[PATCH 4.9 201/240] khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()

Greg Kroah-Hartman
2021-05-20T11:22:15Z

From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit 74e579bf231a337ab3786d59e64bc94f45ca7b3f ]

In writable and !referenced case, the result value should be
SCAN_LACK_REFERENCED_PAGE for trace_mm_collapse_huge_page_isolate()
instead of default 0 (SCAN_FAIL) here.

Link: https://lkml.kernel.org/r/20210306032947.35921-5-linmiaohe@huawei.com
Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/khugepaged.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 753b0e2fef36..0f1bdbae45e2 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -596,17 +596,17 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
mmu_notifier_test_young(vma->vm_mm, address))
referenced++;
}
- if (likely(writable)) {
- if (likely(referenced)) {
- result = SCAN_SUCCEED;
- trace_mm_collapse_huge_page_isolate(page, none_or_zero,
- referenced, writable, result);
- return 1;
- }
- } else {
+
+ if (unlikely(!writable)) {
result = SCAN_PAGE_RO;
+ } else if (unlikely(!referenced)) {
+ result = SCAN_LACK_REFERENCED_PAGE;
+ } else {
+ result = SCAN_SUCCEED;
+ trace_mm_collapse_huge_page_isolate(page, none_or_zero,
+ referenced, writable, result);
+ return 1;
}
-
out:
release_pte_pages(pte, _pte);
trace_mm_collapse_huge_page_isolate(page, none_or_zero,
--
2.30.2