staging: zsmalloc: fix memory leak

This patch fixes a memory leak in zsmalloc where the first
subpage of each zspage is leaked when the zspage is freed.
Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zsmalloc/zsmalloc-main.c

@@ -267,33 +267,39 @@ static unsigned long obj_idx_to_offset(struct page *page,
 	return off + obj_idx * class_size;
 }
 
+static void reset_page(struct page *page)
+{
+	clear_bit(PG_private, &page->flags);
+	clear_bit(PG_private_2, &page->flags);
+	set_page_private(page, 0);
+	page->mapping = NULL;
+	page->freelist = NULL;
+	reset_page_mapcount(page);
+}
+
 static void free_zspage(struct page *first_page)
 {
-	struct page *nextp, *tmp;
+	struct page *nextp, *tmp, *head_extra;
 
 	BUG_ON(!is_first_page(first_page));
 	BUG_ON(first_page->inuse);
 
-	nextp = (struct page *)page_private(first_page);
+	head_extra = (struct page *)page_private(first_page);
 
-	clear_bit(PG_private, &first_page->flags);
-	clear_bit(PG_private_2, &first_page->flags);
-	set_page_private(first_page, 0);
-	first_page->mapping = NULL;
-	first_page->freelist = NULL;
-	reset_page_mapcount(first_page);
+	reset_page(first_page);
 	__free_page(first_page);
 
 	/* zspage with only 1 system page */
-	if (!nextp)
+	if (!head_extra)
 		return;
 
-	list_for_each_entry_safe(nextp, tmp, &nextp->lru, lru) {
+	list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
 		list_del(&nextp->lru);
-		clear_bit(PG_private_2, &nextp->flags);
-		nextp->index = 0;
+		reset_page(nextp);
 		__free_page(nextp);
 	}
+	reset_page(head_extra);
+	__free_page(head_extra);
 }
 
 /* Initialize a newly allocated zspage */