All posts by corbet

An in-kernel machine-learning library

Post Syndicated from corbet original https://lwn.net/Articles/1057569/

For those wanting more machine learning in the kernel, Viacheslav Dubeyko
has posted a
new in-kernel library
for that purpose.

What is the goal of using ML models in Linux kernel? The main goal
is to employ ML models for elaboration of a logic of particular
Linux kernel subsystem based on processing data or/and an efficient
subsystem configuration based on internal state of subsystem. As a
result, it needs: (1) collect data for training, (2) execute ML
model training phase, (3) test trained ML model, (4) use ML model
for executing the inference phase. The ML model inference can be
used for recommendation of Linux kernel subsystem configuration
or/and for injecting a synthesized subsystem logic into kernel
space (for example, eBPF logic).

It is rigorously undocumented
and there are no real users, so it’s not entirely clear what the purpose
is, but there are undoubtedly interesting things that could be done with
it.

[$] Modernizing swapping: the end of the swap map

Post Syndicated from corbet original https://lwn.net/Articles/1057102/

The first installment in this series
introduced several data structures in the kernel’s swap subsystem and
described work to replace some of those with a new “swap table” structure.
The work did not stop there, though; there is more modernization of the
swap subsystem queued for an upcoming development cycle, and even more for
multiple kernel releases after that. Once that work is done, the swap
subsystem will be both simpler and faster than it is now.

[$] Modernizing swapping: introducing the swap table

Post Syndicated from corbet original https://lwn.net/Articles/1056405/

The kernel’s swap subsystem is a complex and often unloved beast. It is
also a critical component in the memory-management subsystem and has a
significant impact on the performance of the system as a whole. At the
2025 Linux Storage, Filesystem, Memory-Management and BPF Summit, Kairui
Song outlined a plan to simplify and
optimize the kernel’s swap code. A first installment
of that work
, written with help from Chris Li, was merged for the 6.18
release. This article will catch up with the 6.18 work, setting the stage
for a future look at the changes that are yet to be merged.

The Award for Excellence in Open Source goes to Greg Kroah-Hartman

Post Syndicated from corbet original https://lwn.net/Articles/1056699/

Daniel Stenberg, the recipient of last year’s Award for Excellence in Open
Source from the European Open Source Academy, presented
that award to this year’s recipient
: Greg Kroah-Hartman.

It’s impossible to overstate the importance of the work Greg has
done on Linux. In software, innovation grabs headlines, but
stability saves lives and livelihoods. Every Android phone, every
web server, every critical system running Linux depends on Greg’s
meticulous work. He ensures that when hospitals, banks,
governments, and individuals rely on Linux, it doesn’t fail
them. His work represents the highest form of service: unglamorous,
relentless, and essential.

Security updates for Friday

Post Syndicated from corbet original https://lwn.net/Articles/1056692/

Security updates have been issued by AlmaLinux (curl, gimp:2.8, glibc, grafana, grafana-pcp, kernel, osbuild-composer, php:8.3, python-urllib3, python3.11, and python3.12), Debian (chromium), Mageia (ceph, gpsd, libxml2, openjdk, openssl, and xen), SUSE (abseil-cpp, assertj-core, coredns, freerdp, java-11-openjdk, java-25-openjdk, libxml2, openssl-1_0_0, openssl-1_1, python, python-filelock, and python311-sse-starlette), and Ubuntu (kernel, linux, linux-aws, linux-aws-hwe, linux-hwe, linux-kvm, linux-oracle, linux, linux-aws, linux-kvm, linux-lts-xenial, linux-aws-fips, linux-fips, linux-fips, and texlive-bin).

A proposed governance structure for openSUSE

Post Syndicated from corbet original https://lwn.net/Articles/1056593/

Jeff Mahoney, who
holds a vice-president position at SUSE, has posted a detailed
proposal
for improving the governance of the openSUSE project.

It’s meant to be a way to move from governance by volume or
persistence toward governance by legitimacy, transparency, and
process – so that disagreements can be resolved fairly and the
project can keep moving forward. Introducing structure and
predictability means it easier for newcomers to the project to
participate without needing to understand decades of accumulated
history. It potentially could provide a clearer roadmap for
developers to find a place to contribute.

The stated purpose is to start a discussion; this is openSUSE, so he is
likely to succeed.

[$] Sub-schedulers for sched_ext

Post Syndicated from corbet original https://lwn.net/Articles/1056014/

The extensible scheduler class (sched_ext)
allows the installation of a custom CPU scheduler built as a set of BPF
programs. Its merging for the 6.12 kernel release moved the kernel away
from the “one scheduler fits all” approach that had been taken until then;
now any system can have its own scheduler optimized for its workloads.
Within any given machine, though, it’s still “one scheduler fits all”; only
one scheduler can be loaded for the system as a whole. The sched_ext
sub-scheduler patch series
from Tejun Heo aims to change that situation
by allowing multiple CPU schedulers to run on a single system.

Security updates for Thursday

Post Syndicated from corbet original https://lwn.net/Articles/1056544/

Security updates have been issued by AlmaLinux (java-25-openjdk, openssl, and python3.9), Debian (gimp, libmatio, pyasn1, and python-django), Fedora (perl-HarfBuzz-Shaper, python-tinycss2, and weasyprint), Mageia (glib2.0), Oracle (curl, fence-agents, gcc-toolset-15-binutils, glibc, grafana, java-1.8.0-openjdk, kernel, mariadb, osbuild-composer, perl, php:8.2, python-urllib3, python3.11, python3.11-urllib3, python3.12, and python3.12-urllib3), SUSE (alloy, avahi, bind, buildah, busybox, container-suseconnect, coredns, gdk-pixbuf, gimp, go1.24, go1.24-openssl, go1.25, helm, kernel, kubernetes, libheif, libpcap, libpng16, openjpeg2, openssl-1_0_0, openssl-1_1, openssl-3, php8, python-jaraco.context, python-marshmallow, python-pyasn1, python-urllib3, python-virtualenv, python311, python313, rabbitmq-server, xen, zli, and zot-registry), and Ubuntu (containerd, containerd-app and wlc).

PC Gamer on the scx_horoscope scheduler

Post Syndicated from corbet original https://lwn.net/Articles/1056354/

PC Gamer has run an
amusing review
of the scx_horoscope
scheduler
for Linux, which uses astrology to optimize scheduling
decisions.

The scheduler is full of bizarre features, like its ability to
perform real planetary calculations based on accurate geocentric
planetary positions, lunar phase scheduling (the full moon gives a
1.4x boost to tasking, apparently) and “zodiac-based task
classification”.

That latter feature is easily one of my favourite bits. Specific
planetary bodies “rule” over specific system tasks, so the Sun is
in charge of critical system processes, the Moon (tied to emotions,
of course) rules over interactive tasks, and Jupiter is assigned to
memory-heavy applications, among others.

A critical GnuPG security update

Post Syndicated from corbet original https://lwn.net/Articles/1056209/

There is a new GnuPG update for a “critical security bug” in recent
GnuPG releases.

A crafted CMS (S/MIME) EnvelopedData message carrying an oversized
wrapped session key can cause a stack buffer overflow in gpg-agent
during the PKDECRYPT–kem=CMS handling. This can easily be used
for a DoS but, worse, the memory corruption can very likley also be
used to mount a remote code execution attack. The bug was
introduced while changing an internal API to the FIPS required KEM
API.

Only versions 2.5.13 through 2.5.16 are affected.

The GNU C Library is moving from Sourceware

Post Syndicated from corbet original https://lwn.net/Articles/1056206/

GNU C Library maintainer Carlos O’Donell has announced
that the project will be moving its core services away from Sourceware in favor of services hosted
at the Linux Foundation.

While it was clear to the GNU Toolchain leadership that
requirements were coming to improve the toolchain cyber-security
posture, these requirements were not clear to all project
developers. As part of receiving this feedback we have worked to
document and define a secure development policy for glibc and at a
higher level the GNU Toolchain. While Sourceware has started
making some critical technical changes, the GNU Toolchain still
faces serious, systemic concerns about securing a global, highly
available service and building a sustainable, diverse sponsorship
model.

This has been a long-running discussion; see this 2022 article for some background.

[$] Implicit arguments for BPF kfuncs

Post Syndicated from corbet original https://lwn.net/Articles/1055559/

The kernel’s “kfunc” mechanism is a way of exporting kernel functions so
that they can be called directly from BPF programs. There are over 300
kfuncs in current kernels, ranging in functionality from string processing
(bpf_strnlen())
to custom schedulers (scx_bpf_kick_cpu())
and beyond. Sometimes these kfuncs need access to context information that
is not directly available to BPF programs, and which thus cannot be passed
in as arguments. The implicit
arguments patch set
from Ihor Solodrai is the latest attempt to solve
this problem.

Kernel prepatch 6.19-rc7

Post Syndicated from corbet original https://lwn.net/Articles/1055796/

The 6.19-rc7 kernel prepatch is out for
testing.

So normally this would be the last rc of the release, but as I’ve
mentioned every rc (because I really want people to be aware and be
able to plan for things) this release we’ll have an rc8 due to the
holiday season.

And while some of the early rc’s were smaller than usual and it
didn’t seem necessary, right now I’m quite happy I made that
call. Not because there’s anything particularly scary here – the
release seems to be going fairly smoothly – but because this rc7
really is larger than things normally are and should be at this
point.


Along with the usual fixes, this -rc also includes a new
document
describing the process to replace the kernel project
leadership should that become necessary in the absence of an arranged
transition. The plan largely follows what was decided at the Maintainers Summit in December.

[$] Filesystem medley: EROFS, NTFS, and XFS

Post Syndicated from corbet original https://lwn.net/Articles/1055062/

Filesystems seem to be one of those many areas where the problems are well
understood, but there is always somebody working toward a better solution.
As a result, filesystem development in the Linux kernel continues at a fast
pace even after all these years. In recent news, the EROFS filesystem is
on the path to gain a useful page-cache-sharing feature, there is a new
NTFS implementation on the horizon, and XFS may be about to get an
infrastructure for self healing.