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Message-ID: <20211001041959.GA17448@lst.de>
Date: Fri, 1 Oct 2021 06:19:59 +0200
From: Christoph Hellwig <hch@....de>
To: Ioana Ciornei <ioana.ciornei@....com>
Cc: Jeremy Linton <jeremy.linton@....com>,
Hamza Mahfooz <someguy@...ective-light.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Christoph Hellwig <hch@....de>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Robin Murphy <robin.murphy@....com>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
Dan Williams <dan.j.williams@...el.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: DPAA2 triggers, [PATCH] dma debug: report -EEXIST errors in
add_dma_entry
On Tue, Sep 14, 2021 at 03:45:06PM +0000, Ioana Ciornei wrote:
> [ 245.927020] fsl_dpaa2_eth dpni.3: scather-gather idx 0 P=20a7320000 N=20a7320 D=20a7320000 L=30 DMA_BIDIRECTIONAL dma map error check not applicableĀ·
> [ 245.927048] fsl_dpaa2_eth dpni.3: scather-gather idx 1 P=20a7320030 N=20a7320 D=20a7320030 L=5a8 DMA_BIDIRECTIONAL dma map error check not applicable
> [ 245.927062] DMA-API: cacheline tracking EEXIST, overlapping mappings aren't supported
>
> The first line is the dump of the dma_debug_entry which is already present
> in the radix tree and the second one is the entry which just triggered
> the EEXIST.
>
> As we can see, they are not actually overlapping, at least from my
> understanding. The first one starts at 0x20a7320000 with a size 0x30
> and the second one at 0x20a7320030.
They overlap the cache lines. Which means if you use this driver
on a system that is not dma coherent you will corrupt data.
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