Linux provides a system call (mkdir()) to create a directory, and a few variants of open() that can open a directory. There is, however, no system call in Linux that can create and open a directory in a single, race-free call. Jori Koolstra has been working on remedying that situation, most recently by repurposing a set of open() flags that currently return an error. There are, however, concerns that show just how hard it can be to create user-space interfaces that do not present traps for application developers.

The kernel's read-copy-update (RCU) subsystem ensures that data will not be deleted until it is known that there are no threads holding references to it. RCU works well and is widely used throughout the kernel, but it can increase memory use and add significant delays before unused kernel objects are cleaned up. Hazard pointers are an alternative approach to lockless data updates that offers better performance, for some situations at least. The kernel community is currently considering a hazard-pointer implementation by Mathieu Desnoyers and Paul McKenney.

The 7.2-rc5 kernel prepatch is out for testing. Linus said: "So it's a bit too big for my liking, but nothing in there strikes me as particularly strange or scary".

The Debian project is considering a general resolution on the use of large language models in the creation of the distribution. There are three alternatives to consider: a total ban on LLM usage, rejecting LLMs "as far as practical", or explicitly allowing LLM usage subject to a set of conditions. The discussion period has just begun; the beginning of the voting period does not yet appear to have been set. Those who want to look over the discussion ahead of the inevitable LWN article can find it over here.

On July 21, the kernel community lost Dan Williams, one of its most beloved contributors. Dave Hansen and Thomas Gleixner, both of whom worked with Williams extensively, have written an obituary and allowed LWN to publish it. He will be deeply missed, but he has left us with a lot to remember him by.

Security updates have been issued by AlmaLinux (compat-openssl11, java-1.8.0-openjdk, java-17-openjdk, kernel, kernel-rt, and sssd), Debian (exim4), Fedora (chromium, dotnet10.0, mbedtls, mupdf, netatalk, python-django5, skopeo, sssd, and wget1), Mageia (libevent and transmission), Oracle (.NET 8.0, 389-ds-base, aardvark-dns, acl, buildah, cifs-utils, dovecot, dracut, galera and mariadb11.8, glibc, hplip, kernel, libxml2, nginx, openexr, podman, postgresql18, rsync, thunderbird, and vim), and SUSE (389-ds, afterburn, agama, alsa, apache-commons-compress, apache-ivy, brotli-java, zstd-jni, avahi, aws-nitro-enclaves-cli, cockpit, cockpit-machines, cockpit-packages, cockpit- podman, cockpit-repos, cockpit-subscriptions, container-suseconnect, containerd, cosign, cryptsetup, curl, dash, dnsmasq, docker, docker-compose, ffmpeg, firefox, freetype2, gawk, gh, glib-networking, glib2, go1.25, go1.25-openssl, go1.26, go1.26-openssl, google-guest-agent, google-osconfig-agent, gpg2, gsasl, gstreamer-plugins-bad, gzip, haproxy, hauler, helm, helm3, ImageMagick, imagemagick, iproute2, java-11-openjdk, java-26-openjdk, jline3, joe, jq, kernel, kernel-devel, krb5, kubevirt, libgcrypt, libpng12, libqt4, libssh2_org, libXfont2, libxml2, mariadb-connector-c, microcode_ctl, multipath-tools, nasm, net-tools, nghttp2, nmap, ntfs-3g_ntfsprogs, openexr, packagekit, pam, patch, perl, perl-DBI, perl-dbi, perl-http-date, perl-libwww-perl, perl-xml-bare, php8, prometheus-ha_cluster_exporter, python-aiohttp, python-cryptography, python-dulwich, python-idna, python-maturin, python-mistune, python-msgpack, python-paramiko, python-Pillow, python-pyasn1, python-soupsieve, python-sqlparse, python-tornado, python-tornado6, python-urllib3, python313, python313-pandas, python314, qemu, radvd, rootlesskit, rpcbind, ruby3.4, runc, s390-tools, shibboleth-sp, sssd, systemd, systemd, systemd-mini, terraform-provider-aws, terraform-provider-azurerm, terraform-provider-external, terraform-provider-google, terraform-provider-helm, terraform-provider-kubernetes, terraform-provid, terraform-provider-susepubliccloud, tiff, tomcat, tomcat10, tomcat11, uriparser, vim, vorbis-tools, wget, wpa_supplicant, xwayland, and yelp).

Version 2.44 of the GNU C Library has been released. Changes include a new /etc/tunables.conf file for the system-wide setting of tunable parameters, a new tunable to control the use of transparent huge pages for read-only executable segments, a number of math-function improvements, a handful of security fixes, and more.

Registration is now open for the 2026 Linux Plumbers Conference, to be held October 5 to 7 in Prague, Czechia. Tickets to this event tend to sell out quickly, so interested attendees probably should not procrastinate.

I have just received the shocking news that Dan Williams, a longtime, high-profile kernel developer, has passed away. I knew him primarily through his long service on the Linux Foundation Technical Advisory Board; he was always a strong, thoughtful, and intelligent presence. Dan will be deeply missed.

There is a support effort underway for Dan's family as they come to terms with this loss.

One of the ideas raised at the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit (LSFMM+BPF) was the creation of an operations structure for the swap subsystem. Like many parts of the kernel, the swap layer evolved over time, with pieces being added as needed; the end result of this evolution is rarely what one would expect had the subsystem been designed today. The interface between the swap layer and the devices it uses is just one example. It appears that one result of the swap subsystem's evolution — the lack of an abstraction layer to interface with underlying storage — will soon be addressed, but in a different way than was initially envisioned.

The Codeberg forge has adopted a pair of new policies, promising not to use hosted projects to train LLMs and, more controversially, banning the hosting of LLM-generated software. The site's blog describes and justifies these policies.

Although often well intentioned, sharing the result of a prompt and calling it "libre software" does not make the world a better place. Codeberg is not and does not want to be a place to dump such generated single-use software that no one else will ever look at. We are a place for people to collaborate and improve software together. Within this context, the recent votes can be understood as a reconfirmation of those principles: As we want to center on human collaboration, we will not actively support or engage in the creation of LLMs and will not put our limited resources to use for storing single-use software that would pollute our FLOSS commons.

Like many development communities, the kernel community has been struggling to determine how large language models will be used in its development process. The news has been dominated recently by a strongly worded missive from Linus Torvalds on the subject, but the discussion has been rather more wide-ranging and nuanced than that. Topics that have been considered recently include the LLM attribution requirement, code-review tools, dependence on proprietary tools, and whether there is a place for concerns about the ethics of LLMs.

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.