1 files changed, 233 insertions, 53 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 508707704d2c..ebad6bbb3501 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -13,24 +13,48 @@
 #include <linux/pagemap.h>
 #include <linux/mempolicy.h>
 #include <linux/cpuset.h>
+#include <linux/mutex.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
 
 #include <linux/hugetlb.h>
+#include "internal.h"
 
 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
-static unsigned long nr_huge_pages, free_huge_pages;
+static unsigned long nr_huge_pages, free_huge_pages, reserved_huge_pages;
 unsigned long max_huge_pages;
 static struct list_head hugepage_freelists[MAX_NUMNODES];
 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
 static unsigned int free_huge_pages_node[MAX_NUMNODES];
-
 /*
  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
  */
 static DEFINE_SPINLOCK(hugetlb_lock);
 
+static void clear_huge_page(struct page *page, unsigned long addr)
+{
+        int i;
+
+        might_sleep();
+        for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
+                cond_resched();
+                clear_user_highpage(page + i, addr);
+        }
+}
+
+static void copy_huge_page(struct page *dst, struct page *src,
+                           unsigned long addr)
+{
+        int i;
+
+        might_sleep();
+        for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
+                cond_resched();
+                copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE);
+        }
+}
+
 static void enqueue_huge_page(struct page *page)
 {
         int nid = page_to_nid(page);
@@ -64,57 +88,176 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
         return page;
 }
 
-static struct page *alloc_fresh_huge_page(void)
+static void free_huge_page(struct page *page)
+{
+        BUG_ON(page_count(page));
+
+        INIT_LIST_HEAD(&page->lru);
+
+        spin_lock(&hugetlb_lock);
+        enqueue_huge_page(page);
+        spin_unlock(&hugetlb_lock);
+}
+
+static int alloc_fresh_huge_page(void)
 {
         static int nid = 0;
         struct page *page;
         page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
                                         HUGETLB_PAGE_ORDER);
-        nid = (nid + 1) % num_online_nodes();
+        nid = next_node(nid, node_online_map);
+        if (nid == MAX_NUMNODES)
+                nid = first_node(node_online_map);
         if (page) {
+                page[1].lru.next = (void *)free_huge_page;      /* dtor */
                 spin_lock(&hugetlb_lock);
                 nr_huge_pages++;
                 nr_huge_pages_node[page_to_nid(page)]++;
                 spin_unlock(&hugetlb_lock);
+                put_page(page); /* free it into the hugepage allocator */
+                return 1;
         }
-        return page;
+        return 0;
 }
 
-void free_huge_page(struct page *page)
+static struct page *alloc_huge_page(struct vm_area_struct *vma,
+                                    unsigned long addr)
 {
-        BUG_ON(page_count(page));
+        struct inode *inode = vma->vm_file->f_dentry->d_inode;
+        struct page *page;
+        int use_reserve = 0;
+        unsigned long idx;
 
-        INIT_LIST_HEAD(&page->lru);
-        page[1].lru.next = NULL;                        /* reset dtor */
+        spin_lock(&hugetlb_lock);
+
+        if (vma->vm_flags & VM_MAYSHARE) {
+
+                /* idx = radix tree index, i.e. offset into file in
+                 * HPAGE_SIZE units */
+                idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
+                        + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+
+                /* The hugetlbfs specific inode info stores the number
+                 * of "guaranteed available" (huge) pages.  That is,
+                 * the first 'prereserved_hpages' pages of the inode
+                 * are either already instantiated, or have been
+                 * pre-reserved (by hugetlb_reserve_for_inode()). Here
+                 * we're in the process of instantiating the page, so
+                 * we use this to determine whether to draw from the
+                 * pre-reserved pool or the truly free pool. */
+                if (idx < HUGETLBFS_I(inode)->prereserved_hpages)
+                        use_reserve = 1;
+        }
+
+        if (!use_reserve) {
+                if (free_huge_pages <= reserved_huge_pages)
+                        goto fail;
+        } else {
+                BUG_ON(reserved_huge_pages == 0);
+                reserved_huge_pages--;
+        }
+
+        page = dequeue_huge_page(vma, addr);
+        if (!page)
+                goto fail;
+
+        spin_unlock(&hugetlb_lock);
+        set_page_refcounted(page);
+        return page;
+
+ fail:
+        WARN_ON(use_reserve); /* reserved allocations shouldn't fail */
+        spin_unlock(&hugetlb_lock);
+        return NULL;
+}
+
+/* hugetlb_extend_reservation()
+ *
+ * Ensure that at least 'atleast' hugepages are, and will remain,
+ * available to instantiate the first 'atleast' pages of the given
+ * inode.  If the inode doesn't already have this many pages reserved
+ * or instantiated, set aside some hugepages in the reserved pool to
+ * satisfy later faults (or fail now if there aren't enough, rather
+ * than getting the SIGBUS later).
+ */
+int hugetlb_extend_reservation(struct hugetlbfs_inode_info *info,
+                               unsigned long atleast)
+{
+        struct inode *inode = &info->vfs_inode;
+        unsigned long change_in_reserve = 0;
+        int ret = 0;
 
         spin_lock(&hugetlb_lock);
-        enqueue_huge_page(page);
+        read_lock_irq(&inode->i_mapping->tree_lock);
+
+        if (info->prereserved_hpages >= atleast)
+                goto out;
+
+        /* Because we always call this on shared mappings, none of the
+         * pages beyond info->prereserved_hpages can have been
+         * instantiated, so we need to reserve all of them now. */
+        change_in_reserve = atleast - info->prereserved_hpages;
+
+        if ((reserved_huge_pages + change_in_reserve) > free_huge_pages) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        reserved_huge_pages += change_in_reserve;
+        info->prereserved_hpages = atleast;
+
+ out:
+        read_unlock_irq(&inode->i_mapping->tree_lock);
         spin_unlock(&hugetlb_lock);
+
+        return ret;
 }
 
-struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
+/* hugetlb_truncate_reservation()
+ *
+ * This returns pages reserved for the given inode to the general free
+ * hugepage pool.  If the inode has any pages prereserved, but not
+ * instantiated, beyond offset (atmost << HPAGE_SIZE), then release
+ * them.
+ */
+void hugetlb_truncate_reservation(struct hugetlbfs_inode_info *info,
+                                  unsigned long atmost)
 {
+        struct inode *inode = &info->vfs_inode;
+        struct address_space *mapping = inode->i_mapping;
+        unsigned long idx;
+        unsigned long change_in_reserve = 0;
         struct page *page;
-        int i;
 
         spin_lock(&hugetlb_lock);
-        page = dequeue_huge_page(vma, addr);
-        if (!page) {
-                spin_unlock(&hugetlb_lock);
-                return NULL;
+        read_lock_irq(&inode->i_mapping->tree_lock);
+
+        if (info->prereserved_hpages <= atmost)
+                goto out;
+
+        /* Count pages which were reserved, but not instantiated, and
+         * which we can now release. */
+        for (idx = atmost; idx < info->prereserved_hpages; idx++) {
+                page = radix_tree_lookup(&mapping->page_tree, idx);
+                if (!page)
+                        /* Pages which are already instantiated can't
+                         * be unreserved (and in fact have already
+                         * been removed from the reserved pool) */
+                        change_in_reserve++;
         }
+
+        BUG_ON(reserved_huge_pages < change_in_reserve);
+        reserved_huge_pages -= change_in_reserve;
+        info->prereserved_hpages = atmost;
+
+ out:
+        read_unlock_irq(&inode->i_mapping->tree_lock);
         spin_unlock(&hugetlb_lock);
-        set_page_count(page, 1);
-        page[1].lru.next = (void *)free_huge_page;      /* set dtor */
-        for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
-                clear_user_highpage(&page[i], addr);
-        return page;
 }
 
 static int __init hugetlb_init(void)
 {
         unsigned long i;
-        struct page *page;
 
         if (HPAGE_SHIFT == 0)
                 return 0;
@@ -123,12 +266,8 @@ static int __init hugetlb_init(void)
                 INIT_LIST_HEAD(&hugepage_freelists[i]);
 
         for (i = 0; i < max_huge_pages; ++i) {
-                page = alloc_fresh_huge_page();
-                if (!page)
+                if (!alloc_fresh_huge_page())
                         break;
-                spin_lock(&hugetlb_lock);
-                enqueue_huge_page(page);
-                spin_unlock(&hugetlb_lock);
         }
         max_huge_pages = free_huge_pages = nr_huge_pages = i;
         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
@@ -154,9 +293,9 @@ static void update_and_free_page(struct page *page)
                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
                                 1 << PG_private | 1<< PG_writeback);
-                set_page_count(&page[i], 0);
         }
-        set_page_count(page, 1);
+        page[1].lru.next = NULL;
+        set_page_refcounted(page);
         __free_pages(page, HUGETLB_PAGE_ORDER);
 }
 
@@ -188,12 +327,8 @@ static inline void try_to_free_low(unsigned long count)
 static unsigned long set_max_huge_pages(unsigned long count)
 {
         while (count > nr_huge_pages) {
-                struct page *page = alloc_fresh_huge_page();
-                if (!page)
+                if (!alloc_fresh_huge_page())
                         return nr_huge_pages;
-                spin_lock(&hugetlb_lock);
-                enqueue_huge_page(page);
-                spin_unlock(&hugetlb_lock);
         }
         if (count >= nr_huge_pages)
                 return nr_huge_pages;
@@ -225,9 +360,11 @@ int hugetlb_report_meminfo(char *buf)
         return sprintf(buf,
                         "HugePages_Total: %5lu\n"
                         "HugePages_Free:  %5lu\n"
+                        "HugePages_Rsvd:  %5lu\n"
                         "Hugepagesize:    %5lu kB\n",
                         nr_huge_pages,
                         free_huge_pages,
+                        reserved_huge_pages,
                         HPAGE_SIZE/1024);
 }
 
@@ -240,11 +377,6 @@ int hugetlb_report_node_meminfo(int nid, char *buf)
                 nid, free_huge_pages_node[nid]);
 }
 
-int is_hugepage_mem_enough(size_t size)
-{
-        return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
-}
-
 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
 unsigned long hugetlb_total_pages(void)
 {
@@ -374,7 +506,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
                         unsigned long address, pte_t *ptep, pte_t pte)
 {
         struct page *old_page, *new_page;
-        int i, avoidcopy;
+        int avoidcopy;
 
         old_page = pte_page(pte);
 
@@ -395,9 +527,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
         }
 
         spin_unlock(&mm->page_table_lock);
-        for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++)
-                copy_user_highpage(new_page + i, old_page + i,
-                                   address + i*PAGE_SIZE);
+        copy_huge_page(new_page, old_page, address);
         spin_lock(&mm->page_table_lock);
 
         ptep = huge_pte_offset(mm, address & HPAGE_MASK);
@@ -442,6 +572,7 @@ retry:
                         ret = VM_FAULT_OOM;
                         goto out;
                 }
+                clear_huge_page(page, address);
 
                 if (vma->vm_flags & VM_SHARED) {
                         int err;
@@ -496,14 +627,24 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         pte_t *ptep;
         pte_t entry;
         int ret;
+        static DEFINE_MUTEX(hugetlb_instantiation_mutex);
 
         ptep = huge_pte_alloc(mm, address);
         if (!ptep)
                 return VM_FAULT_OOM;
 
+        /*
+         * Serialize hugepage allocation and instantiation, so that we don't
+         * get spurious allocation failures if two CPUs race to instantiate
+         * the same page in the page cache.
+         */
+        mutex_lock(&hugetlb_instantiation_mutex);
         entry = *ptep;
-        if (pte_none(entry))
-                return hugetlb_no_page(mm, vma, address, ptep, write_access);
+        if (pte_none(entry)) {
+                ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
+                mutex_unlock(&hugetlb_instantiation_mutex);
+                return ret;
+        }
 
         ret = VM_FAULT_MINOR;
 
@@ -513,6 +654,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                 if (write_access && !pte_write(entry))
                         ret = hugetlb_cow(mm, vma, address, ptep, entry);
         spin_unlock(&mm->page_table_lock);
+        mutex_unlock(&hugetlb_instantiation_mutex);
 
         return ret;
 }
@@ -521,10 +663,10 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
                         struct page **pages, struct vm_area_struct **vmas,
                         unsigned long *position, int *length, int i)
 {
-        unsigned long vpfn, vaddr = *position;
+        unsigned long pfn_offset;
+        unsigned long vaddr = *position;
         int remainder = *length;
 
-        vpfn = vaddr/PAGE_SIZE;
         spin_lock(&mm->page_table_lock);
         while (vaddr < vma->vm_end && remainder) {
                 pte_t *pte;
@@ -552,19 +694,28 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
                         break;
                 }
 
-                if (pages) {
-                        page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
-                        get_page(page);
-                        pages[i] = page;
-                }
+                pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
+                page = pte_page(*pte);
+same_page:
+                get_page(page);
+                if (pages)
+                        pages[i] = page + pfn_offset;
 
                 if (vmas)
                         vmas[i] = vma;
 
                 vaddr += PAGE_SIZE;
-                ++vpfn;
+                ++pfn_offset;
                 --remainder;
                 ++i;
+                if (vaddr < vma->vm_end && remainder &&
+                                pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
+                        /*
+                         * We use pfn_offset to avoid touching the pageframes
+                         * of this compound page.
+                         */
+                        goto same_page;
+                }
         }
         spin_unlock(&mm->page_table_lock);
         *length = remainder;
@@ -572,3 +723,32 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
         return i;
 }
+
+void hugetlb_change_protection(struct vm_area_struct *vma,
+                unsigned long address, unsigned long end, pgprot_t newprot)
+{
+        struct mm_struct *mm = vma->vm_mm;
+        unsigned long start = address;
+        pte_t *ptep;
+        pte_t pte;
+
+        BUG_ON(address >= end);
+        flush_cache_range(vma, address, end);
+
+        spin_lock(&mm->page_table_lock);
+        for (; address < end; address += HPAGE_SIZE) {
+                ptep = huge_pte_offset(mm, address);
+                if (!ptep)
+                        continue;
+                if (!pte_none(*ptep)) {
+                        pte = huge_ptep_get_and_clear(mm, address, ptep);
+                        pte = pte_mkhuge(pte_modify(pte, newprot));
+                        set_huge_pte_at(mm, address, ptep, pte);
+                        lazy_mmu_prot_update(pte);
+                }
+        }
+        spin_unlock(&mm->page_table_lock);
+
+        flush_tlb_range(vma, start, end);
+}
+