diff mbox series

[028/143] mm/khugepaged.c: replace barrier() with READ_ONCE() for a selective variable

Message ID 20210505013412.wFqTFyLJJ%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [001/143] mm: introduce and use mapping_empty() | expand

Commit Message

Andrew Morton May 5, 2021, 1:34 a.m. UTC
From: Yanfei Xu <yanfei.xu@windriver.com>
Subject: mm/khugepaged.c: replace barrier() with READ_ONCE() for a selective variable

READ_ONCE() is more selective and lightweight.  It is more appropriate
that using a READ_ONCE() for the certain variable to prevent the compiler
from reordering.

Link: https://lkml.kernel.org/r/20210323092730.247583-1-yanfei.xu@windriver.com
Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/khugepaged.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

--- a/mm/khugepaged.c~khugepaged-raplace-barrier-with-read_once-for-a-selective-variable
+++ a/mm/khugepaged.c
@@ -2202,11 +2202,9 @@  static void khugepaged_do_scan(void)
 {
 	struct page *hpage = NULL;
 	unsigned int progress = 0, pass_through_head = 0;
-	unsigned int pages = khugepaged_pages_to_scan;
+	unsigned int pages = READ_ONCE(khugepaged_pages_to_scan);
 	bool wait = true;
 
-	barrier(); /* write khugepaged_pages_to_scan to local stack */
-
 	lru_add_drain_all();
 
 	while (progress < pages) {