Stable kernels 5.1.11, 4.19.52, 4.14.127, 4.9.182, and 4.4.182 have been released. They all contain a relatively small set of important fixes; users should upgrade.

At KubeCon + CloudNativeCon Europe 2019 there was a public meeting of the Cloud Native Computing Foundation (CNCF) Technical Oversight Committee (TOC); its members outlined the current state of the CNCF and where things are headed. What emerged was a picture of how the CNCF's governance is evolving as it brings in more projects, launches a new special interest group mechanism, and contemplates what to do with projects that go dormant.

Security updates have been issued by Arch Linux (chromium and thunderbird), Debian (php-horde-form, pyxdg, thunderbird, and znc), Fedora (containernetworking-plugins, mediawiki, and podman), openSUSE (chromium), Red Hat (bind, chromium-browser, and flash-plugin), SUSE (docker, glibc, gstreamer-0_10-plugins-base, gstreamer-plugins-base, postgresql10, sqlite3, and thunderbird), and Ubuntu (firefox).

The 5.2-rc5 kernel prepatch is out for testing. "But the good news is that we're getting to the later parts of the rc series, and things do seem to be calming down. I was hoping rc5 would end up smaller than rc4, and so it turned out."

There's yet another set of stable kernel updates out there: 5.1.10, 4.19.51, and 4.14.126. Each contains another set of important fixes.

The 2019 Linux Storage, Filesystem, and Memory-Management Summit included a detailed discussion about a memory-management fix that addressed one performance regression while causing another. That fix, which was promptly reverted, is still believed by most memory-management developers to implement the correct behavior, so a patch posted by Andrea Arcangeli in early May has relatively broad support. That patch remains unapplied as of this writing, but the discussion surrounding it has continued at a slow pace over the last month. Memory-management subsystem maintainer Andrew Morton is faced with a choice: which performance regression is more important?

Security updates have been issued by Arch Linux (gvim, lib32-openssl, openssl, and vim), Debian (dbus), Fedora (dovecot, evince, js-jquery-jstree, libxslt, php-phpmyadmin-sql-parser, and phpMyAdmin), openSUSE (neovim and rubygem-rack), Oracle (docker-engine and python), Scientific Linux (python), Slackware (mozilla), and SUSE (containerd, docker, docker-runc, go, go1.11, go1.12, golang-github-docker-libnetwork, elfutils, libvirt, and python-requests).

If a user-space process needs to wait for some event to happen, there is a whole range of mechanisms provided by the kernel to make that easy. But calling into the kernel tends not to work well for the shortest of waits — those measured in small numbers of microseconds. For delays of this magnitude, developers often resort to busy loops, which have a much smaller potential for turning a small delay into a larger one. Needless to say, busy waiting has its own disadvantages, so Intel has come up with a set of instructions to support short delays. A patch set from Fenghua Yu to support these instructions is currently working its way through the review process.

Security updates have been issued by Fedora (firefox, kernel, kernel-headers, libreswan, python-urllib3, and vim), Red Hat (python), SUSE (sssd), and Ubuntu (dbus).

The LWN.net Weekly Edition for June 13, 2019 is available.

In an offshoot of the Debian discussion we looked at last week, the Debian project has been discussing the idea of paying developers to work on the distribution. There is some history behind the idea, going back to the controversial Dunc-Tank initiative in 2006, but some think attitudes toward funding developers may have changed—or that a new approach might be better accepted. While it is playing out with regard to Debian right now, it is a topic that other projects have struggled with along the way—and surely will again.

Security updates have been issued by Debian (libgd2, mediawiki, otrs2, vlc, and zookeeper), Fedora (containernetworking-plugins, kernel, kernel-headers, nodejs-tough-cookie, podman, python-django, and python-urllib3), openSUSE (virtualbox), SUSE (gnome-shell, libcroco, and php7), and Ubuntu (dbus, Neovim, and vim).

Python is, famously, a "batteries included" language; it comes with a rich standard library right out of the box, which makes for a highly useful starting point for everyone. But that does have some downsides as well. The standard library modules are largely maintained by the CPython core developers, which adds to their duties; the modules themselves are subject to the CPython release schedule, which may be suboptimal. For those reasons and others, there have been thoughts about retiring some of the older modules; it is a topic that has come up several times over the last year or so.

The Matrix team has announced the first stable release of the Matrix protocol and specification across all APIs. The Synapse 1.0 reference implementation, which implements the full Matrix 1.0 API surface, has also been released. "Now, before you get too excited, it’s critical to understand that Matrix 1.0 is all about providing a stable, self-consistent, self-contained and secure version of the standard which anyone should be able to use to independently implement production-grade Matrix clients, servers, bots and bridges etc. It does not mean that all planned or possible features in Matrix are now specified and implemented, but that the most important core of the protocol is a well-defined stable platform for everyone to build on. On the Synapse side, our focus has been exclusively on ensuring that Synapse correctly implements Matrix 1.0, to provide a stable and secure basis for participating in Matrix without risk of room corruption or other nastinesses." The announcement also covers the launch of the Matrix.org Foundation.

Interfaces for the reporting of events to user space from the kernel have been a recurring topic on the kernel mailing lists for almost as long as the kernel has existed; LWN covered one 15 years ago, for example. Numerous special-purpose event-reporting APIs exist, but there are none that are designed to be a single place to obtain any type of event. David Howells is the latest to attempt to change that situation with a new notification interface that, naturally, uses a ring buffer to transfer events to user space without the need to make system calls. The API itself (which hasn't changed greatly since it was posted in 2018) is not hugely controversial, but the associated security model has inspired a few heated discussions.

Stable kernels 5.1.9, 4.19.50, 4.14.125, 4.9.181, and 4.4.181 have been released. They all contain important fixes and users should upgrade.

Security updates have been issued by CentOS (bind and thunderbird), Mageia (firefox, ghostscript, graphicsmagick, imagemagick, postgresql, and thunderbird), Oracle (kernel), Red Hat (Advanced Virtualization and rh-haproxy18-haproxy), SUSE (bind, gstreamer-0_10-plugins-base, thunderbird, and vim), and Ubuntu (elfutils, glib2.0, and libsndfile).

BPF is probably familiar to many LWN readers, though it's likely not yet quite as well known in the Kubernetes community — but that could soon change. At KubeCon + CloudNativeCon Europe 2019 there were multiple sessions with BPF in the title where developers talked about how BPF can be used to help with Kubernetes security, monitoring, and even chaos engineering testing. We will look at two of those talks that were led by engineers closely aligned with the open-source Cilium project, which is all about bringing BPF to Kubernetes container environments. Thomas Graf, who contributes to BPF development in the Linux kernel, led a session on transparent chaos testing with Envoy, Cilium, and BPF, while his counterpart Dan Wendlandt, who is well known in the OpenStack community for helping to start the Neutron networking project, spoke about using the kernel's BPF capabilities to add visibility and security in a Kubernetes-aware manner.

Security updates have been issued by Arch Linux (chromium and pam-u2f), Debian (cyrus-imapd), Fedora (curl, cyrus-imapd, kernel, kernel-headers, php, and vim), openSUSE (axis, bind, bubblewrap, evolution, firefox, gnome-shell, libpng16, and rmt-server), Oracle (edk2 and kernel), and SUSE (bind, cloud7, and libvirt).

The 5.2-rc4 kernel prepatch is out for testing. "We've had a fairly calm release so far, and on the whole that seems to hold. rc4 isn't smaller than rc3 was (it's a bit bigger), but rc3 was fairly small, so the size increase isn't all that worrisome. I do hope that we'll start actually shrinking now, though."