The patch titled
Subject: mm/khugepaged.c: replace barrier() with READ_ONCE() for a selective variable
has been added to the -mm tree. Its filename is
khugepaged-raplace-barrier-with-read_once-for-a-selective-variable.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/khugepaged-raplace-barrier-with-read_once-for-a-selective-variable.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/khugepaged-raplace-barrier-with-read_once-for-a-selective-variable.patch
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------------------------------------------------------
From: Yanfei Xu <yanfei.xu@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx
Signed-off-by: Yanfei Xu <yanfei.xu@xxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
--- 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) {
_
Patches currently in -mm which might be from yanfei.xu@xxxxxxxxxxxxx are
khugepaged-raplace-barrier-with-read_once-for-a-selective-variable.patch
