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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2011-07-25 17:12:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-25 20:57:08 -0700
commit6c6d5280431544e4036886ea74e3334a98bc5f96 (patch)
tree1362944d254ff1dfa609d84a1e4182a77ce3ca07 /mm/pagewalk.c
parent4b6ddbf7ed4ef2f40e0a27418146eedaa68953c6 (diff)
downloadlinaro-lsk-6c6d5280431544e4036886ea74e3334a98bc5f96.tar.gz
pagewalk: don't look up vma if walk->hugetlb_entry is unused
Currently, walk_page_range() calls find_vma() every page table for walk iteration. but it's completely unnecessary if walk->hugetlb_entry is unused. And we don't have to assume find_vma() is a lightweight operation. So this patch checks the walk->hugetlb_entry and avoids the find_vma() call if possible. This patch also makes some cleanups. 1) remove ugly uninitialized_var() and 2) #ifdef in function body. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matt Mackall <mpm@selenic.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/pagewalk.c')
-rw-r--r--mm/pagewalk.c43
1 files changed, 37 insertions, 6 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 606bbb4125d..ee4ff87c58c 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -126,7 +126,39 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
return 0;
}
-#endif
+
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+ struct vm_area_struct *vma;
+
+ /* We don't need vma lookup at all. */
+ if (!walk->hugetlb_entry)
+ return NULL;
+
+ VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+ vma = find_vma(walk->mm, addr);
+ if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma))
+ return vma;
+
+ return NULL;
+}
+
+#else /* CONFIG_HUGETLB_PAGE */
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+ return NULL;
+}
+
+static int walk_hugetlb_range(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ return 0;
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+
/**
* walk_page_range - walk a memory map's page tables with a callback
@@ -165,18 +197,17 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd = pgd_offset(walk->mm, addr);
do {
- struct vm_area_struct *uninitialized_var(vma);
+ struct vm_area_struct *vma;
next = pgd_addr_end(addr, end);
-#ifdef CONFIG_HUGETLB_PAGE
/*
* handle hugetlb vma individually because pagetable walk for
* the hugetlb page is dependent on the architecture and
* we can't handled it in the same manner as non-huge pages.
*/
- vma = find_vma(walk->mm, addr);
- if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma)) {
+ vma = hugetlb_vma(addr, walk);
+ if (vma) {
if (vma->vm_end < next)
next = vma->vm_end;
/*
@@ -189,7 +220,7 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd = pgd_offset(walk->mm, next);
continue;
}
-#endif
+
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);