linux-kernel - [PATCH 2/5] hugetlb: drop prev_vma in hugetlb_get_unmapped_area

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Message-ID: <4F101935.1040108@linux.vnet.ibm.com>
Date:	Fri, 13 Jan 2012 19:44:53 +0800
From:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	William Irwin <wli@...omorphy.com>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/5] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown

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@...ux.vnet.ibm.com>
---
 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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