diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index be6ba33..8f441da 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3124,7 +3124,11 @@
 			controller if no parameter or 1 is given or disable
 			it if 0 is given (See Documentation/cgroups/memory.txt)
 
-	swiotlb=	[IA-64] Number of I/O TLB slabs
+	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
+			Format: { <int> | force }
+			<int> -- Number of I/O TLB slabs
+			force -- force using of bounce buffers even if they
+			         wouldn't be automatically used by the kernel
 
 	switches=	[HW,M68k]
 
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 615f3de..2e1c102 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -510,7 +510,8 @@
 
 not_found:
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
-	dev_warn(hwdev, "swiotlb buffer is full\n");
+	if (printk_ratelimit())
+		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);
 	return SWIOTLB_MAP_ERROR;
 found:
 	spin_unlock_irqrestore(&io_tlb_lock, flags);