LWN

[$] Hash table memory usage and a BPF interpreter bug

LWN

Anton Protopopov led a short discussion at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit about amount of memory used by hash tables in BPF programs. He thinks that the current memory layout is inefficient, and wants to split the structure that holds table entries into two variants for different kinds of maps. When that proposal proved uncontroversial, he also took the chance to talk about a bug in BPF's call instruction.

[$] Debian's AWKward essential set

LWN

The Debian project has the concept of essential packages, which provide the bare minimum functionality considered absolutely necessary (or "essential") for a system to function. Packages tagged as essential, and the packages that are required by the set of essential packages, are always installed as part of a Debian system. However, Debian's packaging rules do not require developers to explicitly declare dependencies on that set of packages (the essential set) but they can simply rely on the fact that those will always be present. That means that changing the essential set, as the project may wish to do occasionally, is more complicated than it should be. This came to light recently when a Debian developer asked what might be required to remove mawk to slim down the project's container images.

Deepin Desktop removed from openSUSE

LWN

The SUSE Security Team has announced the removal of the Deepin Desktop from openSUSE due to violations of the project's packaging policy.

The discovery of the bypass of the security whitelistings via the deepin-feature-enable package marks a turning point in our assessment of Deepin. We don't believe that the openSUSE Deepin packager acted with bad intent when he implemented the "license agreement" dialog to bypass our whitelisting restrictions. The dialog itself makes the security concerns we have transparent, so this does not happen in a sneaky way, at least not towards users. It was not discussed with us, however, and it violates openSUSE packaging policies. Beyond the security aspect, this also affects general packaging quality assurance: the D-Bus configuration files and Polkit policies installed by the deepin-feature-enable package are unknown to the package manager and won't be cleaned up upon package removal, for example. Such bypasses are not deemed acceptable by us.

Security updates for Wednesday

LWN
Security updates have been issued by Fedora (incus and nodejs20), Red Hat (freetype, kernel, kernel-rt, libsoup, libtiff, redis, redis:6, and thunderbird), SUSE (apparmor, chromium, grafana, ImageMagick, java-11-openjdk, java-17-openjdk, libsoup, libsoup2, libxslt, opensaml, rabbitmq-server, rubygem-rack-1_6, sqlite3, and thunderbird), and Ubuntu (kernel, libfcgi, libraw, libsoup2.4, linux, linux-aws, linux-aws-5.15, linux-gcp, linux-gke, linux-gkeop, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-intel-iotg-5.15, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-nvidia-tegra, linux-nvidia-tegra-igx, linux-oracle, linux-oracle-5.15, linux-raspi, linux, linux-aws, linux-aws-5.4, linux-azure-5.4, linux-gcp, linux-gcp-5.4, linux-hwe-5.4, linux-ibm, linux-kvm, linux-oracle, linux-oracle-5.4, linux, linux-aws, linux-aws-6.8, linux-gcp, linux-gcp-6.8, linux-gke, linux-gkeop, linux-hwe-6.8, linux-ibm, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency, linux-oem-6.8, linux-oracle, linux-oracle-6.8, linux, linux-aws, linux-aws-hwe, linux-gcp, linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle, linux, linux-aws, linux-gcp, linux-gcp-6.11, linux-hwe-6.11, linux-lowlatency, linux-lowlatency-hwe-6.11, linux-oracle, linux-raspi, linux-aws-fips, linux-fips, linux-gcp-fips, linux-azure, linux-azure, linux-azure-4.15, linux-azure, linux-azure-5.15, linux-azure-fde, linux-azure-fde-5.15, linux-azure, linux-azure-6.11, linux-azure-6.8, linux-azure-fips, linux-intel-iot-realtime, linux-realtime, linux-oem-6.11, linux-raspi, linux-realtime, python, python-scrapy, and ruby-carrierwave).

The state of SSL stacks

LWN
Willy Tarreau and William Lallemand have posted an extensive white paper examining the landscape of the available SSL implementations.

OpenSSL 3.0 performs significantly worse than alternative SSL libraries, forcing organizations to provision more hardware just to maintain existing throughput. This raises important questions about performance, energy efficiency, and operational costs.

Examining alternatives—BoringSSL, LibreSSL, WolfSSL, and AWS-LC—reveals a landscape of trade-offs. Each offers different approaches to API compatibility, performance optimization, and QUIC support. For developers navigating the modern SSL ecosystem, understanding these trade-offs is crucial for optimizing performance, maintaining compatibility, and future-proofing their infrastructure.

The end of the USENIX Annual Technical Conference

LWN
On the 50th anniversary of the USENIX organization, its flagship Annual Technical Conference (ATC) is coming to an end.

For the past two decades, as more USENIX conferences have joined the USENIX calendar by focusing on specific topics that grew out of ATC itself, attendance at ATC has steadily decreased to the point where there is no longer a critical mass of researchers and practitioners joining us. Thus, after many years of experiments to adapt this conference to the ever-changing tech landscape and community, the USENIX Board of Directors has made the difficult decision to sunset USENIX ATC.

Many important technologies first saw the light of day at this event.

Mission Center 1.0.0 released

LWN

Version 1.0.0 of Mission Center, a system-monitoring application, has been released. Notable changes in this release include the addition of SMART data for SATA and NVMe devices, display of per-process network usage, as well as a redesigned Apps Page that provides more information about applications and processes. Mission Center's backend application for obtaining system data has been renamed from the Gatherer to Magpie, and is now available as a standalone executable and libraries that can be used by other applications.

[$] Filtering fanotify events with BPF

LWN

Linux systems can have large filesystems; trying to keep up with the stream of fanotify filesystem-monitoring notifications for them can be a struggle. Fanotify is one of a few ways to monitor accesses to filesystems provided by the kernel. Song Liu led a discussion on how to improve in-kernel filtering of fanotify events to a joint session of the filesystem and BPF tracks at the 2025 Linux Storage, Filesystem, Memory-Management, and BPF Summit. He wants to combine the best parts of a few different approaches to efficiently filter filesystem events.

[$] Improving FUSE writeback performance

LWN
In a combined filesystem and memory-management session at the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit (LSFMM+BPF), Joanne Koong led a discussion on improving the writeback performance for the Filesystem in Userspace (FUSE) layer. Writeback is how data that is written to the filesystem is actually flushed to the disk; it is the process of writing dirty pages from the page cache to storage. The current FUSE implementation allocates unmovable memory, then copies the dirty data to it before initiating writeback, which is slow; Koong wanted to change that behavior. Since the session, she has posted a patch set that has been applied by FUSE maintainer Miklos Szeredi.

Security updates for Tuesday

LWN
Security updates have been issued by Fedora (chromium and kappanhang), Red Hat (osbuild-composer and thunderbird), SUSE (chromedriver), and Ubuntu (c-ares, corosync, mysql-8.0, mysql-8.4, openjdk-17, openjdk-21, openjdk-24, openjdk-8, and openjdk-lts).