Post Syndicated from corbet original https://lwn.net/Articles/962897/

Andrea Righi has started
a blog series on writing a user-space CPU scheduler with the BPF-based
extensible scheduler class:

.select_cpu() implements the logic to assign a target CPU to a task
that wants to run, typically you have to decide if you want to keep
the task on the same CPU or if it needs to be migrated to a
different one (for example if the current CPU is busy); if we can
find an idle CPU at this stage there’s no reason to call the
scheduler, the task can be immediately dispatched here.

Post Syndicated from corbet original https://lwn.net/Articles/962881/

Security updates have been issued by Fedora (freeglut, hugin, libmodsecurity, qemu, rust-asyncgit, rust-bat, rust-cargo-c, rust-eza, rust-git-absorb, rust-git-delta, rust-git2, rust-gitui, rust-libgit2-sys, rust-lsd, rust-pore, rust-pretty-git-prompt, rust-shadow-rs, rust-silver, rust-tokei, and rust-vergen), Mageia (packages, radare2, ruby-rack, and wireshark), Oracle (.NET 8.0 and python-pillow), Red Hat (gimp:2.8, java-1.8.0-ibm, and kpatch-patch), SUSE (dpdk and opera), and Ubuntu (bind9, curl, linux-raspi, linux-raspi-5.4, node-ip, and tiff).

Post Syndicated from corbet original https://lwn.net/Articles/962668/

The 6.8-rc5 kernel prepatch is out for
testing. “Absolutely nothing stands out here, although I do wish
things should have calmed down a bit more at this point in the release
process.“

Post Syndicated from corbet original https://lwn.net/Articles/961884/

The futex
mechanism provided by the kernel allows for the creation of efficient and
flexible locking primitives in user space. Futexes work well for many
applications, but not all. One of the exceptions, it seems, is that
perennially difficult-to-support use case: Windows games. With
this
patch series, Elizabeth Figura seeks to provide the sort of locking
that those games need, by way of a special-purpose virtual device.

Post Syndicated from corbet original https://lwn.net/Articles/961764/

The 6.8-rc4 kernel prepatch is out for
testing. “Commit counts and contents look normal for this phase of the
release, nothing here really stands out.”

Post Syndicated from corbet original https://lwn.net/Articles/961545/

David Rowley looks
deeply into the improvements coming to the query planner in
PostgreSQL 16.

For a long time now, PostgreSQL has been able to remove a LEFT JOIN
where no column from the left joined table was required in the
query and the join could not possibly duplicate any rows.

However, in versions prior to PostgreSQL 16, there was no support
for left join removals on partitioned tables. Why? Because the
proofs that the planner uses to determine if there’s any
possibility any inner-side row could duplicate any outer-side row
were not present for partitioned tables.

The PostgreSQL 16 query planner now allows the LEFT JOIN removal
optimization with partitioned tables.

Post Syndicated from corbet original https://lwn.net/Articles/961414/

Stephen Brennan describes
kernel core dumps in excruciating detail.

Kernel core dumps are complex. They are not simply copies of system
memory; they contain plenty of extra metadata which is critical to
understanding their contents. And like any other type of data, the
design of the file formats can enable lots of flexibility and
power. However, due to the broad variety of tools out there, the
diversity of dump formats is overwhelming, and the lack of
documentation or specifications compounds the problem.

Post Syndicated from corbet original https://lwn.net/Articles/961359/

Mitchell Baker has announced
that she is stepping down from the role of Mozilla CEO, effective
immediately. Laura Chambers will be the new CEO “for the remainder of
the year“.

We’re at a critical juncture where public trust in institutions,
governments, and the fabric of the internet has reached
unprecedented lows. There’s a tectonic shift underway as everyone
battles to own the future of AI. It is Mozilla’s opportunity and
imperative to forge a better future. I’m excited about Laura’s
day-to-day involvement and the chance for Mozilla to achieve
more. Our power lies in the collective effort of people
contributing to something better and I’m eager for Mozilla to meet
the needs of this era more fully.

Post Syndicated from corbet original https://lwn.net/Articles/961121/

The generation of random (or, at least, unpredictable) numbers is key to
many security technologies. For this reason, the provision of random data
as a CPU feature has drawn a lot of attention over the years. A proper
hardware-based random-number generator can address the problems that make
randomness hard to obtain in some systems, but only if the manufacturer can
be trusted to not have compromised that generator in some way. A recent
discussion has brought to light a different problem, though: what happens
if a hardware random-number generator can be simply driven into exhaustion?

Post Syndicated from corbet original https://lwn.net/Articles/961355/

The GNU C Library project has
been accepted as a CVE Numbering Authority (CNA), meaning that the
project is now in control of the CVE numbers assigned to its code.

As a CNA the glibc security team will be working to improve the
quality and response time of security advisories and mitigations.

Over the coming months, the glibc security team will define the
process for the CNA and establish best practices that can also be
used by the rest of the GNU Toolchain.

See this article for some background on
this change.

Post Syndicated from corbet original https://lwn.net/Articles/960456/

The LWN.net Weekly Edition for February 8, 2024 is available.

Post Syndicated from corbet original https://lwn.net/Articles/961116/

At the beginning of November, we let it be
known that we were looking to hire a writer/editor to augment the LWN
team. In past attempts, we have found it difficult to attract writers who
could produce the kind of content that LWN readers expect. This time
around, as we have said before, was different; we had a number of
candidates who could have filled the bill and were forced to make some
difficult choices.

While “hire them all” was an attractive idea, it was not one that our
budget would support. We did conclude, however, that we could stretch to a
second hire. So we are pleased to announce that the opportunity to bring
Joe Brockmeier on board was too good to pass up — so we didn’t. You will
start to see his work return to LWN within the next few days.

Post Syndicated from corbet original https://lwn.net/Articles/961173/

Security updates have been issued by Red Hat (gimp) and Ubuntu (firefox, linux-oracle, linux-oracle-5.15, and python-django).

Post Syndicated from corbet original https://lwn.net/Articles/961083/

Security updates have been issued by CentOS (firefox, gstreamer1-plugins-bad-free, and tigervnc), Debian (ruby-sanitize), Fedora (kernel, kernel-headers, qt5-qtwebengine, and runc), Oracle (gnutls, kernel, libssh, rpm, runc, and tigervnc), Red Hat (runc), and SUSE (bouncycastle, jsch, python, and runc).

Post Syndicated from corbet original https://lwn.net/Articles/960041/

A common problem in kernel development is controlling when a
specific task should be done. Kernel code often executes in contexts where
some actions (sleeping, for example, or calling into filesystems) are not
possible. Other actions, while possible, may prevent the kernel from
taking care of a more important task in a timely manner. The kernel
community has developed a number of deferred-execution mechanisms designed
to ensure that every task is handled at the right time. One of those
mechanisms, tasklets, has been eyed for removal for years; that removal
might just happen in the near future.

Post Syndicated from corbet original https://lwn.net/Articles/960842/

The 6.8-rc3 kernel prepatch is out for
testing. “A slightly larger rc3 that I’d have hoped for, although at
this stage in the release process it’s not something that really worries me
yet.”

Post Syndicated from corbet original https://lwn.net/Articles/960606/

Simon Phipps writes
on the Open Source Initiative blog that the latest version of the
European Cyber Resilience Act is much improved: “As a result of all this
effort from so many people, the final text of the CRA mitigated pretty much
all the risks we had identified to individual developers and to Open Source
foundations.”

Post Syndicated from corbet original https://lwn.net/Articles/960604/

Security updates have been issued by Debian (chromium, man-db, and openjdk-17), Fedora (chromium, indent, jupyterlab, kernel, and python-notebook), Gentoo (glibc), Oracle (firefox, thunderbird, and tigervnc), Red Hat (rpm), SUSE (cpio, gdb, gstreamer, openconnect, slurm, slurm_18_08, slurm_20_02, slurm_20_11, slurm_22_05, slurm_23_02, squid, webkit2gtk3, and xerces-c), and Ubuntu (imagemagick and xorg-server, xwayland).

Post Syndicated from corbet original https://lwn.net/Articles/960088/

Filesystem development is not an easy task; the performance demands are
typically high, and the consequences for mistakes usually involve lost data
and irate users. The implementation of a virtual (or “pseudo”) filesystem
— a filesystem implemented within the kernel and lacking a normal backing
store — can also be challenging, but for different reasons. A series of
conversations around the eventfs virtual filesystem has turned a spotlight
on the difficulty of creating a virtual filesystem for Linux.

Post Syndicated from corbet original https://lwn.net/Articles/960446/

A new version of the Damn Small
Linux distribution has come out with an updated definition of “damn
small”:

The new goal of DSL is to pack as much usable desktop distribution
into an image small enough to fit on a single CD, or a hard limit
of 700MB. This project is meant to service older computers and have
them continue to be useful far into the future. Such a notion sits
well with my values. I think of this project as my way of keeping
otherwise usable hardware out of landfills.