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From: Andrew Morton <akpm@linux-foundation.org>
To: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
	Linus <torvalds@linux-foundation.org>
Subject: Re: linux-next: manual merge of the akpm tree with Linus' tree
Date: Thu, 8 Mar 2012 13:24:15 -0800
Message-ID: <20120308132415.15359fc7.akpm@linux-foundation.org> (raw)
In-Reply-To: <4F5882E6.8080202@linux.vnet.ibm.com>

On Thu, 08 Mar 2012 17:59:02 +0800
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote:

> 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().
> 

Well OK, but the changelog is wrong - we don't call find_vma_prev()
here any more.

How does this look?


From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Subject: 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>
---

 arch/x86/mm/hugetlbpage.c |   18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff -puN arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown arch/x86/mm/hugetlbpage.c
--- a/arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown
+++ a/arch/x86/mm/hugetlbpage.c
@@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmappe
 {
 	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 */
_

  reply index

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-08  6:53 Stephen Rothwell
2012-03-08  7:32 ` Andrew Morton
2012-03-08  7:41   ` Stephen Rothwell
2012-03-08  7:50     ` Andrew Morton
2012-03-08  7:50       ` Xiao Guangrong
2012-03-08  9:59       ` Xiao Guangrong
2012-03-08 21:24         ` Andrew Morton [this message]
2012-03-08 23:42           ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2019-12-02  2:17 Stephen Rothwell
2019-12-02  2:08 Stephen Rothwell
2018-10-15  7:22 Stephen Rothwell
2018-10-15  7:04 Stephen Rothwell
2018-03-26  8:56 Stephen Rothwell
2017-01-09  2:51 Stephen Rothwell
2016-12-12  5:49 Stephen Rothwell
2016-01-19  2:42 Stephen Rothwell
2016-01-19  2:36 Stephen Rothwell
2015-07-27  5:26 Stephen Rothwell
2013-09-10  4:38 Stephen Rothwell
2013-09-10 22:27 ` Andrew Morton
2013-09-10 22:29   ` Al Viro
2013-09-10 22:35     ` Andrew Morton
2013-09-10 22:36       ` Al Viro
2013-09-10 22:39         ` Al Viro
2013-09-10 22:41         ` Andrew Morton
2013-09-10 22:48           ` Al Viro
2013-09-10 22:59             ` Al Viro
2013-09-10 23:13               ` Andrew Morton
2013-09-10 23:55                 ` Al Viro
2013-09-11  4:30                 ` Stephen Rothwell
2013-09-10 23:37               ` Linus Torvalds
2013-09-10 23:53                 ` Al Viro
2013-09-11  0:01                   ` Linus Torvalds
2013-09-11  0:39                     ` Dave Chinner
2013-09-13  0:56                 ` Linus Torvalds
2013-09-13  1:12                   ` Linus Torvalds
2013-09-13  1:35                     ` Al Viro
2013-09-13 19:12                     ` Linus Torvalds
2013-09-13 19:28                       ` Linus Torvalds
2013-09-13 19:54                       ` Linus Torvalds
2013-09-13 20:00                       ` Al Viro
2013-09-13 20:18                         ` Al Viro
2013-09-13 20:23                           ` Al Viro
2013-09-13 20:25                         ` Linus Torvalds
2013-09-13 20:31                           ` Linus Torvalds
2013-09-13 20:31                           ` Al Viro
2013-09-13 20:34                             ` Linus Torvalds
2013-09-10 22:35   ` Linus Torvalds
2013-09-10 22:44     ` Andrew Morton
2013-09-11  0:30       ` Stephen Rothwell
2013-09-11  0:41         ` Linus Torvalds
2013-09-10  4:21 Stephen Rothwell
2013-09-10  4:09 Stephen Rothwell
2013-09-10  4:12 ` Stephen Rothwell
2013-09-09  5:38 Stephen Rothwell
2013-09-09  5:22 Stephen Rothwell
2013-09-09  5:16 Stephen Rothwell
2013-08-30  8:44 Stephen Rothwell
2013-05-27  6:20 Stephen Rothwell
2013-05-20  4:04 Stephen Rothwell
2013-05-20 12:19 ` Chris Mason
2013-05-13  5:20 Eric Paris
2013-05-13  2:07 Stephen Rothwell
2013-05-13  2:11 ` Eric Paris
2013-05-13  4:16   ` Stephen Rothwell
2013-05-13  4:49   ` Kees Cook
2013-05-13  5:14     ` Eric Paris
2013-05-02  6:01 Stephen Rothwell
2013-04-29  8:38 Stephen Rothwell
2013-04-19  7:40 Stephen Rothwell
2013-04-16  7:25 Stephen Rothwell
2013-04-03  6:10 Stephen Rothwell
2013-03-25  4:22 Stephen Rothwell
2013-03-04  2:21 Stephen Rothwell
2013-01-04  3:27 Stephen Rothwell
2012-12-11  5:25 Stephen Rothwell
2012-12-11  5:22 Stephen Rothwell
2012-12-11  7:58 ` Glauber Costa
2012-12-07  6:39 Stephen Rothwell
2012-11-30  6:24 Stephen Rothwell
2012-11-26 12:52 Stephen Rothwell
2012-11-26 12:48 Stephen Rothwell
2012-11-26 13:25 ` Xiaotian Feng
2012-11-26 12:34 Stephen Rothwell
2012-10-15  2:07 Stephen Rothwell
2012-10-15 22:14 ` Catalin Marinas
2012-10-01 14:15 Stephen Rothwell
2012-08-22  5:59 Stephen Rothwell
2012-08-22  8:58 ` Mel Gorman
2012-07-27  3:57 Stephen Rothwell
2012-07-02  6:39 Stephen Rothwell
2012-06-04  4:58 Stephen Rothwell
2012-05-31  4:24 Stephen Rothwell
2012-05-31  4:13 Stephen Rothwell
2012-05-31  7:25 ` Johannes Weiner
2012-05-31  8:24   ` Stephen Rothwell
2012-05-31  8:27     ` Stephen Rothwell
2012-05-21  8:23 Stephen Rothwell
2012-05-21  8:13 Stephen Rothwell
2012-05-21  8:16 ` Cyrill Gorcunov
2011-12-28  7:54 Stephen Rothwell
2011-11-08  3:24 Stephen Rothwell
2011-11-01  8:16 Stephen Rothwell
2011-11-01 10:47 ` Tao Ma
2011-09-16  6:09 Stephen Rothwell
2011-08-15  4:52 Stephen Rothwell

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