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[PATCH 09/16] mm: use vm_unmapped_area() in hugetlbfs on i386 architectu

To: Andrew Morton <akpm@linux-foundation.org>, Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org, Russell King <linux@arm.linux.org.uk>, Ralf Baechle <ralf@linux-mips.org>, Paul Mundt <lethal@linux-sh.org>, "David S. Miller" <davem@davemloft.net>, Chris Metcalf <cmetcalf@tilera.com>, x86@kernel.org, William Irwin <wli@holomorphy.com>
Subject: [PATCH 09/16] mm: use vm_unmapped_area() in hugetlbfs on i386 architecture
From: Michel Lespinasse <walken@google.com>
Date: Mon, 5 Nov 2012 14:47:06 -0800
Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org
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Update the i386 hugetlb_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken@google.com>

---
 arch/x86/mm/hugetlbpage.c |  130 +++++++++------------------------------------
 1 files changed, 25 insertions(+), 105 deletions(-)

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 937bff5cdaa7..c00c4a4cd564 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -274,42 +274,15 @@ static unsigned long 
hugetlb_get_unmapped_area_bottomup(struct file *file,
                unsigned long pgoff, unsigned long flags)
 {
        struct hstate *h = hstate_file(file);
-       struct mm_struct *mm = current->mm;
-       struct vm_area_struct *vma;
-       unsigned long start_addr;
-
-       if (len > mm->cached_hole_size) {
-               start_addr = mm->free_area_cache;
-       } else {
-               start_addr = TASK_UNMAPPED_BASE;
-               mm->cached_hole_size = 0;
-       }
-
-full_search:
-       addr = ALIGN(start_addr, huge_page_size(h));
-
-       for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
-               /* At this point:  (!vma || addr < vma->vm_end). */
-               if (TASK_SIZE - len < addr) {
-                       /*
-                        * Start a new search - just in case we missed
-                        * some holes.
-                        */
-                       if (start_addr != TASK_UNMAPPED_BASE) {
-                               start_addr = TASK_UNMAPPED_BASE;
-                               mm->cached_hole_size = 0;
-                               goto full_search;
-                       }
-                       return -ENOMEM;
-               }
-               if (!vma || addr + len <= vma->vm_start) {
-                       mm->free_area_cache = addr + len;
-                       return addr;
-               }
-               if (addr + mm->cached_hole_size < vma->vm_start)
-                       mm->cached_hole_size = vma->vm_start - addr;
-               addr = ALIGN(vma->vm_end, huge_page_size(h));
-       }
+       struct vm_unmapped_area_info info;
+
+       info.flags = 0;
+       info.length = len;
+       info.low_limit = TASK_UNMAPPED_BASE;
+       info.high_limit = TASK_SIZE;
+       info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+       info.align_offset = 0;
+       return vm_unmapped_area(&info);
 }
 
 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
@@ -317,83 +290,30 @@ static unsigned long 
hugetlb_get_unmapped_area_topdown(struct file *file,
                unsigned long pgoff, unsigned long flags)
 {
        struct hstate *h = hstate_file(file);
-       struct mm_struct *mm = current->mm;
-       struct vm_area_struct *vma;
-       unsigned long base = mm->mmap_base;
-       unsigned long addr = addr0;
-       unsigned long largest_hole = mm->cached_hole_size;
-       unsigned long start_addr;
-
-       /* don't allow allocations above current base */
-       if (mm->free_area_cache > base)
-               mm->free_area_cache = base;
-
-       if (len <= largest_hole) {
-               largest_hole = 0;
-               mm->free_area_cache  = base;
-       }
-try_again:
-       start_addr = mm->free_area_cache;
-
-       /* make sure it can fit in the remaining address space */
-       if (mm->free_area_cache < len)
-               goto fail;
-
-       /* either no address requested or can't fit in requested address hole */
-       addr = (mm->free_area_cache - len) & huge_page_mask(h);
-       do {
-               /*
-                * Lookup failure means no vma is above this address,
-                * i.e. return with success:
-                */
-               vma = find_vma(mm, addr);
-               if (!vma)
-                       return addr;
+       struct vm_unmapped_area_info info;
+       unsigned long addr;
 
-               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 if (mm->free_area_cache == vma->vm_end) {
-                       /* pull free_area_cache down to the first hole */
-                       mm->free_area_cache = vma->vm_start;
-                       mm->cached_hole_size = largest_hole;
-               }
+       info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+       info.length = len;
+       info.low_limit = PAGE_SIZE;
+       info.high_limit = mm->mmap_base;
+       info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+       info.align_offset = 0;
+       addr = vm_unmapped_area(&info);
 
-               /* remember the largest hole we saw so far */
-               if (addr + largest_hole < vma->vm_start)
-                       largest_hole = vma->vm_start - addr;
-
-               /* try just below the current vma->vm_start */
-               addr = (vma->vm_start - len) & huge_page_mask(h);
-       } while (len <= vma->vm_start);
-
-fail:
-       /*
-        * if hint left us with no space for the requested
-        * mapping then try again:
-        */
-       if (start_addr != base) {
-               mm->free_area_cache = base;
-               largest_hole = 0;
-               goto try_again;
-       }
        /*
         * A failed mmap() very likely causes application failure,
         * so fall back to the bottom-up function here. This scenario
         * can happen with large stack limits and large mmap()
         * allocations.
         */
-       mm->free_area_cache = TASK_UNMAPPED_BASE;
-       mm->cached_hole_size = ~0UL;
-       addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
-                       len, pgoff, flags);
-
-       /*
-        * Restore the topdown base:
-        */
-       mm->free_area_cache = base;
-       mm->cached_hole_size = ~0UL;
+       if (addr & ~PAGE_MASK) {
+               VM_BUG_ON(addr != -ENOMEM);
+               info.flags = 0;
+               info.low_limit = TASK_UNMAPPED_BASE;
+               info.high_limit = TASK_SIZE;
+               addr = vm_unmapped_area(&info);
+       }
 
        return addr;
 }
-- 
1.7.7.3

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