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>

diff --git a/mm/migrate.c b/mm/migrate.c
index 568433023831ae098dd5a9d3c1dd209d7dd04be7..8c0af0f7cab18a8e01af67142887abd0ca3c0b81 100644 (file)
--- 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);
        }
 
        /*