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Date:   Tue, 11 Aug 2020 22:04:23 -0600
Message-Id: <20200812040423.2707213-1-yuzhao@google.com>
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Subject: [PATCH 1/3] mm: don't call activate_page() on new ksm pages
From:   Yu Zhao <yuzhao@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        Huang Ying <ying.huang@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Michal Hocko <mhocko@suse.com>,
        Yang Shi <yang.shi@linux.alibaba.com>, Qian Cai <cai@lca.pw>,
        Mel Gorman <mgorman@suse.de>,
        Nicholas Piggin <npiggin@gmail.com>,
        "=?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?=" <jglisse@redhat.com>,
        Hugh Dickins <hughd@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Yu Zhao <yuzhao@google.com>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

lru_cache_add_active_or_unevictable() already adds new ksm pages to
active lru. Calling activate_page() isn't really necessary in this
case.

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 mm/swapfile.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6c26916e95fd..cf115ea26a20 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1913,16 +1913,16 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
 	if (page == swapcache) {
 		page_add_anon_rmap(page, vma, addr, false);
+		/*
+		 * Move the page to the active list so it is not
+		 * immediately swapped out again after swapon.
+		 */
+		activate_page(page);
 	} else { /* ksm created a completely new copy */
 		page_add_new_anon_rmap(page, vma, addr, false);
 		lru_cache_add_active_or_unevictable(page, vma);
 	}
 	swap_free(entry);
-	/*
-	 * Move the page to the active list so it is not
-	 * immediately swapped out again after swapon.
-	 */
-	activate_page(page);
 out:
 	pte_unmap_unlock(pte, ptl);
 	if (page != swapcache) {
-- 
2.28.0.236.gb10cc79966-goog