Ondrej Zary
2021-Jun-09 07:10 UTC
[Nouveau] nouveau broken on Riva TNT2 in 5.13.0-rc4: NULL pointer dereference in nouveau_bo_sync_for_device
On Wednesday 09 June 2021, Christian K?nig wrote:> Am 09.06.21 um 08:57 schrieb Ondrej Zary: > > [SNIP] > >> Thanks for the heads up. So the problem with my patch is already fixed, > >> isn't it? > > The NULL pointer dereference in nouveau_bo_wr16 introduced in > > 141b15e59175aa174ca1f7596188bd15a7ca17ba was fixed by > > aea656b0d05ec5b8ed5beb2f94c4dd42ea834e9d. > > > > That's the bug I hit when bisecting the original problem: > > NULL pointer dereference in nouveau_bo_sync_for_device > > It's caused by: > > # first bad commit: [e34b8feeaa4b65725b25f49c9b08a0f8707e8e86] drm/ttm: merge ttm_dma_tt back into ttm_tt > > Good that I've asked :) > > Ok that's a bit strange. e34b8feeaa4b65725b25f49c9b08a0f8707e8e86 was > created mostly automated. > > Do you have the original backtrace of that NULL pointer deref once more?The original backtrace is here: https://lkml.org/lkml/2021/6/5/350 -- Ondrej Zary
Christian König
2021-Jun-09 09:21 UTC
[Nouveau] nouveau broken on Riva TNT2 in 5.13.0-rc4: NULL pointer dereference in nouveau_bo_sync_for_device
Am 09.06.21 um 09:10 schrieb Ondrej Zary:> On Wednesday 09 June 2021, Christian K?nig wrote: >> Am 09.06.21 um 08:57 schrieb Ondrej Zary: >>> [SNIP] >>>> Thanks for the heads up. So the problem with my patch is already fixed, >>>> isn't it? >>> The NULL pointer dereference in nouveau_bo_wr16 introduced in >>> 141b15e59175aa174ca1f7596188bd15a7ca17ba was fixed by >>> aea656b0d05ec5b8ed5beb2f94c4dd42ea834e9d. >>> >>> That's the bug I hit when bisecting the original problem: >>> NULL pointer dereference in nouveau_bo_sync_for_device >>> It's caused by: >>> # first bad commit: [e34b8feeaa4b65725b25f49c9b08a0f8707e8e86] drm/ttm: merge ttm_dma_tt back into ttm_tt >> Good that I've asked :) >> >> Ok that's a bit strange. e34b8feeaa4b65725b25f49c9b08a0f8707e8e86 was >> created mostly automated. >> >> Do you have the original backtrace of that NULL pointer deref once more? > The original backtrace is here: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.org%2Flkml%2F2021%2F6%2F5%2F350&data=04%7C01%7Cchristian.koenig%40amd.com%7Ce905b6bd2aa842ace15508d92b15b96d%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637588195000729460%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=zFqheBbJcOHtYgqG%2Fs63AT1dwuk4REmUDJWHvzaLAlc%3D&reserved=0And the problem is that ttm_dma->dma_address is NULL, right? Mhm, I don't see how that can happen since nouveau is using ttm_sg_tt_init(). Apart from that what nouveau does here is rather questionable since you need a coherent architecture for most things anyway, but that's not what we are trying to fix here. Can you try to narrow down if ttm_sg_tt_init is called before calling this function for the tt object in question? Thanks, Christian.