mm: migration: clean up unmap_and_move()

unmap_and_move() is one a big messy function.  Clean it up.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 666e4e677414e6d790de715761e395116441e6c4..71713fc499628afe896389e32d7fc4fedd29d1ca 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -621,38 +621,18 @@ static int move_to_new_page(struct page *newpage, struct page *page,
        return rc;
 }
 
-/*
- * Obtain the lock on page, remove all ptes and migrate the page
- * to the newly allocated page in newpage.
- */
-static int unmap_and_move(new_page_t get_new_page, unsigned long private,
-                       struct page *page, int force, bool offlining, bool sync)
+static int __unmap_and_move(struct page *page, struct page *newpage,
+                               int force, bool offlining, bool sync)
 {
-       int rc = 0;
-       int *result = NULL;
-       struct page *newpage = get_new_page(page, private, &result);
+       int rc = -EAGAIN;
        int remap_swapcache = 1;
        int charge = 0;
        struct mem_cgroup *mem;
        struct anon_vma *anon_vma = NULL;
 
-       if (!newpage)
-               return -ENOMEM;
-
-       if (page_count(page) == 1) {
-               /* page was freed from under us. So we are done. */
-               goto move_newpage;
-       }
-       if (unlikely(PageTransHuge(page)))
-               if (unlikely(split_huge_page(page)))
-                       goto move_newpage;
-
-       /* prepare cgroup just returns 0 or -ENOMEM */
-       rc = -EAGAIN;
-
        if (!trylock_page(page)) {
                if (!force || !sync)
-                       goto move_newpage;
+                       goto out;
 
                /*
                 * It's not safe for direct compaction to call lock_page.
@@ -668,7 +648,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
                 * altogether.
                 */
                if (current->flags & PF_MEMALLOC)
-                       goto move_newpage;
+                       goto out;
 
                lock_page(page);
        }
@@ -785,27 +765,52 @@ uncharge:
                mem_cgroup_end_migration(mem, page, newpage, rc == 0);
 unlock:
        unlock_page(page);
+out:
+       return rc;
+}
 
-move_newpage:
+/*
+ * Obtain the lock on page, remove all ptes and migrate the page
+ * to the newly allocated page in newpage.
+ */
+static int unmap_and_move(new_page_t get_new_page, unsigned long private,
+                       struct page *page, int force, bool offlining, bool sync)
+{
+       int rc = 0;
+       int *result = NULL;
+       struct page *newpage = get_new_page(page, private, &result);
+
+       if (!newpage)
+               return -ENOMEM;
+
+       if (page_count(page) == 1) {
+               /* page was freed from under us. So we are done. */
+               goto out;
+       }
+
+       if (unlikely(PageTransHuge(page)))
+               if (unlikely(split_huge_page(page)))
+                       goto out;
+
+       rc = __unmap_and_move(page, newpage, force, offlining, sync);
+out:
        if (rc != -EAGAIN) {
-               /*
-                * A page that has been migrated has all references
-                * removed and will be freed. A page that has not been
-                * migrated will have kepts its references and be
-                * restored.
-                */
-               list_del(&page->lru);
+               /*
+                * A page that has been migrated has all references
+                * removed and will be freed. A page that has not been
+                * migrated will have kepts its references and be
+                * restored.
+                */
+               list_del(&page->lru);
                dec_zone_page_state(page, NR_ISOLATED_ANON +
                                page_is_file_cache(page));
                putback_lru_page(page);
        }
-
        /*
         * Move the new page to the LRU. If migration was not successful
         * then this will free the page.
         */
        putback_lru_page(newpage);
-
        if (result) {
                if (rc)
                        *result = rc;