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    SubjectRe: SCSI breakage on non-cache coherent architectures
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    On Mon, 2007-11-19 at 05:32 -0700, Matthew Wilcox wrote:
    > On Mon, Nov 19, 2007 at 04:35:23PM +1100, Benjamin Herrenschmidt wrote:
    > > The other one I'm hitting now is that the SCSI layer nowadays embeds the
    >
    > 'nowadays'? It has always been so.

    Wasn't it kmalloc'ed at one point ?

    > > sense_buffer inside the scsi_cmnd structure without any kind of
    > > alignment whatsoever. I've been hitting irregulary is a crash on SCSI command
    > > completion that seems to be related to corruption of the "request"
    > > pointer in struct scsi_cmnd and I think it might be the cause.
    > > I'm now trying to setup a proper repro-case.
    >
    > What other drivers do is DMA to their own allocation and then memcpy to
    > the sense buffer.

    What "other drivers" ? Those architectures use the same drivers as
    everything else.

    > There is a movement to allocate the sense data as its own sg list, but
    > I don't think that patch has even been posted yet.

    I've seen code creating an sglist from the scsi_cmnd->sense_buffer and
    passing that to drivers. That breaks.

    Ben.

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