Re: [PATCH 0/7] mmc: Try to do proper kmap_local() for scatterlists

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On Thu, 25 Jan 2024 at 15:37, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>
> It was brought to our attention that some MMC host drivers
> are referencing sg_virt(sg) directly on scatterlist entries,
> which will not perform buffer bouncing for CONFIG_HIGHMEM
> pages that reside in highmem.
>
> See the following mail from Christoph and the discussion:
> https://lore.kernel.org/linux-mmc/20240122073423.GA25859@xxxxxx/
>
> This means that bugs with highmem pages can go unnoticed
> until an actual highmem page is finally used and not bounced,
> resulting in things like unpredictable file corruption.
>
> Attempt to fix this by amending all host controllers
> calling sg_virt() for PIO to instead do proper mapping
> and unmapping of the scatterlist entry, possibly bouncing
> it from highmem if need be.
>
> More complicated patches are possible, the most obvious
> to rewrite the PIO loops to use sg_miter_[start|next|stop]()
> see for example mmci.c, but I leave this refactoring as
> a suggestion to each device driver maintainer because I
> can't really test the patches.
>
> All patches are compile-tested except the m68k one,
> sdhci-esdhc-mcf.
>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Thanks for helping out with this! Applied for next!

Kind regards
Uffe


> ---
> Linus Walleij (7):
>       mmc: davinci_mmc: Map the virtual page for PIO
>       mmc: moxart-mmc: Map the virtual page for PIO
>       mmc: mvsdio: Map the virtual page for PIO
>       mmc: mxcmmc: Map the virtual page for PIO
>       mmc: omap: Map the virtual page for PIO
>       mmc: sdhci-esdhc-mcf: Map the virtual page for swapping
>       mmc: sh_mmcif: Map the virtual page for PIO
>
>  drivers/mmc/host/davinci_mmc.c     | 10 ++++++++--
>  drivers/mmc/host/moxart-mmc.c      |  3 ++-
>  drivers/mmc/host/mvsdio.c          |  3 ++-
>  drivers/mmc/host/mxcmmc.c          | 23 +++++++++++++++--------
>  drivers/mmc/host/omap.c            |  7 ++++++-
>  drivers/mmc/host/sdhci-esdhc-mcf.c |  3 ++-
>  drivers/mmc/host/sh_mmcif.c        | 22 ++++++++++++++++++----
>  7 files changed, 53 insertions(+), 18 deletions(-)
> ---
> base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
> change-id: 20240125-mmc-proper-kmap-f2d4cf5d1756
>
> Best regards,
> --
> Linus Walleij <linus.walleij@xxxxxxxxxx>
>




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