From: Greg KH <gre...@linuxfoundation.org>

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Minchan Kim <minchan....@gmail.com>

commit 0dabec93de633a87adfbbe1d800a4c56cd19d73b upstream.

Stable note: Not tracked in Bugzilla. This patch makes later patches
        easier to apply but has no other impact.

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

Signed-off-by: Minchan Kim <minchan....@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
Cc: Mel Gorman <mgor...@suse.de>
Cc: Rik van Riel <r...@redhat.com>
Cc: Michal Hocko <mho...@suse.cz>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Mel Gorman <mgor...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 mm/migrate.c |   75 +++++++++++++++++++++++++++++++----------------------------
 1 file changed, 40 insertions(+), 35 deletions(-)

--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -621,38 +621,18 @@ static int move_to_new_page(struct 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
                 * 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;
+}
+
+/*
+ * 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;
 
-move_newpage:
+       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;


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