1 files changed, 38 insertions, 20 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 352de555626c..34132f8e9109 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -375,7 +375,7 @@ void migrate_page_copy(struct page *newpage, struct page *page)
                  * redo the accounting that clear_page_dirty_for_io undid,
                  * but we can't use set_page_dirty because that function
                  * is actually a signal that all of the page has become dirty.
-                 * Wheras only part of our page may be dirty.
+                 * Whereas only part of our page may be dirty.
                  */
                 __set_page_dirty_nobuffers(newpage);
         }
@@ -564,7 +564,7 @@ static int fallback_migrate_page(struct address_space *mapping,
  *  == 0 - success
  */
 static int move_to_new_page(struct page *newpage, struct page *page,
-                                                int remap_swapcache)
+                                        int remap_swapcache, bool sync)
 {
         struct address_space *mapping;
         int rc;
@@ -586,18 +586,28 @@ static int move_to_new_page(struct page *newpage, struct page *page,
         mapping = page_mapping(page);
         if (!mapping)
                 rc = migrate_page(mapping, newpage, page);
-        else if (mapping->a_ops->migratepage)
+        else {
                 /*
-                 * Most pages have a mapping and most filesystems
-                 * should provide a migration function. Anonymous
-                 * pages are part of swap space which also has its
-                 * own migration function. This is the most common
-                 * path for page migration.
+                 * Do not writeback pages if !sync and migratepage is
+                 * not pointing to migrate_page() which is nonblocking
+                 * (swapcache/tmpfs uses migratepage = migrate_page).
                  */
-                rc = mapping->a_ops->migratepage(mapping,
-                                                newpage, page);
-        else
-                rc = fallback_migrate_page(mapping, newpage, page);
+                if (PageDirty(page) && !sync &&
+                    mapping->a_ops->migratepage != migrate_page)
+                        rc = -EBUSY;
+                else if (mapping->a_ops->migratepage)
+                        /*
+                         * Most pages have a mapping and most filesystems
+                         * should provide a migration function. Anonymous
+                         * pages are part of swap space which also has its
+                         * own migration function. This is the most common
+                         * path for page migration.
+                         */
+                        rc = mapping->a_ops->migratepage(mapping,
+                                                        newpage, page);
+                else
+                        rc = fallback_migrate_page(mapping, newpage, page);
+        }
 
         if (rc) {
                 newpage->mapping = NULL;
@@ -623,7 +633,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         struct page *newpage = get_new_page(page, private, &result);
         int remap_swapcache = 1;
         int charge = 0;
-        struct mem_cgroup *mem = NULL;
+        struct mem_cgroup *mem;
         struct anon_vma *anon_vma = NULL;
 
         if (!newpage)
@@ -641,7 +651,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         rc = -EAGAIN;
 
         if (!trylock_page(page)) {
-                if (!force)
+                if (!force || !sync)
                         goto move_newpage;
 
                 /*
@@ -678,7 +688,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         }
 
         /* charge against new page */
-        charge = mem_cgroup_prepare_migration(page, newpage, &mem);
+        charge = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL);
         if (charge == -ENOMEM) {
                 rc = -ENOMEM;
                 goto unlock;
@@ -686,7 +696,15 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
         BUG_ON(charge);
 
         if (PageWriteback(page)) {
-                if (!force || !sync)
+                /*
+                 * For !sync, there is no point retrying as the retry loop
+                 * is expected to be too short for PageWriteback to be cleared
+                 */
+                if (!sync) {
+                        rc = -EBUSY;
+                        goto uncharge;
+                }
+                if (!force)
                         goto uncharge;
                 wait_on_page_writeback(page);
         }
@@ -757,14 +775,14 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 
 skip_unmap:
         if (!page_mapped(page))
-                rc = move_to_new_page(newpage, page, remap_swapcache);
+                rc = move_to_new_page(newpage, page, remap_swapcache, sync);
 
         if (rc && remap_swapcache)
                 remove_migration_ptes(page, page);
 
         /* Drop an anon_vma reference if we took one */
         if (anon_vma)
-                drop_anon_vma(anon_vma);
+                put_anon_vma(anon_vma);
 
 uncharge:
         if (!charge)
@@ -850,13 +868,13 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
         try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
 
         if (!page_mapped(hpage))
-                rc = move_to_new_page(new_hpage, hpage, 1);
+                rc = move_to_new_page(new_hpage, hpage, 1, sync);
 
         if (rc)
                 remove_migration_ptes(hpage, hpage);
 
         if (anon_vma)
-                drop_anon_vma(anon_vma);
+                put_anon_vma(anon_vma);
 out:
         unlock_page(hpage);