Continued technology scaling is resulting in systems with billions of devices. Unfortunately, these devices are prone to failures from various sources, resulting in even commodity systems being affected by the growing reliability threat. Thus, traditional solutions involving high redundancy or piecemeal solutions targeting specific failure modes will no longer be viable owing to their high overheads. Recent reliability solutions have explored using low-cost monitors that watch for anomalous software behavior as a symptom of hardware faults. We previously proposed the SWAT system that uses such low-cost detectors to detect hardware faults, and a higher cost mechanism for diagnosis. However, all of the prior work in this context, including SWAT, assumes single-threaded applications and has not been demonstrated for multithreaded applications running on multicore systems. This paper presents mSWAT, the first work to apply symptom based detection and diagnosis for faults in multicore ar...