mm: search from free_area_cache for the bigger size

If the required size is bigger than cached_hole_size it is better to
search from free_area_cache - it is easier to get a free region,
specifically for the 64 bit process whose address space is large enough

Do it just as hugetlb_get_unmapped_area_topdown() in arch/x86/mm/hugetlbpage.c

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 0514890..ef59642 100644 (file)
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -195,7 +195,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 {
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
-       unsigned long addr = addr0;
+       unsigned long addr = addr0, start_addr;
 
        /* requested length too big for entire address space */
        if (len > TASK_SIZE)
@@ -223,25 +223,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                mm->free_area_cache = mm->mmap_base;
        }
 
+try_again:
        /* either no address requested or can't fit in requested address hole */
-       addr = mm->free_area_cache;
-
-       /* make sure it can fit in the remaining address space */
-       if (addr > len) {
-               unsigned long tmp_addr = align_addr(addr - len, filp,
-                                                   ALIGN_TOPDOWN);
-
-               vma = find_vma(mm, tmp_addr);
-               if (!vma || tmp_addr + len <= vma->vm_start)
-                       /* remember the address as a hint for next time */
-                       return mm->free_area_cache = tmp_addr;
-       }
-
-       if (mm->mmap_base < len)
-               goto bottomup;
+       start_addr = addr = mm->free_area_cache;
 
-       addr = mm->mmap_base-len;
+       if (addr < len)
+               goto fail;
 
+       addr -= len;
        do {
                addr = align_addr(addr, filp, ALIGN_TOPDOWN);
 
@@ -263,6 +252,17 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                addr = vma->vm_start-len;
        } while (len < vma->vm_start);
 
+fail:
+       /*
+        * if hint left us with no space for the requested
+        * mapping then try again:
+        */
+       if (start_addr != mm->mmap_base) {
+               mm->free_area_cache = mm->mmap_base;
+               mm->cached_hole_size = 0;
+               goto try_again;
+       }
+
 bottomup:
        /*
         * A failed mmap() very likely causes application failure,

diff --git a/mm/mmap.c b/mm/mmap.c
index 4f31764..9e0c0de 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1442,7 +1442,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 {
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
-       unsigned long addr = addr0;
+       unsigned long addr = addr0, start_addr;
 
        /* requested length too big for entire address space */
        if (len > TASK_SIZE)
@@ -1466,22 +1466,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                mm->free_area_cache = mm->mmap_base;
        }
 
+try_again:
        /* either no address requested or can't fit in requested address hole */
-       addr = mm->free_area_cache;
+       start_addr = addr = mm->free_area_cache;
 
-       /* 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);
-       }
-
-       if (mm->mmap_base < len)
-               goto bottomup;
-
-       addr = mm->mmap_base-len;
+       if (addr < len)
+               goto fail;
 
+       addr -= len;
        do {
                /*
                 * Lookup failure means no vma is above this address,
@@ -1501,7 +1493,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                addr = vma->vm_start-len;
        } while (len < vma->vm_start);
 
-bottomup:
+fail:
+       /*
+        * if hint left us with no space for the requested
+        * mapping then try again:
+        *
+        * Note: this is different with the case of bottomup
+        * which does the fully line-search, but we use find_vma
+        * here that causes some holes skipped.
+        */
+       if (start_addr != mm->mmap_base) {
+               mm->free_area_cache = mm->mmap_base;
+               mm->cached_hole_size = 0;
+               goto try_again;
+       }
+
        /*
         * A failed mmap() very likely causes application failure,
         * so fall back to the bottom-up function here. This scenario