One of the more significant changes in the 7.0 kernel release is to use the lazy-preemption mode by default in the CPU scheduler. The scheduler developers have wanted to reduce the number of preemption modes for years, and lazy preemption looks like a step toward that goal. But then there came this report from Salvatore Dipietro that lazy preemption caused a 50% performance regression on a PostgreSQL benchmark. Investigation showed that the situation is not actually so grave, but the episode highlights just how sensitive some workloads can be to configuration changes; there may be surprises in store for other users as well.

The 7.1 merge window opened on April 12 with the release of the 7.0 kernel. Since then, 3,855 non-merge changesets have been pulled into the mainline repository for the next release. This merge window is thus just getting started, but there has still been a fair amount of interesting work moving into the mainline.

Inside this week's LWN.net Weekly Edition:

• Front: LLM security reports; OpenWrt One build system; Vim forks; removing read-only THPs; 7.0 statistics; MusicBrainz Picard.
• Briefs: OpenSSL 4.0.0; Relicensing; Servo; Zig 0.16.0; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

Version 4.0.0 of the OpenSSL cryptographic library has been released. This release includes support for a number of new cryptographic algorithms and has a number of incompatible changes as well; see the announcement for the details.

Linus Torvalds released the 7.0 kernel as expected on April 12, ending a relatively busy development cycle. The 7.0 release brings a large number of interesting changes; see the LWN merge-window summaries (part 1, part 2) for all the details. Here, instead, comes our traditional look at where those changes came from and who supported that work.

Linus has released the 7.0 kernel after a busy nine-week development cycle.

The last week of the release continued the same "lots of small fixes" trend, but it all really does seem pretty benign, so I've tagged the final 7.0 and pushed it out.

I suspect it's a lot of AI tool use that will keep finding corner cases for us for a while, so this may be the "new normal" at least for a while. Only time will tell.

Significant changes in this release include the removal of the "experimental" status for Rust code, a new filtering mechanism for io_uring operations, a switch to lazy preemption by default in the CPU scheduler, support for time-slice extension, the nullfs filesystem, self-healing support for the XFS filesystem, a number of improvements to the swap subsystem (described in this article and this one), general support for AccECN congestion notification, and more. See the LWN merge-window summaries (part 1, part 2) and the KernelNewbies 7.0 page for more details.

The 6.19.12, 6.18.22, 6.12.81, 6.6.134, and 6.1.168 stable kernel updates have been released; each contains another set of important fixes.

Things do not always go the way kernel developers think they will. When the kernel gained support for the creation of read-only transparent huge pages for the page cache in 2019, the developer of that feature, Song Liu, added a Kconfig file entry promising that support for writable huge pages would arrive "in the next few release cycles". Over six years later, that promise is still present, but it will never be fulfilled. Instead, the read-only option will soon be removed, reflecting how the core of the memory-subsystem has changed underneath this particular feature.

Linus has released 7.0-rc7 for testing. "Things look set for a final release next weekend, but please keep testing. The Easter bunny is watching".

LWN recently reported on the Trivy compromise that led, in turn, to the compromise of the LiteLLM system; that article made the point that the extent of the problem was likely rather larger than was known. The Next Web now reports that the Trivy attack was used to compromise a wide range of European Commission systems.

The European Union's computer emergency response team said on Thursday that a supply chain attack on an open-source security scanner gave hackers the keys to the European Commission's cloud infrastructure, resulting in the theft and public leak of approximately 92 gigabytes of compressed data including the personal information and email contents of staff across dozens of EU institutions.

The kernel provides a number of ways for processes to communicate with each other, but they never quite seem to fit the bill for many users. There are currently a few proposals for interprocess communication (IPC) enhancements circulating on the mailing lists. The most straightforward one adds a new system call for POSIX message queues that enables the addition of new features. For those wanting an entirely new way to do interprocess communication, there is a proposal to add a new subsystem for that purpose to io_uring. Finally, the bus1 proposal has made a return after ten years.