From: Miaohe Lin <linmiaohe@huawei.com>
Date: Wed, 5 May 2021 01:33:46 +0000 (-0700)
Subject: khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()
X-Git-Tag: v5.4.120~62
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3ddbd4beadfa1f7ce400c8683385399b02baf963;p=users%2Fdwmw2%2Flinux.git

khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()

[ 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>
---

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index f0d7e6483ba32..3c2326568193c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -628,17 +628,17 @@ 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,