On 1/22/2024 6:06 PM, Steven Rostedt wrote:
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.
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);
-- Steve
