<!DOCTYPE html><html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> <div class="moz-cite-prefix">On 1/22/2024 6:06 PM, Steven Rostedt wrote: </div> <blockquote type="cite" cite="mid:20240122180605.28daf23a@gandalf.local.home"> <pre class="moz-quote-pre" wrap="">I just kicked off testing some patches on top of 6.8-rc1 and triggered this immediately: [ note this happened on both my 32 bit an 64 bit test machines, this is just the 32 bit output ] BUG: kernel NULL pointer dereference, address: 00000238 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page *pdpt = 0000000000000000 *pde = f000ff53f000ff53 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.8.0-rc1-test-00001-g2b44760609e9-dirty #1056 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events work_for_cpu_fn EIP: ttm_device_init+0xb4/0x274 Code: 86 10 09 00 00 83 c4 0c 85 c0 0f 84 96 01 00 00 8b 45 ac 8d 9e 94 00 00 00 89 46 08 89 f0 e8 27 05 00 00 8b 55 a8 0f b6 45 98 <8b> 8a 38 02 00 00 50 0f b6 45 9c 50 89 d8 e8 95 ee ff ff 8b 45 a0 EAX: 00000000 EBX: c135a7e4 ECX: c135a7b0 EDX: 00000000 ESI: c135a750 EDI: 0007bc1d EBP: c11d7e4c ESP: c11d7de4 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246 CR0: 80050033 CR2: 00000238 CR3: 145c4000 CR4: 000006f0 Call Trace: ? show_regs+0x4f/0x58 ? __die+0x1d/0x58 ? page_fault_oops+0x171/0x330 ? lock_acquire+0xa4/0x280 ? kernelmode_fixup_or_oops.constprop.0+0x7c/0xcc ? __bad_area_nosemaphore.constprop.0+0x124/0x1b4 ? __mutex_lock+0x17f/0xb00 ? bad_area_nosemaphore+0xf/0x14 ? do_user_addr_fault+0x140/0x3e4 ? exc_page_fault+0x5b/0x1d8 ? pvclock_clocksource_read_nowd+0x130/0x130 ? handle_exception+0x133/0x133 ? pvclock_clocksource_read_nowd+0x130/0x130 ? ttm_device_init+0xb4/0x274 ? pvclock_clocksource_read_nowd+0x130/0x130 ? ttm_device_init+0xb4/0x274 qxl_ttm_init+0x34/0x130 qxl_bo_init+0xd/0x10 qxl_device_init+0x52a/0x92c qxl_pci_probe+0x91/0x1ac local_pci_probe+0x3d/0x84 work_for_cpu_fn+0x16/0x20 process_one_work+0x1bc/0x4a0 worker_thread+0x310/0x3a8 kthread+0xea/0x110 ? rescuer_thread+0x2f0/0x2f0 ? kthread_complete_and_exit+0x1c/0x1c ret_from_fork+0x34/0x4c ? kthread_complete_and_exit+0x1c/0x1c ret_from_fork_asm+0x12/0x18 entry_INT80_32+0xf0/0xf0 Modules linked in: CR2: 0000000000000238 ---[ end trace 0000000000000000 ]--- The crash happened here: int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *funcs, struct device *dev, struct address_space *mapping, struct drm_vma_offset_manager *vma_manager, bool use_dma_alloc, bool use_dma32) { struct ttm_global *glob = &ttm_glob; int ret; if (WARN_ON(vma_manager == NULL)) return -EINVAL; ret = ttm_global_init(); if (ret) return ret; bdev->wq = alloc_workqueue("ttm", WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16); if (!bdev->wq) { ttm_global_release(); return -ENOMEM; } bdev->funcs = funcs; ttm_sys_man_init(bdev); 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. I currently "fixed" this with a: if (!dev) return -EINVAL; at the start of this function just so that I can continue running my tests, but that is obviously incorrect.</pre> </blockquote> In one of my previous revisions of this patch when I was experimenting, I used something like below. Wonder if that could work in your case and/or in general.  diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index 43e27ab77f95..4c3902b94be4 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -195,6 +195,7 @@ int ttm_device_init(struct ttm_device *bdev, struct ttm_device_funcs *funcs, bool use_dma_alloc, bool use_dma32) { struct ttm_global *glob = &ttm_glob; + bool node_has_cpu = false; int ret; if (WARN_ON(vma_manager == NULL)) @@ -213,7 +214,12 @@ int ttm_device_init(struct ttm_device *bdev, struct ttm_device_funcs *funcs, bdev->funcs = funcs; ttm_sys_man_init(bdev); - ttm_pool_init(&bdev->pool, dev, NUMA_NO_NODE, use_dma_alloc, use_dma32); + + node_has_cpu = node_state(dev->numa_node, N_CPU); + if (node_has_cpu) + ttm_pool_init(&bdev->pool, dev, dev->numa_node, use_dma_alloc, use_dma32); + else + ttm_pool_init(&bdev->pool, dev, NUMA_NO_NODE, use_dma_alloc, +use_dma32); bdev->vma_manager = vma_manager; spin_lock_init(&bdev->lru_lock); <blockquote type="cite" cite="mid:20240122180605.28daf23a@gandalf.local.home"> <pre class="moz-quote-pre" wrap=""> -- Steve </pre> </blockquote> </body> </html>