Re: [PATCH v3] drm/scheduler re-insert Bailing job to avoid memleak

[Andrey Grodzovsky <andrey.grodzovsky@amd.com>]

I actually have a race condition concern here - see bellow -

On 2021-03-17 3:43 a.m., Christian König wrote:
> I was hoping Andrey would take a look since I'm really busy with other 
> work right now.
>
> Regards,
> Christian.
>
> Am 17.03.21 um 07:46 schrieb Zhang, Jack (Jian):
>> Hi, Andrey/Crhistian and Team,
>>
>> I didn't receive the reviewer's message from maintainers on panfrost 
>> driver for several days.
>> Due to this patch is urgent for my current working project.
>> Would you please help to give some review ideas?
>>
>> Many Thanks,
>> Jack
>> -----Original Message-----
>> From: Zhang, Jack (Jian)
>> Sent: Tuesday, March 16, 2021 3:20 PM
>> To: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; 
>> Koenig, Christian <Christian.Koenig@amd.com>; Grodzovsky, Andrey 
>> <Andrey.Grodzovsky@amd.com>; Liu, Monk <Monk.Liu@amd.com>; Deng, 
>> Emily <Emily.Deng@amd.com>; Rob Herring <robh@kernel.org>; Tomeu 
>> Vizoso <tomeu.vizoso@collabora.com>; Steven Price <steven.price@arm.com>
>> Subject: RE: [PATCH v3] drm/scheduler re-insert Bailing job to avoid 
>> memleak
>>
>> [AMD Public Use]
>>
>> Ping
>>
>> -----Original Message-----
>> From: Zhang, Jack (Jian)
>> Sent: Monday, March 15, 2021 1:24 PM
>> To: Jack Zhang <Jack.Zhang1@amd.com>; 
>> dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; 
>> Koenig, Christian <Christian.Koenig@amd.com>; Grodzovsky, Andrey 
>> <Andrey.Grodzovsky@amd.com>; Liu, Monk <Monk.Liu@amd.com>; Deng, 
>> Emily <Emily.Deng@amd.com>; Rob Herring <robh@kernel.org>; Tomeu 
>> Vizoso <tomeu.vizoso@collabora.com>; Steven Price <steven.price@arm.com>
>> Subject: RE: [PATCH v3] drm/scheduler re-insert Bailing job to avoid 
>> memleak
>>
>> [AMD Public Use]
>>
>> Hi, Rob/Tomeu/Steven,
>>
>> Would you please help to review this patch for panfrost driver?
>>
>> Thanks,
>> Jack Zhang
>>
>> -----Original Message-----
>> From: Jack Zhang <Jack.Zhang1@amd.com>
>> Sent: Monday, March 15, 2021 1:21 PM
>> To: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; 
>> Koenig, Christian <Christian.Koenig@amd.com>; Grodzovsky, Andrey 
>> <Andrey.Grodzovsky@amd.com>; Liu, Monk <Monk.Liu@amd.com>; Deng, 
>> Emily <Emily.Deng@amd.com>
>> Cc: Zhang, Jack (Jian) <Jack.Zhang1@amd.com>
>> Subject: [PATCH v3] drm/scheduler re-insert Bailing job to avoid memleak
>>
>> re-insert Bailing jobs to avoid memory leak.
>>
>> V2: move re-insert step to drm/scheduler logic
>> V3: add panfrost's return value for bailing jobs in case it hits the 
>> memleak issue.
>>
>> Signed-off-by: Jack Zhang <Jack.Zhang1@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 4 +++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c    | 8 ++++++--
>>   drivers/gpu/drm/panfrost/panfrost_job.c    | 4 ++--
>>   drivers/gpu/drm/scheduler/sched_main.c     | 8 +++++++-
>>   include/drm/gpu_scheduler.h                | 1 +
>>   5 files changed, 19 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> index 79b9cc73763f..86463b0f936e 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> @@ -4815,8 +4815,10 @@ int amdgpu_device_gpu_recover(struct 
>> amdgpu_device *adev,
>>                       job ? job->base.id : -1);
>>             /* even we skipped this reset, still need to set the job 
>> to guilty */
>> -        if (job)
>> +        if (job) {
>>               drm_sched_increase_karma(&job->base);
>> +            r = DRM_GPU_SCHED_STAT_BAILING;
>> +        }
>>           goto skip_recovery;
>>       }
>>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>> index 759b34799221..41390bdacd9e 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>> @@ -34,6 +34,7 @@ static enum drm_gpu_sched_stat 
>> amdgpu_job_timedout(struct drm_sched_job *s_job)
>>       struct amdgpu_job *job = to_amdgpu_job(s_job);
>>       struct amdgpu_task_info ti;
>>       struct amdgpu_device *adev = ring->adev;
>> +    int ret;
>>         memset(&ti, 0, sizeof(struct amdgpu_task_info));
>>   @@ -52,8 +53,11 @@ static enum drm_gpu_sched_stat 
>> amdgpu_job_timedout(struct drm_sched_job *s_job)
>>             ti.process_name, ti.tgid, ti.task_name, ti.pid);
>>         if (amdgpu_device_should_recover_gpu(ring->adev)) {
>> -        amdgpu_device_gpu_recover(ring->adev, job);
>> -        return DRM_GPU_SCHED_STAT_NOMINAL;
>> +        ret = amdgpu_device_gpu_recover(ring->adev, job);
>> +        if (ret == DRM_GPU_SCHED_STAT_BAILING)
>> +            return DRM_GPU_SCHED_STAT_BAILING;
>> +        else
>> +            return DRM_GPU_SCHED_STAT_NOMINAL;
>>       } else {
>>           drm_sched_suspend_timeout(&ring->sched);
>>           if (amdgpu_sriov_vf(adev))
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c 
>> b/drivers/gpu/drm/panfrost/panfrost_job.c
>> index 6003cfeb1322..e2cb4f32dae1 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
>> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
>> @@ -444,7 +444,7 @@ static enum drm_gpu_sched_stat 
>> panfrost_job_timedout(struct drm_sched_job
>>        * spurious. Bail out.
>>        */
>>       if (dma_fence_is_signaled(job->done_fence))
>> -        return DRM_GPU_SCHED_STAT_NOMINAL;
>> +        return DRM_GPU_SCHED_STAT_BAILING;
>>         dev_err(pfdev->dev, "gpu sched timeout, js=%d, config=0x%x, 
>> status=0x%x, head=0x%x, tail=0x%x, sched_job=%p",
>>           js,
>> @@ -456,7 +456,7 @@ static enum drm_gpu_sched_stat 
>> panfrost_job_timedout(struct drm_sched_job
>>         /* Scheduler is already stopped, nothing to do. */
>>       if (!panfrost_scheduler_stop(&pfdev->js->queue[js], sched_job))
>> -        return DRM_GPU_SCHED_STAT_NOMINAL;
>> +        return DRM_GPU_SCHED_STAT_BAILING;
>>         /* Schedule a reset if there's no reset in progress. */
>>       if (!atomic_xchg(&pfdev->reset.pending, 1)) diff --git 
>> a/drivers/gpu/drm/scheduler/sched_main.c 
>> b/drivers/gpu/drm/scheduler/sched_main.c
>> index 92d8de24d0a1..a44f621fb5c4 100644
>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>> @@ -314,6 +314,7 @@ static void drm_sched_job_timedout(struct 
>> work_struct *work)  {
>>       struct drm_gpu_scheduler *sched;
>>       struct drm_sched_job *job;
>> +    int ret;
>>         sched = container_of(work, struct drm_gpu_scheduler, 
>> work_tdr.work);
>>   @@ -331,8 +332,13 @@ static void drm_sched_job_timedout(struct 
>> work_struct *work)
>>           list_del_init(&job->list);
>>           spin_unlock(&sched->job_list_lock);
>>   -        job->sched->ops->timedout_job(job);
>> +        ret = job->sched->ops->timedout_job(job);
>>   +        if (ret == DRM_GPU_SCHED_STAT_BAILING) {
>> +            spin_lock(&sched->job_list_lock);
>> +            list_add(&job->node, &sched->ring_mirror_list);
>> +            spin_unlock(&sched->job_list_lock);
>> +        }


At this point we don't hold GPU reset locks anymore, and so we could
be racing against another TDR thread from another scheduler ring of same 
device
or another XGMI hive member. The other thread might be in the middle of 
luckless
iteration of mirror list (drm_sched_stop, drm_sched_start and 
drm_sched_resubmit)
and so locking job_list_lock will not help. Looks like it's required to 
take all GPU rest locks
here.

Andrey


>>           /*
>>            * Guilty job did complete and hence needs to be manually 
>> removed
>>            * See drm_sched_stop doc.
>> diff --git a/include/drm/gpu_scheduler.h 
>> b/include/drm/gpu_scheduler.h index 4ea8606d91fe..8093ac2427ef 100644
>> --- a/include/drm/gpu_scheduler.h
>> +++ b/include/drm/gpu_scheduler.h
>> @@ -210,6 +210,7 @@ enum drm_gpu_sched_stat {
>>       DRM_GPU_SCHED_STAT_NONE, /* Reserve 0 */
>>       DRM_GPU_SCHED_STAT_NOMINAL,
>>       DRM_GPU_SCHED_STAT_ENODEV,
>> +    DRM_GPU_SCHED_STAT_BAILING,
>>   };
>>     /**
>> -- 
>> 2.25.1
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