mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages

Some part of putback_lru_pages() and putback_movable_pages() is
duplicated, so it could confuse us what we should use.  We can remove
putback_lru_pages() since it is not really needed now.  This makes us
undestand and maintain the code more easily.

And comment on putback_movable_pages() is stale now, so fix it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 20 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 13bedcc4656b..8a73d66be102 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -72,28 +72,12 @@ int migrate_prep_local(void)
 }
 
 /*
- * Add isolated pages on the list back to the LRU under page lock
- * to avoid leaking evictable pages back onto unevictable list.
- */
-void putback_lru_pages(struct list_head *l)
-{
-        struct page *page;
-        struct page *page2;
-
-        list_for_each_entry_safe(page, page2, l, lru) {
-                list_del(&page->lru);
-                dec_zone_page_state(page, NR_ISOLATED_ANON +
-                                page_is_file_cache(page));
-                        putback_lru_page(page);
-        }
-}
-
-/*
  * Put previously isolated pages back onto the appropriate lists
  * from where they were once taken off for compaction/migration.
  *
- * This function shall be used instead of putback_lru_pages(),
- * whenever the isolated pageset has been built by isolate_migratepages_range()
+ * This function shall be used whenever the isolated pageset has been
+ * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
+ * and isolate_huge_page().
  */
 void putback_movable_pages(struct list_head *l)
 {
@@ -1725,7 +1709,12 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
         nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
                                      node, MIGRATE_ASYNC, MR_NUMA_MISPLACED);
         if (nr_remaining) {
-                putback_lru_pages(&migratepages);
+                if (!list_empty(&migratepages)) {
+                        list_del(&page->lru);
+                        dec_zone_page_state(page, NR_ISOLATED_ANON +
+                                        page_is_file_cache(page));
+                        putback_lru_page(page);
+                }
                 isolated = 0;
         } else
                 count_vm_numa_event(NUMA_PAGE_MIGRATE);