kmalloc/malloc for dma ?

Hello,

I have some sample code which uses 2 test application:
1. test application in kernel , which allocates buffer using kmalloc
(GFP_KERNEL)
2. test application in userspace which allocates buffer using malloc

In both cases the buffers are DMA through PCI.
I don't understand how is it that the buffers are allocated with
malloc/kmalloc for DMA.
Is there any idea ?

Regards,
Ran