The 7.2-rc4 kernel prepatch is out for testing. Linus said: "This whole week I had the feeling that people were starting to go on summer vacation, but running the numbers shows that I must have been wrong - it all looks pretty normal."

Adrian Mastronardi has released a book called Half a Second; it is a detailed look into the XZ backdoor attempt of 2024. The book is freely available under a (non-free) noncommercial, no-derivatives CC license.

Half a Second tells that story as one continuous narrative: the burned-out volunteer who maintained the code alone and was patiently, expertly manipulated into giving it up; the engineer whose half-second of curiosity caught the attack through a chain of luck and hard-won instinct; and the operator who built it, who has never been identified and, this book argues, may never be.

The 7.1.4, 6.18.39, and 6.12.96 stable kernel updates have been released; each contains a fairly large set of important fixes.

The extensible scheduler class (sched_ext) allows the installation of custom CPU schedulers as a set of BPF programs. While sched_ext, in its current form, has already led to a lot of interesting scheduler-development work, the subsystem itself is still undergoing rapid evolution. Among other work, the ability to set up a hierarchy of sub-schedulers is approaching completion, and a longstanding incompatibility with proxy execution is coming to an end.

Inside this week's LWN.net Weekly Edition:

• Front: Fighting scraper bots; io_uring queues; Filesystem testing; BPF shielding; Sending packets from BPF; Kitty; QBE.
• Briefs: Shim security; seunshare vulnerability; Debian bookworm; Rust 1.97.0; Linux.org; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

Processes that use io_uring tend to keep a lot of balls in the air; being able to have many operations underway at any given time is part of the point of that API in the first place. The io_uring subsystem must, as a result, keep track of a lot of tasks that have to be performed at the right time. In current kernels, io_uring uses a standard kernel linked-list primitive to track those work items. As of the 7.2 kernel release, though, io_uring will, instead, use a new lockless, multi-producer, single-consumer (MPSC) queue, resulting in some notable performance gains. Lockless algorithms tend to be tricky, but the one used here is relatively approachable and shows how these algorithms can work.

The CMU CERT Coordination Center has put out an advisory that many exploitable versions of the shim binary, used to boot Linux on systems with UEFI secure boot enabled, were never added to the revocation list.

An attacker with administrative privileges or the ability to modify the boot process could use one of the vulnerable shim bootloaders to bypass Secure Boot protections and execute arbitrary code before the operating system loads. Code executed during this early boot phase may achieve persistent compromise of the platform, including the ability to load unsigned or malicious kernel components that can survive system reboots and, in some cases, operating system reinstallation.

The advisory contains a list of vulnerable shims.

Rob Kennedy has posted the story of the birth of Linux.org — one of the earliest Linux-related web sites — and its more recent rebirth.

The site was founded in May 1994 by Michael McLagan, at a time when Linux itself was barely three years old. Linus Torvalds had only just released it to the world, there was no real way for a newcomer to find their footing, no search engines, no Wikipedia, none of the infrastructure people take for granted now for figuring out a new piece of technology. Michael built linux.org to fill that gap, a place for people to learn about Linux and follow the movement as it grew.

The Maintainers Summit is an annual, invitation-only gathering of kernel developers and maintainers to discuss development-process issues; see LWN's 2025 Maintainers Summit coverage for an example. The call for topics for the 2026 gathering (Prague, October 8) has gone out. One of the best ways to obtain an invitation to the Summit is with a good topic proposal. For best consideration, topics should be submitted before July 24.

The 7.2-rc3 kernel prepatch is out for testing. Linus said: "Things continue to look normal (the 'new normal' with slightly higher rates of commits, although I do get the feeling that we're seeing that slightly balanced out by people starting to go on summer vacation)".

Our article "Fighting the AI scraper bot scourge", published in early 2025, discussed the problem of widespread scraping of web sites in search of training data for large language models and related projects. This activity overwhelms sites with traffic. Over a year after that article is published, the problem is still growing. The hammering of sites by shadowy actors has reached new heights, and the open web is becoming increasingly difficult to maintain. Where is this traffic coming from, and what can be done about it?

Security updates have been issued by AlmaLinux (aardvark-dns, cups, edk2, gstreamer1-plugins-bad-free, gstreamer1-plugins-good, gstreamer1-plugins-ugly-free, kernel, libsolv, libtasn1, libxml2, nginx:1.24, nginx:1.26, oci-seccomp-bpf-hook, python-urllib3, and tomcat), Debian (rlottie), Fedora (c-ares, k9s, kind, libXfont2, nmap, pam, perl-DBI, php, python-pendulum, tmux, and xorg-x11-server-Xwayland), Mageia (7zip and ack), Slackware (tigervnc), SUSE (alloy, cargo-c, chromium, clamav, cosign, dirmngr, firefox, flannel, fluidsynth, gnutls, go1.25, go1.26, gol, GraphicsMagick, helm, kernel-devel, libaom, libexif, openQA, os-autoinst, python-Django, python-idna, python-sqlparse, rust-keylime, rustup, sccache, SUSE Manager Client Tools, SUSE_Multi-Linux_Manager Client Tools, transmission, and warewulf4), and Ubuntu (curl, expat, golang-go.crypto, libheif, libidn, libraw, libsoup2.4, linux, linux-azure-4.15, linux-azure-fips, linux-fips, linux-gcp-4.15, linux-gcp-fips, linux-kvm, linux-oracle, linux-aws, linux-aws-fips, linux-azure-fips, linux-fips, linux-raspi, linux-xilinx-zynqmp, and python2.7, python3.5).

Version 1.97.0 of the Rust programming language has been released. Changes include using a new symbol-mangling scheme by default, support for denying warnings in Cargo, and an end to the practice of hiding the linker's output after a successful build.

Security updates have been issued by AlmaLinux (389-ds-base, aardvark-dns, buildah, compat-openssl10, freeipmi, frr, gnutls, grafana, grafana-pcp, kernel, kernel-rt, libyang, nginx, openexr, pcs, perl-HTTP-Daemon, postgresql:18, python3.14-pip, skopeo, tomcat9, and wireshark), Debian (chromium and pgextwlist), Fedora (openssh, opkssh, perl-CSS-Minifier-XS, python-jiter, python-nh3, python-pendulum, rust-jiter, and upower), Mageia (openvpn and vips), Oracle (389-ds-base, aardvark-dns, compat-openssl10, container-tools:ol8, freeipmi, kernel, libyang, perl-HTTP-Daemon, python3.14-pip, and skopeo), Slackware (libXfont2, proftpd, and xorg-server), SUSE (alloy, apache2, apptainer, assimp, chromium, clamav, docker, docker-compose, dracut, glib-networking, go-sendxmpp, go1.26-openssl, gstreamer-plugins-good, haproxy, hauler, jackson-annotations, jackson-bom, jackson-core, jackson- databind, jackson-dataformats-binary, jackson-modules-base, jackson-parent, kernel, krb5, kubevirt, libslirp, libXfont2, mpv, libkpipewirerecord6, ffmpegthumbs-kf5, netty, netty-tcnative, openqa, os-autoinst, podman, python-maturin, python-msgpack, python313-yt-dlp, radare2, rust-keylime, systemd, systemd, systemd-mini, tomcat11, trivy, xorg-x11-server, and xwayland), and Ubuntu (apache2, clamav, linux-raspi, and mailcap).

Security updates have been issued by AlmaLinux (container-tools:rhel8, kernel-rt, libreoffice, nodejs:22, nodejs:24, opentelemetry-collector, perl-HTTP-Daemon, and python-markdown), Debian (dpkg, imagemagick, and postfix), Fedora (betterleaks, docker-compose, firefox, helm, perl-Compress-Raw-Bzip2, perl-IO-Compress, perl-JavaScript-Minifier-XS, python-cramjam, python-fastar, python-pillow-jxl-plugin, python-rignore, and tor), Oracle (grafana, grafana-pcp, and ruby:4.0), Slackware (tftp), SUSE (gi-docgen, glibc, helm, helm3, json-c-devel, kubevirt-1.6, librpmbuild10, python313-dulwich, python313-lxml_html_clean, python313-openapi-spec-validator, and sdbootutil), and Ubuntu (ruby-addressable).

Conversations about the kernel's filesystem implementations often involve a layer called "iomap", but relatively few people can reliably say what iomap actually is. That is just the kind of gap that LWN exists to fill. In short, iomap handles the mapping between data in the filesystem space (identified by a file of interest, and an offset within that file) and in the storage space (which may be a memory location, or a set of blocks on a storage device). Using that mapping, iomap handles a long list of common, filesystem-related tasks, allowing a lot of boilerplate code to be removed from individual filesystem implementations.

The 7.2-rc2 kernel prepatch is out for testing. Linus said: "It's Sunday afternoon, and rc2 is out. Things look very normal - it's not a small rc2, but it's in line with recent releases, and slightly smaller than rc2 was in 7.1. Let's see how that all continues, but so far so good."

The kernel community (like many other free-software projects) has recently seen a large influx of patches developed with the assistance of large language models (LLMs). Those patches tend to come from developers who were previously unknown to the community. At the moment, though, the memory-management developers are evaluating two large patch sets, developed with LLM assistance, that were submitted by established and well-respected developers. The rather different reception accorded to that work may give insights into how LLM-generated contributions will be handled going forward.

Linus Torvalds released 7.2-rc1 and closed the 7.2 merge window on June 28; by that time, 13,412 non-merge commits had found their way into the mainline. That makes this the busiest merge window since the 6.7 development cycle in 2024 (15,418 commits, including 2,800 for the entire bcachefs development history). Just under half of those commits arrived after LWN's summary of the first half of the merge window was written. As usual, the commits in the latter part of the merge window were more heavily focused on fixes, but there were still a lot of new features and significant changes merged as well.

The 7.2-rc1 kernel prepatch is out for testing. Linus said: "So two weeks have passed, and the merge window is closed. Things look reasonably normal for this release (knock wood)."