Linux Kernel 7.2 Updates: Reserved THP Proposal, Stable Fixes, and RAID5 Scalability Boost

Bytedance engineer Qi Zheng has proposed a new feature called Reserved THP for the Linux kernel, aiming to combine the best attributes of HugeTLB and Transparent Huge Pages (THP). The request for comments (RFC) patch series was submitted on June 27, 2026, to the Linux Kernel Mailing List.

The proposal addresses a specific internal use case at Bytedance: during hot upgrades, processes requiring 16GB of HugeTLB memory needed an additional 16GB reserved, leading to wasted memory when the old process exited. Zheng noted that approximately 10GB of the old process's memory is cold and could be reclaimed, but HugeTLB does not support swap, making reclamation difficult.

How Reserved THP Works

Reserved THP would be THP that can be reserved and consumed via methods like madvise(), while normal memory allocations cannot touch it. This mirrors HugeTLB's reservation guarantees but adds THP's support for swap, providing a flexible solution for scenarios like hot upgrades. Key differences from existing mechanisms include:

• HugeTLB offers reservations and guaranteed allocation but no swap support.
• THP integrates tightly with memory management and supports swap but lacks reservations.
• Reserved THP aims to provide reservation capabilities with swap functionality, reducing memory waste in hot-upgrade scenarios.

The RFC notes that previous kernel discussions have explored unifying THP and HugeTLB, but they remain separate. This proposal could be a stepping stone toward that unification.

Stable Kernel Updates and RAID5 Improvements

Three stable kernel updates were released at the same time: versions 7.1.2, 7.0.14, and 6.18.37. Each contains a relatively small number of important fixes, according to LWN.net. Administrators running these longterm or stable series are urged to apply the updates promptly.

Separately, a patch series targeting MD RAID5 scalability has shown performance improvements of up to 10 to 17 percent in some configurations. The patches focus on reducing contention and improving parallelism within the software RAID5 code. The work is part of ongoing efforts to optimize Linux's block layer for modern hardware.

These changes come as the Linux kernel tree surpasses 43 million lines in version 7.2, with ongoing driver removals, performance tuning, and new feature proposals. The Reserved THP proposal, stable updates, and RAID5 patches collectively underscore the kernel's evolution toward better memory management, reliability, and throughput.

Qi Zheng and colleagues at Bytedance plan to continue developing Reserved THP, seeking community feedback on the RFC. The stable kernel updates are available for download now.