Torvalds removes unsafe __get_user() and __put_user() from the x86 Linux kernel

Linus Torvalds has removed __get_user() and __put_user() and their interfaces from the x86 kernel across 48 commits and 50 files, cutting 801 lines. The functions turned out slower than standard helpers on modern CPUs due to STAC/CLAC costs and skipped address validation. Claude was used for part of the conversion.

• The removal spans 48 commits and 50 files, cutting 801 lines of code
• STAC/CLAC overhead makes the functions slower than standard helpers on modern CPUs
• Skipping address validation made __get_user() and __put_user() unsafe
• Nontrivial uses on sparc32, m68k and MIPS are left to their maintainers