内存不足V4L2 申请DMC缓存报错问题

当内存不足时，V4L2可能存在申请DMA缓存报错，如下日志：

13:36:54:125 [15070.640862] rkcifhw fdfe0000.rkcif: swiotlb buffer is full (sz: 1843200 bytes)
13:36:54:125 [15070.640891] rkcifhw fdfe0000.rkcif: swiotlb: coherent allocation failed, size=1843200
13:36:54:125 [15070.640906] CPU: 3 PID: 2343 Comm: HwBinder:296_4 Tainted: G        W         4.19.232 #743
13:36:54:125 [15070.640916] Hardware name: Rockchip RK3568 EVB2 LP4X V10 Board (DT)
13:36:54:125 [15070.640922] Call trace:
13:36:54:125 [15070.640936]  dump_backtrace+0x0/0x15c
13:36:54:126 [15070.640943]  show_stack+0x14/0x1c
13:36:54:126 [15070.640952]  dump_stack+0xb8/0xf0
13:36:54:126 [15070.640967]  swiotlb_alloc+0x150/0x154
13:36:54:126 [15070.640978]  __dma_alloc+0x138/0x1d0
13:36:54:126 [15070.640991]  vb2_dc_alloc+0xec/0x1b8
13:36:54:126 [15070.641001]  __vb2_queue_alloc+0x198/0x488
13:36:54:126 [15070.641012]  vb2_core_reqbufs+0x1ec/0x380
13:36:54:127 [15070