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From:   Zi Yan <zi.yan@sent.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        Michal Hocko <mhocko@kernel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>,
        John Hubbard <jhubbard@nvidia.com>,
        Mark Hairgrove <mhairgrove@nvidia.com>,
        Nitin Gupta <nigupta@nvidia.com>,
        David Nellans <dnellans@nvidia.com>, Zi Yan <ziy@nvidia.com>
Subject: [RFC PATCH 03/31] mm: migrate: Add tmpfs exchange support.
Date:   Fri, 15 Feb 2019 14:08:28 -0800
Message-Id: <20190215220856.29749-4-zi.yan@sent.com>
In-Reply-To: <20190215220856.29749-1-zi.yan@sent.com>
References: <20190215220856.29749-1-zi.yan@sent.com>
Reply-To: ziy@nvidia.com
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From: Zi Yan <ziy@nvidia.com>

tmpfs uses the same migrate routine as anonymous pages, enabling
exchange pages for it is easy.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 mm/exchange.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/exchange.c b/mm/exchange.c
index 8cf286fc0f10..851f1a99b48b 100644
--- a/mm/exchange.c
+++ b/mm/exchange.c
@@ -466,7 +466,10 @@ static int exchange_from_to_pages(struct page *to_page, struct page *from_page,
 		rc = exchange_page_move_mapping(to_page_mapping, from_page_mapping,
 					to_page, from_page, NULL, NULL, mode, 0, 0);
 	} else {
-		if (to_page_mapping->a_ops->migratepage == buffer_migrate_page) {
+		/* shmem */
+		if (to_page_mapping->a_ops->migratepage == migrate_page)
+			goto exchange_mappings;
+		else if (to_page_mapping->a_ops->migratepage == buffer_migrate_page) {
 
 			if (!page_has_buffers(to_page))
 				goto exchange_mappings;
-- 
2.20.1