepage_subpool *spool; + + spool = kmalloc(sizeof(*spool), GFP_KERNEL); + if (!spool) + return NULL; + + spin_lock_init(&spool->lock); + spool->count = 1; + spool->max_hpages = nr_blocks; + spool->used_hpages = 0; + + return spool; +} + +void hugepage_put_subpool(struct hugepage_subpool *spool) +{ + spin_lock(&spool->lock); + BUG_ON(!spool->count); + spool->count--; + unlock_or_release_subpool(spool); +} + +static int hugepage_subpool_get_pages(struct hugepage_subpool *spool, + long delta) +{ + int ret = 0; + + if (!spool) + return 0; + + spin_lock(&spool->lock); + if ((spool->used_hpages + delta) <= spool->max_hpages) { + spool->used_hpages += delta; + } else { + ret = -ENOMEM; + } + spin_unlock(&spool->lock); + + return ret; +} + +static void hugepage_subpool_put_pages(struct hugepage_subpool *spool, + long delta) +{ + if (!spool) + return; + + spin_lock(&spool->lock); + spool->used_hpages -= delta; + /* If hugetlbfs_put_super couldn't free spool due to + * an outstanding quota reference, free it now. */ + unlock_or_release_subpool(spool); +} + +static inline struct hugepage_subpool *subpool_inode(struct inode *inode) +{ + return HUGETLBFS_SB(inode->i_sb)->spool; +} + +static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma) +{ + return subpool_inode(vma->vm_file->f_dentry->d_inode); +} + +/* + * Region tracking -- allows tracking of reservations and instantiated pages + * across the pages in a mapping. + * + * The region data structures are protected by a combination of the mmap_sem + * and the hugetlb_instantion_mutex. To access or modify a region the caller + * must either hold the mmap_sem for write, or the mmap_sem for read and + * the hugetlb_instantiation mutex: + * + * down_write(&mm->mmap_sem); + * or + * down_read(&mm->mmap_sem); + * mutex_lock(&hugetlb_instantiation_mutex); + */ +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 guarantee to record the reservation. */ + if (&rg->link == head || t < rg->from) { + nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); + if (!nrg) + 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 further 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 long region_count(struct list_head *head, long f, long t) +{ + struct file_region *rg; + long chg = 0; + + /* Locate each segment we overlap with, and count that overlap. */ + list_for_each_entry(rg, head, link) { + int seg_from; + int seg_to; + + if (rg->to <= f) + continue; + if (rg->from >= t) + break; + + seg_from = max(rg->from, f); + seg_to = min(rg->to, t); + + chg += seg_to - seg_from; + } + + return chg; +} + +/* + * Convert the address within this vma to the page offset within + * the mapping, in pagecache page units; huge pages here. + */ +static pgoff_t vma_hugecache_offset(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + return ((address - vma->vm_start) >> huge_page_shift(h)) + + (vma->vm_pgoff >> huge_page_order(h)); +} + +pgoff_t linear_hugepage_index(struct vm_area_struct *vma, + unsigned long address) +{ + return vma_hugecache_offset(hstate_vma(vma), vma, address); +} + +/* + * Return the size of the pages allocated when backing a VMA. In the majority + * cases this will be same size as used by the page table entries. + */ +unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) +{ + struct hstate *hstate; + + if (!is_vm_hugetlb_page(vma)) + return PAGE_SIZE; + + hstate = hstate_vma(vma); + + return 1UL << (hstate->order + PAGE_SHIFT); +} +EXPORT_SYMBOL_GPL(vma_kernel_pagesize); + +/* + * Return the page size being used by the MMU to back a VMA. In the majority + * of cases, the page size used by the kernel matches the MMU size. On + * architectures where it differs, an architecture-specific version of this + * function is required. + */ +#ifndef vma_mmu_pagesize +unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) +{ + return vma_kernel_pagesize(vma); +} +#endif + +/* + * Flags for MAP_PRIVATE reservations. These are stored in the bottom + * bits of the reservation map pointer, which are always clear due to + * alignment. + */ +#define HPAGE_RESV_OWNER (1UL << 0) +#define HPAGE_RESV_UNMAPPED (1UL << 1) +#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) + +/* + * These helpers are used to track how many pages are reserved for + * faults in a MAP_PRIVATE mapping. Only the process that called mmap() + * is guaranteed to have their future faults succeed. + * + * With the exception of reset_vma_resv_huge_pages() which is called at fork(), + * the reserve counters are updated with the hugetlb_lock held. It is safe + * to reset the VMA at fork() time as it is not in use yet and there is no + * chance of the global counters getting corrupted as a result of the values. + * + * The private mapping reservation is represented in a subtly different + * manner to a shared mapping. A shared mapping has a region map associated + * with the underlying file, this region map represents the backing file + * pages which have ever had a reservation assigned which this persists even + * after the page is instantiated. A private mapping has a region map + * associated with the original mmap which is attached to all VMAs which + * reference it, this region map represents those offsets which have consumed + * reservation ie. where pages have been instantiated. + */ +static unsigned long get_vma_private_data(struct vm_area_struct *vma) +{ + return (unsigned long)vma->vm_private_data; +} + +static void set_vma_private_data(struct vm_area_struct *vma, + unsigned long value) +{ + vma->vm_private_data = (void *)value; +} + +struct resv_map { + struct kref refs; + struct list_head regions; +}; + +static struct resv_map *resv_map_alloc(void) +{ + struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); + if (!resv_map) + return NULL; + + kref_init(&resv_map->refs); + INIT_LIST_HEAD(&resv_map->regions); + + return resv_map; +} + +static void resv_map_release(struct kref *ref) +{ + struct resv_map *resv_map = container_of(ref, struct resv_map, refs); + + /* Clear out any active regions before we release the map. */ + region_truncate(&resv_map->regions, 0); + kfree(resv_map); +} + +static struct resv_map *vma_resv_map(struct vm_area_struct *vma) +{ + VM_BUG_ON(!is_vm_hugetlb_page(vma)); + if (!(vma->vm_flags & VM_MAYSHARE)) + return (struct resv_map *)(get_vma_private_data(vma) & + ~HPAGE_RESV_MASK); + return NULL; +} + +static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) +{ + VM_BUG_ON(!is_vm_hugetlb_page(vma)); + VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); + + set_vma_private_data(vma, (get_vma_private_data(vma) & + HPAGE_RESV_MASK) | (unsigned long)map); +} + +static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) +{ + VM_BUG_ON(!is_vm_hugetlb_page(vma)); + VM_BUG_ON(vma->vm_flags & VM_MAYSHARE); + + set_vma_private_data(vma, get_vma_private_data(vma) | flags); +} + +static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) +{ + VM_BUG_ON(!is_vm_hugetlb_page(vma)); + + return (get_vma_private_data(vma) & flag) != 0; +} + +/* Decrement the reserved pages in the hugepage pool by one */ +static void decrement_hugepage_resv_vma(struct hstate *h, + struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_NORESERVE) + return; + + if (vma->vm_flags & VM_MAYSHARE) { + /* Shared mappings always use reserves */ + h->resv_huge_pages--; + } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + /* + * Only the process that called mmap() has reserves for + * private mappings. + */ + h->resv_huge_pages--; + } +} + +/* Reset counters to 0 and clear all HPAGE_RESV_* flags */ +void reset_vma_resv_huge_pages(struct vm_area_struct *vma) +{ + VM_BUG_ON(!is_vm_hugetlb_page(vma)); + if (!(vma->vm_flags & VM_MAYSHARE)) + vma->vm_private_data = (void *)0; +} + +/* Returns true if the VMA has associated reserve pages */ +static int vma_has_reserves(struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_MAYSHARE) + return 1; + if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + return 1; + return 0; +} + +static void copy_gigantic_page(struct page *dst, struct page *src) +{ + int i; + struct hstate *h = page_hstate(src); + struct page *dst_base = dst; + struct page *src_base = src; + + for (i = 0; i < pages_per_huge_page(h); ) { + cond_resched(); + copy_highpage(dst, src); + + i++; + dst = mem_map_next(dst, dst_base, i); + src = mem_map_next(src, src_base, i); + } +} + +void copy_huge_page(struct page *dst, struct page *src) +{ + int i; + struct hstate *h = page_hstate(src); + + if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) { + copy_gigantic_page(dst, src); + return; + } + + might_sleep(); + for (i = 0; i < pages_per_huge_page(h); i++) { + cond_resched(); + copy_highpage(dst + i, src + i); + } +} + +static void enqueue_huge_page(struct hstate *h, struct page *page) +{ + int nid = page_to_nid(page); + list_add(&page->lru, &h->hugepage_freelists[nid]); + h->free_huge_pages++; + h->free_huge_pages_node[nid]++; +} + +static struct page *dequeue_huge_page_node(struct hstate *h, int nid) +{ + struct page *page; + + if (list_empty(&h->hugepage_freelists[nid])) + return NULL; + page = list_entry(h->hugepage_freelists[nid].next, struct page, lru); + list_del(&page->lru); + set_page_refcounted(page); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + return page; +} + +static struct page *dequeue_huge_page_vma(struct hstate *h, + struct vm_area_struct *vma, + unsigned long address, int avoid_reserve) +{ + struct page *page = NULL; + struct mempolicy *mpol; + nodemask_t *nodemask; + struct zonelist *zonelist; + struct zone *zone; + struct zoneref *z; + unsigned int cpuset_mems_cookie; + +retry_cpuset: + cpuset_mems_cookie = get_mems_allowed(); + zonelist = huge_zonelist(vma, address, + htlb_alloc_mask, &mpol, &nodemask); + /* + * A child process with MAP_PRIVATE mappings created by their parent + * have no page reserves. This check ensures that reservations are + * not "stolen". The child may still get SIGKILLed + */ + if (!vma_has_reserves(vma) && + h->free_huge_pages - h->resv_huge_pages == 0) + goto err; + + /* If reserves cannot be used, ensure enough pages are in the pool */ + if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) + goto err; + + for_each_zone_zonelist_nodemask(zone, z, zonelist, + MAX_NR_ZONES - 1, nodemask) { + if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) { + page = dequeue_huge_page_node(h, zone_to_nid(zone)); + if (page) { + if (!avoid_reserve) + decrement_hugepage_resv_vma(h, vma); + break; + } + } + } + + mpol_cond_put(mpol); + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page)) + goto retry_cpuset; + return page; + +err: + mpol_cond_put(mpol); + return NULL; +} + +static void update_and_free_page(struct hstate *h, struct page *page) +{ + int i; + + VM_BUG_ON(h->order >= MAX_ORDER); + + h->nr_huge_pages--; + h->nr_huge_pages_node[page_to_nid(page)]--; + for (i = 0; i < pages_per_huge_page(h); 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_compound_page_dtor(page, NULL); + set_page_refcounted(page); + arch_release_hugepage(page); + __free_pages(page, huge_page_order(h)); +} + +struct hstate *size_to_hstate(unsigned long size) +{ + struct hstate *h; + + for_each_hstate(h) { + if (huge_page_size(h) == size) + return h; + } + return NULL; +} + +static void free_huge_page(struct page *page) +{ + /* + * Can't pass hstate in here because it is called from the + * compound page destructor. + */ + struct hstate *h = page_hstate(page); + int nid = page_to_nid(page); + struct hugepage_subpool *spool = + (struct hugepage_subpool *)page_private(page); + + set_page_private(page, 0); + page->mapping = NULL; + BUG_ON(page_count(page)); + BUG_ON(page_mapcount(page)); + INIT_LIST_HEAD(&page->lru); + + spin_lock(&hugetlb_lock); + if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) { + update_and_free_page(h, page); + h->surplus_huge_pages--; + h->surplus_huge_pages_node[nid]--; + } else { + enqueue_huge_page(h, page); + } + spin_unlock(&hugetlb_lock); + hugepage_subpool_put_pages(spool, 1); +} + +static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) +{ + set_compound_page_dtor(page, free_huge_page); + spin_lock(&hugetlb_lock); + h->nr_huge_pages++; + h->nr_huge_pages_node[nid]++; + spin_unlock(&hugetlb_lock); + put_page(page); /* free it into the hugepage allocator */ +} + +static void prep_compound_gigantic_page(struct page *page, unsigned long order) +{ + int i; + int nr_pages = 1 << order; + struct page *p = page + 1; + + /* we rely on prep_new_huge_page to set the destructor */ + set_compound_order(page, order); + __SetPageHead(page); + for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { + __SetPageTail(p); + set_page_count(p, 0); + p->first_page = page; + } +} + +int PageHuge(struct page *page) +{ + compound_page_dtor *dtor; + + if (!PageCompound(page)) + return 0; + + page = compound_head(page); + dtor = get_compound_page_dtor(page); + + return dtor == free_huge_page; +} +EXPORT_SYMBOL_GPL(PageHuge); + +static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) +{ + struct page *page; + + if (h->order >= MAX_ORDER) + return NULL; + + page = alloc_pages_exact_node(nid, + htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| + __GFP_REPEAT|__GFP_NOWARN, + huge_page_order(h)); + if (page) { + if (arch_prepare_hugepage(page)) { + __free_pages(page, huge_page_order(h)); + return NULL; + } + prep_new_huge_page(h, page, nid); + } + + return page; +} + +/* + * common helper functions for hstate_next_node_to_{alloc|free}. + * We may have allocated or freed a huge page based on a different + * nodes_allowed previously, so h->next_node_to_{alloc|free} might + * be outside of *nodes_allowed. Ensure that we use an allowed + * node for alloc or free. + */ +static int next_node_allowed(int nid, nodemask_t *nodes_allowed) +{ + nid = next_node(nid, *nodes_allowed); + if (nid == MAX_NUMNODES) + nid = first_node(*nodes_allowed); + VM_BUG_ON(nid >= MAX_NUMNODES); + + return nid; +} + +static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) +{ + if (!node_isset(nid, *nodes_allowed)) + nid = next_node_allowed(nid, nodes_allowed); + return nid; +} + +/* + * returns the previously saved node ["this node"] from which to + * allocate a persistent huge page for the pool and advance the + * next node from which to allocate, handling wrap at end of node + * mask. + */ +static int hstate_next_node_to_alloc(struct hstate *h, + nodemask_t *nodes_allowed) +{ + int nid; + + VM_BUG_ON(!nodes_allowed); + + nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); + h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); + + return nid; +} + +static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) +{ + struct page *page; + int start_nid; + int next_nid; + int ret = 0; + + start_nid = hstate_next_node_to_alloc(h, nodes_allowed); + next_nid = start_nid; + + do { + page = alloc_fresh_huge_page_node(h, next_nid); + if (page) { + ret = 1; + break; + } + next_nid = hstate_next_node_to_alloc(h, nodes_allowed); + } while (next_nid != start_nid); + + if (ret) + count_vm_event(HTLB_BUDDY_PGALLOC); + else + count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); + + return ret; +} + +/* + * helper for free_pool_huge_page() - return the previously saved + * node ["this node"] from which to free a huge page. Advance the + * next node id whether or not we find a free huge page to free so + * that the next attempt to free addresses the next node. + */ +static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) +{ + int nid; + + VM_BUG_ON(!nodes_allowed); + + nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); + h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); + + return nid; +} + +/* + * Free huge page from pool from next node to free. + * Attempt to keep persistent huge pages more or less + * balanced over allowed nodes. + * Called with hugetlb_lock locked. + */ +static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, + bool acct_surplus) +{ + int start_nid; + int next_nid; + int ret = 0; + + start_nid = hstate_next_node_to_free(h, nodes_allowed); + next_nid = start_nid; + + do { + /* + * If we're returning unused surplus pages, only examine + * nodes with surplus pages. + */ + if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) && + !list_empty(&h->hugepage_freelists[next_nid])) { + struct page *page = + list_entry(h->hugepage_freelists[next_nid].next, + struct page, lru); + list_del(&page->lru); + h->free_huge_pages--; + h->free_huge_pages_node[next_nid]--; + if (acct_surplus) { + h->surplus_huge_pages--; + h->surplus_huge_pages_node[next_nid]--; + } + update_and_free_page(h, page); + ret = 1; + break; + } + next_nid = hstate_next_node_to_free(h, nodes_allowed); + } while (next_nid != start_nid); + + return ret; +} + +static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) +{ + struct page *page; + unsigned int r_nid; + + if (h->order >= MAX_ORDER) + return NULL; + + /* + * Assume we will successfully allocate the surplus page to + * prevent racing processes from causing the surplus to exceed + * overcommit + * + * This however introduces a different race, where a process B + * tries to grow the static hugepage pool while alloc_pages() is + * called by process A. B will only examine the per-node + * counters in determining if surplus huge pages can be + * converted to normal huge pages in adjust_pool_surplus(). A + * won't be able to increment the per-node counter, until the + * lock is dropped by B, but B doesn't drop hugetlb_lock until + * no more huge pages can be converted from surplus to normal + * state (and doesn't try to convert again). Thus, we have a + * case where a surplus huge page exists, the pool is grown, and + * the surplus huge page still exists after, even though it + * should just have been converted to a normal huge page. This + * does not leak memory, though, as the hugepage will be freed + * once it is out of use. It also does not allow the counters to + * go out of whack in adjust_pool_surplus() as we don't modify + * the node values until we've gotten the hugepage and only the + * per-node value is checked there. + */ + spin_lock(&hugetlb_lock); + if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { + spin_unlock(&hugetlb_lock); + return NULL; + } else { + h->nr_huge_pages++; + h->surplus_huge_pages++; + } + spin_unlock(&hugetlb_lock); + + if (nid == NUMA_NO_NODE) + page = alloc_pages(htlb_alloc_mask|__GFP_COMP| + __GFP_REPEAT|__GFP_NOWARN, + huge_page_order(h)); + else + page = alloc_pages_exact_node(nid, + htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| + __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h)); + + if (page && arch_prepare_hugepage(page)) { + __free_pages(page, huge_page_order(h)); + page = NULL; + } + + spin_lock(&hugetlb_lock); + if (page) { + r_nid = page_to_nid(page); + set_compound_page_dtor(page, free_huge_page); + /* + * We incremented the global counters already + */ + h->nr_huge_pages_node[r_nid]++; + h->surplus_huge_pages_node[r_nid]++; + __count_vm_event(HTLB_BUDDY_PGALLOC); + } else { + h->nr_huge_pages--; + h->surplus_huge_pages--; + __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); + } + spin_unlock(&hugetlb_lock); + + return page; +} + +/* + * This allocation function is useful in the context where vma is irrelevant. + * E.g. soft-offlining uses this function because it only cares physical + * address of error page. + */ +struct page *alloc_huge_page_node(struct hstate *h, int nid) +{ + struct page *page; + + spin_lock(&hugetlb_lock); + page = dequeue_huge_page_node(h, nid); + spin_unlock(&hugetlb_lock); + + if (!page) + page = alloc_buddy_huge_page(h, nid); + + return page; +} + +/* + * Increase the hugetlb pool such that it can accommodate a reservation + * of size 'delta'. + */ +static int gather_surplus_pages(struct hstate *h, int delta) +{ + struct list_head surplus_list; + struct page *page, *tmp; + int ret, i; + int needed, allocated; + bool alloc_ok = true; + + needed = (h->resv_huge_pages + delta) - h->free_huge_pages; + if (needed <= 0) { + h->resv_huge_pages += delta; + return 0; + } + + allocated = 0; + INIT_LIST_HEAD(&surplus_list); + + ret = -ENOMEM; +retry: + spin_unlock(&hugetlb_lock); + for (i = 0; i < needed; i++) { + page = alloc_buddy_huge_page(h, NUMA_NO_NODE); + if (!page) { + alloc_ok = false; + break; + } + list_add(&page->lru, &surplus_list); + } + allocated += i; + + /* + * After retaking hugetlb_lock, we need to recalculate 'needed' + * because either resv_huge_pages or free_huge_pages may have changed. + */ + spin_lock(&hugetlb_lock); + needed = (h->resv_huge_pages + delta) - + (h->free_huge_pages + allocated); + if (needed > 0) { + if (alloc_ok) + goto retry; + /* + * We were not able to allocate enough pages to + * satisfy the entire reservation so we free what + * we've allocated so far. + */ + goto free; + } + /* + * The surplus_list now contains _at_least_ the number of extra pages + * needed to accommodate the reservation. Add the appropriate number + * of pages to the hugetlb pool and free the extras back to the buddy + * allocator. Commit the entire reservation here to prevent another + * process from stealing the pages as they are added to the pool but + * before they are reserved. + */ + needed += allocated; + h->resv_huge_pages += delta; + ret = 0; + + /* Free the needed pages to the hugetlb pool */ + list_for_each_entry_safe(page, tmp, &surplus_list, lru) { + if ((--needed) < 0) + break; + list_del(&page->lru); + /* + * This page is now managed by the hugetlb allocator and has + * no users -- drop the buddy allocator's reference. + */ + put_page_testzero(page); + VM_BUG_ON(page_count(page)); + enqueue_huge_page(h, page); + } +free: + spin_unlock(&hugetlb_lock); + + /* Free unnecessary surplus pages to the buddy allocator */ + if (!list_empty(&surplus_list)) { + list_for_each_entry_safe(page, tmp, &surplus_list, lru) { + list_del(&page->lru); + put_page(page); + } + } + spin_lock(&hugetlb_lock); + + return ret; +} + +/* + * When releasing a hugetlb pool reservation, any surplus pages that were + * allocated to satisfy the reservation must be explicitly freed if they were + * never used. + * Called with hugetlb_lock held. + */ +static void return_unused_surplus_pages(struct hstate *h, + unsigned long unused_resv_pages) +{ + unsigned long nr_pages; + + /* Uncommit the reservation */ + h->resv_huge_pages -= unused_resv_pages; + + /* Cannot return gigantic pages currently */ + if (h->order >= MAX_ORDER) + return; + + nr_pages = min(unused_resv_pages, h->surplus_huge_pages); + + /* + * We want to release as many surplus pages as possible, spread + * evenly across all nodes with memory. Iterate across these nodes + * until we can no longer free unreserved surplus pages. This occurs + * when the nodes with surplus pages have no free pages. + * free_pool_huge_page() will balance the the freed pages across the + * on-line nodes with memory and will handle the hstate accounting. + */ + while (nr_pages--) { + if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1)) + break; + } +} + +/* + * Determine if the huge page at addr within the vma has an associated + * reservation. Where it does not we will need to logically increase + * reservation and actually increase subpool usage before an allocation + * can occur. Where any new reservation would be required the + * reservation change is prepared, but not committed. Once the page + * has been allocated from the subpool and instantiated the change should + * be committed via vma_commit_reservation. No action is required on + * failure. + */ +static long vma_needs_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + struct inode *inode = mapping->host; + + if (vma->vm_flags & VM_MAYSHARE) { + pgoff_t idx = vma_hugecache_offset(h, vma, addr); + return region_chg(&inode->i_mapping->private_list, + idx, idx + 1); + + } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + return 1; + + } else { + long err; + pgoff_t idx = vma_hugecache_offset(h, vma, addr); + struct resv_map *reservations = vma_resv_map(vma); + + err = region_chg(&reservations->regions, idx, idx + 1); + if (err < 0) + return err; + return 0; + } +} +static void vma_commit_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + struct inode *inode = mapping->host; + + if (vma->vm_flags & VM_MAYSHARE) { + pgoff_t idx = vma_hugecache_offset(h, vma, addr); + region_add(&inode->i_mapping->private_list, idx, idx + 1); + + } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + pgoff_t idx = vma_hugecache_offset(h, vma, addr); + struct resv_map *reservations = vma_resv_map(vma); + + /* Mark this page used in the map. */ + region_add(&reservations->regions, idx, idx + 1); + } +} + +static struct page *alloc_huge_page(struct vm_area_struct *vma, + unsigned long addr, int avoid_reserve) +{ + struct hugepage_subpool *spool = subpool_vma(vma); + struct hstate *h = hstate_vma(vma); + struct page *page; + long chg; + + /* + * Processes that did not create the mapping will have no + * reserves and will not have accounted against subpool + * limit. Check that the subpool limit can be made before + * satisfying the allocation MAP_NORESERVE mappings may also + * need pages and subpool limit allocated allocated if no reserve + * mapping overlaps. + */ + chg = vma_needs_reservation(h, vma, addr); + if (chg < 0) + return ERR_PTR(-VM_FAULT_OOM); + if (chg) + if (hugepage_subpool_get_pages(spool, chg)) + return ERR_PTR(-VM_FAULT_SIGBUS); + + spin_lock(&hugetlb_lock); + page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); + spin_unlock(&hugetlb_lock); + + if (!page) { + page = alloc_buddy_huge_page(h, NUMA_NO_NODE); + if (!page) { + hugepage_subpool_put_pages(spool, chg); + return ERR_PTR(-VM_FAULT_SIGBUS); + } + } + + set_page_private(page, (unsigned long)spool); + + vma_commit_reservation(h, vma, addr); + + return page; +} + +int __weak alloc_bootmem_huge_page(struct hstate *h) +{ + struct huge_bootmem_page *m; + int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]); + + while (nr_nodes) { + void *addr; + + addr = __alloc_bootmem_node_nopanic( + NODE_DATA(hstate_next_node_to_alloc(h, + &node_states[N_HIGH_MEMORY])), + huge_page_size(h), huge_page_size(h), 0); + + if (addr) { + /* + * Use the beginning of the huge page to store the + * huge_bootmem_page struct (until gather_bootmem + * puts them into the mem_map). + */ + m = addr; + goto found; + } + nr_nodes--; + } + return 0; + +found: + BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1)); + /* Put them into a private list first because mem_map is not up yet */ + list_add(&m->list, &huge_boot_pages); + m->hstate = h; + return 1; +} + +static void prep_compound_huge_page(struct page *page, int order) +{ + if (unlikely(order > (MAX_ORDER - 1))) + prep_compound_gigantic_page(page, order); + else + prep_compound_page(page, order); +} + +/* Put bootmem huge pages into the standard lists after mem_map is up */ +static void __init gather_bootmem_prealloc(void) +{ + struct huge_bootmem_page *m; + + list_for_each_entry(m, &huge_boot_pages, list) { + struct hstate *h = m->hstate; + struct page *page; + +#ifdef CONFIG_HIGHMEM + page = pfn_to_page(m->phys >> PAGE_SHIFT); + free_bootmem_late((unsigned long)m, + sizeof(struct huge_bootmem_page)); +#else + page = virt_to_page(m); +#endif + __ClearPageReserved(page); + WARN_ON(page_count(page) != 1); + prep_compound_huge_page(page, h->order); + prep_new_huge_page(h, page, page_to_nid(page)); + /* + * If we had gigantic hugepages allocated at boot time, we need + * to restore the 'stolen' pages to totalram_pages in order to + * fix confusing memory reports from free(1) and another + * side-effects, like CommitLimit going negative. + */ + if (h->order > (MAX_ORDER - 1)) + totalram_pages += 1 << h->order; + } +} + +static void __init hugetlb_hstate_alloc_pages(struct hstate *h) +{ + unsigned long i; + + for (i = 0; i < h->max_huge_pages; ++i) { + if (h->order >= MAX_ORDER) { + if (!alloc_bootmem_huge_page(h)) + break; + } else if (!alloc_fresh_huge_page(h, + &node_states[N_HIGH_MEMORY])) + break; + } + h->max_huge_pages = i; +} + +static void __init hugetlb_init_hstates(void) +{ + struct hstate *h; + + for_each_hstate(h) { + /* oversize hugepages were init'ed in early boot */ + if (h->order < MAX_ORDER) + hugetlb_hstate_alloc_pages(h); + } +} + +static char * __init memfmt(char *buf, unsigned long n) +{ + if (n >= (1UL << 30)) + sprintf(buf, "%lu GB", n >> 30); + else if (n >= (1UL << 20)) + sprintf(buf, "%lu MB", n >> 20); + else + sprintf(buf, "%lu KB", n >> 10); + return buf; +} + +static void __init report_hugepages(void) +{ + struct hstate *h; + + for_each_hstate(h) { + char buf[32]; + printk(KERN_INFO "HugeTLB registered %s page size, " + "pre-allocated %ld pages\n", + memfmt(buf, huge_page_size(h)), + h->free_huge_pages); + } +} + +#ifdef CONFIG_HIGHMEM +static void try_to_free_low(struct hstate *h, unsigned long count, + nodemask_t *nodes_allowed) +{ + int i; + + if (h->order >= MAX_ORDER) + return; + + for_each_node_mask(i, *nodes_allowed) { + struct page *page, *next; + struct list_head *freel = &h->hugepage_freelists[i]; + list_for_each_entry_safe(page, next, freel, lru) { + if (count >= h->nr_huge_pages) + return; + if (PageHighMem(page)) + continue; + list_del(&page->lru); + update_and_free_page(h, page); + h->free_huge_pages--; + h->free_huge_pages_node[page_to_nid(page)]--; + } + } +} +#else +static inline void try_to_free_low(struct hstate *h, unsigned long count, + nodemask_t *nodes_allowed) +{ +} +#endif + +/* + * Increment or decrement surplus_huge_pages. Keep node-specific counters + * balanced by operating on them in a round-robin fashion. + * Returns 1 if an adjustment was made. + */ +static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, + int delta) +{ + int start_nid, next_nid; + int ret = 0; + + VM_BUG_ON(delta != -1 && delta != 1); + + if (delta < 0) + start_nid = hstate_next_node_to_alloc(h, nodes_allowed); + else + start_nid = hstate_next_node_to_free(h, nodes_allowed); + next_nid = start_nid; + + do { + int nid = next_nid; + if (delta < 0) { + /* + * To shrink on this node, there must be a surplus page + */ + if (!h->surplus_huge_pages_node[nid]) { + next_nid = hstate_next_node_to_alloc(h, + nodes_allowed); + continue; + } + } + if (delta > 0) { + /* + * Surplus cannot exceed the total number of pages + */ + if (h->surplus_huge_pages_node[nid] >= + h->nr_huge_pages_node[nid]) { + next_nid = hstate_next_node_to_free(h, + nodes_allowed); + continue; + } + } + + h->surplus_huge_pages += delta; + h->surplus_huge_pages_node[nid] += delta; + ret = 1; + break; + } while (next_nid != start_nid); + + return ret; +} + +#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) +static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, + nodemask_t *nodes_allowed) +{ + unsigned long min_count, ret; + + if (h->order >= MAX_ORDER) + return h->max_huge_pages; + + /* + * Increase the pool size + * First take pages out of surplus state. Then make up the + * remaining difference by allocating fresh huge pages. + * + * We might race with alloc_buddy_huge_page() here and be unable + * to convert a surplus huge page to a normal huge page. That is + * not critical, though, it just means the overall size of the + * pool might be one hugepage larger than it needs to be, but + * within all the constraints specified by the sysctls. + */ + spin_lock(&hugetlb_lock); + while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { + if (!adjust_pool_surplus(h, nodes_allowed, -1)) + break; + } + + while (count > persistent_huge_pages(h)) { + /* + * If this allocation races such that we no longer need the + * page, free_huge_page will handle it by freeing the page + * and reducing the surplus. + */ + spin_unlock(&hugetlb_lock); + ret = alloc_fresh_huge_page(h, nodes_allowed); + spin_lock(&hugetlb_lock); + if (!ret) + goto out; + + /* Bail for signals. Probably ctrl-c from user */ + if (signal_pending(current)) + goto out; + } + + /* + * Decrease the pool size + * First return free pages to the buddy allocator (being careful + * to keep enough around to satisfy reservations). Then place + * pages into surplus state as needed so the pool will shrink + * to the desired size as pages become free. + * + * By placing pages into the surplus state independent of the + * overcommit value, we are allowing the surplus pool size to + * exceed overcommit. There are few sane options here. Since + * alloc_buddy_huge_page() is checking the global counter, + * though, we'll note that we're not allowed to exceed surplus + * and won't grow the pool anywhere else. Not until one of the + * sysctls are changed, or the surplus pages go out of use. + */ + min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; + min_count = max(count, min_count); + try_to_free_low(h, min_count, nodes_allowed); + while (min_count < persistent_huge_pages(h)) { + if (!free_pool_huge_page(h, nodes_allowed, 0)) + break; + } + while (count < persistent_huge_pages(h)) { + if (!adjust_pool_surplus(h, nodes_allowed, 1)) + break; + } +out: + ret = persistent_huge_pages(h); + spin_unlock(&hugetlb_lock); + return ret; +} + +#define HSTATE_ATTR_RO(_name) \ + static struct kobj_attribute _name##_attr = __ATTR_RO(_name) + +#define HSTATE_ATTR(_name) \ + static struct kobj_attribute _name##_attr = \ + __ATTR(_name, 0644, _name##_show, _name##_store) + +static struct kobject *hugepages_kobj; +static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; + +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); + +static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) +{ + int i; + + for (i = 0; i < HUGE_MAX_HSTATE; i++) + if (hstate_kobjs[i] == kobj) { + if (nidp) + *nidp = NUMA_NO_NODE; + return &hstates[i]; + } + + return kobj_to_node_hstate(kobj, nidp); +} + +static ssize_t nr_hugepages_show_common(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long nr_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + nr_huge_pages = h->nr_huge_pages; + else + nr_huge_pages = h->nr_huge_pages_node[nid]; + + return sprintf(buf, "%lu\n", nr_huge_pages); +} + +static ssize_t nr_hugepages_store_common(bool obey_mempolicy, + struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t len) +{ + int err; + int nid; + unsigned long count; + struct hstate *h; + NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); + + err = strict_strtoul(buf, 10, &count); + if (err) + goto out; + + h = kobj_to_hstate(kobj, &nid); + if (h->order >= MAX_ORDER) { + err = -EINVAL; + goto out; + } + + if (nid == NUMA_NO_NODE) { + /* + * global hstate attribute + */ + if (!(obey_mempolicy && + init_nodemask_of_mempolicy(nodes_allowed))) { + NODEMASK_FREE(nodes_allowed); + nodes_allowed = &node_states[N_HIGH_MEMORY]; + } + } else if (nodes_allowed) { + /* + * per node hstate attribute: adjust count to global, + * but restrict alloc/free to the specified node. + */ + count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; + init_nodemask_of_node(nodes_allowed, nid); + } else + nodes_allowed = &node_states[N_HIGH_MEMORY]; + + h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); + + if (nodes_allowed != &node_states[N_HIGH_MEMORY]) + NODEMASK_FREE(nodes_allowed); + + return len; +out: + NODEMASK_FREE(nodes_allowed); + return err; +} + +static ssize_t nr_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return nr_hugepages_show_common(kobj, attr, buf); +} + +static ssize_t nr_hugepages_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t len) +{ + return nr_hugepages_store_common(false, kobj, attr, buf, len); +} +HSTATE_ATTR(nr_hugepages); + +#ifdef CONFIG_NUMA + +/* + * hstate attribute for optionally mempolicy-based constraint on persistent + * huge page alloc/free. + */ +static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return nr_hugepages_show_common(kobj, attr, buf); +} + +static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t len) +{ + return nr_hugepages_store_common(true, kobj, attr, buf, len); +} +HSTATE_ATTR(nr_hugepages_mempolicy); +#endif + + +static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj, NULL); + return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); +} + +static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + int err; + unsigned long input; + struct hstate *h = kobj_to_hstate(kobj, NULL); + + if (h->order >= MAX_ORDER) + return -EINVAL; + + err = strict_strtoul(buf, 10, &input); + if (err) + return err; + + spin_lock(&hugetlb_lock); + h->nr_overcommit_huge_pages = input; + spin_unlock(&hugetlb_lock); + + return count; +} +HSTATE_ATTR(nr_overcommit_hugepages); + +static ssize_t free_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long free_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + free_huge_pages = h->free_huge_pages; + else + free_huge_pages = h->free_huge_pages_node[nid]; + + return sprintf(buf, "%lu\n", free_huge_pages); +} +HSTATE_ATTR_RO(free_hugepages); + +static ssize_t resv_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj, NULL); + return sprintf(buf, "%lu\n", h->resv_huge_pages); +} +HSTATE_ATTR_RO(resv_hugepages); + +static ssize_t surplus_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long surplus_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + surplus_huge_pages = h->surplus_huge_pages; + else + surplus_huge_pages = h->surplus_huge_pages_node[nid]; + + return sprintf(buf, "%lu\n", surplus_huge_pages); +} +HSTATE_ATTR_RO(surplus_hugepages); + +static struct attribute *hstate_attrs[] = { + &nr_hugepages_attr.attr, + &nr_overcommit_hugepages_attr.attr, + &free_hugepages_attr.attr, + &resv_hugepages_attr.attr, + &surplus_hugepages_attr.attr, +#ifdef CONFIG_NUMA + &nr_hugepages_mempolicy_attr.attr, +#endif + NULL, +}; + +static struct attribute_group hstate_attr_group = { + .attrs = hstate_attrs, +}; + +static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, + struct kobject **hstate_kobjs, + struct attribute_group *hstate_attr_group) +{ + int retval; + int hi = h - hstates; + + hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); + if (!hstate_kobjs[hi]) + return -ENOMEM; + + retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); + if (retval) + kobject_put(hstate_kobjs[hi]); + + return retval; +} + +static void __init hugetlb_sysfs_init(void) +{ + struct hstate *h; + int err; + + hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); + if (!hugepages_kobj) + return; + + for_each_hstate(h) { + err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, + hstate_kobjs, &hstate_attr_group); + if (err) + printk(KERN_ERR "Hugetlb: Unable to add hstate %s", + h->name); + } +} + +#ifdef CONFIG_NUMA + +/* + * node_hstate/s - associate per node hstate attributes, via their kobjects, + * with node devices in node_devices[] using a parallel array. The array + * index of a node device or _hstate == node id. + * This is here to avoid any static dependency of the node device driver, in + * the base kernel, on the hugetlb module. + */ +struct node_hstate { + struct kobject *hugepages_kobj; + struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; +}; +struct node_hstate node_hstates[MAX_NUMNODES]; + +/* + * A subset of global hstate attributes for node devices + */ +static struct attribute *per_node_hstate_attrs[] = { + &nr_hugepages_attr.attr, + &free_hugepages_attr.attr, + &surplus_hugepages_attr.attr, + NULL, +}; + +static struct attribute_group per_node_hstate_attr_group = { + .attrs = per_node_hstate_attrs, +}; + +/* + * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. + * Returns node id via non-NULL nidp. + */ +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) +{ + int nid; + + for (nid = 0; nid < nr_node_ids; nid++) { + struct node_hstate *nhs = &node_hstates[nid]; + int i; + for (i = 0; i < HUGE_MAX_HSTATE; i++) + if (nhs->hstate_kobjs[i] == kobj) { + if (nidp) + *nidp = nid; + return &hstates[i]; + } + } + + BUG(); + return NULL; +} + +/* + * Unregister hstate attributes from a single node device. + * No-op if no hstate attributes attached. + */ +void hugetlb_unregister_node(struct node *node) +{ + struct hstate *h; + struct node_hstate *nhs = &node_hstates[node->dev.id]; + + if (!nhs->hugepages_kobj) + return; /* no hstate attributes */ + + for_each_hstate(h) + if (nhs->hstate_kobjs[h - hstates]) { + kobject_put(nhs->hstate_kobjs[h - hstates]); + nhs->hstate_kobjs[h - hstates] = NULL; + } + + kobject_put(nhs->hugepages_kobj); + nhs->hugepages_kobj = NULL; +} + +/* + * hugetlb module exit: unregister hstate attributes from node devices + * that have them. + */ +static void hugetlb_unregister_all_nodes(void) +{ + int nid; + + /* + * disable node device registrations. + */ + register_hugetlbfs_with_node(NULL, NULL); + + /* + * remove hstate attributes from any nodes that have them. + */ + for (nid = 0; nid < nr_node_ids; nid++) + hugetlb_unregister_node(&node_devices[nid]); +} + +/* + * Register hstate attributes for a single node device. + * No-op if attributes already registered. + */ +void hugetlb_register_node(struct node *node) +{ + struct hstate *h; + struct node_hstate *nhs = &node_hstates[node->dev.id]; + int err; + + if (nhs->hugepages_kobj) + return; /* already allocated */ + + nhs->hugepages_kobj = kobject_create_and_add("hugepages", + &node->dev.kobj); + if (!nhs->hugepages_kobj) + return; + + for_each_hstate(h) { + err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, + nhs->hstate_kobjs, + &per_node_hstate_attr_group); + if (err) { + printk(KERN_ERR "Hugetlb: Unable to add hstate %s" + " for node %d\n", + h->name, node->dev.id); + hugetlb_unregister_node(node); + break; + } + } +} + +/* + * hugetlb init time: register hstate attributes for all registered node + * devices of nodes that have memory. All on-line nodes should have + * registered their associated device by this time. + */ +static void hugetlb_register_all_nodes(void) +{ + int nid; + + for_each_node_state(nid, N_HIGH_MEMORY) { + struct node *node = &node_devices[nid]; + if (node->dev.id == nid) + hugetlb_register_node(node); + } + + /* + * Let the node device driver know we're here so it can + * [un]register hstate attributes on node hotplug. + */ + register_hugetlbfs_with_node(hugetlb_register_node, + hugetlb_unregister_node); +} +#else /* !CONFIG_NUMA */ + +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) +{ + BUG(); + if (nidp) + *nidp = -1; + return NULL; +} + +static void hugetlb_unregister_all_nodes(void) { } + +static void hugetlb_register_all_nodes(void) { } + +#endif + +static void __exit hugetlb_exit(void) +{ + struct hstate *h; + + hugetlb_unregister_all_nodes(); + + for_each_hstate(h) { + kobject_put(hstate_kobjs[h - hstates]); + } + + kobject_put(hugepages_kobj); +} +module_exit(hugetlb_exit); + +static int __init hugetlb_init(void) +{ + /* Some platform decide whether they support huge pages at boot + * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when + * there is no such support + */ + if (HPAGE_SHIFT == 0) + return 0; + + if (!size_to_hstate(default_hstate_size)) { + default_hstate_size = HPAGE_SIZE; + if (!size_to_hstate(default_hstate_size)) + hugetlb_add_hstate(HUGETLB_PAGE_ORDER); + } + default_hstate_idx = size_to_hstate(default_hstate_size) - hstates; + if (default_hstate_max_huge_pages) + default_hstate.max_huge_pages = default_hstate_max_huge_pages; + + hugetlb_init_hstates(); + + gather_bootmem_prealloc(); + + report_hugepages(); + + hugetlb_sysfs_init(); + + hugetlb_register_all_nodes(); + + return 0; +} +module_init(hugetlb_init); + +/* Should be called on processing a hugepagesz=... option */ +void __init hugetlb_add_hstate(unsigned order) +{ + struct hstate *h; + unsigned long i; + + if (size_to_hstate(PAGE_SIZE << order)) { + printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n"); + return; + } + BUG_ON(max_hstate >= HUGE_MAX_HSTATE); + BUG_ON(order == 0); + h = &hstates[max_hstate++]; + h->order = order; + h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); + h->nr_huge_pages = 0; + h->free_huge_pages = 0; + for (i = 0; i < MAX_NUMNODES; ++i) + INIT_LIST_HEAD(&h->hugepage_freelists[i]); + h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]); + h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]); + snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", + huge_page_size(h)/1024); + + parsed_hstate = h; +} + +static int __init hugetlb_nrpages_setup(char *s) +{ + unsigned long *mhp; + static unsigned long *last_mhp; + + /* + * !max_hstate means we haven't parsed a hugepagesz= parameter yet, + * so this hugepages= parameter goes to the "default hstate". + */ + if (!max_hstate) + mhp = &default_hstate_max_huge_pages; + else + mhp = &parsed_hstate->max_huge_pages; + + if (mhp == last_mhp) { + printk(KERN_WARNING "hugepages= specified twice without " + "interleaving hugepagesz=, ignoring\n"); + return 1; + } + + if (sscanf(s, "%lu", mhp) <= 0) + *mhp = 0; + + /* + * Global state is always initialized later in hugetlb_init. + * But we need to allocate >= MAX_ORDER hstates here early to still + * use the bootmem allocator. + */ + if (max_hstate && parsed_hstate->order >= MAX_ORDER) + hugetlb_hstate_alloc_pages(parsed_hstate); + + last_mhp = mhp; + + return 1; +} +__setup("hugepages=", hugetlb_nrpages_setup); + +static int __init hugetlb_default_setup(char *s) +{ + default_hstate_size = memparse(s, &s); + return 1; +} +__setup("default_hugepagesz=", hugetlb_default_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 int hugetlb_sysctl_handler_common(bool obey_mempolicy, + struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp; + int ret; + + tmp = h->max_huge_pages; + + if (write && h->order >= MAX_ORDER) + return -EINVAL; + + table->data = &tmp; + table->maxlen = sizeof(unsigned long); + ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); + if (ret) + goto out; + + if (write) { + NODEMASK_ALLOC(nodemask_t, nodes_allowed, + GFP_KERNEL | __GFP_NORETRY); + if (!(obey_mempolicy && + init_nodemask_of_mempolicy(nodes_allowed))) { + NODEMASK_FREE(nodes_allowed); + nodes_allowed = &node_states[N_HIGH_MEMORY]; + } + h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed); + + if (nodes_allowed != &node_states[N_HIGH_MEMORY]) + NODEMASK_FREE(nodes_allowed); + } +out: + return ret; +} + +int hugetlb_sysctl_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + + return hugetlb_sysctl_handler_common(false, table, write, + buffer, length, ppos); +} + +#ifdef CONFIG_NUMA +int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + return hugetlb_sysctl_handler_common(true, table, write, + buffer, length, ppos); +} +#endif /* CONFIG_NUMA */ + +int hugetlb_treat_movable_handler(struct ctl_table *table, int write, + void __user *buffer, + size_t *length, loff_t *ppos) +{ + proc_dointvec(table, write, buffer, length, ppos); + if (hugepages_treat_as_movable) + htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; + else + htlb_alloc_mask = GFP_HIGHUSER; + return 0; +} + +int hugetlb_overcommit_handler(struct ctl_table *table, int write, + void __user *buffer, + size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp; + int ret; + + tmp = h->nr_overcommit_huge_pages; + + if (write && h->order >= MAX_ORDER) + return -EINVAL; + + table->data = &tmp; + table->maxlen = sizeof(unsigned long); + ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); + if (ret) + goto out; + + if (write) { + spin_lock(&hugetlb_lock); + h->nr_overcommit_huge_pages = tmp; + spin_unlock(&hugetlb_lock); + } +out: + return ret; +} + +#endif /* CONFIG_SYSCTL */ + +void hugetlb_report_meminfo(struct seq_file *m) +{ + struct hstate *h = &default_hstate; + seq_printf(m, + "HugePages_Total: %5lu\n" + "HugePages_Free: %5lu\n" + "HugePages_Rsvd: %5lu\n" + "HugePages_Surp: %5lu\n" + "Hugepagesize: %8lu kB\n", + h->nr_huge_pages, + h->free_huge_pages, + h->resv_huge_pages, + h->surplus_huge_pages, + 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); +} + +int hugetlb_report_node_meminfo(int nid, char *buf) +{ + struct hstate *h = &default_hstate; + return sprintf(buf, + "Node %d HugePages_Total: %5u\n" + "Node %d HugePages_Free: %5u\n" + "Node %d HugePages_Surp: %5u\n", + nid, h->nr_huge_pages_node[nid], + nid, h->free_huge_pages_node[nid], + nid, h->surplus_huge_pages_node[nid]); +} + +/* Return the number pages of memory we physically have, in PAGE_SIZE units. */ +unsigned long hugetlb_total_pages(void) +{ + struct hstate *h = &default_hstate; + return h->nr_huge_pages * pages_per_huge_page(h); +} + +static int hugetlb_acct_memory(struct hstate *h, long delta) +{ + int ret = -ENOMEM; + + spin_lock(&hugetlb_lock); + /* + * 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 (delta > 0) { + if (gather_surplus_pages(h, delta) < 0) + goto out; + + if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { + return_unused_surplus_pages(h, delta); + goto out; + } + } + + ret = 0; + if (delta < 0) + return_unused_surplus_pages(h, (unsigned long) -delta); + +out: + spin_unlock(&hugetlb_lock); + return ret; +} + +static void hugetlb_vm_op_open(struct vm_area_struct *vma) +{ + struct resv_map *reservations = vma_resv_map(vma); + + /* + * This new VMA should share its siblings reservation map if present. + * The VMA will only ever have a valid reservation map pointer where + * it is being copied for another still existing VMA. As that VMA + * has a reference to the reservation map it cannot disappear until + * after this open call completes. It is therefore safe to take a + * new reference here without additional locking. + */ + if (reservations) + kref_get(&reservations->refs); +} + +static void resv_map_put(struct vm_area_struct *vma) +{ + struct resv_map *reservations = vma_resv_map(vma); + + if (!reservations) + return; + kref_put(&reservations->refs, resv_map_release); +} + +static void hugetlb_vm_op_close(struct vm_area_struct *vma) +{ + struct hstate *h = hstate_vma(vma); + struct resv_map *reservations = vma_resv_map(vma); + struct hugepage_subpool *spool = subpool_vma(vma); + unsigned long reserve; + unsigned long start; + unsigned long end; + + if (reservations) { + start = vma_hugecache_offset(h, vma, vma->vm_start); + end = vma_hugecache_offset(h, vma, vma->vm_end); + + reserve = (end - start) - + region_count(&reservations->regions, start, end); + + resv_map_put(vma); + + if (reserve) { + hugetlb_acct_memory(h, -reserve); + hugepage_subpool_put_pages(spool, reserve); + } + } +} + +/* + * 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 int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + BUG(); + return 0; +} + +const struct vm_operations_struct hugetlb_vm_ops = { + .fault = hugetlb_vm_op_fault, + .open = hugetlb_vm_op_open, + .close = hugetlb_vm_op_close, +}; + +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 = huge_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(huge_ptep_get(ptep))); + if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) + update_mmu_cache(vma, address, ptep); +} + + +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; + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + + cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; + + for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { + src_pte = huge_pte_offset(src, addr); + if (!src_pte) + continue; + dst_pte = huge_pte_alloc(dst, addr, sz); + if (!dst_pte) + goto nomem; + + /* If the pagetables are shared don't copy or take references */ + if (dst_pte == src_pte) + continue; + + spin_lock(&dst->page_table_lock); + spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); + if (!huge_pte_none(huge_ptep_get(src_pte))) { + if (cow) + huge_ptep_set_wrprotect(src, addr, src_pte); + entry = huge_ptep_get(src_pte); + ptepage = pte_page(entry); + get_page(ptepage); + page_dup_rmap(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; +} + +static int is_hugetlb_entry_migration(pte_t pte) +{ + swp_entry_t swp; + + if (huge_pte_none(pte) || pte_present(pte)) + return 0; + swp = pte_to_swp_entry(pte); + if (non_swap_entry(swp) && is_migration_entry(swp)) + return 1; + else + return 0; +} + +static int is_hugetlb_entry_hwpoisoned(pte_t pte) +{ + swp_entry_t swp; + + if (huge_pte_none(pte) || pte_present(pte)) + return 0; + swp = pte_to_swp_entry(pte); + if (non_swap_entry(swp) && is_hwpoison_entry(swp)) + return 1; + else + return 0; +} + +void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, + unsigned long end, struct page *ref_page) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long address; + pte_t *ptep; + pte_t pte; + struct page *page; + struct page *tmp; + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + + /* + * A page gathering list, protected by per file i_mmap_mutex. 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 & ~huge_page_mask(h)); + BUG_ON(end & ~huge_page_mask(h)); + + mmu_notifier_invalidate_range_start(mm, start, end); + spin_lock(&mm->page_table_lock); + for (address = start; address < end; address += sz) { + ptep = huge_pte_offset(mm, address); + if (!ptep) + continue; + + if (huge_pmd_unshare(mm, &address, ptep)) + continue; + + pte = huge_ptep_get(ptep); + if (huge_pte_none(pte)) + continue; + + /* + * HWPoisoned hugepage is already unmapped and dropped reference + */ + if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) + continue; + + page = pte_page(pte); + /* + * If a reference page is supplied, it is because a specific + * page is being unmapped, not a range. Ensure the page we + * are about to unmap is the actual page of interest. + */ + if (ref_page) { + if (page != ref_page) + continue; + + /* + * Mark the VMA as having unmapped its page so that + * future faults in this VMA will fail rather than + * looking like data was lost + */ + set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); + } + + pte = huge_ptep_get_and_clear(mm, address, ptep); + if (pte_dirty(pte)) + set_page_dirty(page); + list_add(&page->lru, &page_list); + + /* Bail out after unmapping reference page if supplied */ + if (ref_page) + break; + } + flush_tlb_range(vma, start, end); + spin_unlock(&mm->page_table_lock); + mmu_notifier_invalidate_range_end(mm, start, end); + list_for_each_entry_safe(page, tmp, &page_list, lru) { + page_remove_rmap(page); + list_del(&page->lru); + put_page(page); + } +} + +void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, + unsigned long end, struct page *ref_page) +{ + mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); + __unmap_hugepage_range(vma, start, end, ref_page); + mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); +} + +/* + * This is called when the original mapper is failing to COW a MAP_PRIVATE + * mappping it owns the reserve page for. The intention is to unmap the page + * from other VMAs and let the children be SIGKILLed if they are faulting the + * same region. + */ +static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, + struct page *page, unsigned long address) +{ + struct hstate *h = hstate_vma(vma); + struct vm_area_struct *iter_vma; + struct address_space *mapping; + struct prio_tree_iter iter; + pgoff_t pgoff; + + /* + * vm_pgoff is in PAGE_SIZE units, hence the different calculation + * from page cache lookup which is in HPAGE_SIZE units. + */ + address = address & huge_page_mask(h); + pgoff = vma_hugecache_offset(h, vma, address); + mapping = vma->vm_file->f_dentry->d_inode->i_mapping; + + /* + * Take the mapping lock for the duration of the table walk. As + * this mapping should be shared between all the VMAs, + * __unmap_hugepage_range() is called as the lock is already held + */ + mutex_lock(&mapping->i_mmap_mutex); + vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + /* Do not unmap the current VMA */ + if (iter_vma == vma) + continue; + + /* + * Unmap the page from other VMAs without their own reserves. + * They get marked to be SIGKILLed if they fault in these + * areas. This is because a future no-page fault on this VMA + * could insert a zeroed page instead of the data existing + * from the time of fork. This would look like data corruption + */ + if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) + __unmap_hugepage_range(iter_vma, + address, address + huge_page_size(h), + page); + } + mutex_unlock(&mapping->i_mmap_mutex); + + return 1; +} + +/* + * Hugetlb_cow() should be called with page lock of the original hugepage held. + * Called with hugetlb_instantiation_mutex held and pte_page locked so we + * cannot race with other handlers or page migration. + * Keep the pte_same checks anyway to make transition from the mutex easier. + */ +static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, pte_t pte, + struct page *pagecache_page) +{ + struct hstate *h = hstate_vma(vma); + struct page *old_page, *new_page; + int avoidcopy; + int outside_reserve = 0; + + old_page = pte_page(pte); + +retry_avoidcopy: + /* If no-one else is actually using this page, avoid the copy + * and just make the page writable */ + avoidcopy = (page_mapcount(old_page) == 1); + if (avoidcopy) { + if (PageAnon(old_page)) + page_move_anon_rmap(old_page, vma, address); + set_huge_ptep_writable(vma, address, ptep); + return 0; + } + + /* + * If the process that created a MAP_PRIVATE mapping is about to + * perform a COW due to a shared page count, attempt to satisfy + * the allocation without using the existing reserves. The pagecache + * page is used to determine if the reserve at this address was + * consumed or not. If reserves were used, a partial faulted mapping + * at the time of fork() could consume its reserves on COW instead + * of the full address range. + */ + if (!(vma->vm_flags & VM_MAYSHARE) && + is_vma_resv_set(vma, HPAGE_RESV_OWNER) && + old_page != pagecache_page) + outside_reserve = 1; + + page_cache_get(old_page); + + /* Drop page_table_lock as buddy allocator may be called */ + spin_unlock(&mm->page_table_lock); + new_page = alloc_huge_page(vma, address, outside_reserve); + + if (IS_ERR(new_page)) { + page_cache_release(old_page); + + /* + * If a process owning a MAP_PRIVATE mapping fails to COW, + * it is due to references held by a child and an insufficient + * huge page pool. To guarantee the original mappers + * reliability, unmap the page from child processes. The child + * may get SIGKILLed if it later faults. + */ + if (outside_reserve) { + BUG_ON(huge_pte_none(pte)); + if (unmap_ref_private(mm, vma, old_page, address)) { + BUG_ON(huge_pte_none(pte)); + spin_lock(&mm->page_table_lock); + ptep = huge_pte_offset(mm, address & huge_page_mask(h)); + if (likely(pte_same(huge_ptep_get(ptep), pte))) + goto retry_avoidcopy; + /* + * race occurs while re-acquiring page_table_lock, and + * our job is done. + */ + return 0; + } + WARN_ON_ONCE(1); + } + + /* Caller expects lock to be held */ + spin_lock(&mm->page_table_lock); + return -PTR_ERR(new_page); + } + + /* + * When the original hugepage is shared one, it does not have + * anon_vma prepared. + */ + if (unlikely(anon_vma_prepare(vma))) { + page_cache_release(new_page); + page_cache_release(old_page); + /* Caller expects lock to be held */ + spin_lock(&mm->page_table_lock); + return VM_FAULT_OOM; + } + + copy_user_huge_page(new_page, old_page, address, vma, + pages_per_huge_page(h)); + __SetPageUptodate(new_page); + + /* + * Retake the page_table_lock to check for racing updates + * before the page tables are altered + */ + spin_lock(&mm->page_table_lock); + ptep = huge_pte_offset(mm, address & huge_page_mask(h)); + if (likely(pte_same(huge_ptep_get(ptep), pte))) { + /* Break COW */ + mmu_notifier_invalidate_range_start(mm, + address & huge_page_mask(h), + (address & huge_page_mask(h)) + huge_page_size(h)); + huge_ptep_clear_flush(vma, address, ptep); + set_huge_pte_at(mm, address, ptep, + make_huge_pte(vma, new_page, 1)); + page_remove_rmap(old_page); + hugepage_add_new_anon_rmap(new_page, vma, address); + /* Make the old page be freed below */ + new_page = old_page; + mmu_notifier_invalidate_range_end(mm, + address & huge_page_mask(h), + (address & huge_page_mask(h)) + huge_page_size(h)); + } + page_cache_release(new_page); + page_cache_release(old_page); + return 0; +} + +/* Return the pagecache page at a given address within a VMA */ +static struct page *hugetlbfs_pagecache_page(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + struct address_space *mapping; + pgoff_t idx; + + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, address); + + return find_lock_page(mapping, idx); +} + +/* + * Return whether there is a pagecache page to back given address within VMA. + * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. + */ +static bool hugetlbfs_pagecache_present(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + struct address_space *mapping; + pgoff_t idx; + struct page *page; + + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, address); + + page = find_get_page(mapping, idx); + if (page) + put_page(page); + return page != NULL; +} + +static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, unsigned int flags) +{ + struct hstate *h = hstate_vma(vma); + int ret = VM_FAULT_SIGBUS; + int anon_rmap = 0; + pgoff_t idx; + unsigned long size; + struct page *page; + struct address_space *mapping; + pte_t new_pte; + + /* + * Currently, we are forced to kill the process in the event the + * original mapper has unmapped pages from the child due to a failed + * COW. Warn that such a situation has occurred as it may not be obvious + */ + if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { + printk(KERN_WARNING + "PID %d killed due to inadequate hugepage pool\n", + current->pid); + return ret; + } + + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, address); + + /* + * 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) >> huge_page_shift(h); + if (idx >= size) + goto out; + page = alloc_huge_page(vma, address, 0); + if (IS_ERR(page)) { + ret = -PTR_ERR(page); + goto out; + } + clear_huge_page(page, address, pages_per_huge_page(h)); + __SetPageUptodate(page); + + if (vma->vm_flags & VM_MAYSHARE) { + int err; + struct inode *inode = mapping->host; + + err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); + if (err) { + put_page(page); + if (err == -EEXIST) + goto retry; + goto out; + } + + spin_lock(&inode->i_lock); + inode->i_blocks += blocks_per_huge_page(h); + spin_unlock(&inode->i_lock); + } else { + lock_page(page); + if (unlikely(anon_vma_prepare(vma))) { + ret = VM_FAULT_OOM; + goto backout_unlocked; + } + anon_rmap = 1; + } + } else { + /* + * If memory error occurs between mmap() and fault, some process + * don't have hwpoisoned swap entry for errored virtual address. + * So we need to block hugepage fault by PG_hwpoison bit check. + */ + if (unlikely(PageHWPoison(page))) { + ret = VM_FAULT_HWPOISON | + VM_FAULT_SET_HINDEX(h - hstates); + goto backout_unlocked; + } + } + + /* + * If we are going to COW a private mapping later, we examine the + * pending reservations for this page now. This will ensure that + * any allocations necessary to record that reservation occur outside + * the spinlock. + */ + if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) + if (vma_needs_reservation(h, vma, address) < 0) { + ret = VM_FAULT_OOM; + goto backout_unlocked; + } + + spin_lock(&mm->page_table_lock); + size = i_size_read(mapping->host) >> huge_page_shift(h); + if (idx >= size) + goto backout; + + ret = 0; + if (!huge_pte_none(huge_ptep_get(ptep))) + goto backout; + + if (anon_rmap) + hugepage_add_new_anon_rmap(page, vma, address); + else + page_dup_rmap(page); + 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 ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { + /* Optimization, do the COW without a second fault */ + ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); + } + + spin_unlock(&mm->page_table_lock); + unlock_page(page); +out: + return ret; + +backout: + spin_unlock(&mm->page_table_lock); +backout_unlocked: + unlock_page(page); + put_page(page); + goto out; +} + +int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, unsigned int flags) +{ + pte_t *ptep; + pte_t entry; + int ret; + struct page *page = NULL; + struct page *pagecache_page = NULL; + static DEFINE_MUTEX(hugetlb_instantiation_mutex); + struct hstate *h = hstate_vma(vma); + + address &= huge_page_mask(h); + + ptep = huge_pte_offset(mm, address); + if (ptep) { + entry = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_migration(entry))) { + migration_entry_wait(mm, (pmd_t *)ptep, address); + return 0; + } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) + return VM_FAULT_HWPOISON_LARGE | + VM_FAULT_SET_HINDEX(h - hstates); + } + + ptep = huge_pte_alloc(mm, address, huge_page_size(h)); + 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 = huge_ptep_get(ptep); + if (huge_pte_none(entry)) { + ret = hugetlb_no_page(mm, vma, address, ptep, flags); + goto out_mutex; + } + + ret = 0; + + /* + * If we are going to COW the mapping later, we examine the pending + * reservations for this page now. This will ensure that any + * allocations necessary to record that reservation occur outside the + * spinlock. For private mappings, we also lookup the pagecache + * page now as it is used to determine if a reservation has been + * consumed. + */ + if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) { + if (vma_needs_reservation(h, vma, address) < 0) { + ret = VM_FAULT_OOM; + goto out_mutex; + } + + if (!(vma->vm_flags & VM_MAYSHARE)) + pagecache_page = hugetlbfs_pagecache_page(h, + vma, address); + } + + /* + * hugetlb_cow() requires page locks of pte_page(entry) and + * pagecache_page, so here we need take the former one + * when page != pagecache_page or !pagecache_page. + * Note that locking order is always pagecache_page -> page, + * so no worry about deadlock. + */ + page = pte_page(entry); + get_page(page); + if (page != pagecache_page) + lock_page(page); + + spin_lock(&mm->page_table_lock); + /* Check for a racing update before calling hugetlb_cow */ + if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) + goto out_page_table_lock; + + + if (flags & FAULT_FLAG_WRITE) { + if (!pte_write(entry)) { + ret = hugetlb_cow(mm, vma, address, ptep, entry, + pagecache_page); + goto out_page_table_lock; + } + entry = pte_mkdirty(entry); + } + entry = pte_mkyoung(entry); + if (huge_ptep_set_access_flags(vma, address, ptep, entry, + flags & FAULT_FLAG_WRITE)) + update_mmu_cache(vma, address, ptep); + +out_page_table_lock: + spin_unlock(&mm->page_table_lock); + + if (pagecache_page) { + unlock_page(pagecache_page); + put_page(pagecache_page); + } + if (page != pagecache_page) + unlock_page(page); + put_page(page); + +out_mutex: + mutex_unlock(&hugetlb_instantiation_mutex); + + return ret; +} + +/* Can be overriden by architectures */ +__attribute__((weak)) struct page * +follow_huge_pud(struct mm_struct *mm, unsigned long address, + pud_t *pud, int write) +{ + BUG(); + return NULL; +} + +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 int flags) +{ + unsigned long pfn_offset; + unsigned long vaddr = *position; + int remainder = *length; + struct hstate *h = hstate_vma(vma); + + spin_lock(&mm->page_table_lock); + while (vaddr < vma->vm_end && remainder) { + pte_t *pte; + int absent; + 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 & huge_page_mask(h)); + absent = !pte || huge_pte_none(huge_ptep_get(pte)); + + /* + * When coredumping, it suits get_dump_page if we just return + * an error where there's an empty slot with no huge pagecache + * to back it. This way, we avoid allocating a hugepage, and + * the sparse dumpfile avoids allocating disk blocks, but its + * huge holes still show up with zeroes where they need to be. + */ + if (absent && (flags & FOLL_DUMP) && + !hugetlbfs_pagecache_present(h, vma, vaddr)) { + remainder = 0; + break; + } + + if (absent || + ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { + int ret; + + spin_unlock(&mm->page_table_lock); + ret = hugetlb_fault(mm, vma, vaddr, + (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); + spin_lock(&mm->page_table_lock); + if (!(ret & VM_FAULT_ERROR)) + continue; + + remainder = 0; + break; + } + + pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; + page = pte_page(huge_ptep_get(pte)); +same_page: + if (pages) { + pages[i] = mem_map_offset(page, pfn_offset); + get_page(pages[i]); + } + + if (vmas) + vmas[i] = vma; + + vaddr += PAGE_SIZE; + ++pfn_offset; + --remainder; + ++i; + if (vaddr < vma->vm_end && remainder && + pfn_offset < pages_per_huge_page(h)) { + /* + * 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 ? i : -EFAULT; +} + +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; + struct hstate *h = hstate_vma(vma); + + BUG_ON(address >= end); + flush_cache_range(vma, address, end); + + mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); + spin_lock(&mm->page_table_lock); + for (; address < end; address += huge_page_size(h)) { + ptep = huge_pte_offset(mm, address); + if (!ptep) + continue; + if (huge_pmd_unshare(mm, &address, ptep)) + continue; + if (!huge_pte_none(huge_ptep_get(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); + } + } + spin_unlock(&mm->page_table_lock); + mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); + + flush_tlb_range(vma, start, end); +} + +int hugetlb_reserve_pages(struct inode *inode, + long from, long to, + struct vm_area_struct *vma, + vm_flags_t vm_flags) +{ + long ret, chg; + struct hstate *h = hstate_inode(inode); + struct hugepage_subpool *spool = subpool_inode(inode); + + /* + * Only apply hugepage reservation if asked. At fault time, an + * attempt will be made for VM_NORESERVE to allocate a page + * without using reserves + */ + if (vm_flags & VM_NORESERVE) + return 0; + + /* + * Shared mappings base their reservation on the number of pages that + * are already allocated on behalf of the file. Private mappings need + * to reserve the full area even if read-only as mprotect() may be + * called to make the mapping read-write. Assume !vma is a shm mapping + */ + if (!vma || vma->vm_flags & VM_MAYSHARE) + chg = region_chg(&inode->i_mapping->private_list, from, to); + else { + struct resv_map *resv_map = resv_map_alloc(); + if (!resv_map) + return -ENOMEM; + + chg = to - from; + + set_vma_resv_map(vma, resv_map); + set_vma_resv_flags(vma, HPAGE_RESV_OWNER); + } + + if (chg < 0) { + ret = chg; + goto out_err; + } + + /* There must be enough pages in the subpool for the mapping */ + if (hugepage_subpool_get_pages(spool, chg)) { + ret = -ENOSPC; + goto out_err; + } + + /* + * Check enough hugepages are available for the reservation. + * Hand the pages back to the subpool if there are not + */ + ret = hugetlb_acct_memory(h, chg); + if (ret < 0) { + hugepage_subpool_put_pages(spool, chg); + goto out_err; + } + + /* + * Account for the reservations made. Shared mappings record regions + * that have reservations as they are shared by multiple VMAs. + * When the last VMA disappears, the region map says how much + * the reservation was and the page cache tells how much of + * the reservation was consumed. Private mappings are per-VMA and + * only the consumed reservations are tracked. When the VMA + * disappears, the original reservation is the VMA size and the + * consumed reservations are stored in the map. Hence, nothing + * else has to be done for private mappings here + */ + if (!vma || vma->vm_flags & VM_MAYSHARE) + region_add(&inode->i_mapping->private_list, from, to); + return 0; +out_err: + if (vma) + resv_map_put(vma); + return ret; +} + +void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) +{ + struct hstate *h = hstate_inode(inode); + long chg = region_truncate(&inode->i_mapping->private_list, offset); + struct hugepage_subpool *spool = subpool_inode(inode); + + spin_lock(&inode->i_lock); + inode->i_blocks -= (blocks_per_huge_page(h) * freed); + spin_unlock(&inode->i_lock); + + hugepage_subpool_put_pages(spool, (chg - freed)); + hugetlb_acct_memory(h, -(chg - freed)); +} + +#ifdef CONFIG_MEMORY_FAILURE + +/* Should be called in hugetlb_lock */ +static int is_hugepage_on_freelist(struct page *hpage) +{ + struct page *page; + struct page *tmp; + struct hstate *h = page_hstate(hpage); + int nid = page_to_nid(hpage); + + list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) + if (page == hpage) + return 1; + return 0; +} + +/* + * This function is called from memory failure code. + * Assume the caller holds page lock of the head page. + */ +int dequeue_hwpoisoned_huge_page(struct page *hpage) +{ + struct hstate *h = page_hstate(hpage); + int nid = page_to_nid(hpage); + int ret = -EBUSY; + + spin_lock(&hugetlb_lock); + if (is_hugepage_on_freelist(hpage)) { + list_del(&hpage->lru); + set_page_refcounted(hpage); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + ret = 0; + } + spin_unlock(&hugetlb_lock); + return ret; +} +#endif |