mm/z3fold: remove unneeded page_mapcount_reset and ClearPagePrivate

Page->page_type and PagePrivate are not used in z3fold.  We should remove
these confusing unneeded operations.  The z3fold do these here is due to
referring to zsmalloc's migration code which does need these operations.

Link: https://lkml.kernel.org/r/20220308134311.59086-5-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/z3fold.c

@@ -420,7 +420,6 @@ static void free_z3fold_page(struct page *page, bool headless)
 		__ClearPageMovable(page);
 		unlock_page(page);
 	}
-	ClearPagePrivate(page);
 	__free_page(page);
 }
 
@@ -1635,7 +1634,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
 	INIT_LIST_HEAD(&new_zhdr->buddy);
 	new_mapping = page_mapping(page);
 	__ClearPageMovable(page);
-	ClearPagePrivate(page);
 
 	get_page(newpage);
 	z3fold_page_lock(new_zhdr);
@@ -1655,7 +1653,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
 
 	queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
 
-	page_mapcount_reset(page);
 	clear_bit(PAGE_CLAIMED, &page->private);
 	put_page(page);
 	return 0;