[AMD Official Use Only - General] -----Original Message----- From: Steven Rostedt <rostedt@xxxxxxxxxxx> Sent: Monday, January 22, 2024 6:19 PM To: LKML <linux-kernel@xxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>; Bhardwaj, Rajneesh <Rajneesh.Bhardwaj@xxxxxxx>; Kuehling, Felix <Felix.Kuehling@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx Subject: Re: [BUG] BUG: kernel NULL pointer dereference at ttm_device_init+0xb4 On Mon, 22 Jan 2024 18:15:47 -0500 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > ttm_pool_init(&bdev->pool, dev, dev_to_node(dev), use_dma_alloc, use_dma32); <<<------- BUG! > > > > Specifically, it appears that dev is NULL and dev_to_node() doesn't > > like having a NULL pointer passed to it. > > > > Yeah, that qxl_ttm_init() has: > > /* No others user of address space so set it to 0 */ > r = ttm_device_init(&qdev->mman.bdev, &qxl_bo_driver, NULL, > qdev->ddev.anon_inode->i_mapping, > qdev->ddev.vma_offset_manager, > false, false); > > Where that NULL is "dev"! > > Thus that will never work here. Perhaps this is the real fix? I think the fix might be already applied to drm misc. Please see, https://lkml.iu.edu/hypermail/linux/kernel/2401.1/06778.html -- Steve diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index f5187b384ae9..bc217b4d6b04 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -215,7 +215,8 @@ int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *func ttm_sys_man_init(bdev); - ttm_pool_init(&bdev->pool, dev, dev_to_node(dev), use_dma_alloc, use_dma32); + ttm_pool_init(&bdev->pool, dev, dev ? dev_to_node(dev) : NUMA_NO_NODE, + use_dma_alloc, use_dma32); bdev->vma_manager = vma_manager; spin_lock_init(&bdev->lru_lock);
