linux-kernel - Re: [PATCH v2 1/2] drm/ttm: Only allocate huge pages with new flag TTM_PAGE_FLAG

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Date:   Tue, 1 May 2018 15:59:06 +0200
From:   Michel Dänzer <michel@...nzer.net>
To:     Dave Airlie <airlied@...il.com>,
        "Koenig, Christian" <christian.koenig@....com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        amd-gfx mailing list <amd-gfx@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] drm/ttm: Only allocate huge pages with new flag
 TTM_PAGE_FLAG_TRANSHUGE

On 2018-05-01 01:15 AM, Dave Airlie wrote:
>>
>>
>> Yes, I fixed the original false positive messages myself with the swiotlb
>> maintainer and I was CCed in fixing the recent fallout from Chris changes as
>> well.
> 
> So do we have a good summary of where this at now?
> 
> I'm getting reports on 4.16.4 still displaying these, what hammer do I
> need to hit things with to get 4.16.x+1 to not do this?
> 
> Is there still outstanding issues upstream.

There are, https://patchwork.freedesktop.org/patch/219765/ should
hopefully fix the last of it.


> [...] I've no idea if the swiotlb things people report are the false
> positive, or some new thing.

The issues I've seen reported with 4.16 are false positives from TTM's
perspective, which uses DMA_ATTR_NO_WARN to suppress these warnings, due
to multiple regressions introduced by commit
0176adb004065d6815a8e67946752df4cd947c5b "swiotlb: refactor
 coherent buffer allocation" in 4.16-rc1.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer