Re: [PATCH] Revert "drm/amdgpu: remove ctx->lock"

[Luben Tuikov <luben.tuikov@amd.com>]

On 2022-07-11 23:22, Tales Lelo da Aparecida wrote:
> On 21/06/2022 11:42, Luben Tuikov wrote:
>> This reverts commit e68efb27647f2106d6b545667f35b2ea39746b57.
>>
>> We see that the bo validate list gets corrupted, in
>> amdgpu_cs_list_validate(), the lobj->tv.bo is NULL. Then getting usermm on
>> the next line, references a NULL bo and we get a koops.
>>
>> Bisecting leads to the commit being reverted as the cause of the list
>> corruption. See the link below for details of the corruption failure.
>>
>> Cc: Christian König <christian.koenig@amd.com>
>> Cc: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
>> Cc: Alex Deucher <Alexander.Deucher@amd.com>
>> Cc: Vitaly Prosyak <Vitaly.Prosyak@amd.com>
>> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Famd%2F-%2Fissues%2F2048%23note_1427539&amp;data=05%7C01%7Cluben.tuikov%40amd.com%7C32a7f3eaffff490fc69f08da63b5c925%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637931929684937036%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=eXMfeyqaPhBIl9iJa4kbQtN1r4OhFZSGkZiGRJ3MQsQ%3D&amp;reserved=0
>> Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c  | 16 +++++-----------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c |  2 ++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h |  1 +
>>   3 files changed, 8 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 36ac1f1d11e6b4..e619031753b927 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -128,6 +128,8 @@ static int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, union drm_amdgpu_cs
>>   		goto free_chunk;
>>   	}
>>   
>> +	mutex_lock(&p->ctx->lock);
>> +
>>   	/* skip guilty context job */
>>   	if (atomic_read(&p->ctx->guilty) == 1) {
>>   		ret = -ECANCELED;
>> @@ -585,16 +587,6 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
>>   		}
>>   	}
>>   
>> -	/* Move fence waiting after getting reservation lock of
>> -	 * PD root. Then there is no need on a ctx mutex lock.
>> -	 */
>> -	r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entity);
>> -	if (unlikely(r != 0)) {
>> -		if (r != -ERESTARTSYS)
>> -			DRM_ERROR("amdgpu_ctx_wait_prev_fence failed.\n");
>> -		goto error_validate;
>> -	}
>> -
>>   	amdgpu_cs_get_threshold_for_moves(p->adev, &p->bytes_moved_threshold,
>>   					  &p->bytes_moved_vis_threshold);
>>   	p->bytes_moved = 0;
>> @@ -722,6 +714,7 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, int error,
>>   	dma_fence_put(parser->fence);
>>   
>>   	if (parser->ctx) {
>> +		mutex_unlock(&parser->ctx->lock);
>>   		amdgpu_ctx_put(parser->ctx);
>>   	}
>>   	if (parser->bo_list)
>> @@ -965,7 +958,7 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device *adev,
>>   	if (parser->job->uf_addr && ring->funcs->no_user_fence)
>>   		return -EINVAL;
>>   
>> -	return 0;
>> +	return amdgpu_ctx_wait_prev_fence(parser->ctx, parser->entity);
>>   }
>>   
>>   static int amdgpu_cs_process_fence_dep(struct amdgpu_cs_parser *p,
>> @@ -1384,6 +1377,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>>   		goto out;
>>   
>>   	r = amdgpu_cs_submit(&parser, cs);
>> +
>>   out:
>>   	amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
>>   
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> index 53f9268366f29e..2ef5296216d64d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> @@ -286,6 +286,7 @@ static int amdgpu_ctx_init(struct amdgpu_ctx_mgr *mgr, int32_t priority,
>>   	kref_init(&ctx->refcount);
>>   	ctx->mgr = mgr;
>>   	spin_lock_init(&ctx->ring_lock);
>> +	mutex_init(&ctx->lock);
>>   
>>   	ctx->reset_counter = atomic_read(&mgr->adev->gpu_reset_counter);
>>   	ctx->reset_counter_query = ctx->reset_counter;
>> @@ -400,6 +401,7 @@ static void amdgpu_ctx_fini(struct kref *ref)
>>   		drm_dev_exit(idx);
>>   	}
>>   
>> +	mutex_destroy(&ctx->lock);
>>   	kfree(ctx);
>>   }
>>   
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
>> index 0fa0e56daf67e9..cc7c8afff4144c 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
>> @@ -53,6 +53,7 @@ struct amdgpu_ctx {
>>   	bool				preamble_presented;
>>   	int32_t				init_priority;
>>   	int32_t				override_priority;
>> +	struct mutex			lock;
>>   	atomic_t			guilty;
>>   	unsigned long			ras_counter_ce;
>>   	unsigned long			ras_counter_ue;
>>
>> base-commit: f4b3c543a2a759ce657de4b6b7e88eaddee85ec2
> 
> Hello,
> 
> Applied on amd-staging-drm-next (with two additional commits from 
> torvalds/master to allow me to compile using GCC12: 52a9dab6, 82880283) 
> and tested with IGT using a RX580*; the errors on the "amd_cs_nop" tests 
> are gone!
> 
> * Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 
> 470/480/570/570X/580/580X/590] (rev e7)
> 
> The remaining IGT tests matching ".*amdgpu.*" were not affected. (FYI, 
> amdgpu/amd_plane, amdgpu/amd_bypass, amdgpu/amd_plane, 
> amdgpu/amd_vrr_range are failing in here, some should skip instead, but 
> that's another thread to come)
> 
> Tested-by: Tales Aparecida <tales.aparecida@gmail.com>
> 
> Thanks for your time,
> Tales

Hi Tales,

Thank you for testing this patch and letting us know of the results.
This helps a lot.


Best Regards,
-- 
Luben