From mboxrd@z Thu Jan  1 00:00:00 1970
From: Haggai Eran <haggaie@mellanox.com>
Subject: Re: [PATCH v2 01/12] IB/core: Guarantee that a local_dma_lkey is
 available
Date: Sun, 2 Aug 2015 16:09:01 +0300
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To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>, Doug Ledford <dledford@redhat.com>, linux-rdma@vger.kernel.org
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On 31/07/2015 02:22, Jason Gunthorpe wrote:
>  int ib_dealloc_pd(struct ib_pd *pd)
>  {
> +	if (pd->local_mr) {
> +		if (ib_dereg_mr(pd->local_mr))
> +			return -EBUSY;
> +		pd->local_mr = NULL;
> +	}
> +

It looks like ib_uverbs_alloc_pd calls ib_device.alloc_pd() directly,
and some drivers don't use kzalloc for allocating the pd, so the
ib_dereg_mr call above results in a general protection fault.

Haggai