Re: amdgpu/TTM oopses since merging swiotlb_dma_ops into the dma_direct code

[Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Thu, Jan 10, 2019 at 04:26:43PM +0100, Sibren Vasse wrote:
> On Thu, 10 Jan 2019 at 14:57, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org> wrote:
> >
> > On Thu, Jan 10, 2019 at 10:59:02AM +0100, Michel Dänzer wrote:
> > >
> > > Hi Christoph,
> > >
> > >
> > > https://bugs.freedesktop.org/109234 (please ignore comments #6-#9) was
> > > bisected to your commit 55897af63091 "dma-direct: merge swiotlb_dma_ops
> > > into the dma_direct code". Any ideas?
> >
> > From the trace it looks like we git the case where swiotlb tries
> > to copy back data from a bounce buffer, but hits a dangling or NULL
> > pointer.  So a couple questions for the submitter:
> My apologies if I misunderstand something, this subject matter is new to me.
> 
> >
> >  - does the system have more than 4GB memory and thus use swiotlb?
> My system has 8GB memory. The other report on the bug tracker had 16GB.
> 
> >    (check /proc/meminfo, and if something SWIOTLB appears in dmesg)
> /proc/meminfo: https://ptpb.pw/4rxI
> Can I grep dmesg for a string?

Can you attach the 'dmesg'? 

> 
> >  - does the device this happens on have a DMA mask smaller than
> >    the available memory, that is should swiotlb be used here to start
> >    with?
> It's a MSI Radeon RX 570 Gaming X 4GB. The other report was a RX 580.
> lshw output: https://ptpb.pw/6s0H
> 
> 
> Regards,
> 
> Sibren