From 013567be19761e2d14fc2a2676fe7686ac54c9ac Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Fri, 11 May 2018 16:02:00 -0700
Subject: [PATCH] mm: migrate: fix double call of radix_tree_replace_slot()

radix_tree_replace_slot() is called twice for head page, it's obviously
a bug.  Let's fix it.

Link: http://lkml.kernel.org/r/20180423072101.GA12157@hori1.linux.bs1.fc.nec.co.jp
Fixes: e71769ae5260 ("mm: enable thp migration for shmem thp")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Zi Yan <zi.yan@sent.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/migrate.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 568433023831..8c0af0f7cab1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -528,14 +528,12 @@ int migrate_page_move_mapping(struct address_space *mapping,
 		int i;
 		int index = page_index(page);
 
-		for (i = 0; i < HPAGE_PMD_NR; i++) {
+		for (i = 1; i < HPAGE_PMD_NR; i++) {
 			pslot = radix_tree_lookup_slot(&mapping->i_pages,
 						       index + i);
 			radix_tree_replace_slot(&mapping->i_pages, pslot,
 						newpage + i);
 		}
-	} else {
-		radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
 	}
 
 	/*