From 48b03eea321c85185d173cb0d112698b79b1c98e Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Thu, 25 Feb 2021 17:17:49 -0800
Subject: [PATCH] mm/mlock: stop counting mlocked pages when none vma is found
There will be no vma satisfies addr < vm_end when find_vma() returns NULL.
Thus it's meaningless to traverse the vma list below because we can't
find any vma to count mlocked pages. Stop counting mlocked pages in this
case to save some vma list traversal cycles.
Link: https://lkml.kernel.org/r/20210204110705.17586-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/mlock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/mlock.c b/mm/mlock.c
index 73960bb3464d..f8f8cc32d03d 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -622,7 +622,7 @@ static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
vma = find_vma(mm, start);
if (vma == NULL)
- vma = mm->mmap;
+ return 0;
for (; vma ; vma = vma->vm_next) {
if (start >= vma->vm_end)