All posts by corbet

[$] Custom out-of-memory killers in BPF

Post Syndicated from corbet original https://lwn.net/Articles/1019230/

The out-of-memory (OOM) killer has long been a scary and controversial part
of the Linux kernel. It is summoned from some dark place when the system
as a whole (or, more recently, any given control group) is running so low
on memory that further allocations are not possible; its job is to kill off
processes until a sufficient amount of memory has been freed. Roman
Gushchin has found a way to make the OOM killer even scarier: adding the
ability to load
custom OOM killers in BPF.

[$] LWN.net Weekly Edition for May 1, 2025

Post Syndicated from corbet original https://lwn.net/Articles/1018680/

Inside this week’s LWN.net Weekly Edition:

  • Front: Mailman 2 vulnerabilities; AI in Debian; __nonstring__; Cache-aware scheduling; Freezing filesystems; Socket-level storage; Debugging information; LWN in 2025.
  • Briefs: Debian election; Kali Linux key; OpenBSD 7.7; Firefox 138.0; GCC 15.1; Meson 1.8.0; Valgrind 3.25.0; FSF review; OSI retrospective; Mastodon; Quotes; …
  • Announcements: Newsletters, conferences, security updates, patches, and more.

Albertson: Future of OSL in Jeopardy

Post Syndicated from corbet original https://lwn.net/Articles/1019520/

Lance Albertson writes
that the Oregon State University Open Source Lab, the home of many
prominent free-software projects over the years, has run into financial
trouble:

I am writing to inform you about a critical and time-sensitive
situation facing the Open Source Lab. Over the past several years,
we have been operating at a deficit due to a decline in corporate
donations. While OSU’s College of Engineering (CoE) has generously
filled this gap, recent changes in university funding have led to a
significant reduction in CoE’s budget. As a result, our current
funding model is no longer sustainable and CoE needs to find ways
to cut programs.

Earlier this week, I was informed that unless we secure $250,000 in
committed funds, the OSL will be forced to shut down later this
year.

The conclusion of the FSF board review

Post Syndicated from corbet original https://lwn.net/Articles/1019479/

The Free Software Foundation has announced
the completion of the review of its board of directors; the process
resulted in the reconfirmation of all five sitting board members.

The review examined board members Ian Kelling, Geoffrey Knauth,
Henry Poole, Richard Stallman, and Gerald Sussman. The process
generated detailed philosophical and policy discussions between
board members and the FSF’s global associate members on topics
ranging from the firmness of the Free Software Definition,
developments in machine learning, to the board’s president
position.

How LWN is faring in 2025

Post Syndicated from corbet original https://lwn.net/Articles/1019217/

Just over six months ago, The Economist described the US economy as “the envy of the
world“. That headline would be unlikely to appear now. The economic
boom referenced in that article feels like a distant memory, markets are
falling, and uncertainty is at an all-time high. Like everybody else, LWN
is affected by the current turbulence in the political and economic
spheres; we expect to get through this period, but there will be some
challenges.

Barnes: Parallel ./configure

Post Syndicated from corbet original https://lwn.net/Articles/1019303/

Tavian Barnes takes on
the tedious process of waiting for configure scripts to run.

I paid good money for my 24 CPU cores, but ./configure can only
manage to use 69% of one of them. As a result, this random project
takes about 13.5× longer to configure the build than it does to
actually do the build.

The purpose of a ./configure script is basically to run the
compiler a bunch of times and check which runs succeeded. In this
way it can test whether particular headers, functions, struct
fields, etc. exist, which lets people write portable software. This
is an embarrassingly parallel problem, but Autoconf can’t
parallelize it, and neither can CMake, neither can Meson, etc.,
etc.

(Thanks to Paul Wise).

[$] Cache awareness for the CPU scheduler

Post Syndicated from corbet original https://lwn.net/Articles/1018334/

The kernel’s CPU scheduler has to balance a wide range of objectives. The
tasks in the system must be scheduled fairly, with latency for any given
task kept within bounds. All of the CPUs in the system should be kept busy
if there is enough work to do, but unneeded CPUs should be shut down to
reduce power consumption. A task should also run on the CPU that is most
likely to have cached the memory that task is using. This patch
series from Chen Yu aims to improve how the scheduler handles cache
locality for multi-threaded processes.

Signing key change for Kali Linux

Post Syndicated from corbet original https://lwn.net/Articles/1019255/

The Kali Linux distribution has announced
that software updates will soon start failing for all users:

This is not only you, this is for everyone, and this is entirely
our fault. We lost access to the signing key of the repository, so
we had to create a new one. At the same time, we froze the
repository (you might have noticed that there was no update since
Friday 18th), so nobody was impacted yet. But we’re going to
unfreeze the repository this week, and it’s now signed with the new
key.

The announcement includes instructions for how to recover from the problem.

Security updates for Tuesday

Post Syndicated from corbet original https://lwn.net/Articles/1019272/

Security updates have been issued by AlmaLinux (glibc, php:8.1, and thunderbird), Debian (libreoffice), Fedora (caddy), Mageia (chromium-browser-stable), Red Hat (php:8.1), SUSE (glow), and Ubuntu (kicad, linux-aws-5.15, linux-azure-nvidia, linux-gcp-5.15, mistral, python-mistral-lib, tomcat8, and trafficserver).

Security updates for Friday

Post Syndicated from corbet original https://lwn.net/Articles/1018912/

Security updates have been issued by AlmaLinux (thunderbird), Debian (libbpf), Fedora (golang-github-openprinting-ipp-usb, ImageMagick, mingw-libsoup, mingw-poppler, and pgbouncer), SUSE (glib2, govulncheck-vulndb, libsoup-2_4-1, libxml2-2, mozjs60, ruby2.5, and thunderbird), and Ubuntu (linux, linux-azure, linux-azure-5.4, linux-bluefield, linux-gcp, linux-hwe-5.4, linux-ibm, linux-kvm, linux-oracle, linux-oracle-5.4, linux-aws, linux-aws-5.4, linux-gcp-5.4, linux-iot, linux-aws-fips, linux-azure-fips, linux-fips, linux-gcp-fips, linux-hwe-6.8, linux-ibm-5.4, linux-oracle-5.15, openssh, and php-twig).

[$] Some __nonstring__ turbulence

Post Syndicated from corbet original https://lwn.net/Articles/1018486/

New compiler releases often bring with them new warnings; those warnings
are usually welcome, since they help developers find problems before they
turn into nasty bugs. Adapting to new warnings can also create disruption
in the development process, though, especially when an important developer
upgrades to a new compiler at an unfortunate time. This is just the
scenario that played out with the 6.15-rc3
kernel release and the implementation of
-Wunterminated-string-initialization in GCC 15.

[$] DMA addresses for UIO

Post Syndicated from corbet original https://lwn.net/Articles/1017449/

The Userspace
I/O (UIO) subsystem was first added to the kernel by
Hans J. Koch for the 2.6.32 release in 2007. Its purpose is to facilitate
the writing of drivers (mostly) in user space; to that end, it provides
access to a number of resources that user-space code normally cannot touch.
One piece that is missing, though, is DMA addresses. A proposal to
fill that gap from Bastien Curutchet is running into some opposition,
though.