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Fri, 30 Oct 2020 17:36:16 +0000 Date: Fri, 30 Oct 2020 14:36:15 -0300 From: Jason Gunthorpe To: Bob Pearson CC: , , Bob Pearson Subject: Re: [PATCH for-next v2] RDMA/rxe: fix regression caused by recent patch Message-ID: <20201030173615.GG2620339@nvidia.com> References: <20201030171106.4191-1-rpearson@hpe.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20201030171106.4191-1-rpearson@hpe.com> X-ClientProxiedBy: MN2PR10CA0002.namprd10.prod.outlook.com (2603:10b6:208:120::15) To DM6PR12MB3834.namprd12.prod.outlook.com (2603:10b6:5:14a::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (156.34.48.30) by MN2PR10CA0002.namprd10.prod.outlook.com (2603:10b6:208:120::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; Fri, 30 Oct 2020 17:36:16 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kYYJz-00DTMm-60; Fri, 30 Oct 2020 14:36:15 -0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1604079379; bh=ZdekYiSFfvfh90iOsI7zy7QXfyXTXSw9F7sWq0a3nVk=; h=ARC-Seal:ARC-Message-Signature:ARC-Authentication-Results:Date: From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:X-ClientProxiedBy:MIME-Version: X-MS-Exchange-MessageSentRepresentingType; b=o/82SJ/BHQJGy3nJAtZx4CLH2G05aqG6Kq7qlevZGMfKRdErTnCzN+3EeiP3M95Os ejsqBwQy4o9/GYN+1XssrrG0pBmV9scvIg1NuD+zF2p3KO9bZYb1arv9LMlggcPRrp G0zEVHwHAz0oQrw4zcjnFMrIzL1UepZ3HX3W2D7pc4Q8omuiZLFhtnt3754y/sP13B znoLFYv4iEvtYCDSqzvn6SjIZbM7to/0aNsYwXb1K2qKDWqfWb5BYk/Gydp40Xkc9c ldT+bbE+hsHxDufEPUDiA5H+fzNPDt/2dP0peckw5nu516HqCKLRNo0Ed79LhQt8+3 En76XaLw/trYA== Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Fri, Oct 30, 2020 at 12:11:07PM -0500, Bob Pearson wrote: > The commit referenced below performs additional checking on > devices used for DMA. Specifically it checks that > > device->dma_mask != NULL > > Rdma_rxe uses this device when pinning MR memory but did not > set the value of dma_mask. In fact rdma_rxe does not perform > any DMA operations so the value is never used but is checked. > > This patch gives dma_mask a valid value extracted from the device > backing the ndev used by rxe. > > Without this patch rdma_rxe does not function. > > N.B. This patch needs to be applied before the recent fix to add back > IB_USER_VERBS_CMD_POST_SEND to uverbs_cmd_mask. > > Dennis Dallesandro reported that Parav's similar patch did not apply > cleanly to rxe. This one does to for-next head of tree as of yesterday. > > Fixes: f959dcd6ddfd2 ("dma-direct: Fix potential NULL pointer dereference") > Signed-off-by: Bob Pearson > drivers/infiniband/sw/rxe/rxe_verbs.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c > index 7652d53af2c1..c857e83323ed 100644 > +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c > @@ -1128,19 +1128,32 @@ int rxe_register_device(struct rxe_dev *rxe, const char *ibdev_name) > int err; > struct ib_device *dev = &rxe->ib_dev; > struct crypto_shash *tfm; > + u64 dma_mask; > > strlcpy(dev->node_desc, "rxe", sizeof(dev->node_desc)); > > dev->node_type = RDMA_NODE_IB_CA; > dev->phys_port_cnt = 1; > dev->num_comp_vectors = num_possible_cpus(); > - dev->dev.parent = rxe_dma_device(rxe); > dev->local_dma_lkey = 0; > addrconf_addr_eui48((unsigned char *)&dev->node_guid, > rxe->ndev->dev_addr); > dev->dev.dma_parms = &rxe->dma_parms; > dma_set_max_seg_size(&dev->dev, UINT_MAX); > - dma_set_coherent_mask(&dev->dev, dma_get_required_mask(&dev->dev)); > + > + /* rdma_rxe never does real DMA but does rely on > + * pinning user memory in MRs to avoid page faults > + * in responder and completer tasklets. This code > + * supplies a valid dma_mask from the underlying > + * network device. It is never used but is checked. > + */ > + dev->dev.parent = rxe_dma_device(rxe); Oh! This is another bug, the parent of an ib_device should never be set to a net_device!! This is probably why we get all those mysterious syzkaller faults :| Just leave it NULL > + dma_mask = *(dev->dev.parent->dma_mask); > + err = dma_coerce_mask_and_coherent(&dev->dev, dma_mask); Why not use Parav's logic? Jason