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

[Christian KÃnig]

Am 21.04.20 um 15:39 schrieb èåå:
> åääï"Christian KÃnig" <christian.koenig@xxxxxxx>
> åéææï2020-04-21 21:02:27
> æääï"èåå" <bernard@xxxxxxxx>
> æéäïAlex Deucher <alexander.deucher@xxxxxxx>,"David (ChunMing) Zhou" <David1.Zhou@xxxxxxx>,David Airlie <airlied@xxxxxxxx>,Daniel Vetter <daniel@xxxxxxxx>,Tom St Denis <tom.stdenis@xxxxxxx>,Ori Messinger <Ori.Messinger@xxxxxxx>,Sam Ravnborg <sam@xxxxxxxxxxxx>,amd-gfx@xxxxxxxxxxxxxxxxxxxxx,dri-devel@xxxxxxxxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx,opensource.kernel@xxxxxxxx
> äéïRe: [PATCH] amdgpu: fixes memleak issue when init failed>Am 21.04.20 um 14:09 schrieb èåå:
> > > From: "Christian KÃnig" <christian.koenig@xxxxxxx>
> > > Date: 2020-04-21 19:22:49
> > > To:  Bernard Zhao <bernard@xxxxxxxx>,Alex Deucher <alexander.deucher@xxxxxxx>,"David (ChunMing) Zhou" <David1.Zhou@xxxxxxx>,David Airlie <airlied@xxxxxxxx>,Daniel Vetter <daniel@xxxxxxxx>,Tom St Denis <tom.stdenis@xxxxxxx>,Ori Messinger <Ori.Messinger@xxxxxxx>,Sam Ravnborg <sam@xxxxxxxxxxxx>,amd-gfx@xxxxxxxxxxxxxxxxxxxxx,dri-devel@xxxxxxxxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx
> > > Cc:  opensource.kernel@xxxxxxxx
> > > 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) {
ÂÂÂ DRM_ERROR("Failed to create device file mem_info_vram_total\n");
ÂÂÂ 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)
ÂÂÂ DRM_ERROR("Failed to create device file mem_info_vram_total 
(%d)\n", r);

...
return 0;

Regards,
Christian.


> > 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@xxxxxxxx>
> > > > > ---
> > > > >     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;
> > > > >     }
> > > > >     
> > > > >     /**