Peter Oskolkov posted patches titled Introduce FUTEX_SWAP, which attempts to begin the process of upstreaming a Google in-house threading performance optimisation that’s been deployed widely in production for many years. The basic idea is to move from a 1:1 (kernel threading) model in which every thread has both a userspace and kernel context to an M:N (hybrid) model in which there are N userspace threads multiplexed onto M kernel contexts. The work is described in a paper and a video linked from the patch: https://lwn.net/Articles/824409.
Steven Price posted patches enabling KVM guest support for Arm’s Memory Tagging Extension (MTE). The new architecture feature aims to enhance application security by assigning tags to memory locations. When a memory access is performed, the correct tag must be used. If it’s not (as in various security vulnerabilities involving exploit code) then the exploit can’t function. It can be extended to guest virtual machines, for example running in the cloud.
Ted Ts’o reminded everyone that he’s collecting submissions of topics for the 2020 Maintainers/Kernel Summit. So far a limited number of proposals have been made, which he attributed to the pandemic and its impact on organising events.