Kernel: BPF callx, J1939 fix, RISC-V IOMMU

BPF gained indirect subprogram calls on bpf-next while memory management and architecture series advanced. A CAN J1939 validation fix closed a local panic path, and debate continued over virtualized swap accounting.

BPF indirect subprogram calls land on bpf-next

A 17-patch series adding callx support for indirect calls of BPF subprograms via function pointers has landed on bpf-next. The work updates the JIT, verifier, liveness analysis, and call-graph handling. Complex BPF programs gain more flexible control flow while retaining existing safety checks.

J1939 packet number check closes local panic

A patch to the CAN J1939 stack validates the EDPO packet number in ETP.CM_DPO messages. Without the check an unprivileged user on a virtual CAN interface could trigger an skb dereference and kernel panic. The fix removes a straightforward local denial-of-service vector in industrial networking code.

RISC-V IOMMU enables MSI remapping and VFIO

Version 6 of a 16-patch series adds IMSIC MSI remapping and iommufd support for RISC-V. The changes enable IOMMU_DMA and VFIO by default. The architecture moves closer to feature parity with other platforms for device passthrough and DMA isolation.

Userland page table freeing made RCU-safe

A 12-patch series at version 5 converts remaining architectures to RCU-safe page table freeing. It removes the MMU_GATHER_RCU_TABLE_FREE option and enables lockless RCU walks. The memory management core becomes simpler while page table teardown gains concurrency.

Frequency-guided promotion proposed for MGLRU

An RFC version 2 series introduces frequency-guided promotion for the multi-generational LRU together with flag and API cleanups. The authors report 10-40 percent gains and fixes for PSI and workingset tracking. Reclaim heuristic work now has new interfaces and performance data to evaluate.

Path forward debated for virtualized swap

Memory management developers are discussing how to redefine memory.swap cgroup semantics for virtualized and zswap entries. Google engineers have cited breakage risks for existing v1 and v2 deployments. The thread seeks a balance between new virtualization needs and compatibility for current users.

mlx5 VFIO self-test support reaches v7

Jason Gunthorpe posted a 10-patch series adding mlx5 support for VFIO self tests. The series was largely generated by Claude over four days. Automated testing coverage expands for the Mellanox driver under VFIO.

BPF-based MIPI-DSI panel driver proposed

A six-patch series proposes a generic MIPI-DSI panel driver whose initialization sequences are supplied from userspace via BPF. The design follows the HID-BPF model. Panel bring-up can proceed without a new kernel driver for every variant.