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From:   Miaohe Lin <linmiaohe@huawei.com>
To:     <akpm@linux-foundation.org>
CC:     <willy@infradead.org>, <vbabka@suse.cz>, <dhowells@redhat.com>,
        <neilb@suse.de>, <apopple@nvidia.com>, <david@redhat.com>,
        <surenb@google.com>, <peterx@redhat.com>,
        <naoya.horiguchi@nec.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>, <linmiaohe@huawei.com>
Subject: [PATCH 09/15] mm/swap: avoid calling swp_swap_info when try to check SWP_STABLE_WRITES
Date:   Mon, 9 May 2022 21:14:10 +0800
Message-ID: <20220509131416.17553-10-linmiaohe@huawei.com>
In-Reply-To: <20220509131416.17553-1-linmiaohe@huawei.com>
References: <20220509131416.17553-1-linmiaohe@huawei.com>
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Use flags of si directly to check SWP_STABLE_WRITES to avoid possible
READ_ONCE and thus save some cpu cycles.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index 9c3e7e6ac202..89dd15504f3d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3892,7 +3892,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 			 */
 			exclusive = true;
 		} else if (exclusive && PageWriteback(page) &&
-			  (swp_swap_info(entry)->flags & SWP_STABLE_WRITES)) {
+			  (si->flags & SWP_STABLE_WRITES)) {
 			/*
 			 * This is tricky: not all swap backends support
 			 * concurrent page modifications while under writeback.
-- 
2.23.0