Linux 6.1 Will Try To Print The CPU Core Where A Seg Fault Occurs

A change now merged for Linux 6.1 will attempt to print the CPU core where a segmentation fault happens. The hope by printing the CPU/core where a segmentation fault happens is that over time trends may materialize with this information potentially being useful for helping to spot faulty CPUs.

Particularly among hyperscalers and those with large fleets of multi-socket servers or even single CPUs, printing the CPU/core where a segmentation fault occurs may be useful if it keeps occurring. If otherwise unexplained seg faults keep occurring on the same CPU or particular core(s), it may provide some insight that there could be a problem with the CPU itself. Up to now the Linux kernel hasn't printed the likely CPU core where such a fault happens.

This change for Linux 6.1 is acknowledged as just being the "likely" CPU core at segmentation fault time but does have chances of being incorrect, but the current approach to handling this was deemed the best way forward by upstream developers. Hopefully over time this information will prove helpful to Linux administrators.

The change was merged as part of the x86/cpu updates for Linux 6.1. That pull also has an optimization to make clear_user() faster. Details on that via this commit.