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BPF is, famously, not part of the kernel's promises of user-space stability. New kernels can and do break existing BPF programs; the BPF developers try to fix unintentional regressions as they happen, but the whole thing can be something of a bumpy ride for users trying to deploy BPF programs across multiple kernel versions. Shung-Hsi Yu and Daniel Xu had two different approaches to...

Andrew Morton, the lead maintainer for the kernel's memory-management subsystem, tends to be quiet during the Linux Storage, Filesystem, Memory-Management, and BPF Summit, preferring to let the developers work things out on their own. That changes, though, when he leads the traditional development-process session in the memory-management track. At the 2025 gathering, this discussion covered a number of ways in which the process could...

Security updates have been issued by Debian (glib2.0, jinja2, kernel, mediawiki, perl, subversion, twitter-bootstrap3, twitter-bootstrap4, and wpa), Fedora (c-ares, chromium, condor, corosync, cri-tools1.29, exim, firefox, matrix-synapse, nextcloud, openvpn, perl-Data-Entropy, suricata, upx, varnish, webkitgtk, yarnpkg, and zabbix), Mageia (giflib, gnupg2, graphicsmagick, and poppler), Oracle (delve and golang, go-toolset:ol8, grub2, and webkit2gtk3), Red Hat (kernel and kernel-rt), SUSE (chromium, fontforge-20230101, govulncheck-vulndb, kernel, liblzma5-32bit, pgadmin4, python311-Django, and...

Linus has released 6.15-rc2 for testing. "Nothing particularly stands out to me, but it's early in the release yet, so let's see how it goes."

Knowing how frequently accessed a page of memory is (its "hotness") is a key input to many memory-management heuristics. Jonathan Cameron, in a memory-management track at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit, pointed out that the number of sources of that kind of data is growing over time. He wanted to explore the questions of what commonality exists between data from...

Eduard Zingerman presented a daring proposal that "makes sense if you think about it a bit" at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit. He wants to inline performance-sensitive kernel functions into the BPF programs that call them. His prototype does not yet address all of the design problems inherent in that idea, but it did spark a lengthy discussion about the...

Security updates have been issued by AlmaLinux (delve and golang and go-toolset:rhel8), Debian (webkit2gtk), Fedora (openvpn, thunderbird, uboot-tools, and zabbix), SUSE (expat, fontforge, govulncheck-vulndb, and kernel), and Ubuntu (haproxy and libsoup2.4, libsoup3).

Building on the discussion in the two previous sessions on untorn (or atomic) writes, for buffered I/O and for XFS using direct I/O, Ojaswin Mujoo remotely led a session on support for the feature on ext4. That took place in the combined storage and filesystem track at the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit. Part of the support for the feature...

Over on the Red Hat Developer site, David Malcolm has an article about improvements in GCC 15, specifically focusing on the diagnostic information that the compiler emits. This includes ASCII art with a "⚠️" warning emoji to display the execution path when it detects a problem (like an infinite loop in one of his examples), better C++ template errors, machine-readable diagnostics using Static Analysis...

Compute Express Link (CXL) memory is not like the ordinary RAM that one might install into a computer; it can come and go at any time and is often not present when the kernel is booting. That complicates the management of this memory. During the memory-management track of the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit, Gregory Price ran a session on the...

Greg Kroah-Hartman has announced the release of eight stable kernels: 6.14.2, 6.13.11, 6.12.23, 6.6.87, 6.1.134, 5.15.180, 5.10.236, and 5.4.292. These all contain a large assortment of important kernel fixes throughout the tree.

The Data Access MONitor (DAMON) subsystem provides access to detailed memory-management statistics, along with a set of tools for implementing policies based on those statistics. An update on DAMON by its primary author, SeongJae Park, has been a fixture of the Linux Storage, Filesystem, Memory-Management, and BPF Summit for some years. The 2025 Summit was no exception; Park led two sessions on recent and...

Security updates have been issued by AlmaLinux (tomcat and webkit2gtk3), Debian (chromium), Fedora (ghostscript), Mageia (atop, docker-containerd, and xz), Red Hat (go-toolset:rhel8), SUSE (apache2-mod_auth_openidc, apparmor, etcd, expat, firefox, kernel, libmozjs-128-0, and libpoppler-cpp2), and Ubuntu (dino-im, linux, linux-aws, linux-aws-hwe, linux-azure, linux-azure-4.15, linux-gcp, linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle, linux, linux-aws, linux-kvm, linux-lts-xenial, linux-fips, linux-fips, linux-aws-fips, linux-azure-fips, linux-gcp-fips, opensc, and poppler).

Inside this week's LWN.net Weekly Edition: Front: Debian project leader election; 6.15 Merge window; Lots of LSFMM coverage; Joplin. Briefs: Firefox hardening; OpenSSH 10.0; Supply chain security; FreeDOS 1.4; OpenSSL 3.5.0; Rust 1.86.0; Quotes; ... Announcements: Newsletters, conferences, security updates, patches, and more.

Tom Schuster, Frederik Braun, and Christoph Kerschbaumer have published an article on the Firefox Security team's Attack & Defense blog that explains recent work to harden Firefox's frontend code. We have rewritten over 600 JavaScript event handlers to mitigate XSS and other injection attacks in the main Firefox user interface. This mitigation will ship in Firefox 138. However, blocking the execution of scripts in...

In a combined storage and filesystem track session at the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit, John Garry continued the theme of "untorn" (or atomic) writes that started in the previous session. It was also an update on where things have gone for untorn writes since his session at last year's summit. Beyond that, he looked at some of the plans...

Four candidates have stepped up to run in the 2025 Debian Project Leader (DPL) election. Andreas Tille, who is in his first term as DPL, is running again. Sruthi Chandran, Gianfranco Costamagna, and Julian Andres Klode are the other candidates running for a chance to serve a term as DPL. The campaigning phase ended on April 5, and Debian members began voting on April 6. Voting...

The 6.15 merge window saw the inclusion of a new type of lock for BPF programs: a resilient queued spinlock that Kumar Kartikeya Dwivedi has been working on for some time. Eventually, he hopes to convert all of the spinlocks currently used in the BPF subsystem to his new lock. He gave a remote presentation about the design of the lock at the 2025...

Tiered-memory systems feature multiple types of memory with varying performance characteristics; on such systems, good performance depends on keeping the most frequently used data in the fastest memory. Identifying that data and placing it properly is a challenge that has kept developers busy for years. Bharata Rao, presenting remotely during a memory-management-track session at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit, led...

The kernel samepage merging (KSM) subsystem works by finding pages in memory with the same contents, then replacing the duplicated copies with a single, shared copy. KSM can improve memory utilization in a system, but has some problems as well. In two memory-management-track sessions at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit, Mathieu Desnoyers and Sourav Panda proposed improvements to KSM to...

OpenSSH 10.0 has been released. Support for the DSA signature algorithm, which was disabled by default beginning in 2015, has been removed. Other notable changes include using the post-quantum algorithm mlkem768x25519-sha256 for key agreement by default, support for systemd-style socket activation in Portable OpenSSH, and moving code for user authentication from the sshd-session binary to the new ssh-auth binary: Splitting this code into a...

Security updates have been issued by Debian (lemonldap-ng, libbssolv-perl, and phpmyadmin), Fedora (augeas, mariadb10.11, and thunderbird), Oracle (gimp, libxslt, python3.11, python3.12, tomcat, and xorg-x11-server), Red Hat (expat, grafana, opentelemetry-collector, and webkit2gtk3), SUSE (azure-cli-core, doomsday, kernel, and poppler), and Ubuntu (dotnet8, dotnet9, erlang, and poppler).

Version 3.5.0 of OpenSSL has been released. This release adds support for server-side QUIC (RFC 9000), a new configuration option (no-tls-deprecated-ec) that disables support for TLS groups deprecated in RFC 8422, and more.

Version 1.4 of FreeDOS has been released. This is the first stable release since 2022, and includes improvements to the Fdisk hard-disk-management program, and reliability updates for the mTCP set of TCP/IP applications for DOS. This version was much smoother because Jerome Shidel, our distribution manager, had an idea after FreeDOS 1.3 that we could have a rolling test release that collected all of...