From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgg@ziepe.ca>
Subject: Re: use exact allocation for dma coherent memory
Date: Wed, 19 Jun 2019 13:29:03 -0300
Message-ID: <20190619162903.GF9360@ziepe.ca>
References: <20190614134726.3827-1-hch@lst.de>
 <20190617082148.GF28859@kadam>
 <20190617083342.GA7883@lst.de>
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To: Christoph Hellwig <hch@lst.de>, Potnuri Bharat Teja <bharat@chelsio.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>, Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, Ian Abbott <abbotti@mev.co.uk>, H Hartley Sweeten <hsweeten@visionengravers.com>, devel@driverdev.osuosl.org, linux-s390@vger.kernel.org, Intel Linux Wireless <linuxwifi@intel.com>, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, iommu@lists.linux-foundati
List-Id: intel-gfx@lists.freedesktop.org

On Mon, Jun 17, 2019 at 10:33:42AM +0200, Christoph Hellwig wrote:
> > 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.

Gah, this addr gets fed into io_remap_pfn_range/remap_pfn_range too..

Potnuri, you should fix this.. 

You probably need to use dma_mmap_from_dev_coherent() in the mmap ?

Jason