From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 6199F6B025E for ; Mon, 5 Dec 2016 03:33:21 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id g23so15433010wme.4 for ; Mon, 05 Dec 2016 00:33:21 -0800 (PST) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [58.251.152.64]) by mx.google.com with ESMTPS id q31si6846408lfi.259.2016.12.05.00.33.18 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 05 Dec 2016 00:33:20 -0800 (PST) Message-ID: <584523E4.9030600@huawei.com> Date: Mon, 5 Dec 2016 16:23:00 +0800 From: Xishi Qiu MIME-Version: 1.0 Subject: [RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Mel Gorman , Yaowei Bai Cc: Linux MM , LKML , Yisheng Xie By reading the code, I find the following code maybe optimized by compiler, maybe page->flags and old_flags use the same register, so use ACCESS_ONCE in page_cpupid_xchg_last() to fix the problem. Signed-off-by: Xishi Qiu --- mm/mmzone.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/mmzone.c b/mm/mmzone.c index 5652be8..e0b698e 100644 --- a/mm/mmzone.c +++ b/mm/mmzone.c @@ -102,7 +102,7 @@ int page_cpupid_xchg_last(struct page *page, int cpupid) int last_cpupid; do { - old_flags = flags = page->flags; + old_flags = flags = ACCESS_ONCE(page->flags); last_cpupid = page_cpupid_last(page); flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT); -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org