Re: linux-next: manual merge of the akpm tree with Linus' tree

Xiao Guangrong
2012-03-08T09:59:23Z

On 03/08/2012 03:50 PM, Andrew Morton wrote:

> Doh. The author reviewed that for me too!
>
> I'll drop it - please rework, retest and resend?
>

Andrew, the patch has been reworked.

Subject: [PATCH] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown()

After the call find_vma_prev(mm, addr, &prev_vma), the following condition
is always true:

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

it can happily drop prev_vma and use find_vma() instead of find_vma_prev().

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/mm/hugetlbpage.c | 18 +++++-------------
1 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 8ecbb4b..0c1701b 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;
@@ -337,22 +337,14 @@ 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 */
--
1.7.7.6