Messages in this thread Patch in this message | | | Date | Mon, 5 Dec 2016 16:23:00 +0800 | From | Xishi Qiu <> | Subject | [RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() |
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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 <qiuxishi@huawei.com> --- 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
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