Re: [PATCH v3 1/2] mm/page_ref: use atomic_set_release in page_ref_unfreeze

[Kirill A. Shutemov]

On Mon, Feb 12, 2018 at 04:58:50PM +0300, Konstantin Khlebnikov wrote:
> page_ref_unfreeze() has exactly that semantic. No functional
> changes: just minus one barrier and proper handling of PPro errata.
> 
> Signed-off-by: Konstantin Khlebnikov 

Acked-by: Kirill A. Shutemov 

-- 
 Kirill A. Shutemov

[PATCH v3 1/2] mm/page_ref: use atomic_set_release in page_ref_unfreeze

[Konstantin Khlebnikov]

page_ref_unfreeze() has exactly that semantic. No functional
changes: just minus one barrier and proper handling of PPro errata.

Signed-off-by: Konstantin Khlebnikov 
---
 include/linux/page_ref.h |3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h
index 760d74a0e9a9..14d14beb1f7f 100644
--- a/include/linux/page_ref.h
+++ b/include/linux/page_ref.h
@@ -175,8 +175,7 @@ static inline void page_ref_unfreeze(struct page *page, int 
count)
VM_BUG_ON_PAGE(page_count(page) != 0, page);
VM_BUG_ON(count == 0);
 
-   smp_mb();
-   atomic_set(&page->_refcount, count);
+   atomic_set_release(&page->_refcount, count);
if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze))
__page_ref_unfreeze(page, count);
 }