diff --git a/[refs] b/[refs]
index ae952189b0e1..2a3ea7bc2f5d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0016fdee927f7aa0f428494bcf11ae60c7470a02
+refs/heads/master: a5ddde4a558b3bd1e3dc50e274a0db2ea7a8fd06
diff --git a/trunk/lib/swiotlb.c b/trunk/lib/swiotlb.c
index db724ba7ebf6..1272b23e4769 100644
--- a/trunk/lib/swiotlb.c
+++ b/trunk/lib/swiotlb.c
@@ -301,6 +301,10 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir)
 	start_dma_addr = virt_to_bus(io_tlb_start) & mask;
 
 	offset_slots = ALIGN(start_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+
+	/*
+ 	 * Carefully handle integer overflow which can occur when mask == ~0UL.
+ 	 */
 	max_slots = mask + 1
 		    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
 		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);