hugetlb: remove prev_vma from hugetlb_get_unmapped_area_topdown()

After looking up the vma which covers or follows the cached search
address, the following condition is always true:

	!prev_vma || (addr >= prev_vma->vm_end)

so we can stop checking the previous VMA altogether.

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 13 deletions

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index c20e81c3425d..f6679a7fb8ca 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 {
         struct hstate *h = hstate_file(file);
         struct mm_struct *mm = current->mm;
-        struct vm_area_struct *vma, *prev_vma;
+        struct vm_area_struct *vma;
         unsigned long base = mm->mmap_base;
         unsigned long addr = addr0;
         unsigned long largest_hole = mm->cached_hole_size;
@@ -340,22 +340,14 @@ try_again:
                 if (!vma)
                         return addr;
 
-                /*
-                 * new region fits between prev_vma->vm_end and
-                 * vma->vm_start, use it:
-                 */
-                prev_vma = vma->vm_prev;
-                if (addr + len <= vma->vm_start &&
-                            (!prev_vma || (addr >= prev_vma->vm_end))) {
+                if (addr + len <= vma->vm_start) {
                         /* remember the address as a hint for next time */
                         mm->cached_hole_size = largest_hole;
                         return (mm->free_area_cache = addr);
-                } else {
+                } else if (mm->free_area_cache == vma->vm_end) {
                         /* pull free_area_cache down to the first hole */
-                        if (mm->free_area_cache == vma->vm_end) {
-                                mm->free_area_cache = vma->vm_start;
-                                mm->cached_hole_size = largest_hole;
-                        }
+                        mm->free_area_cache = vma->vm_start;
+                        mm->cached_hole_size = largest_hole;
                 }
 
                 /* remember the largest hole we saw so far */