kbuild speedups, BPF Landlock friction, ARM cleanup

Kernel traffic focused on build-system performance gains and contested BPF interfaces to Landlock. Security fixes for trampolines and libbpf, plus ARM platform removal and swap redesign proposals, rounded out the day.

kbuild series claims large build speedups

A 23-patch kbuild series proposes parallelization and Kconfig caching that the author says can cut allmodconfig build times by up to 36 percent. Linus Torvalds and eleven other developers are reviewing the changes on linux-kernel. Frequent rebuilders have a direct stake in whether the claimed wall-clock savings hold up.

BPF Landlock ruleset interface meets resistance

A 15-patch bpf-next series adds a BPF interface for applying Landlock rulesets. The BPF maintainer objects to exposing LSM kfuncs for this purpose on stability and community-friction grounds, while the LSM maintainer pushes back. The dispute matters because it tests the boundary between BPF helpers and LSM policy machinery.

BPF trampoline use-after-free patched

A two-patch bpf series fixes a use-after-free of programs detached from busy trampolines by employing nop-skip patching and adds a KASAN-triggering selftest. Five participants discussed the v2 revision. The fix is relevant for anyone using BPF trampolines under concurrent detach loads.

Rust UFS driver RFC draws midlayer objections

An RFC introduces a Rust UFS host controller driver that bypasses the SCSI midlayer to speak directly to blk-mq. Maintainers object to the duplication and invoke earlier USB precedent, with seven participants on rust-for-linux. The exchange highlights continuing disagreement over how Rust drivers should reuse or avoid existing midlayers.

Deprecated ARM platforms removal series

Arnd Bergmann posted a 13-patch series that removes multiple deprecated ARM platforms from mach-*. The work has collected acks and only limited pushback from enthusiasts across 36 participants. The cleanup reduces ongoing maintenance cost for hardware that is no longer practical to support.

libbpf struct_ops offset validation

A three-patch bpf series corrects an ASan-reported out-of-bounds read in libbpf struct_ops bitfield handling and adds member-offset validation. Three participants reviewed the v2 patches. The change hardens struct_ops map users against malformed member layouts.

xswap extendable swap devices proposed

A 12-patch MM series introduces xswap, dynamically growable and shrinkable swap devices backed solely by zswap with lazy cluster metadata. The thread so far has a single participant presenting the design. Memory-management developers gain a path to more flexible swap sizing without traditional backing stores.

close() EINTR behavior RFC

An RFC proposes that Linux close() never return EINTR, closing an ABI and POSIX mismatch and removing unsafe retry semantics. Four participants discussed the single-patch idea. Applications that currently special-case EINTR from close would be affected by the change.