On 2/20/20 9:41 AM, Li, Dennis wrote:
[AMD Official Use Only - Internal Distribution Only]
Hi, Christian and Monk,
When doing SDMA copy, a RAS uncorrectable error happens, which will cause this issue. The RAS uncorrectable error event will trigger driver to do BACO reset which will set the status of SDMA scheduler to no ready. And then drm_sched_entity_get_free_sched will return NULL in drm_sched_entity_select_rq, which cause entity->rq to NULL.
This can happen only in drm_sched_job_init() which gets called in
amdgpu_job_submit() which is after when we get this NULL ptr exception.
entity = p->direct ? &p->vm->direct : &p->vm->delayed;
ring = container_of(entity->rq->sched, struct amdgpu_ring, sched);
WARN_ON(ib->length_dw == 0);
amdgpu_ring_pad_ib(ring, ib);
WARN_ON(ib->length_dw > p->num_dw_left);
r = amdgpu_job_submit(p->job, entity, AMDGPU_FENCE_OWNER_VM,
&f); <-- Here
if (r)
goto error;
Could it be possible that we are doing drm_sched_entity_init() for
direct and indirect entity with zero scheds in amdgpu_vm_init() ?
Regards,
Nirmoy
Best Regards
Dennis Li
-----Original Message-----
From: Liu, Monk <Monk.Liu@xxxxxxx>
Sent: Wednesday, February 19, 2020 7:30 PM
To: Koenig, Christian <Christian.Koenig@xxxxxxx>; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Zhou1, Tao <Tao.Zhou1@xxxxxxx>; Chen, Guchun <Guchun.Chen@xxxxxxx>
Subject: 回复: [PATCH] drm/amdgpu: fix a bug NULL pointer dereference
+ if (!entity->rq)
+ return 0;
+
Yes, supposedly we shouldn't get 'entity->rq == NULL' case , that looks the true bug
-----邮件原件-----
发件人: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> 代表 Christian K?nig
发送时间: 2020年2月19日 18:50
收件人: Zhang, Hawking <Hawking.Zhang@xxxxxxx>; Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Zhou1, Tao <Tao.Zhou1@xxxxxxx>; Chen, Guchun <Guchun.Chen@xxxxxxx>
主题: Re: [PATCH] drm/amdgpu: fix a bug NULL pointer dereference
Well of hand this patch looks like a clear NAK to me.
Returning without raising an error is certainly the wrong thing to do here because we just drop the necessary page table updates.
How does the entity->rq ends up as NULL in the first place?
Regards,
Christian.
Am 19.02.20 um 07:26 schrieb Zhang, Hawking:
[AMD Official Use Only - Internal Distribution Only]
Reviewed-by: Hawking Zhang <Hawking.Zhang@xxxxxxx>
Regards,
Hawking
-----Original Message-----
From: Dennis Li <Dennis.Li@xxxxxxx>
Sent: Wednesday, February 19, 2020 12:05
To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander
<Alexander.Deucher@xxxxxxx>; Zhou1, Tao <Tao.Zhou1@xxxxxxx>; Zhang,
Hawking <Hawking.Zhang@xxxxxxx>; Chen, Guchun <Guchun.Chen@xxxxxxx>
Cc: Li, Dennis <Dennis.Li@xxxxxxx>
Subject: [PATCH] drm/amdgpu: fix a bug NULL pointer dereference
check whether the queue of entity is null to avoid null pointer dereference.
Change-Id: I08d56774012cf229ba2fe7a011c1359e8d1e2781
Signed-off-by: Dennis Li <Dennis.Li@xxxxxxx>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
index 4cc7881f438c..67cca463ddcc 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
@@ -95,6 +95,9 @@ 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 0;
+
ring = container_of(entity->rq->sched, struct amdgpu_ring, sched);
WARN_ON(ib->length_dw == 0);
--
2.17.1
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