1 files changed, 19 insertions, 31 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index bd1808e194a7..b51eadf6d952 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -722,11 +722,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
         if (vma->vm_file) {
                 mapping = vma->vm_file->f_mapping;
 
-                mutex_lock(&mapping->i_mmap_mutex);
+                i_mmap_lock_write(mapping);
                 flush_dcache_mmap_lock(mapping);
                 vma_interval_tree_insert(vma, &mapping->i_mmap);
                 flush_dcache_mmap_unlock(mapping);
-                mutex_unlock(&mapping->i_mmap_mutex);
+                i_mmap_unlock_write(mapping);
         }
 
         /* add the VMA to the tree */
@@ -795,11 +795,11 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
         if (vma->vm_file) {
                 mapping = vma->vm_file->f_mapping;
 
-                mutex_lock(&mapping->i_mmap_mutex);
+                i_mmap_lock_write(mapping);
                 flush_dcache_mmap_lock(mapping);
                 vma_interval_tree_remove(vma, &mapping->i_mmap);
                 flush_dcache_mmap_unlock(mapping);
-                mutex_unlock(&mapping->i_mmap_mutex);
+                i_mmap_unlock_write(mapping);
         }
 
         /* remove from the MM's tree and list */
@@ -1149,8 +1149,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
                            unsigned long len,
                            unsigned long capabilities)
 {
-        struct page *pages;
-        unsigned long total, point, n;
+        unsigned long total, point;
         void *base;
         int ret, order;
 
@@ -1182,33 +1181,23 @@ static int do_mmap_private(struct vm_area_struct *vma,
         order = get_order(len);
         kdebug("alloc order %d for %lx", order, len);
 
-        pages = alloc_pages(GFP_KERNEL, order);
-        if (!pages)
-                goto enomem;
-
         total = 1 << order;
-        atomic_long_add(total, &mmap_pages_allocated);
-
         point = len >> PAGE_SHIFT;
 
-        /* we allocated a power-of-2 sized page set, so we may want to trim off
-         * the excess */
+        /* we don't want to allocate a power-of-2 sized page set */
         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
-                while (total > point) {
-                        order = ilog2(total - point);
-                        n = 1 << order;
-                        kdebug("shave %lu/%lu @%lu", n, total - point, total);
-                        atomic_long_sub(n, &mmap_pages_allocated);
-                        total -= n;
-                        set_page_refcounted(pages + total);
-                        __free_pages(pages + total, order);
-                }
+                total = point;
+                kdebug("try to alloc exact %lu pages", total);
+                base = alloc_pages_exact(len, GFP_KERNEL);
+        } else {
+                base = (void *)__get_free_pages(GFP_KERNEL, order);
         }
 
-        for (point = 1; point < total; point++)
-                set_page_refcounted(&pages[point]);
+        if (!base)
+                goto enomem;
+
+        atomic_long_add(total, &mmap_pages_allocated);
 
-        base = page_address(pages);
         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
         region->vm_start = (unsigned long) base;
         region->vm_end   = region->vm_start + len;
@@ -2094,14 +2083,14 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
         down_write(&nommu_region_sem);
-        mutex_lock(&inode->i_mapping->i_mmap_mutex);
+        i_mmap_lock_read(inode->i_mapping);
 
         /* search for VMAs that fall within the dead zone */
         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
                 /* found one - only interested if it's shared out of the page
                  * cache */
                 if (vma->vm_flags & VM_SHARED) {
-                        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
+                        i_mmap_unlock_read(inode->i_mapping);
                         up_write(&nommu_region_sem);
                         return -ETXTBSY; /* not quite true, but near enough */
                 }
@@ -2113,8 +2102,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
          * we don't check for any regions that start beyond the EOF as there
          * shouldn't be any
          */
-        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
-                                  0, ULONG_MAX) {
+        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
                 if (!(vma->vm_flags & VM_SHARED))
                         continue;
 
@@ -2129,7 +2117,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
                 }
         }
 
-        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
+        i_mmap_unlock_read(inode->i_mapping);
         up_write(&nommu_region_sem);
         return 0;
 }