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);