mm/hugetlb.c: just use put_page_testzero() instead of page_count()

We test the page reference count is zero or not here, it can be a bug here
if page refercence count is not zero.  So we can just use
put_page_testzero() instead of page_count().

Link: https://lkml.kernel.org/r/20201007170949.GA6416@rlk
Signed-off-by: Hui Su <sh_def@163.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4b809cc..987d4b5 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2014,8 +2014,7 @@ retry:
                 * This page is now managed by the hugetlb allocator and has
                 * no users -- drop the buddy allocator's reference.
                 */
-               put_page_testzero(page);
-               VM_BUG_ON_PAGE(page_count(page), page);
+               VM_BUG_ON_PAGE(!put_page_testzero(page), page);
                enqueue_huge_page(h, page);
        }
 free: