Two milestones arrived in the same release candidate last weekend, and both have been years in the making. Linux 7.2-rc4 dropped on July 19 with Cache-Aware Scheduling finally merged into the mainline kernel — a task placement optimization that has been in development across multiple kernel cycles — and with the last vestiges of the deprecated strncpy API permanently removed after a six-year cleanup effort.
The full rc4 changelog covers both changes along with Btrfs large folios enabled by default, initial AMDGPU HDMI 2.1 FRL support, USB4STREAM, and AMD ISP4 camera support. The stable 7.2 release is currently tracking for August 2026.
Cache-Aware Scheduling: What It Does
Modern CPUs — particularly AMD's Zen architecture — have complex cache hierarchies. Tasks running on different cores don't all share the same L3 cache slices, and migrating a thread across a cache boundary means cold-starting its working set. The kernel's existing scheduler knows about CPU topology (cores, clusters, NUMA nodes) but has historically made migration decisions without explicitly accounting for cache warmth or the cost of crossing cache domain lines.
Cache-Aware Scheduling (CAS) adds that accounting. The scheduler now tracks cache affinity and weights migration decisions against the cost of reloading hot data. According to the LKML merge announcement, benchmarks on AMD Zen 5 hardware show up to 100% higher throughput in database workloads — MongoDB is the cited reference — due to dramatically reduced cache misses during task migration. The gain varies by workload: highly cache-sensitive server applications benefit the most, while single-threaded workloads see little change.
Linus Torvalds noted in the rc4 announcement that AI-assisted profiling tools were used during CAS development to identify migration patterns that human reviewers had consistently missed — a first for a major scheduler subsystem change.
The End of strncpy
The kernel's long campaign against strncpy is over. The function has been considered unsafe in kernel code since at least 2018 because it doesn't guarantee null termination of the destination buffer when the source string is longer than the specified size — a class of bug responsible for several historical vulnerabilities. The kernel community began a systematic replacement effort around 2020, migrating call sites to strscpy and related safe alternatives.
As of 7.2-rc4, the final call sites are gone and the internal strncpy implementation has been removed from the kernel's string library. New code that tries to use it will fail to compile. For users, this means one fewer category of string-handling bug is possible in kernel drivers and subsystems going forward.
Other Notable Changes in rc4
- Btrfs large folios: The Btrfs filesystem now enables large folios (multi-page memory mappings) by default, reducing memory management overhead and improving sequential I/O throughput on NVMe storage.
- AMDGPU HDMI 2.1 FRL: Initial support for Fixed Rate Link signaling in AMD's GPU driver, required for true 4K/144Hz and 8K/60Hz output over HDMI 2.1 on newer AMD hardware.
- USB4STREAM: A new USB4 streaming transport protocol that allows high-bandwidth low-latency data transfer between USB4 devices, targeted at external GPU and capture card use cases.
Ubuntu 26.10 Target
Linux 7.2 is the target kernel for Ubuntu 26.10 "Stonking Stingray", which means these changes will land in the standard Ubuntu release track when 26.10 ships in October 2026. For users on Ubuntu 26.04 LTS, the 7.2 kernel will be available via the hardware enablement stack shortly after the stable release.
Stable release is expected in late August 2026 if the rc cycle stays on its current schedule.