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Date: Tue, 1 Jul 2025 10:20:41 -0400
From: Keith Busch <kbusch@kernel.org>
To: Ben Copeland <ben.copeland@linaro.org>
Cc: Christoph Hellwig <hch@lst.de>, linux-kernel@vger.kernel.org,
	lkft-triage@lists.linaro.org, regressions@lists.linux.dev,
	linux-nvme@lists.infradead.org,
	Dan Carpenter <dan.carpenter@linaro.org>, axboe@kernel.dk,
	sagi@grimberg.me, iommu@lists.linux.dev
Subject: Re: next-20250627: IOMMU DMA warning during NVMe I/O completion
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On Tue, Jul 01, 2025 at 02:05:04PM +0100, Ben Copeland wrote:
> Even though SGLs are not supported, I gave you the patch a spin and
> saw the same stack traces.

Right, that patch applies only if SGL is not supported, but it's only
fixing part of the problem, so I expected it would still fail.

The dma teardown needs to be symetric to the dma mapping, but we've
removed the sg-table now, so we don't have the original mapping context
in the completion path here. Christoph replied with a patch that tries
to infer it based on the dma_addr continuity, which I think should work
for you, but I'll have to look a bit closer to be confident it's always
the correct assumption.