From 03f5d58fa42fb337b921e57f8e2c2d4df7df890d Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Date: Thu, 5 Apr 2018 16:23:24 -0700
Subject: [PATCH] mm/page_ref: use atomic_set_release in page_ref_unfreeze

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

Link: http://lkml.kernel.org/r/151844393004.210639.4672319312617954272.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 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);
 }
-- 
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