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From:   Ondrej Zary <linux@zary.sk>
To:     Ben Skeggs <bskeggs@redhat.com>
Subject: Re: nouveau broken on Riva TNT2 in 5.13.0-rc4: NULL pointer dereference in nouveau_bo_sync_for_device
Date:   Sun, 6 Jun 2021 23:16:03 +0200
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On Saturday 05 June 2021 23:34:23 Ondrej Zary wrote:
> On Saturday 05 June 2021 21:43:52 Ondrej Zary wrote:
> > Hello,
> > I'm testing 5.13.0-rc4 and nouveau crashes with NULL pointer dereference in nouveau_bo_sync_for_device.
> > Found various reports like this but that was back in februaryso that should be fixed now.
> 
> So it is the same bug. Broken since 5.11. This revert fixes it in 5.11:
> https://lists.freedesktop.org/archives/dri-devel/2021-February/298531.html
> 
> Added some debug printks to nouveau_bo_sync_for_device:
> [   22.225048] ttm_dma=fc33b500
> [   22.225066] ttm_dma->num_pages=18
> [   22.225071] i=0 num_pages=16
> [   22.225077] ttm_dma->dma_address=00000000
> [   22.225094] BUG: kernel NULL pointer dereference, address: 00000000
> 
> So ttm->dma_address is NULL.
> 

Tested reverting f295c8cfec833c2707ff1512da10d65386dde7af again and it does not work...
Not sure what I did before.

Bisecting between 5.10 and 5.11 is impossible - I keep hitting neverending stream of bugs.
As always with nouveau...

-- 
Ondrej Zary