mm: simplify find_vma_prev()
commit 297c5eee37 ("mm: make the vma list be doubly linked") added the
vm_prev member to vm_area_struct. We can simplify find_vma_prev() by
using it. Also, this change helps to improve page fault performance
because it has stronger locality of reference.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index adea3b8..3f758c7 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1603,39 +1603,19 @@
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;
+ struct vm_area_struct *vma;
- /* 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;
- }
- }
-
-out:
- *pprev = prev;
- return prev ? prev->vm_next : vma;
+ vma = find_vma(mm, addr);
+ *pprev = vma ? vma->vm_prev : NULL;
+ return vma;
}
/*