drm/i915/gtt: Don't leak scratch page on mapping error

Free the scratch page if dma mapping fails.

Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 619dad1..5e3bfa9 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2143,8 +2143,10 @@
 #ifdef CONFIG_INTEL_IOMMU
 	dma_addr = pci_map_page(dev->pdev, page, 0, PAGE_SIZE,
 				PCI_DMA_BIDIRECTIONAL);
-	if (pci_dma_mapping_error(dev->pdev, dma_addr))
+	if (pci_dma_mapping_error(dev->pdev, dma_addr)) {
+		__free_page(page);
 		return -EINVAL;
+	}
 #else
 	dma_addr = page_to_phys(page);
 #endif