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[PATCH 11/16] mm: use vm_unmapped_area() on arm architecture

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 11/16] mm: use vm_unmapped_area() on arm architecture
From: Michel Lespinasse <walken@google.com>
Date: Mon, 5 Nov 2012 14:47:08 -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 arm arch_get_unmapped_area[_topdown] functions to make
use of vm_unmapped_area() instead of implementing a brute force search.

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

---
 arch/arm/mm/mmap.c |  119 ++++++++++------------------------------------------
 1 files changed, 23 insertions(+), 96 deletions(-)

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index ce8cb1970d7a..267e63f58098 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -72,6 +72,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
        unsigned long start_addr;
        int do_align = 0;
        int aliasing = cache_is_vipt_aliasing();
+       struct vm_unmapped_area_info info;
 
        /*
         * We only need to do colour alignment if either the I or D
@@ -104,46 +105,14 @@ arch_get_unmapped_area(struct file *filp, unsigned long 
addr,
                    (!vma || addr + len <= vma->vm_start))
                        return addr;
        }
-       if (len > mm->cached_hole_size) {
-               start_addr = addr = mm->free_area_cache;
-       } else {
-               start_addr = addr = mm->mmap_base;
-               mm->cached_hole_size = 0;
-       }
 
-full_search:
-       if (do_align)
-               addr = COLOUR_ALIGN(addr, pgoff);
-       else
-               addr = PAGE_ALIGN(addr);
-
-       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 = addr = TASK_UNMAPPED_BASE;
-                               mm->cached_hole_size = 0;
-                               goto full_search;
-                       }
-                       return -ENOMEM;
-               }
-               if (!vma || addr + len <= vma->vm_start) {
-                       /*
-                        * Remember the place where we stopped the search:
-                        */
-                       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 = vma->vm_end;
-               if (do_align)
-                       addr = COLOUR_ALIGN(addr, pgoff);
-       }
+       info.flags = 0;
+       info.length = len;
+       info.low_limit = mm->mmap_base;
+       info.high_limit = TASK_SIZE;
+       info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+       info.align_offset = pgoff << PAGE_SHIFT;
+       return vm_unmapped_area(&info);
 }
 
 unsigned long
@@ -156,6 +125,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const 
unsigned long addr0,
        unsigned long addr = addr0;
        int do_align = 0;
        int aliasing = cache_is_vipt_aliasing();
+       struct vm_unmapped_area_info info;
 
        /*
         * We only need to do colour alignment if either the I or D
@@ -187,70 +157,27 @@ arch_get_unmapped_area_topdown(struct file *filp, const 
unsigned long addr0,
                        return addr;
        }
 
-       /* check if free_area_cache is useful for us */
-       if (len <= mm->cached_hole_size) {
-               mm->cached_hole_size = 0;
-               mm->free_area_cache = mm->mmap_base;
-       }
-
-       /* either no address requested or can't fit in requested address hole */
-       addr = mm->free_area_cache;
-       if (do_align) {
-               unsigned long base = COLOUR_ALIGN_DOWN(addr - len, pgoff);
-               addr = base + len;
-       }
-
-       /* make sure it can fit in the remaining address space */
-       if (addr > len) {
-               vma = find_vma(mm, addr-len);
-               if (!vma || addr <= vma->vm_start)
-                       /* remember the address as a hint for next time */
-                       return (mm->free_area_cache = addr-len);
-       }
+       info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+       info.length = len;
+       info.low_limit = PAGE_SIZE;
+       info.high_limit = mm->mmap_base;
+       info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+       info.align_offset = pgoff << PAGE_SHIFT;
+       addr = vm_unmapped_area(&info);
 
-       if (mm->mmap_base < len)
-               goto bottomup;
-
-       addr = mm->mmap_base - len;
-       if (do_align)
-               addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-
-       do {
-               /*
-                * Lookup failure means no vma is above this address,
-                * else if new region fits below vma->vm_start,
-                * return with success:
-                */
-               vma = find_vma(mm, addr);
-               if (!vma || addr+len <= vma->vm_start)
-                       /* remember the address as a hint for next time */
-                       return (mm->free_area_cache = addr);
-
-               /* remember the largest hole we saw so far */
-               if (addr + mm->cached_hole_size < vma->vm_start)
-                       mm->cached_hole_size = vma->vm_start - addr;
-
-               /* try just below the current vma->vm_start */
-               addr = vma->vm_start - len;
-               if (do_align)
-                       addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-       } while (len < vma->vm_start);
-
-bottomup:
        /*
         * 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->cached_hole_size = ~0UL;
-       mm->free_area_cache = TASK_UNMAPPED_BASE;
-       addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
-       /*
-        * Restore the topdown base:
-        */
-       mm->free_area_cache = mm->mmap_base;
-       mm->cached_hole_size = ~0UL;
+       if (addr & ~PAGE_MASK) {
+               VM_BUG_ON(addr != -ENOMEM);
+               info.flags = 0;
+               info.low_limit = mm->mmap_base;
+               info.high_limit = TASK_SIZE;
+               addr = vm_unmapped_area(&info);
+       }
 
        return addr;
 }
-- 
1.7.7.3

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