Kernel hazard pointers, futexes, and fixes

Kernel traffic on 2026-09-21 focused on concurrency primitives, NVMe multipath recovery, and several memory-safety fixes, with additional cleanup of arm64 big-endian support and an early live-update RFC for VMs. Debate over real-world value and locking correctness dominated the higher-profile threads.

Hazard-pointer series meets skepticism

Paul McKenney and Mathieu Desnoyers posted a third RFC of 28 patches adding a simple hazard-pointer implementation and torture tests. Linus Torvalds questioned the real-world value of the series on linux-kernel. Readers who track lockless algorithms should watch whether the complexity is judged worth carrying in mainline.

Stealable FUTEX_PING RFC raises deadlock concerns

An RFC of 12 patches proposes FUTEX_PING, a stealable futex built on proxy execution for priority-inheritance locks. Peter Zijlstra and others raised deadlock and locking-order concerns during review. The design matters for latency-sensitive code that wants transferable PI locks without classic ownership handoff.

NVMe TP8028 rapid path failure recovery at v6

A v6 series of 18 patches implements NVMe TP8028 cross-controller reset for multipath failure recovery on both host and target. The work targets setups where a controller failure must not leave I/O stranded. Storage developers following NVMe fabric resilience have a concrete recovery path under review.

Garmin GPS USB driver underflow and OOB read fixed

A v2 patch corrects a signed integer underflow and out-of-bounds read in the garmin_gps USB serial driver. The issue can be triggered by a userspace write to /dev/ttyUSB0. The change closes a local attack surface in a long-standing device driver still present in the tree.

arm64 removes unused big-endian support

Will Deacon posted a v3 series of 14 patches that strips all big-endian kernel support on arm64 after CONFIG_CPU_BIG_ENDIAN was marked BROKEN. The cleanup deletes dead code paths that no longer had users. Architecture maintainers and distribution builders can drop related configuration and testing cost.

NOMMU GUP fix for FOLL_PIN refcount mismatch

A v3 patch makes NOMMU __get_user_pages_locked honour FOLL_PIN, correcting a refcount mismatch. The bug could produce use-after-free when io_uring fixed buffers are used. Systems without an MMU that pin user pages need the correction to stay safe.

MD badblocks metadata OOB read fixed

A two-patch series fixes an out-of-bounds read in md_write_metadata driven by bblog_size. The flaw can leak kernel memory to disk during badblocks metadata writes. RAID operators and anyone processing untrusted array metadata should treat the fix as material.

Orphaned VMs RFC for kexec host live update

An RFC of 46 patches presents an early proof of concept for orphaned virtual machines that continue running across kexec-based host live updates. The design adds a KVM caretaker and architecture hooks to preserve CPUs. Operators seeking host updates without stopping VMs will watch whether the approach moves beyond the initial PoC.