Re: [PATCH 15/20] drm/i915/selftests: handle allocation failures

[Matthew Auld <matthew.auld@intel.com>]

On 03/02/2022 09:05, Thomas Hellström wrote:
> 
> On 1/26/22 16:21, Matthew Auld wrote:
>> If we have to contend with non-mappable LMEM, then we need to ensure the
>> object fits within the mappable portion, like in the selftests, where we
>> later try to CPU access the pages. However if it can't then we need to
>> gracefully handle this, without throwing an error.
>>
>> Also it looks like TTM will return -ENOMEM if the object can't be
>> placed.
> 
> We should probably have a look at why that happens. I thought ttm would 
> return -ENOSPC, which we then converted to -ENXIO in i915_ttm_err_to_gem().

IIRC it was in ttm_bo_mem_space(), where right at the end it does ret = 
-ENOMEM, after failing to evict buffers.

> 
> /Thomas
> 
> 
> 
>> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/gem/selftests/huge_pages.c      | 2 +-
>>   drivers/gpu/drm/i915/selftests/intel_memory_region.c | 8 +++++++-
>>   2 files changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c 
>> b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> index 42db9cd30978..3caa178bbd07 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> @@ -1344,7 +1344,7 @@ static int igt_ppgtt_smoke_huge(void *arg)
>>           err = i915_gem_object_pin_pages_unlocked(obj);
>>           if (err) {
>> -            if (err == -ENXIO || err == -E2BIG) {
>> +            if (err == -ENXIO || err == -E2BIG || err == -ENOMEM) {
>>                   i915_gem_object_put(obj);
>>                   size >>= 1;
>>                   goto try_again;
>> diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c 
>> b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> index 04ae29779206..87bff7f83554 100644
>> --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> @@ -822,8 +822,14 @@ static int igt_lmem_create_with_ps(void *arg)
>>           i915_gem_object_lock(obj, NULL);
>>           err = i915_gem_object_pin_pages(obj);
>> -        if (err)
>> +        if (err) {
>> +            if (err == -ENXIO || err == -E2BIG || err == -ENOMEM) {
>> +                pr_info("%s not enough lmem for ps(%u) err=%d\n",
>> +                    __func__, ps, err);
>> +                err = 0;
>> +            }
>>               goto out_put;
>> +        }
>>           daddr = i915_gem_object_get_dma_address(obj, 0);
>>           if (!IS_ALIGNED(daddr, ps)) {