In spite of switching to paged allocation of Rx buffers, the driver still
called dma_unmap_single() in the Rx queues tear-down path.
The DMA region unmapping code in free_skb_rx_queue() basically predates
the introduction of paged allocation to the driver. While being refactored,
it apparently hasn't reflected the change in the DMA API usage by its
counterpart gfar_new_page().
As a result, setting an interface to the DOWN state now yields the following:
# ip link set eth2 down
fsl-gianfar ffe24000.ethernet: DMA-API: device driver frees DMA memory with wrong function [device address=0x000000001ecd0000] [size=40]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 189 at lib/dma-debug.c:1123 check_unmap+0x8e0/0xa28
CPU: 1 PID: 189 Comm: ip Tainted: G O 4.9.5 #1
task: dee73400 task.stack: dede2000
NIP: c02101e8 LR: c02101e8 CTR: c0260d74
REGS: dede3bb0 TRAP: 0700 Tainted: G O (4.9.5)
MSR: 00021000 <CE,ME> CR: 28002222 XER: 00000000