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Date:   Tue, 09 Jun 2020 13:38:46 +0200
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From:   Takashi Iwai <tiwai@suse.de>
To:     Christoph Hellwig <hch@lst.de>
Cc:     David Rientjes <rientjes@google.com>,
        "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
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        Pavel Machek <pavel@ucw.cz>, perex@perex.cz,
        tglx@linutronix.de, tiwai@suse.com, x86@kernel.org
Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash
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On Tue, 09 Jun 2020 13:31:23 +0200,
Christoph Hellwig wrote:
> 
> On Tue, Jun 09, 2020 at 11:31:20AM +0200, Takashi Iwai wrote:
> > > > How would be a proper way to get the virtually mapped SG-buffer pages
> > > > with coherent memory?  (Also allowing user-space mmap, too)
> > > 
> > > dma_mmap_coherent / dma_mmap_attrs for userspace.  We don't really
> > > have a good way for kernel space mappings.
> > 
> > And that's the missing piece right now...  :-<
> 
> Can you point me to the relevant places (allocation and vmap mostly)
> so that I can take a look at how to fix this mess?

Found in sound/core/sgbuf.c.  It's specific to x86.
Also, for V4L, drivers/media/v4l2-core/videobuf-dma-sg.c.


thanks,

Takashi