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Date:   Fri, 14 Jun 2019 16:48:57 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Greg KH <gregkh@linuxfoundation.org>
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Subject: Re: [PATCH 12/16] staging/comedi: mark as broken
Message-ID: <20190614144857.GA9088@lst.de>
References: <20190614134726.3827-1-hch@lst.de> <20190614134726.3827-13-hch@lst.de> <20190614140239.GA7234@kroah.com>
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On Fri, Jun 14, 2019 at 04:02:39PM +0200, Greg KH wrote:
> Perhaps a hint as to how we can fix this up?  This is the first time
> I've heard of the comedi code not handling dma properly.

It can be fixed by:

 a) never calling virt_to_page (or vmalloc_to_page for that matter)
    on dma allocation
 b) never remapping dma allocation with conflicting cache modes
    (no remapping should be doable after a) anyway).