[PATCH 2/5] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown

From: Xiao Guangrong
Date: Fri Jan 13 2012 - 06:47:34 EST


Afte call find_vma_prev(mm, addr, &prev_vma), following condition is always
true:
!prev_vma || (addr >= prev_vma->vm_end)
it can be happily drop prev_vma and use find_vma instead of find_vma_prev

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/hugetlbpage.c | 21 ++++++---------------
1 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index f581a18..e12debc 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, addr = addr0;
unsigned long largest_hole = mm->cached_hole_size;
int first_time = 1;
@@ -333,24 +333,15 @@ try_again:
* Lookup failure means no vma is above this address,
* i.e. return with success:
*/
- if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
- return addr;
-
- /*
- * new region fits between prev_vma->vm_end and
- * vma->vm_start, use it:
- */
- if (addr + len <= vma->vm_start &&
- (!prev_vma || (addr >= prev_vma->vm_end))) {
+ vma = find_vma(mm, addr);
+ if (!vma || 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 */
--
1.7.7.5

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