+/*
+ * 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));
+}
+
+/*
+ * 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 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)) {
+ clear_gigantic_page(page, addr, sz);
+ return;
+ }
+
+ 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)) {
+ copy_gigantic_page(dst, src, addr, vma);
+ return;
+ }
+
+ 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_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);
+}
+
+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);
+ 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;
+}
+
+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,
+ 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.
+ * 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 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 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 hstate *h = hstate_vma(vma);
+ struct page *page;
+ struct address_space *mapping = vma->vm_file->f_mapping;
+ struct inode *inode = mapping->host;
+ long 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;
+}
+
+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 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,
+ &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;
+ }