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

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Message-ID: <AKoA0wCVCNOygUrJso2wM4qv.3.1587516987209.Hmail.bernard@vivo.com>
Date:   Wed, 22 Apr 2020 08:56:27 +0800 (GMT+08:00)
From:   赵军奎 <bernard@...o.com>
To:     Christian König <christian.koenig@....com>
Cc:     Alex Deucher <alexander.deucher@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Tom St Denis <tom.stdenis@....com>,
        Ori Messinger <Ori.Messinger@....com>,
        Sam Ravnborg <sam@...nborg.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        opensource.kernel@...o.com
Subject: Re:Re: [PATCH] amdgpu: fixes memleak issue when init failed


发件人："Christian König" <christian.koenig@....com>
发送日期：2020-04-21 22:53:47
收件人："赵军奎" <bernard@...o.com>
抄送人：Alex Deucher <alexander.deucher@....com>,"David (ChunMing) Zhou" <David1.Zhou@....com>,David Airlie <airlied@...ux.ie>,Daniel Vetter <daniel@...ll.ch>,Tom St Denis <tom.stdenis@....com>,Ori Messinger <Ori.Messinger@....com>,Sam Ravnborg <sam@...nborg.org>,amd-gfx@...ts.freedesktop.org,dri-devel@...ts.freedesktop.org,linux-kernel@...r.kernel.org,opensource.kernel@...o.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@....com>
>> 发送日期：2020-04-21 21:02:27
>> 收件人："赵军奎" <bernard@...o.com>
>> 抄送人：Alex Deucher <alexander.deucher@....com>,"David (ChunMing) Zhou" <David1.Zhou@....com>,David Airlie <airlied@...ux.ie>,Daniel Vetter <daniel@...ll.ch>,Tom St Denis <tom.stdenis@....com>,Ori Messinger <Ori.Messinger@....com>,Sam Ravnborg <sam@...nborg.org>,amd-gfx@...ts.freedesktop.org,dri-devel@...ts.freedesktop.org,linux-kernel@...r.kernel.org,opensource.kernel@...o.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@....com>
>>>> Date: 2020-04-21 19:22:49
>>>> To:  Bernard Zhao <bernard@...o.com>,Alex Deucher <alexander.deucher@....com>,"David (ChunMing) Zhou" <David1.Zhou@....com>,David Airlie <airlied@...ux.ie>,Daniel Vetter <daniel@...ll.ch>,Tom St Denis <tom.stdenis@....com>,Ori Messinger <Ori.Messinger@....com>,Sam Ravnborg <sam@...nborg.org>,amd-gfx@...ts.freedesktop.org,dri-devel@...ts.freedesktop.org,linux-kernel@...r.kernel.org
>>>> Cc:  opensource.kernel@...o.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?
2 There is no need to free the kzmalloc space(no possibility of memory leak )?

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@...o.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;
>>>>>>     }
>>>>>>     
>>>>>>     /**
>>
>