Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
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:   Sat, 5 Jun 2021 23:34:23 +0200
User-Agent: KMail/1.9.10
Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <202106052143.52488.linux@zary.sk>
In-Reply-To: <202106052143.52488.linux@zary.sk>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <202106052334.23943.linux@zary.sk>
Precedence: bulk

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.

-- 
Ondrej Zary