[PATCH 3/3] drm/amdgpu: Fix multi-level page table bugs for large BOs

Michel Dänzer michel at daenzer.net
Wed Mar 29 14:46:27 UTC 2017

On 29/03/17 11:32 PM, Felix Kuehling wrote:
> On 17-03-29 02:52 AM, Christian König wrote:
>> Please clean that up and also remove all those WARN_ON(), we don't
>> want to spam the system log with backtraces like this.
> I disagree. When you see the backtraces from WARN_ONs in
> amdgpu_vm_get_pt, it means the driver is trying to update a page table
> that hasn't been allocated. Without those WARN_ONs there is absolutely
> no warning of any kind - amdgpu_vm_update_pte just fails silently (it's
> a void function).
> Therefore I wouldn't call those warnings spam. Given that the VM PT
> allocation code for multi-levels is non-trivial, I think that's a good
> sanity check to have and really helpful to see in a log when user report
> random VM faults.

WARN_ON_ONCE might be a compromise. We'll still get a backtrace, but it
won't cause crazy log spam if the bad condition is consistently hit.

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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