[PATCH] cpuset: rework cpuset_zone_allowed api
[linux-2.6.git] / mm / hugetlb.c
index eb40556..089092d 100644 (file)
 #include <linux/nodemask.h>
 #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, resv_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);
@@ -47,8 +72,9 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
        struct zone **z;
 
        for (z = zonelist->zones; *z; z++) {
-               nid = (*z)->zone_pgdat->node_id;
-               if (!list_empty(&hugepage_freelists[nid]))
+               nid = zone_to_nid(*z);
+               if (cpuset_zone_allowed_softwall(*z, GFP_HIGHUSER) &&
+                   !list_empty(&hugepage_freelists[nid]))
                        break;
        }
 
@@ -62,57 +88,65 @@ 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) {
+               set_compound_page_dtor(page, free_huge_page);
                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;
-}
-
-void free_huge_page(struct page *page)
-{
-       BUG_ON(page_count(page));
-
-       INIT_LIST_HEAD(&page->lru);
-       page[1].mapping = NULL;
-
-       spin_lock(&hugetlb_lock);
-       enqueue_huge_page(page);
-       spin_unlock(&hugetlb_lock);
+       return 0;
 }
 
-struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
+static struct page *alloc_huge_page(struct vm_area_struct *vma,
+                                   unsigned long addr)
 {
        struct page *page;
-       int i;
 
        spin_lock(&hugetlb_lock);
+       if (vma->vm_flags & VM_MAYSHARE)
+               resv_huge_pages--;
+       else if (free_huge_pages <= resv_huge_pages)
+               goto fail;
+
        page = dequeue_huge_page(vma, addr);
-       if (!page) {
-               spin_unlock(&hugetlb_lock);
-               return NULL;
-       }
+       if (!page)
+               goto fail;
+
        spin_unlock(&hugetlb_lock);
-       set_page_count(page, 1);
-       page[1].mapping = (void *)free_huge_page;
-       for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
-               clear_highpage(&page[i]);
+       set_page_refcounted(page);
        return page;
+
+fail:
+       spin_unlock(&hugetlb_lock);
+       return NULL;
 }
 
 static int __init hugetlb_init(void)
 {
        unsigned long i;
-       struct page *page;
 
        if (HPAGE_SHIFT == 0)
                return 0;
@@ -121,12 +155,8 @@ 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);
@@ -147,21 +177,22 @@ static void update_and_free_page(struct page *page)
 {
        int i;
        nr_huge_pages--;
-       nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
+       nr_huge_pages_node[page_to_nid(page)]--;
        for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
                page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
                                1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
                                1 << PG_private | 1<< PG_writeback);
-               set_page_count(&page[i], 0);
        }
-       set_page_count(page, 1);
+       page[1].lru.next = NULL;
+       set_page_refcounted(page);
        __free_pages(page, HUGETLB_PAGE_ORDER);
 }
 
 #ifdef CONFIG_HIGHMEM
 static void try_to_free_low(unsigned long count)
 {
-       int i, nid;
+       int i;
+
        for (i = 0; i < MAX_NUMNODES; ++i) {
                struct page *page, *next;
                list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
@@ -169,9 +200,8 @@ static void try_to_free_low(unsigned long count)
                                continue;
                        list_del(&page->lru);
                        update_and_free_page(page);
-                       nid = page_zone(page)->zone_pgdat->node_id;
                        free_huge_pages--;
-                       free_huge_pages_node[nid]--;
+                       free_huge_pages_node[page_to_nid(page)]--;
                        if (count >= nr_huge_pages)
                                return;
                }
@@ -186,17 +216,14 @@ 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;
 
        spin_lock(&hugetlb_lock);
+       count = max(count, resv_huge_pages);
        try_to_free_low(count);
        while (count < nr_huge_pages) {
                struct page *page = dequeue_huge_page(NULL, 0);
@@ -223,9 +250,11 @@ 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,
+                       resv_huge_pages,
                        HPAGE_SIZE/1024);
 }
 
@@ -238,11 +267,6 @@ 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)
 {
@@ -320,7 +344,6 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
                        entry = *src_pte;
                        ptepage = pte_page(entry);
                        get_page(ptepage);
-                       add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
                        set_huge_pte_at(dst, addr, dst_pte, entry);
                }
                spin_unlock(&src->page_table_lock);
@@ -332,84 +355,73 @@ nomem:
        return -ENOMEM;
 }
 
-void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
-                         unsigned long end)
+void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
+                           unsigned long end)
 {
        struct mm_struct *mm = vma->vm_mm;
        unsigned long address;
        pte_t *ptep;
        pte_t pte;
        struct page *page;
+       struct page *tmp;
+       /*
+        * 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 & ~HPAGE_MASK);
        BUG_ON(end & ~HPAGE_MASK);
 
        spin_lock(&mm->page_table_lock);
-
-       /* Update high watermark before we lower rss */
-       update_hiwater_rss(mm);
-
        for (address = start; address < end; address += HPAGE_SIZE) {
                ptep = huge_pte_offset(mm, address);
                if (!ptep)
                        continue;
 
+               if (huge_pmd_unshare(mm, &address, ptep))
+                       continue;
+
                pte = huge_ptep_get_and_clear(mm, address, ptep);
                if (pte_none(pte))
                        continue;
 
                page = pte_page(pte);
-               put_page(page);
-               add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
+               list_add(&page->lru, &page_list);
        }
-
        spin_unlock(&mm->page_table_lock);
        flush_tlb_range(vma, start, end);
+       list_for_each_entry_safe(page, tmp, &page_list, lru) {
+               list_del(&page->lru);
+               put_page(page);
+       }
 }
 
-static struct page *find_or_alloc_huge_page(struct vm_area_struct *vma,
-                       unsigned long addr, struct address_space *mapping,
-                       unsigned long idx, int shared)
+void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
+                         unsigned long end)
 {
-       struct page *page;
-       int err;
-
-retry:
-       page = find_lock_page(mapping, idx);
-       if (page)
-               goto out;
-
-       if (hugetlb_get_quota(mapping))
-               goto out;
-       page = alloc_huge_page(vma, addr);
-       if (!page) {
-               hugetlb_put_quota(mapping);
-               goto out;
-       }
-
-       if (shared) {
-               err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
-               if (err) {
-                       put_page(page);
-                       hugetlb_put_quota(mapping);
-                       if (err == -EEXIST)
-                               goto retry;
-                       page = NULL;
-               }
-       } else {
-               /* Caller expects a locked page */
-               lock_page(page);
+       /*
+        * It is undesirable to test vma->vm_file as it should be non-null
+        * for valid hugetlb area. However, vm_file will be NULL in the error
+        * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
+        * do_mmap_pgoff() nullifies vma->vm_file before calling this function
+        * to clean up. Since no pte has actually been setup, it is safe to
+        * do nothing in this case.
+        */
+       if (vma->vm_file) {
+               spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
+               __unmap_hugepage_range(vma, start, end);
+               spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
        }
-out:
-       return page;
 }
 
 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);
 
@@ -426,18 +438,11 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 
        if (!new_page) {
                page_cache_release(old_page);
-
-               /* Logically this is OOM, not a SIGBUS, but an OOM
-                * could cause the kernel to go killing other
-                * processes which won't help the hugepage situation
-                * at all (?) */
-               return VM_FAULT_SIGBUS;
+               return VM_FAULT_OOM;
        }
 
        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);
@@ -471,12 +476,36 @@ int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
         * Use page lock to guard against racing truncation
         * before we get page_table_lock.
         */
-       page = find_or_alloc_huge_page(vma, address, mapping, idx,
-                       vma->vm_flags & VM_SHARED);
-       if (!page)
-               goto out;
-
-       BUG_ON(!PageLocked(page));
+retry:
+       page = find_lock_page(mapping, idx);
+       if (!page) {
+               size = i_size_read(mapping->host) >> HPAGE_SHIFT;
+               if (idx >= size)
+                       goto out;
+               if (hugetlb_get_quota(mapping))
+                       goto out;
+               page = alloc_huge_page(vma, address);
+               if (!page) {
+                       hugetlb_put_quota(mapping);
+                       ret = VM_FAULT_OOM;
+                       goto out;
+               }
+               clear_huge_page(page, address);
+
+               if (vma->vm_flags & VM_SHARED) {
+                       int err;
+
+                       err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
+                       if (err) {
+                               put_page(page);
+                               hugetlb_put_quota(mapping);
+                               if (err == -EEXIST)
+                                       goto retry;
+                               goto out;
+                       }
+               } else
+                       lock_page(page);
+       }
 
        spin_lock(&mm->page_table_lock);
        size = i_size_read(mapping->host) >> HPAGE_SHIFT;
@@ -487,7 +516,6 @@ int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!pte_none(*ptep))
                goto backout;
 
-       add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
        new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
                                && (vma->vm_flags & VM_SHARED)));
        set_huge_pte_at(mm, address, ptep, new_pte);
@@ -516,14 +544,24 @@ 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;
 
@@ -533,6 +571,7 @@ 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;
 }
@@ -541,10 +580,10 @@ 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;
@@ -572,19 +611,29 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        break;
                }
 
+               pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
+               page = pte_page(*pte);
+same_page:
                if (pages) {
-                       page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
                        get_page(page);
-                       pages[i] = page;
+                       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;
@@ -592,3 +641,189 @@ 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(&vma->vm_file->f_mapping->i_mmap_lock);
+       spin_lock(&mm->page_table_lock);
+       for (; address < end; address += HPAGE_SIZE) {
+               ptep = huge_pte_offset(mm, address);
+               if (!ptep)
+                       continue;
+               if (huge_pmd_unshare(mm, &address, 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);
+       spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
+
+       flush_tlb_range(vma, start, end);
+}
+
+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 guarentee to record the reservation. */
+       if (&rg->link == head || t < rg->from) {
+               nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
+               if (nrg == 0)
+                       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 int hugetlb_acct_memory(long delta)
+{
+       int ret = -ENOMEM;
+
+       spin_lock(&hugetlb_lock);
+       if ((delta + resv_huge_pages) <= free_huge_pages) {
+               resv_huge_pages += delta;
+               ret = 0;
+       }
+       spin_unlock(&hugetlb_lock);
+       return ret;
+}
+
+int hugetlb_reserve_pages(struct inode *inode, long from, long to)
+{
+       long ret, chg;
+
+       chg = region_chg(&inode->i_mapping->private_list, from, to);
+       if (chg < 0)
+               return chg;
+       ret = hugetlb_acct_memory(chg);
+       if (ret < 0)
+               return ret;
+       region_add(&inode->i_mapping->private_list, from, to);
+       return 0;
+}
+
+void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
+{
+       long chg = region_truncate(&inode->i_mapping->private_list, offset);
+       hugetlb_acct_memory(freed - chg);
+}