diff options
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 2293 |
1 files changed, 2293 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c new file mode 100644 index 0000000..6058b53 --- /dev/null +++ b/mm/hugetlb.c @@ -0,0 +1,2293 @@ +/* + * 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/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 <asm/page.h> +#include <asm/pgtable.h> +#include <asm/io.h> + +#include <linux/hugetlb.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); + +/* + * 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 futher than + * us then we must extend ourselves. Account for its + * existing reservation. */ + if (rg->to > t) { + chg += rg->to - t; + t = rg->to; + } + chg -= rg->to - rg->from; + } + return chg; +} + +static long region_truncate(struct list_head *head, long end) +{ + struct file_region *rg, *trg; + long chg = 0; + + /* Locate the region we are either in or before. */ + list_for_each_entry(rg, head, link) + if (end <= rg->to) + break; + if (&rg->link == head) + return 0; + + /* If we are in the middle of a region then adjust it. */ + if (end > rg->from) { + chg = rg->to - end; + rg->to = end; + rg = list_entry(rg->link.next, typeof(*rg), link); + } + + /* Drop any remaining regions. */ + list_for_each_entry_safe(rg, trg, rg->link.prev, link) { + if (&rg->link == head) + break; + chg += rg->to - rg->from; + list_del(&rg->link); + kfree(rg); + } + return chg; +} + +static 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)); +} + +/* + * 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_SHARED)) + 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_SHARED); + + 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_SHARED); + + 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_SHARED) { + /* 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_SHARED)) + 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_SHARED) + return 1; + if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + return 1; + return 0; +} + +static void clear_gigantic_page(struct page *page, + unsigned long addr, unsigned long sz) +{ + int i; + struct page *p = page; + + might_sleep(); + for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) { + cond_resched(); + clear_user_highpage(p, addr + i * PAGE_SIZE); + } +} +static void clear_huge_page(struct page *page, + unsigned long addr, unsigned long sz) +{ + int i; + + if (unlikely(sz > MAX_ORDER_NR_PAGES)) + return clear_gigantic_page(page, addr, sz); + + might_sleep(); + for (i = 0; i < sz/PAGE_SIZE; i++) { + cond_resched(); + clear_user_highpage(page + i, addr + i * PAGE_SIZE); + } +} + +static void copy_gigantic_page(struct page *dst, struct page *src, + unsigned long addr, struct vm_area_struct *vma) +{ + int i; + struct hstate *h = hstate_vma(vma); + struct page *dst_base = dst; + struct page *src_base = src; + might_sleep(); + for (i = 0; i < pages_per_huge_page(h); ) { + cond_resched(); + copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); + + i++; + dst = mem_map_next(dst, dst_base, i); + src = mem_map_next(src, src_base, i); + } +} +static void copy_huge_page(struct page *dst, struct page *src, + unsigned long addr, struct vm_area_struct *vma) +{ + int i; + struct hstate *h = hstate_vma(vma); + + if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) + return copy_gigantic_page(dst, src, addr, vma); + + might_sleep(); + for (i = 0; i < pages_per_huge_page(h); i++) { + cond_resched(); + copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); + } +} + +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(struct hstate *h) +{ + int nid; + struct page *page = NULL; + + for (nid = 0; nid < MAX_NUMNODES; ++nid) { + if (!list_empty(&h->hugepage_freelists[nid])) { + page = list_entry(h->hugepage_freelists[nid].next, + struct page, lru); + list_del(&page->lru); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + break; + } + } + return page; +} + +static struct page *dequeue_huge_page_vma(struct hstate *h, + struct vm_area_struct *vma, + unsigned long address, int avoid_reserve) +{ + int nid; + struct page *page = NULL; + struct mempolicy *mpol; + nodemask_t *nodemask; + struct zonelist *zonelist = huge_zonelist(vma, address, + htlb_alloc_mask, &mpol, &nodemask); + struct zone *zone; + struct zoneref *z; + + /* + * 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) + return NULL; + + /* If reserves cannot be used, ensure enough pages are in the pool */ + if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) + return NULL; + + for_each_zone_zonelist_nodemask(zone, z, zonelist, + MAX_NR_ZONES - 1, nodemask) { + nid = zone_to_nid(zone); + if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) && + !list_empty(&h->hugepage_freelists[nid])) { + page = list_entry(h->hugepage_freelists[nid].next, + struct page, lru); + list_del(&page->lru); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + + if (!avoid_reserve) + decrement_hugepage_resv_vma(h, vma); + + break; + } + } + mpol_cond_put(mpol); + return page; +} + +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 address_space *mapping; + + mapping = (struct address_space *) page_private(page); + set_page_private(page, 0); + BUG_ON(page_count(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); + if (mapping) + hugetlb_put_quota(mapping, 1); +} + +/* + * 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, int delta) +{ + static int prev_nid; + int nid = prev_nid; + int ret = 0; + + VM_BUG_ON(delta != -1 && delta != 1); + do { + nid = next_node(nid, node_online_map); + if (nid == MAX_NUMNODES) + nid = first_node(node_online_map); + + /* To shrink on this node, there must be a surplus page */ + if (delta < 0 && !h->surplus_huge_pages_node[nid]) + continue; + /* Surplus cannot exceed the total number of pages */ + if (delta > 0 && h->surplus_huge_pages_node[nid] >= + h->nr_huge_pages_node[nid]) + continue; + + h->surplus_huge_pages += delta; + h->surplus_huge_pages_node[nid] += delta; + ret = 1; + break; + } while (nid != prev_nid); + + prev_nid = nid; + return ret; +} + +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 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_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; +} + +/* + * Use a helper variable to find the next node and then + * copy it back to hugetlb_next_nid afterwards: + * otherwise there's a window in which a racer might + * pass invalid nid MAX_NUMNODES to alloc_pages_node. + * But we don't need to use a spin_lock here: it really + * doesn't matter if occasionally a racer chooses the + * same nid as we do. Move nid forward in the mask even + * if we just successfully allocated a hugepage so that + * the next caller gets hugepages on the next node. + */ +static int hstate_next_node(struct hstate *h) +{ + int next_nid; + next_nid = next_node(h->hugetlb_next_nid, node_online_map); + if (next_nid == MAX_NUMNODES) + next_nid = first_node(node_online_map); + h->hugetlb_next_nid = next_nid; + return next_nid; +} + +static int alloc_fresh_huge_page(struct hstate *h) +{ + struct page *page; + int start_nid; + int next_nid; + int ret = 0; + + start_nid = h->hugetlb_next_nid; + + do { + page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid); + if (page) + ret = 1; + next_nid = hstate_next_node(h); + } while (!page && h->hugetlb_next_nid != start_nid); + + if (ret) + count_vm_event(HTLB_BUDDY_PGALLOC); + else + count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); + + return ret; +} + +static struct page *alloc_buddy_huge_page(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + struct page *page; + unsigned int 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); + + page = alloc_pages(htlb_alloc_mask|__GFP_COMP| + __GFP_REPEAT|__GFP_NOWARN, + huge_page_order(h)); + + if (page && arch_prepare_hugepage(page)) { + __free_pages(page, huge_page_order(h)); + return NULL; + } + + spin_lock(&hugetlb_lock); + if (page) { + /* + * 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)); + nid = page_to_nid(page); + set_compound_page_dtor(page, free_huge_page); + /* + * We incremented the global counters already + */ + h->nr_huge_pages_node[nid]++; + h->surplus_huge_pages_node[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; +} + +/* + * Increase the hugetlb pool such that it can accomodate 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; + + 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, NULL, 0); + if (!page) { + /* + * We were not able to allocate enough pages to + * satisfy the entire reservation so we free what + * we've allocated so far. + */ + spin_lock(&hugetlb_lock); + needed = 0; + goto free; + } + + list_add(&page->lru, &surplus_list); + } + allocated += needed; + + /* + * 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) + goto retry; + + /* + * The surplus_list now contains _at_least_ the number of extra pages + * needed to accomodate 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: + /* 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); + enqueue_huge_page(h, page); + } + + /* Free unnecessary surplus pages to the buddy allocator */ + if (!list_empty(&surplus_list)) { + spin_unlock(&hugetlb_lock); + list_for_each_entry_safe(page, tmp, &surplus_list, lru) { + list_del(&page->lru); + /* + * The page has a reference count of zero already, so + * call free_huge_page directly instead of using + * put_page. This must be done with hugetlb_lock + * unlocked which is safe because free_huge_page takes + * hugetlb_lock before deciding how to free the page. + */ + free_huge_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. + */ +static void return_unused_surplus_pages(struct hstate *h, + unsigned long unused_resv_pages) +{ + static int nid = -1; + struct page *page; + unsigned long nr_pages; + + /* + * We want to release as many surplus pages as possible, spread + * evenly across all nodes. Iterate across all nodes until we + * can no longer free unreserved surplus pages. This occurs when + * the nodes with surplus pages have no free pages. + */ + unsigned long remaining_iterations = num_online_nodes(); + + /* 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); + + while (remaining_iterations-- && nr_pages) { + nid = next_node(nid, node_online_map); + if (nid == MAX_NUMNODES) + nid = first_node(node_online_map); + + if (!h->surplus_huge_pages_node[nid]) + continue; + + if (!list_empty(&h->hugepage_freelists[nid])) { + page = list_entry(h->hugepage_freelists[nid].next, + struct page, lru); + list_del(&page->lru); + update_and_free_page(h, page); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + h->surplus_huge_pages--; + h->surplus_huge_pages_node[nid]--; + nr_pages--; + remaining_iterations = num_online_nodes(); + } + } +} + +/* + * 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 quota 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 quota'd allocated + * an instantiated the change should be committed via vma_commit_reservation. + * No action is required on failure. + */ +static int 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_SHARED) { + 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 { + int 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_SHARED) { + 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 hstate *h = hstate_vma(vma); + struct page *page; + struct address_space *mapping = vma->vm_file->f_mapping; + struct inode *inode = mapping->host; + unsigned int chg; + + /* + * Processes that did not create the mapping will have no reserves and + * will not have accounted against quota. Check that the quota can be + * made before satisfying the allocation + * MAP_NORESERVE mappings may also need pages and quota allocated + * if no reserve mapping overlaps. + */ + chg = vma_needs_reservation(h, vma, addr); + if (chg < 0) + return ERR_PTR(chg); + if (chg) + if (hugetlb_get_quota(inode->i_mapping, chg)) + return ERR_PTR(-ENOSPC); + + 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, vma, addr); + if (!page) { + hugetlb_put_quota(inode->i_mapping, chg); + return ERR_PTR(-VM_FAULT_OOM); + } + } + + set_page_refcounted(page); + set_page_private(page, (unsigned long) mapping); + + vma_commit_reservation(h, vma, addr); + + return page; +} + +__attribute__((weak)) int alloc_bootmem_huge_page(struct hstate *h) +{ + struct huge_bootmem_page *m; + int nr_nodes = nodes_weight(node_online_map); + + while (nr_nodes) { + void *addr; + + addr = __alloc_bootmem_node_nopanic( + NODE_DATA(h->hugetlb_next_nid), + 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; + if (m) + goto found; + } + hstate_next_node(h); + 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 page *page = virt_to_page(m); + struct hstate *h = m->hstate; + __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)); + } +} + +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)) + 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) +{ + int i; + + if (h->order >= MAX_ORDER) + return; + + for (i = 0; i < MAX_NUMNODES; ++i) { + 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) +{ +} +#endif + +#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) +{ + 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, -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); + spin_lock(&hugetlb_lock); + if (!ret) + 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); + while (min_count < persistent_huge_pages(h)) { + struct page *page = dequeue_huge_page(h); + if (!page) + break; + update_and_free_page(h, page); + } + while (count < persistent_huge_pages(h)) { + if (!adjust_pool_surplus(h, 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_hstate(struct kobject *kobj) +{ + int i; + for (i = 0; i < HUGE_MAX_HSTATE; i++) + if (hstate_kobjs[i] == kobj) + return &hstates[i]; + BUG(); + return NULL; +} + +static ssize_t nr_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj); + return sprintf(buf, "%lu\n", h->nr_huge_pages); +} +static ssize_t nr_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); + + err = strict_strtoul(buf, 10, &input); + if (err) + return 0; + + h->max_huge_pages = set_max_huge_pages(h, input); + + return count; +} +HSTATE_ATTR(nr_hugepages); + +static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj); + 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); + + err = strict_strtoul(buf, 10, &input); + if (err) + return 0; + + 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 = kobj_to_hstate(kobj); + return sprintf(buf, "%lu\n", h->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); + 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 = kobj_to_hstate(kobj); + return sprintf(buf, "%lu\n", h->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, + NULL, +}; + +static struct attribute_group hstate_attr_group = { + .attrs = hstate_attrs, +}; + +static int __init hugetlb_sysfs_add_hstate(struct hstate *h) +{ + int retval; + + hstate_kobjs[h - hstates] = kobject_create_and_add(h->name, + hugepages_kobj); + if (!hstate_kobjs[h - hstates]) + return -ENOMEM; + + retval = sysfs_create_group(hstate_kobjs[h - hstates], + &hstate_attr_group); + if (retval) + kobject_put(hstate_kobjs[h - hstates]); + + 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); + if (err) + printk(KERN_ERR "Hugetlb: Unable to add hstate %s", + h->name); + } +} + +static void __exit hugetlb_exit(void) +{ + struct hstate *h; + + 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(); + + 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->hugetlb_next_nid = first_node(node_online_map); + 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 +int hugetlb_sysctl_handler(struct ctl_table *table, int write, + struct file *file, void __user *buffer, + size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp; + + if (!write) + tmp = h->max_huge_pages; + + table->data = &tmp; + table->maxlen = sizeof(unsigned long); + proc_doulongvec_minmax(table, write, file, buffer, length, ppos); + + if (write) + h->max_huge_pages = set_max_huge_pages(h, tmp); + + return 0; +} + +int hugetlb_treat_movable_handler(struct ctl_table *table, int write, + struct file *file, void __user *buffer, + size_t *length, loff_t *ppos) +{ + proc_dointvec(table, write, file, 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, + struct file *file, void __user *buffer, + size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp; + + if (!write) + tmp = h->nr_overcommit_huge_pages; + + table->data = &tmp; + table->maxlen = sizeof(unsigned long); + proc_doulongvec_minmax(table, write, file, buffer, length, ppos); + + if (write) { + spin_lock(&hugetlb_lock); + h->nr_overcommit_huge_pages = tmp; + spin_unlock(&hugetlb_lock); + } + + return 0; +} + +#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 dissappear 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 hugetlb_vm_op_close(struct vm_area_struct *vma) +{ + struct hstate *h = hstate_vma(vma); + struct resv_map *reservations = vma_resv_map(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); + + kref_put(&reservations->refs, resv_map_release); + + if (reserve) { + hugetlb_acct_memory(h, -reserve); + hugetlb_put_quota(vma->vm_file->f_mapping, 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; +} + +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, 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; + 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); + 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 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_lock. The + * lock is used to avoid list corruption from multiple unmapping + * of the same page since we are using page->lru. + */ + LIST_HEAD(page_list); + + WARN_ON(!is_vm_hugetlb_page(vma)); + BUG_ON(start & ~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; + + /* + * 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) { + pte = huge_ptep_get(ptep); + if (huge_pte_none(pte)) + continue; + page = pte_page(pte); + 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 (huge_pte_none(pte)) + continue; + + page = pte_page(pte); + if (pte_dirty(pte)) + set_page_dirty(page); + list_add(&page->lru, &page_list); + } + spin_unlock(&mm->page_table_lock); + flush_tlb_range(vma, start, end); + mmu_notifier_invalidate_range_end(mm, start, end); + list_for_each_entry_safe(page, tmp, &page_list, lru) { + list_del(&page->lru); + put_page(page); + } +} + +void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, + unsigned long end, struct page *ref_page) +{ + spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); + __unmap_hugepage_range(vma, start, end, ref_page); + spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); +} + +/* + * 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 = ((address - vma->vm_start) >> PAGE_SHIFT) + + (vma->vm_pgoff >> PAGE_SHIFT); + mapping = (struct address_space *)page_private(page); + + 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); + } + + return 1; +} + +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_count(old_page) == 1); + if (avoidcopy) { + 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_SHARED) && + is_vma_resv_set(vma, HPAGE_RESV_OWNER) && + old_page != pagecache_page) + outside_reserve = 1; + + page_cache_get(old_page); + 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(page_count(old_page) != 1); + BUG_ON(huge_pte_none(pte)); + goto retry_avoidcopy; + } + WARN_ON_ONCE(1); + } + + return -PTR_ERR(new_page); + } + + spin_unlock(&mm->page_table_lock); + copy_huge_page(new_page, old_page, address, vma); + __SetPageUptodate(new_page); + 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 */ + huge_ptep_clear_flush(vma, address, ptep); + 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 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); +} + +static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, int write_access) +{ + struct hstate *h = hstate_vma(vma); + int ret = VM_FAULT_SIGBUS; + 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 occured 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, huge_page_size(h)); + __SetPageUptodate(page); + + if (vma->vm_flags & VM_SHARED) { + 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 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 (write_access && !(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; + + 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, 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, int write_access) +{ + pte_t *ptep; + pte_t entry; + int ret; + struct page *pagecache_page = NULL; + static DEFINE_MUTEX(hugetlb_instantiation_mutex); + struct hstate *h = hstate_vma(vma); + + 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, write_access); + 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 (write_access && !pte_write(entry)) { + if (vma_needs_reservation(h, vma, address) < 0) { + ret = VM_FAULT_OOM; + goto out_mutex; + } + + if (!(vma->vm_flags & VM_SHARED)) + pagecache_page = hugetlbfs_pagecache_page(h, + vma, address); + } + + 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 (write_access) { + 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, write_access)) + update_mmu_cache(vma, address, entry); + +out_page_table_lock: + spin_unlock(&mm->page_table_lock); + + if (pagecache_page) { + unlock_page(pagecache_page); + put_page(pagecache_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; +} + +static int huge_zeropage_ok(pte_t *ptep, int write, int shared) +{ + if (!ptep || write || shared) + return 0; + else + return huge_pte_none(huge_ptep_get(ptep)); +} + +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, + int write) +{ + unsigned long pfn_offset; + unsigned long vaddr = *position; + int remainder = *length; + struct hstate *h = hstate_vma(vma); + int zeropage_ok = 0; + int shared = vma->vm_flags & VM_SHARED; + + 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 & huge_page_mask(h)); + if (huge_zeropage_ok(pte, write, shared)) + zeropage_ok = 1; + + if (!pte || + (huge_pte_none(huge_ptep_get(pte)) && !zeropage_ok) || + (write && !pte_write(huge_ptep_get(pte)))) { + int ret; + + spin_unlock(&mm->page_table_lock); + ret = hugetlb_fault(mm, vma, vaddr, write); + spin_lock(&mm->page_table_lock); + if (!(ret & VM_FAULT_ERROR)) + continue; + + remainder = 0; + if (!i) + i = -EFAULT; + break; + } + + pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; + page = pte_page(huge_ptep_get(pte)); +same_page: + if (pages) { + if (zeropage_ok) + pages[i] = ZERO_PAGE(0); + else + 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; +} + +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); + + spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); + 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); + spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); + + flush_tlb_range(vma, start, end); +} + +int hugetlb_reserve_pages(struct inode *inode, + long from, long to, + struct vm_area_struct *vma) +{ + long ret, chg; + struct hstate *h = hstate_inode(inode); + + if (vma && vma->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_SHARED) + 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) + return chg; + + if (hugetlb_get_quota(inode->i_mapping, chg)) + return -ENOSPC; + ret = hugetlb_acct_memory(h, chg); + if (ret < 0) { + hugetlb_put_quota(inode->i_mapping, chg); + return ret; + } + if (!vma || vma->vm_flags & VM_SHARED) + region_add(&inode->i_mapping->private_list, from, to); + return 0; +} + +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); + + spin_lock(&inode->i_lock); + inode->i_blocks -= blocks_per_huge_page(h); + spin_unlock(&inode->i_lock); + + hugetlb_put_quota(inode->i_mapping, (chg - freed)); + hugetlb_acct_memory(h, -(chg - freed)); +} |
