Post Syndicated from corbet original https://lwn.net/Articles/1070980/
The second 7.1 kernel prepatch is out for
testing. “It’s not small, and while it’s a bit early to say for sure, I
“
do suspect we’re seeing the same continued pattern of more patches than
usual – probably due to AI tooling – that we saw in 7.0.
Post Syndicated from corbet original https://lwn.net/Articles/1070072/
Hyrum’s Law states that any
observable behavior of a system will eventually be depended upon by
somebody. The kernel community is currently contending with a clear
demonstration of that principle. The recent work to address some restartable-sequences
performance problems in the 6.19 release maintained the documented API
in all respects, but that was not enough; Google’s TCMalloc
library, as it turns out, violates the documented API, prevents other code
from using restartable features, and breaks with 6.19. But the kernel’s
no-regressions rule is forcing developers to find a way to accommodate
TCMalloc’s behavior.
Post Syndicated from corbet original https://lwn.net/Articles/1069206/
Inside this week’s LWN.net Weekly Edition:
Post Syndicated from corbet original https://lwn.net/Articles/1067785/
By the time Linus Torvalds released 7.1-rc1
and closed the 7.1 merge window, 12,996 non-merge changesets had been
pulled into the mainline repository; just over 9,000 of those arrived after
the first-half summary was written. These
changes were more driver-oriented than those seen earlier, but still also
included many new features across the kernel as a whole.
Post Syndicated from corbet original https://lwn.net/Articles/1069722/
Linus has released 7.1-rc1 and closed the
merge window for this release.
Things look fairly normal, although we do have a few different
projects to cull some old hardware support to help minimize
maintenance burden: phasing out i486 support (configs deleted, code
deletions to follow) and independently starting to remove some
really old networking hardware support, and removing some SoC
support that never went anywhere.But we’re more than making up for any stale code removal with all
the new features and code added, so the diffstat still shows many
more lines added than removed.
Post Syndicated from corbet original https://lwn.net/Articles/1064861/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1068686/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1068928/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1068906/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1067029/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1067250/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1066922/
Inside this week’s LWN.net Weekly Edition:
Post Syndicated from corbet original https://lwn.net/Articles/1067622/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1066723/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1067279/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1066582/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1066406/
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
Post Syndicated from corbet original https://lwn.net/Articles/1066371/
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.
Post Syndicated from corbet original https://lwn.net/Articles/1065490/
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.