Microsoft Code Change Nearly Breaks Linux 6.13 Release

A code change contributed by a Microsoft engineer nearly caused a major disruption to the upcoming stable release of Linux kernel 6.13. Intended as a performance improvement, the change introduced issues on certain systems, especially those with Control Flow Integrity (CFI) enabled, such as machines with Intel Alder Lake processors. An urgent patch from Intel engineer Peter Zijlstra disabled the problematic code, preventing a delay in the 6.13 release. This incident highlights the critical importance of code review and thorough testing before merging code into large, open-source projects.