ARM: dma-mapping: free allocated page if unable to map

If the attempt to map a page for DMA fails (eg, because we're out of
mapping space) then we must not hold on to the page we allocated for
DMA - doing so will result in a memory leak.

Cc: <stable@kernel.org>
Reported-by: Bryan Phillippe <bp@darkforest.org>
Tested-by: Bryan Phillippe <bp@darkforest.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 0a0a1e7..c3ff82f 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -324,6 +324,8 @@
 
 	if (addr)
 		*handle = pfn_to_dma(dev, page_to_pfn(page));
+	else
+		__dma_free_buffer(page, size);
 
 	return addr;
 }