提交 6bd4837d 编写于 作者: K KOSAKI Motohiro 提交者: Linus Torvalds

mm: simplify find_vma_prev()

commit 297c5eee ("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: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NKAMEZAWA 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 948f017b
......@@ -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;
}
/*
......
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