[020/143] khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()

Commit Message

Andrew Morton May 5, 2021, 1:33 a.m. UTC

From: Miaohe Lin <[e-mail]>
Subject: khugepaged: fix wrong result value for trace_mm_collapse_huge_page_isolate()

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/[e-mail]
Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages")
Signed-off-by: Miaohe Lin <[e-mail]>
Acked-by: Kirill A. Shutemov <[e-mail]>
Cc: Dan Carpenter <[e-mail]>
Cc: Ebru Akagunduz <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/khugepaged.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Patch

--- a/mm/khugepaged.c~khugepaged-fix-wrong-result-value-for-trace_mm_collapse_huge_page_isolate
+++ a/mm/khugepaged.c
@@ -716,17 +716,17 @@  next:
 		if (pte_write(pteval))
 			writable = true;
 	}
-	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, compound_pagelist);
 	trace_mm_collapse_huge_page_isolate(page, none_or_zero,