The kernel coverage here at LWN often touches on memory-management topics and, as a result, tends to talk a lot about both pages and folios. As the folio transition in the kernel has moved forward, it has often become difficult to decide which term to use in writing that is meant to be both approachable and technically correct. As this work continues, it will be increasingly common to use "folio" rather than page. This article is intended to be a convenient reference for readers wanting to differentiate the two terms or understand the state of this transition.

The famfs filesystem first showed up on the mailing lists in early 2024; since then, it has been the topic of regular discussions at the Linux Storage, Filesystem, Memory Management and BPF (LSFMM+BPF) Summit. It has also, as result of those discussions, been through some significant changes since that initial posting. So it is not surprising that a suggestion that it needed to be rewritten yet again was not entirely well received. How much more rewriting will actually be needed is unclear, but more discussion appears certain.

The 7.0.1, 6.19.14, 6.18.24, and 6.12.83 stable kernels have been released; each contains another set of important fixes. Note that the 6.19.x line ends with 6.19.14.

There are a number of ongoing efforts to remove kernel code, mostly from the networking subsystem, as an alternative to dealing with the increase in security-bug reports from large language models. The proposed removals include ISA and PCMCIA Ethernet drivers, a pair of PCI drivers, the ax25 and amateur radio subsystem, the ATM protocols and drivers, and the ISDN subsystem.

Remove the amateur radio (AX.25, NET/ROM, ROSE) protocol implementation and all associated hamradio device drivers from the kernel tree. This set of protocols has long been a huge bug/syzbot magnet, and since nobody stepped up to help us deal with the influx of the AI-generated bug reports we need to move it out of tree to protect our sanity.

This Firefox blog post reports that the Firefox 150 release includes fixes for 271 vulnerabilities found by the Claude Mythos preview.

Elite security researchers find bugs that fuzzers can't largely by reasoning through the source code. This is effective, but time-consuming and bottlenecked on scarce human expertise. Computers were completely incapable of doing this a few months ago, and now they excel at it. We have many years of experience picking apart the work of the world's best security researchers, and Mythos Preview is every bit as capable. So far we've found no category or complexity of vulnerability that humans can find that this model can't.

This can feel terrifying in the immediate term, but it's ultimately great news for defenders. A gap between machine-discoverable and human-discoverable bugs favors the attacker, who can concentrate many months of costly human effort to find a single bug. Closing this gap erodes the attacker's long-term advantage by making all discoveries cheap.

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.