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

commit d8e89b47 upstream.

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.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/arm/mm/dma-mapping.c

@@ -322,6 +322,8 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 
 	if (addr)
 		*handle = pfn_to_dma(dev, page_to_pfn(page));
+	else
+		__dma_free_buffer(page, size);
 
 	return addr;
 }