Re: 4.19-rc3: IOMMU PT warnings: WARNING: CPU: 0 PID: 1 at mm/page_alloc.c:4065 __alloc_pages_slowpath+0xb7b/0xcd0

[Christoph Hellwig]

On Mon, Sep 10, 2018 at 11:16:12AM +0300, Meelis Roos wrote:
> In 4.19-rc1, I found that to keep Intel integrated graphics working when 
> VT-d is on, I need to have IOMMU passthough on or GPU init would fail 
> with DMAR error and the screen would display static gibberish. So I 
> turned IOMMU PT on by default in kernel config. It worked, also in rc2.
> 
> Now with rc3, it still works but I get some warning splats in dmesg 
> about IOMMU passthrough:

Any chance you could bisect this down to a specific commit?  For
a start it might be worth if it is reproducable with:

   git://git.infradead.org/users/hch/dma-mapping.git dma-mapping-4.19-2

which were the only dma-mapping changes post -rc2.