RE: WARNING in dma_map_page_attrs

From: Parav Pandit <parav@nvidia.com>
To: "hch@lst.de" <hch@lst.de>
Cc: Jakub Kicinski <kuba@kernel.org>,
	syzbot <syzbot+34dc2fea3478e659af01@syzkaller.appspotmail.com>,
	"christian.koenig@amd.com" <christian.koenig@amd.com>,
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	<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>,
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	<syzkaller-bugs@googlegroups.com>,
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Subject: RE: WARNING in dma_map_page_attrs
Date: Fri, 30 Oct 2020 09:35:40 +0000	[thread overview]
Message-ID: <BY5PR12MB4322B3F74495D950A2DF59FCDC150@BY5PR12MB4322.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20201028173108.GA10135@lst.de>


> From: hch@lst.de <hch@lst.de>
> Sent: Wednesday, October 28, 2020 11:01 PM
> 
> 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.
Ok. thanks for the input.
Sending updated fix to set 64-bit mask for 64-bit platform and 32-bit mask otherwise.