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Message-ID: <20241207135217.00000f0f@gmail.com>
Date: Sat, 7 Dec 2024 13:52:17 +0800
From: Furong Xu <0x1207@...il.com>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
andrew+netdev@...n.ch, Alexandre Torgue <alexandre.torgue@...s.st.com>,
Jose Abreu <joabreu@...opsys.com>, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
Abeni <pabeni@...hat.com>, MaximeCoquelin <mcoquelin.stm32@...il.com>,
xfr@...look.com, Jon Hunter <jonathanh@...dia.com>, Thierry Reding
<thierry.reding@...il.com>, Simon Horman <horms@...nel.org>, Hariprasad
Kelam <hkelam@...vell.com>
Subject: Re: [PATCH net] net: stmmac: fix TSO DMA API usage causing oops
On Fri, 06 Dec 2024 12:40:11 +0000, "Russell King (Oracle)" <rmk+kernel@...linux.org.uk> wrote:
> Commit 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap
> for non-paged SKB data") moved the assignment of tx_skbuff_dma[]'s
> members to be later in stmmac_tso_xmit().
>
> The buf (dma cookie) and len stored in this structure are passed to
> dma_unmap_single() by stmmac_tx_clean(). The DMA API requires that
> the dma cookie passed to dma_unmap_single() is the same as the value
> returned from dma_map_single(). However, by moving the assignment
> later, this is not the case when priv->dma_cap.addr64 > 32 as "des"
> is offset by proto_hdr_len.
>
> This causes problems such as:
>
> dwc-eth-dwmac 2490000.ethernet eth0: Tx DMA map failed
>
> and with DMA_API_DEBUG enabled:
>
> DMA-API: dwc-eth-dwmac 2490000.ethernet: device driver tries to +free DMA memory it has not allocated [device address=0x000000ffffcf65c0] [size=66 bytes]
>
> Fix this by maintaining "des" as the original DMA cookie, and use
> tso_des to pass the offset DMA cookie to stmmac_tso_allocator().
>
> Full details of the crashes can be found at:
> https://lore.kernel.org/all/d8112193-0386-4e14-b516-37c2d838171a@nvidia.com/
> https://lore.kernel.org/all/klkzp5yn5kq5efgtrow6wbvnc46bcqfxs65nz3qy77ujr5turc@bwwhelz2l4dw/
>
> Reported-by: Jon Hunter <jonathanh@...dia.com>
> Reported-by: Thierry Reding <thierry.reding@...il.com>
> Fixes: 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data")
Much appreciated for this fix.
Reviewed-by: Furong Xu <0x1207@...il.com>
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