Re: [PATCH] amdgpu: fixes memleak issue when init failed

["Christian König" <christian.koenig@amd.com>]

Am 22.04.20 um 02:56 schrieb 赵军奎:
> 发件人："Christian König" <christian.koenig@amd.com>
> 发送日期：2020-04-21 22:53:47
> 收件人："赵军奎" <bernard@vivo.com>
> 抄送人：Alex Deucher <alexander.deucher@amd.com>,"David (ChunMing) Zhou" <David1.Zhou@amd.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,Tom St Denis <tom.stdenis@amd.com>,Ori Messinger <Ori.Messinger@amd.com>,Sam Ravnborg <sam@ravnborg.org>,amd-gfx@lists.freedesktop.org,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org,opensource.kernel@vivo.com
> 主题：Re: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 15:39 schrieb 赵军奎:
>>> 发件人："Christian König" <christian.koenig@amd.com>
>>> 发送日期：2020-04-21 21:02:27
>>> 收件人："赵军奎" <bernard@vivo.com>
>>> 抄送人：Alex Deucher <alexander.deucher@amd.com>,"David (ChunMing) Zhou" <David1.Zhou@amd.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,Tom St Denis <tom.stdenis@amd.com>,Ori Messinger <Ori.Messinger@amd.com>,Sam Ravnborg <sam@ravnborg.org>,amd-gfx@lists.freedesktop.org,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org,opensource.kernel@vivo.com
>>> 主题：Re: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 14:09 schrieb 赵军奎:
>>>>> From: "Christian König" <christian.koenig@amd.com>
>>>>> Date: 2020-04-21 19:22:49
>>>>> To:  Bernard Zhao <bernard@vivo.com>,Alex Deucher <alexander.deucher@amd.com>,"David (ChunMing) Zhou" <David1.Zhou@amd.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,Tom St Denis <tom.stdenis@amd.com>,Ori Messinger <Ori.Messinger@amd.com>,Sam Ravnborg <sam@ravnborg.org>,amd-gfx@lists.freedesktop.org,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org
>>>>> Cc:  opensource.kernel@vivo.com
>>>>> Subject: Re: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 13:17 schrieb Bernard Zhao:
>>>>>>> VRAM manager and DRM MM when init failed, there is no operaction
>>>>>>> to free kzalloc memory & remove device file.
>>>>>>> This will lead to memleak & cause stability issue.
>>>>>> NAK, failure to create sysfs nodes are not critical.
>>>>>>
>>>>>> Christian.
>>>>>>
>>>>> OK, get it.
>>>>> By the way, should i modify this patch to just handle <kfree(mgr)> in error branch, or that it is also unnecessary?
>>>> What you can do is to drop the "return ret" if anything with the sysfs
>>>> nodes goes wrong and instead print the error code.
>>> Emmm, for this part, i am not sure, my modify first print the error, secone release not free memory,
>>> and last return error, make everything clear to the system.
>>> I think it`s the same with what you mentioned, is there something that I misunderstood?
>> Yes, maybe an example makes it more clear what to do here. Currently we
>> print and error and return when something with the sysfs files goes wrong:
>>
>> if (ret) {
>>      DRM_ERROR("Failed to create device file mem_info_vram_total\n");
>>      return ret;
>> }
>>
>> But what we should do instead is just to print an error and continue and
>> in the end return success status:
>>
>> if (ret)
>>      DRM_ERROR("Failed to create device file mem_info_vram_total
>> (%d)\n", r);
>>
>> ...
>> return 0;
>>
>> Regards,
>> Christian.
>>
> Emmm,  i am still confused about two points:
> 1 Does that mean there is no failed case in this function?

Well the kzalloc can still fail.

> 2 There is no need to free the kzmalloc space(no possibility of memory leak )?

Correct, yes.

Regards,
Christian.

>
> Regards,
> Bernard
>
>>>> It's really annoying that loading, unloading and loading the driver
>>>> again sometimes fails because we have a bug in the sysfs files cleanup.
>>>>
>>>> We certainly should fix those bugs as well, but they are just not
>>>> critical for correct driver functionality.
>>>>
>>>> Regards,
>>>> Christian.
>>>>> Regards,
>>>>> Bernard
>>>>>
>>>>>>> Signed-off-by: Bernard Zhao <bernard@vivo.com>
>>>>>>> ---
>>>>>>>      drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 24 ++++++++++++++++----
>>>>>>>      1 file changed, 19 insertions(+), 5 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>>>> index 82a3299e53c0..4c5fb153e6b4 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>>>>>> @@ -175,30 +175,44 @@ static int amdgpu_vram_mgr_init(struct ttm_mem_type_manager *man,
>>>>>>>      	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_total);
>>>>>>>      	if (ret) {
>>>>>>>      		DRM_ERROR("Failed to create device file mem_info_vram_total\n");
>>>>>>> -		return ret;
>>>>>>> +		goto VRAM_TOTAL_FAIL;
>>>>>>>      	}
>>>>>>>      	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
>>>>>>>      	if (ret) {
>>>>>>>      		DRM_ERROR("Failed to create device file mem_info_vis_vram_total\n");
>>>>>>> -		return ret;
>>>>>>> +		goto VIS_VRAM_TOTA_FAIL;
>>>>>>>      	}
>>>>>>>      	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_used);
>>>>>>>      	if (ret) {
>>>>>>>      		DRM_ERROR("Failed to create device file mem_info_vram_used\n");
>>>>>>> -		return ret;
>>>>>>> +		goto VRAM_USED_FAIL;
>>>>>>>      	}
>>>>>>>      	ret = device_create_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
>>>>>>>      	if (ret) {
>>>>>>>      		DRM_ERROR("Failed to create device file mem_info_vis_vram_used\n");
>>>>>>> -		return ret;
>>>>>>> +		goto VIS_VRAM_USED_FAIL;
>>>>>>>      	}
>>>>>>>      	ret = device_create_file(adev->dev, &dev_attr_mem_info_vram_vendor);
>>>>>>>      	if (ret) {
>>>>>>>      		DRM_ERROR("Failed to create device file mem_info_vram_vendor\n");
>>>>>>> -		return ret;
>>>>>>> +		goto VRAM_VERDOR_FAIL;
>>>>>>>      	}
>>>>>>>      
>>>>>>>      	return 0;
>>>>>>> +
>>>>>>> +VRAM_VERDOR_FAIL:
>>>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_used);
>>>>>>> +VIS_VRAM_USED_FAIL:
>>>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vram_used);
>>>>>>> +RVAM_USED_FAIL:
>>>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vis_vram_total);
>>>>>>> +VIS_VRAM_TOTA_FAIL:
>>>>>>> +	device_remove_file(adev->dev, &dev_attr_mem_info_vram_total);
>>>>>>> +VRAM_TOTAL_FAIL:
>>>>>>> +	kfree(mgr);
>>>>>>> +	man->priv = NULL;
>>>>>>> +
>>>>>>> +	return ret;
>>>>>>>      }
>>>>>>>      
>>>>>>>      /**
>