[PATCH] drm/amdgpu: Check entity rq

[Pan, Xinhui]

> 2020年3月25日 15:48，Koenig, Christian <Christian.Koenig at amd.com> 写道：
> 
> Am 25.03.20 um 06:47 schrieb xinhui pan:
>> Hit panic during GPU recovery test. drm_sched_entity_select_rq might
>> set NULL to rq. So add a check like drm_sched_job_init does.
> 
> NAK, the rq should never be set to NULL in the first place.
> 
> How did that happened?

well, I have not check the details.
but just got the call trace below.
looks like sched is not ready, and drm_sched_entity_select_rq set entity->rq to NULL.
in the next amdgpu_vm_sdma_commit, hit panic when we deference entity->rq.

297567 [   44.667677] amdgpu 0000:03:00.0: GPU reset begin!
297568 [   44.929047] [drm] scheduler sdma0 is not ready, skipping
297569 [   44.929048] [drm] scheduler sdma1 is not ready, skipping
297570 [   44.934608] [drm:amdgpu_gem_va_ioctl [amdgpu]] *ERROR* Couldn't update BO_VA (-2)
297571 [   44.947941] BUG: kernel NULL pointer dereference, address: 0000000000000038
297572 [   44.955132] #PF: supervisor read access in kernel mode
297573 [   44.960451] #PF: error_code(0x0000) - not-present page
297574 [   44.965714] PGD 0 P4D 0
297575 [   44.968331] Oops: 0000 [#1] SMP PTI
297576 [   44.971911] CPU: 7 PID: 2496 Comm: gnome-shell Tainted: G        W         5.4.0-rc7+ #1
297577 [   44.980221] Hardware name: System manufacturer System Product Name/Z170-A, BIOS 1702 01/28/2016
297578 [   44.989177] RIP: 0010:amdgpu_vm_sdma_commit+0x55/0x190 [amdgpu]
297579 [   44.995242] Code: 47 20 80 7f 10 00 4c 8b a0 88 01 00 00 48 8b 47 08 4c 8d a8 70 01 00 00 75 07 4c 8d a8 88 02 00 00 49 8b 45 10 41 8b 54 24 08 <48> 8b 40 38 85 d2 48 8d b8 30 ff ff f       f 0f 84 06 01 00 00 48 8b 80
297580 [   45.014931] RSP: 0018:ffffb66e008839d0 EFLAGS: 00010246
297581 [   45.020504] RAX: 0000000000000000 RBX: ffffb66e00883a30 RCX: 0000000000100400
297582 [   45.028062] RDX: 000000000000003c RSI: ffff8df123662138 RDI: ffffb66e00883a30
297583 [   45.035662] RBP: ffffb66e00883a00 R08: ffffb66e0088395c R09: ffffb66e00883960
297584 [   45.043298] R10: 0000000000100240 R11: 0000000000000035 R12: ffff8df1425385e8
297585 [   45.050916] R13: ffff8df13cfd1288 R14: ffff8df123662138 R15: ffff8df13cfd1000
297586 [   45.058524] FS:  00007fcc8f6b2100(0000) GS:ffff8df15e380000(0000) knlGS:0000000000000000
297587 [   45.067114] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
297588 [   45.073206] CR2: 0000000000000038 CR3: 0000000641fb6006 CR4: 00000000003606e0
297589 [   45.080791] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
297590 [   45.088277] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
297591 [   45.095773] Call Trace:
297592 [   45.098354]  amdgpu_vm_bo_update_mapping+0x1c1/0x1f0 [amdgpu]
297593 [   45.104427]  ? mark_held_locks+0x4d/0x80
297594 [   45.108682]  amdgpu_vm_bo_update+0x3b7/0x960 [amdgpu]
297595 [   45.114049]  ? rcu_read_lock_sched_held+0x4f/0x80
297596 [   45.119111]  amdgpu_gem_va_ioctl+0x4f3/0x510 [amdgpu]
297597 [   45.124495]  ? amdgpu_gem_va_map_flags+0x70/0x70 [amdgpu]
297598 [   45.130250]  drm_ioctl_kernel+0xb0/0x100 [drm]
297599 [   45.134988]  ? amdgpu_gem_va_map_flags+0x70/0x70 [amdgpu]
297600 [   45.140742]  ? drm_ioctl_kernel+0xb0/0x100 [drm]
297601 [   45.145622]  drm_ioctl+0x389/0x450 [drm]
297602 [   45.149804]  ? amdgpu_gem_va_map_flags+0x70/0x70 [amdgpu]
297603 [   45.155551]  ? trace_hardirqs_on+0x3b/0xf0
297604 [   45.159892]  amdgpu_drm_ioctl+0x4f/0x80 [amdgpu]
297605 [   45.172104]  do_vfs_ioctl+0xa9/0x6f0
297606 [   45.175909]  ? tomoyo_file_ioctl+0x19/0x20
297607 [   45.180241]  ksys_ioctl+0x75/0x80
297608 [   45.183760]  ? do_syscall_64+0x17/0x230
297609 [   45.187833]  __x64_sys_ioctl+0x1a/0x20
297610 [   45.191846]  do_syscall_64+0x5f/0x230
297611 [   45.195764]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
297612 [   45.201126] RIP: 0033:0x7fcc8c7725d7

> 
> Regards,
> Christian.
> 
>> 
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Alex Deucher <alexander.deucher at amd.com>
>> Cc: Felix Kuehling <Felix.Kuehling at amd.com>
>> Signed-off-by: xinhui pan <xinhui.pan at amd.com>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c | 2 ++
>>  1 file changed, 2 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> index cf96c335b258..d30d103e48a2 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> @@ -95,6 +95,8 @@ static int amdgpu_vm_sdma_commit(struct amdgpu_vm_update_params *p,
>>  	int r;
>>    	entity = p->direct ? &p->vm->direct : &p->vm->delayed;
>> +	if (!entity->rq)
>> +		return -ENOENT;
>>  	ring = container_of(entity->rq->sched, struct amdgpu_ring, sched);
>>    	WARN_ON(ib->length_dw == 0);
>