gpu: ion: Stop trying to allocate from an order on first failure

With this patch the system heap will only try to allocate from each
order as long as allocations succeed.  If it failes to obtain a higher
order allocation, it doesn't retry that order.
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_system_heap.c

@@ -32,7 +32,8 @@ struct page_info {
 };
 
 static struct page_info *alloc_largest_available(unsigned long size,
-						 bool split_pages)
+						 bool split_pages,
+						 unsigned int max_order)
 {
 	static unsigned int orders[] = {8, 4, 0};
 	struct page *page;
@@ -42,6 +43,8 @@ static struct page_info *alloc_largest_available(unsigned long size,
 	for (i = 0; i < ARRAY_SIZE(orders); i++) {
 		if (size < (1 << orders[i]) * PAGE_SIZE)
 			continue;
+		if (max_order < orders[i])
+			continue;
 		page = alloc_pages(GFP_HIGHUSER | __GFP_ZERO |
 				   __GFP_NOWARN | __GFP_NORETRY, orders[i]);
 		if (!page)
@@ -71,13 +74,17 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
 	bool split_pages = ion_buffer_fault_user_mappings(buffer);
 
 
+	unsigned int max_order = orders[0];
+
 	INIT_LIST_HEAD(&pages);
 	while (size_remaining > 0) {
-		info = alloc_largest_available(size_remaining, split_pages);
+		info = alloc_largest_available(size_remaining, split_pages,
+					       max_order);
 		if (!info)
 			goto err;
 		list_add_tail(&info->list, &pages);
 		size_remaining -= (1 << info->order) * PAGE_SIZE;
+		max_order = info->order;
 		i++;
 	}