linux-kernel - Re: [PATCH 2/2] drm/amdgpu: Make use of drm_wedge_app

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Message-ID: <Z8KjZfLYjH6ehYwy@black.fi.intel.com>
Date: Sat, 1 Mar 2025 08:04:21 +0200
From: Raag Jadav <raag.jadav@...el.com>
To: André Almeida <andrealmeid@...lia.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	kernel-dev@...lia.com, amd-gfx@...ts.freedesktop.org,
	intel-xe@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
	Alex Deucher <alexander.deucher@....com>,
	'Christian König' <christian.koenig@....com>,
	siqueira@...lia.com, airlied@...il.com, simona@...ll.ch,
	rodrigo.vivi@...el.com, jani.nikula@...ux.intel.com
Subject: Re: [PATCH 2/2] drm/amdgpu: Make use of drm_wedge_app_info

On Fri, Feb 28, 2025 at 06:49:43PM -0300, André Almeida wrote:
> Hi Raag,
> 
> On 2/28/25 11:58, Raag Jadav wrote:
> > On Fri, Feb 28, 2025 at 09:13:53AM -0300, André Almeida wrote:
> > > To notify userspace about which app (if any) made the device get in a
> > > wedge state, make use of drm_wedge_app_info parameter, filling it with
> > > the app PID and name.
> > > 
> > > Signed-off-by: André Almeida <andrealmeid@...lia.com>
> > > ---
> > >   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 19 +++++++++++++++++--
> > >   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c    |  6 +++++-
> > >   2 files changed, 22 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > index 00b9b87dafd8..e06adf6f34fd 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > @@ -6123,8 +6123,23 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
> > >   	atomic_set(&adev->reset_domain->reset_res, r);
> > > -	if (!r)
> > > -		drm_dev_wedged_event(adev_to_drm(adev), DRM_WEDGE_RECOVERY_NONE, NULL);
> > > +	if (!r) {
> > > +		struct drm_wedge_app_info aux, *info = NULL;
> > > +
> > > +		if (job) {
> > > +			struct amdgpu_task_info *ti;
> > > +
> > > +			ti = amdgpu_vm_get_task_info_pasid(adev, job->pasid);
> > > +			if (ti) {
> > > +				aux.pid = ti->pid;
> > > +				aux.comm = ti->process_name;
> > > +				info = &aux;
> > > +				amdgpu_vm_put_task_info(ti);
> > > +			}
> > > +		}
> > Is this guaranteed to be guilty app and not some scheduled worker?
> 
> This is how amdgpu decides which app is the guilty one earlier in the code
> as in the print:
> 
>     ti = amdgpu_vm_get_task_info_pasid(ring->adev, job->pasid);
> 
>     "Process information: process %s pid %d thread %s pid %d\n"
> 
> So I think it's consistent with what the driver thinks it's the guilty
> process.

Sure, but with something like app_info we're kind of hinting to userspace
that an application was _indeed_ involved with reset. Is that also guaranteed?

Is it possible that an application needlessly suffers from a false positive
scenario (reset due to other factors)?

Raag