linux-kernel - [PATCH] mm, THP, swap: Check whether CONFIG_THP

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Date:   Mon, 22 May 2017 10:18:14 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Huang Ying <ying.huang@...el.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Minchan Kim <minchan@...nel.org>
Subject: [PATCH] mm, THP, swap: Check whether CONFIG_THP_SWAP enabled earlier

From: Huang Ying <ying.huang@...el.com>

This patch is only a code clean up patch without functionality
changes.  It moves CONFIG_THP_SWAP checking from inside swap slot
allocation to before we start swapping the THP.  This makes the code
path a little easier to be followed and understood.

Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Minchan Kim <minchan@...nel.org>
---
 mm/swap_slots.c | 3 +--
 mm/vmscan.c     | 3 ++-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 90c1032a8ac3..14c2a91289e5 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -310,8 +310,7 @@ swp_entry_t get_swap_page(struct page *page)
 	entry.val = 0;
 
 	if (PageTransHuge(page)) {
-		if (IS_ENABLED(CONFIG_THP_SWAP))
-			get_swap_pages(1, true, &entry);
+		get_swap_pages(1, true, &entry);
 		return entry;
 	}
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f7e949ac9756..90722afd4916 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1134,7 +1134,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				 * away. Chances are some or all of the
 				 * tail pages can be freed without IO.
 				 */
-				if (!compound_mapcount(page) &&
+				if ((!IS_ENABLED(CONFIG_THP_SWAP) ||
+				     !compound_mapcount(page)) &&
 				    split_huge_page_to_list(page, page_list))
 					goto activate_locked;
 			}
-- 
2.11.0