From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
commit 297c5eee37 (mm: make the vma list be doubly linked) added
vm_prev member into vm_area_struct. Therefore we can simplify
find_vma_prev() by using it. Also, this change help to improve
page fault performance because it has strong locality of reference.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
---
mm/mmap.c | 36 ++++++++----------------------------
1 files changed, 8 insertions(+), 28 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index eae90af..b9c0241 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1603,39 +1603,19 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
EXPORT_SYMBOL(find_vma);
-/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
+/*
+ * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
+ * Note: pprev is set to NULL when return value is NULL.
+ */
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
struct vm_area_struct **pprev)
{
- struct vm_area_struct *vma = NULL, *prev = NULL;
- struct rb_node *rb_node;
- if (!mm)
- goto out;
-
- /* Guard against addr being lower than the first VMA */
- vma = mm->mmap;
-
- /* Go through the RB tree quickly. */
- rb_node = mm->mm_rb.rb_node;
-
- while (rb_node) {
- struct vm_area_struct *vma_tmp;
- vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
-
- if (addr < vma_tmp->vm_end) {
- rb_node = rb_node->rb_left;
- } else {
- prev = vma_tmp;
- if (!prev->vm_next || (addr < prev->vm_next->vm_end))
- break;
- rb_node = rb_node->rb_right;
- }
- }
+ struct vm_area_struct *vma;
-out:
- *pprev = prev;
- return prev ? prev->vm_next : vma;
+ vma = find_vma(mm, addr);
+ *pprev = vma ? vma->vm_prev : NULL;
+ return vma;
}
/*
--
1.7.1
--
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