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[PATCH 10/16] mm: use vm_unmapped_area() on mips 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 10/16] mm: use vm_unmapped_area() on mips architecture
From: Michel Lespinasse <walken@google.com>
Date: Mon, 5 Nov 2012 14:47:07 -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 mips 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/mips/mm/mmap.c |   99 +++++++++------------------------------------------
 1 files changed, 17 insertions(+), 82 deletions(-)

diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index 302d779d5b0d..e4b54b233e17 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -71,6 +71,7 @@ static unsigned long arch_get_unmapped_area_common(struct 
file *filp,
        struct vm_area_struct *vma;
        unsigned long addr = addr0;
        int do_color_align;
+       struct vm_unmapped_area_info info;
 
        if (unlikely(len > TASK_SIZE))
                return -ENOMEM;
@@ -107,97 +108,31 @@ static unsigned long arch_get_unmapped_area_common(struct 
file *filp,
                        return addr;
        }
 
-       if (dir == UP) {
-               addr = mm->mmap_base;
-               if (do_color_align)
-                       addr = COLOUR_ALIGN(addr, pgoff);
-               else
-                       addr = PAGE_ALIGN(addr);
+       info.length = len;
+       info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
+       info.align_offset = pgoff << PAGE_SHIFT;
 
-               for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
-                       /* At this point:  (!vma || addr < vma->vm_end). */
-                       if (TASK_SIZE - len < addr)
-                               return -ENOMEM;
-                       if (!vma || addr + len <= vma->vm_start)
-                               return addr;
-                       addr = vma->vm_end;
-                       if (do_color_align)
-                               addr = COLOUR_ALIGN(addr, pgoff);
-                }
-        } else {
-               /* 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;
-               }
+       if (dir == DOWN) {
+               info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+               info.low_limit = PAGE_SIZE;
+               info.high_limit = mm->mmap_base;
+               addr = vm_unmapped_area(&info);
+
+               if (!(addr & ~PAGE_MASK))
+                       return addr;
 
-               /*
-                * either no address requested, or the mapping can't fit into
-                * the requested address hole
-                */
-               addr = mm->free_area_cache;
-               if (do_color_align) {
-                       unsigned long base =
-                               COLOUR_ALIGN_DOWN(addr - len, pgoff);
-                       addr = base + len;
-               }
-
-               /* make sure it can fit in the remaining address space */
-               if (likely(addr > len)) {
-                       vma = find_vma(mm, addr - len);
-                       if (!vma || addr <= vma->vm_start) {
-                               /* cache the address as a hint for next time */
-                               return mm->free_area_cache = addr - len;
-                       }
-               }
-
-               if (unlikely(mm->mmap_base < len))
-                       goto bottomup;
-
-               addr = mm->mmap_base - len;
-               if (do_color_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 (likely(!vma || addr + len <= vma->vm_start)) {
-                               /* cache 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_color_align)
-                               addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-               } while (likely(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;
-
-               return addr;
        }
+
+       info.flags = 0;
+       info.low_limit = mm->mmap_base;
+       info.high_limit = TASK_SIZE;
+       return vm_unmapped_area(&info);
 }
 
 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
-- 
1.7.7.3

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