staging: androind: Replace BUG_ONs with WARN_ONs

BUG_ON() is replaced with WARN_ON at ion_page_pool.c
Fixes the following issue:
Avoid crashing the kernel - try using WARN_ON & recovery code ratherthan BUG() or BUG_ON().

Signed-off-by: Tomer Samara <tomersamara98@gmail.com>

drivers/staging/android/ion/ion_page_pool.c

@@ -46,11 +46,13 @@ static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
 	struct page *page;
 
 	if (high) {
-		BUG_ON(!pool->high_count);
+		if (WARN_ON(!pool->high_count))
+			return NULL:
 		page = list_first_entry(&pool->high_items, struct page, lru);
 		pool->high_count--;
 	} else {
-		BUG_ON(!pool->low_count);
+		if (WARN_ON(!pool->low_count))
+			return NULL;
 		page = list_first_entry(&pool->low_items, struct page, lru);
 		pool->low_count--;
 	}
@@ -65,7 +67,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 {
 	struct page *page = NULL;
 
-	BUG_ON(!pool);
+	if (WARN_ON(!pool))
+		return NULL;
 
 	mutex_lock(&pool->mutex);
 	if (pool->high_count)
@@ -82,7 +85,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 
 void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 {
-	BUG_ON(pool->order != compound_order(page));
+	if (WARN_ON(pool->order != compound_order(page)))
+		return;
 
 	ion_page_pool_add(pool, page);
 }