As TFA says, they are running the algorithm multiple times and they check that the results match, to guard against transient errors caused by radiation.

The permanent errors caused by radiation must be identified by periodic self tests. When the permanent damage is in a redundant structure, e.g. as mentioned in TFA when they find some memory bits that are permanently damaged, they must avoid using what is damaged.

Eventually radiation will destroy something that is essential, but until then the Snapdragon CPU should be usable.