netdev - Re: [PATCH/RFC v3 net] ravb: unmap descriptors when freeing rings

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Date:   Fri, 10 Feb 2017 14:52:50 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:     Simon Horman <horms+renesas@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH/RFC v3 net] ravb: unmap descriptors when freeing rings

On Wed, Jan 25, 2017 at 5:18 PM, Sergei Shtylyov
<sergei.shtylyov@...entembedded.com> wrote:
> On 01/24/2017 09:21 PM, Simon Horman wrote:
>
>> From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
>>
>> "swiotlb buffer is full" errors occur after repeated initialisation of a
>> device - f.e. suspend/resume or ip link set up/down. This is because
>> memory
>> mapped using dma_map_single() in ravb_ring_format() and ravb_start_xmit()
>> is not released.  Resolve this problem by unmapping descriptors when
>> freeing rings.
>
>
>    Could you look into the sh_eth driver which seems to have the same issue?

Indeed, after a few suspend/resume cycles on r8a7791/koelsch:

WARNING: CPU: 1 PID: 1699 at lib/dma-debug.c:517 add_dma_entry+0xfc/0x148
DMA-API: exceeded 7 overlapping mappings of cacheline 0x0000000001a827e3

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds