Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 28 Oct 2020 18:31:08 +0100
From:   "hch@lst.de" <hch@lst.de>
To:     Parav Pandit <parav@nvidia.com>
Cc:     "hch@lst.de" <hch@lst.de>, Jakub Kicinski <kuba@kernel.org>,
        syzbot <syzbot+34dc2fea3478e659af01@syzkaller.appspotmail.com>,
        "christian.koenig@amd.com" <christian.koenig@amd.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "linaro-mm-sig-owner@lists.linaro.org" 
        <linaro-mm-sig-owner@lists.linaro.org>,
        "linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
        "m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "robin.murphy@arm.com" <robin.murphy@arm.com>,
        "sumit.semwal@linaro.org" <sumit.semwal@linaro.org>,
        "syzkaller-bugs@googlegroups.com" <syzkaller-bugs@googlegroups.com>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: Re: WARNING in dma_map_page_attrs
Message-ID: <20201028173108.GA10135@lst.de>
References: <000000000000335adc05b23300f6@google.com> <000000000000a0f8a305b261fe4a@google.com> <20201024111516.59abc9ec@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> <BY5PR12MB4322CC03CE0D34B83269676ADC190@BY5PR12MB4322.namprd12.prod.outlook.com> <20201027081103.GA22877@lst.de> <BY5PR12MB43221380BB0259FF0693BB0CDC160@BY5PR12MB4322.namprd12.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <BY5PR12MB43221380BB0259FF0693BB0CDC160@BY5PR12MB4322.namprd12.prod.outlook.com>
User-Agent: Mutt/1.5.17 (2007-11-01)
Precedence: bulk

On Tue, Oct 27, 2020 at 12:52:30PM +0000, Parav Pandit wrote:
> 
> > From: hch@lst.de <hch@lst.de>
> > Sent: Tuesday, October 27, 2020 1:41 PM
> > 
> > On Mon, Oct 26, 2020 at 05:23:48AM +0000, Parav Pandit wrote:
> > > Hi Christoph,
> > >
> > > > From: Jakub Kicinski <kuba@kernel.org>
> > > > Sent: Saturday, October 24, 2020 11:45 PM
> > > >
> > > > CC: rdma, looks like rdma from the stack trace
> > > >
> > > > On Fri, 23 Oct 2020 20:07:17 -0700 syzbot wrote:
> > > > > syzbot has found a reproducer for the following issue on:
> > > > >
> > > > > HEAD commit:    3cb12d27 Merge tag 'net-5.10-rc1' of
> > git://git.kernel.org/..
> > >
> > > In [1] you mentioned that dma_mask should not be set for dma_virt_ops.
> > > So patch [2] removed it.
> > >
> > > But check to validate the dma mask for all dma_ops was added in [3].
> > >
> > > What is the right way? Did I misunderstood your comment about
> > dma_mask in [1]?
> > 
> > No, I did not say we don't need the mask.  I said copying over the various
> > dma-related fields from the parent is bogus.
> > 
> > I think rxe (and ther other drivers/infiniband/sw drivers) need a simple
> > dma_coerce_mask_and_coherent and nothing else.
> 
> I see. Does below fix make sense?
> Is DMA_MASK_NONE correct?

DMA_MASK_NONE is gone in 5.10.  I think you want DMA_BIT_MASK(64).
That isn't actually correct for 32-bit platforms, but good enough.