Re: use exact allocation for dma coherent memory

Christoph Hellwig
2019-06-17T08:34:16Z

> drivers/infiniband/hw/cxgb4/qp.c
> 129 static int alloc_host_sq(struct c4iw_rdev *rdev, struct t4_sq *sq)
> 130 {
> 131 sq->queue = dma_alloc_coherent(&(rdev->lldi.pdev->dev), sq->memsize,
> 132 &(sq->dma_addr), GFP_KERNEL);
> 133 if (!sq->queue)
> 134 return -ENOMEM;
> 135 sq->phys_addr = virt_to_phys(sq->queue);
> 136 dma_unmap_addr_set(sq, mapping, sq->dma_addr);
> 137 return 0;
> 138 }
>
> Is this a bug?

Yes. This will blow up badly on many platforms, as sq->queue
might be vmapped, ioremapped, come from a pool without page backing.