linux-kernel - Re: [PATCH] drm/amdgpu: add vm fault information to devcoredump

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Date: Thu, 7 Mar 2024 14:07:15 +0530
From: "Khatri, Sunil" <sukhatri@....com>
To: Christian König <christian.koenig@....com>,
 Sunil Khatri <sunil.khatri@....com>, Alex Deucher
 <alexander.deucher@....com>, Shashank Sharma <shashank.sharma@....com>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, Mukul Joshi <mukul.joshi@....com>,
 Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>
Subject: Re: [PATCH] drm/amdgpu: add vm fault information to devcoredump


On 3/7/2024 1:47 PM, Christian König wrote:
> Am 06.03.24 um 19:19 schrieb Sunil Khatri:
>> Add page fault information to the devcoredump.
>>
>> Output of devcoredump:
>> **** AMDGPU Device Coredump ****
>> version: 1
>> kernel: 6.7.0-amd-staging-drm-next
>> module: amdgpu
>> time: 29.725011811
>> process_name: soft_recovery_p PID: 1720
>>
>> Ring timed out details
>> IP Type: 0 Ring Name: gfx_0.0.0
>>
>> [gfxhub] Page fault observed for GPU family:143
>> Faulty page starting at address 0x0000000000000000
>> Protection fault status register:0x301031
>>
>> VRAM is lost due to GPU reset!
>>
>> Signed-off-by: Sunil Khatri <sunil.khatri@....com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_reset.c | 15 ++++++++++++++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_reset.h |  1 +
>>   2 files changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.c
>> index 147100c27c2d..d7fea6cdf2f9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.c
>> @@ -203,8 +203,20 @@ amdgpu_devcoredump_read(char *buffer, loff_t 
>> offset, size_t count,
>>                  coredump->ring->name);
>>       }
>>   +    if (coredump->fault_info.status) {
>> +        struct amdgpu_vm_fault_info *fault_info = 
>> &coredump->fault_info;
>> +
>> +        drm_printf(&p, "\n[%s] Page fault observed for GPU 
>> family:%d\n",
>> +               fault_info->vmhub ? "mmhub" : "gfxhub",
>> +               coredump->adev->family);
>> +        drm_printf(&p, "Faulty page starting at address 0x%016llx\n",
>> +               fault_info->addr);
>> +        drm_printf(&p, "Protection fault status register:0x%x\n",
>> +               fault_info->status);
>> +    }
>> +
>>       if (coredump->reset_vram_lost)
>> -        drm_printf(&p, "VRAM is lost due to GPU reset!\n");
>> +        drm_printf(&p, "\nVRAM is lost due to GPU reset!\n");
>>       if (coredump->adev->reset_info.num_regs) {
>>           drm_printf(&p, "AMDGPU register dumps:\nOffset:     
>> Value:\n");
>>   @@ -253,6 +265,7 @@ void amdgpu_coredump(struct amdgpu_device 
>> *adev, bool vram_lost,
>>       if (job) {
>>           s_job = &job->base;
>>           coredump->ring = to_amdgpu_ring(s_job->sched);
>> +        coredump->fault_info = job->vm->fault_info;
>
> That's illegal. The VM pointer might already be stale at this point.
>
> I think you need to add the fault info of the last fault globally in 
> the VRAM manager or move this to the process info Shashank is working on.
> Are you saying that during the reset or otherwise a vm which is part 
> of this job could have been freed  and we might have a NULL 
> dereference or invalid reference? Till now based on the resets and 
> pagefaults that i have created till now using the same app which we 
> are using for IH overflow i am able to get the valid vm only.
>
> Assuming  amdgpu_vm is freed for this job or stale, are you suggesting 
> to update this information in adev-> vm_manager along with existing 
> per vm fault_info or only in vm_manager ?
>
> Regards,
> Christian.
>
>>       }
>>         coredump->adev = adev;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.h
>> index 60522963aaca..3197955264f9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_reset.h
>> @@ -98,6 +98,7 @@ struct amdgpu_coredump_info {
>>       struct timespec64               reset_time;
>>       bool                            reset_vram_lost;
>>       struct amdgpu_ring            *ring;
>> +    struct amdgpu_vm_fault_info    fault_info;
>>   };
>>   #endif
>